The ACTH stimulation test is performed to examine the response of the adrenal gland to an exogenously administered dose of ACTH. Normal patients have a doubling of the serum Cortisol level after a dose of ACTH. The serum Cortisol level should rise to >20 mg/dL if there is adequate adrenal function. An inadequate response suggests adrenal gland hypofunction. Note: Cosyntropin (Cortrosyn) is an ACTH analogue that stimulates the adrenal gland and its ACTH receptors.
About 20 mg of hydrocortisone is secreted by the adrenal cortex daily. During stress, the cortex can increase the output to 200 mg daily.
Remember: Patients taking steroids or people with disease of the adrenals will have decreased ability to produce more glucocorticoids (hydrocortisone) in times of stress (extractions). The reason for this is as follows:
Secretion of glucocorticoids is stimulated by ACTH, a hormone produced in the anterior pituitary. The pituitary responds to stress by increasing ACTH output and, therefore, glucocorticoid production increases. Arelative lack of glucocorticoids will also increase output of ACTH. An overabundance of circulating systemic steroids will inhibit production of ACTH. Large doses of steroids repress ACTH production, which leads to atrophy of adrenal cortex.
• take as long as a year to regain full adrenal cortical function • may show signs of hyperpigmentation
The following guidelines may help determine if a patient's adrenal function is suppressed, however, if any doubt exists, consult the patient's physician before performing surgery.
Some Guidelines: • People on small doses (5 mg prednisone/day) will have suppression when they have been on the regimen for a month. • People taking the equivalence of 100 mg cortisol/day (20-30 mg prednisone/day) will have abnormal cortical function in a week. • Short-term therapy (1-3 days) of even high-dose steroids will not alter adrenal cortical function. • A person who has been on suppressive doses of steroids will take as long as a year to regain full adrenal cortical function.
Patients with adrenal insufficiency are hyperpigmented. This is most noticeable on the buccal and labial mucosa, although other areas such as the gingiva may be involved. The hyperpigmentation is a result of hypersecretion of ACTH, which can stimulate melanocytes to produce pigment.
Patients with decreased adrenal gland hormone production experience weakness, weight loss, orthostatic hypotension, nausea, and vomiting. Patients with severe adrenal insufficiency cannot increase steroid production in response to stress and in extreme situations may have cardiovascular collapse. It is important that an adrenally insufficient patient have adequate steroid replacement, since the stress of oral surgery can precipitate adrenal crisis.
In adrenal crisis, an intravenous or intramuscular injection of hydrocortisone must be given immediately. Supportive treatment of low blood pressure with intravenous fluids is usually necessary. Hospitalization is required for adequate treatment and monitoring.
adren cort
Patients with glucocorticoid hypersecretion have:
• ectopic ACTH Syndrome
• MEN I
• cushing syndrome
• addison disease
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adren cort
A 52-year-old woman requests removal of a painful mandibular second molar. She tells you that she has not rested for 2 days and nights because of the pain. Her medical history is unremarkable, except that she takes 20 mg of prednisone daily for erythema multiforme. How do you treat this patient?
• have patient discontinue the prednisone for 2 days prior to the extraction
•give steroid supplementation and remove the tooth with local anesthesia and sedation
• instruct the patient to take 3 grams of amoxicillin 1 hour prior to extraction
• no special treatment is necessary prior to extraction
Cushing syndrome is a hormonal disorder caused by prolonged exposure of the body's tissues to high levels of the hormone Cortisol. This results in characteristic changes in body hiatus, including moon facies, truncal obesity, muscular wasting, and hirsutism. Sometimes called "hypercortisolism," it is relatively rare and most commonly affects adults aged 20 to 50. The female-to-male incidence ratio is approximately 5:1.
Patients with Cushing syndrome are often hypertensive because of fluid retention. Long-term glucocorticoid excess can result in decreased collagen production, a tendency to bruise easily, poor wound healing, and osteoporosis. They are often at increased risk for infection.
Laboratory studies may reveal increased blood glucose levels because of interference with
carbohydrate metabolism, and examination of the peripheral blood smear may demon
strate slight decrease in eosinophil and lymphocyte counts.
Important: The patient's cardiovascular status must be evaluated and treated if necessary prior to surgery.
Note: The most common cause of Cushing syndrome is a tumor in the pituitary gland.
• give steroid supplementation and remove the tooth with local anesthesia and sedation
Important: The fear here is that the patient may not have sufficient adrenal cortex secretion (adrenal insufficiency) to withstand the stress of an extraction without taking additional steroids. (This holds true for any patient who has been treated with steroid therapy).
Patients with adrenal insufficiency, patients on daily steroid therapy, and patients who have recently finished a course of steroids should receive steroid supplementation for dental procedures.
The concerns about adrenal insufficiency should be raised on the basis of clinical history. In the majority of cases, the dentist should ask:
• Is it known that the patient's adrenal glands do not function adequately? • Is the patient on chronic steroid therapy at doses of prednisone higher than 15 mg/day? • Has the patient been on steroid therapy at doses of prednisone higher than 15 mg/day within the last 2 weeks? *** If the answer to any of the above questions is yes, the dentist should assume that the patient will need stress-dose steroids.
General guidelines for the management of patients on steroid therapy: • Steroid supplementation in patients who can develop adrenal insufficiency • Early morning appointments • Shorter appointments • Minimize stress • Use sedation techniques when appropriate • Modify dental treatment plan when appropriate • The major goal in these patients is to avoid precipitating of adrenal insufficiency
Remember: Erythema multiforme is a hypersensitivity syndrome characterized by polymorphous eruption of skin and mucous membranes. Macules, papules, nodules, vesicles, or bullae and target or ("bull's-eye-shaped") lesions are seen. A severe form of this condition is known as Stevens-Johnson syndrome. These patients may be receiving moderate doses of systemic corticosteroids and therefore may be unable to withstand the stress of an extraction. Consultation with their physician is absolutely necessary before treating these patients.
anat Which of the following foramen/location pairings are correct? Select all that apply.
• greater palatine foramen/distal to the apex of maxillary 1 st molar
• incisive foramen/posterior to the interproximal space of the central incisors
• lesser palatine foramen/lateral to the greater palatine foramen
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anat
The facial nerve carries which of the following? Select all that apply.
• incisive foramen/posterior to the interproximal space of the central incisors
The greater palatine foramen is generally located halfway between the gingival margin and midline of the palate, approximately 5 mm anterior to the junction of the hard and soft palate (vibrating line) distal to the apex of the maxillary second molar. The hard palate is perforated by the following foramina:
• The incisive foramen, posterior to the maxillary incisors, transmits the nasopalatine nerves and the terminal branches of the sphenopalatine artery • The greater palatine foramen, is most frequently located distal to the maxillary second molar, transmits the greater palatine vessels and nerve • The lesser palatine foramen, just posterior to the greater palatine foramen, transmits the lesser palatine vessels and nerve
Nerves of the palate:
• Sensory Innervation to the palate: is supplied by the maxillary (CN V-2) nerve. The anterior part of the hard palate is supplied by the nasopalatine nerve, which passes through the incisive foramen. The posterior part of the hard palate is supplied by the greater palatine nerve which passes through the greater palatine foramen. The soft palate is supplied by the lesser palatine nerve which passes through the lesser palatine foramen. • Motor Innervation: the tensor veli palatini is innervated by a muscular branch from the mandibular division of the trigeminal nerve (CN V). All other muscles are innervated by the pharyngeal plexus (motor portion from the vagus nerve and cranial part of the accessory nerve),
The greater palatine block or GP block is useful for dental procedures involving palatal soft tissues distal to the maxillary canine. This maxillary block anesthetizes the posterior portion of the hard palate, anteriorly as far as the maxillary first premolar and medially to the midline. Target area: the greater (anterior) palatine nerve as it passes anteriorly between the soft tissues and bone of the hard palate.
The nasopalatine nerve block anesthetizes the anterior portion of the hard palate (soft and hard tissues) from the mesial aspect of the right first premolar to the mesial aspect of the left first premolar. Target area: incisive foramen, beneath the incisive papilla.
The facial nerve leaves the cranial cavity by passing through the internal acoustic meatus, which leads to the facial canal inside the temporal bone. Finally, the nerve exits the skull by way of the stylomastoid foramen of the temporal bone. Note: If you cut the facial nerve just after its exit from the stylomastoid foramen, it would cause a loss of innervation to the muscles of facial expression.
The facial nerve carries an efferent component for the muscles of facial expression and for the preganglionic parasympathetic innervation of the lacrimal gland (relaying in the pterygopalatine ganglion) and submandibular and sublingual glands (relaying in the submandibular ganglion).
The afferent component serves a tiny patch of skin behind the ear, taste sensation, and the body of the tongue.
Clinical information: 1. Bell palsy: involves unilateral facial paralysis with no known cause, except that there is a loss of excitability of the involved facial nerve. The onset of this paralysis is abrupt, and most symptoms reach their peak in 2 days. One theory of its cause is that the facial nerve becomes inflamed within the temporal bone, possibly with a viral etiology. 2. Trigeminal neuralgia (tic douloureux): also has no known cause but involves the afferent nerves of the trigeminal nerve. It usually involves the maxillary or mandibular nerve branches but not the ophthalmic branch. One theory is that this lesion is caused by pressure on the sensory root of the trigeminal ganglion by area blood vessels. Clinically, the patient feels excruciating short-term pain (tic) when facial trigger zones are touched or when speaking or masticating, setting off associated brief muscle spasms in the area. The right side of the face is affected more commonly than the left. It is more common in females. Carba-mazepine (Tegretol) is still the mainstay of treatment.
anat Which component of the TMJ has the most vasculature and innervation?
The articular disc (meniscus) is composed of dense fibrous connective tissue, and it is
p o ^ d m between the condyle and the fossa, thereby dividing the joint into superior and
inferior joint spaces.
band o f , h e J £ Z d i - is contjuou, with ,he capsular ligament, me condyle, and the supenor
belly of the lateral pterygoid muscle.
Note- The retrodiscal tissue is highly vascularized and innervated, whereas the articular disc for the most part is not. Only the extreme periphery of the articular disc is slightly innervated.
• hiatus semilunaris Unfortunately, this opening lies high up on the medial wall of the sinus, so that the sinus readily accumulates fluid. Since the frontal and anterior ethmoidal sinuses drain into the infundibulum, which in turn drains into the hiatus semilunaris, the chance that infection may spread from these sinuses into the maxillary sinus is great. 2 types of sinusitis: acute and chronic: common clinical manifestations include sinus congestion, discharge, pressure, face pain, and headaches.
Acute Sinusitis: the most common form of sinusitis, typically caused by a cold that results in inflammation of the sinus membranes, normally resolves in 1 to 2 weeks. Sometimes a secondary bacterial infection may settle in the passageways after a cold; bacterial populations normally located in the area (Streptococcus pneumoniae and Haemophilus influenzae) may begin to increase, producing an acute bacterial sinusitis. Clinical signs of acute sinusitis include:
• Severe pain, constant and localized • Tenderness to percussion of the maxillary posterior teeth • A mucopurulent exudate • Any unusual motion or jarring accentuates the pain • Tenderness over the anterior sinus wall
Chronic sinusitis: an infection of the sinuses that is present for longer than 1 month and requires longer duration medical therapy. Typically either chronic bacterial sinusitis or chronic noninfectious sinusitis. Chronic bacterial sinusitis is treated with antibiotics (ampicillin or augmentin). Chronic noninfectious sinusitis often is treated with steroids (topical or oral) and nasal washes. Locations of sinusitis:
• Maxillary: the most common location for sinusitis; associated with all of the common signs and symptoms but also results in tooth pain, usually in the molar region • Sphenoid: rare, but in this location can result in problems with the pituitary gland, cavernous sinus syndrome, and meningitis • Frontal: usually associated with pain over the forehead and possibly fever • Ethmoid: potential complications include meningitis and orbital cellulitis.
Note: The maxillary sinus is innervated by the maxillary division of the trigeminal nerve (CN V-2). Specifically, the ASA, PSA, and MSA nerves as well as the infraorbital nerve.
anat The arises from the anterior surface of the external carotid artery and then passes near the greater cornu of the hyoid bone.
anat A dentist is performing a routine restoration on the left mandibular first molar. He is giving an inferior alveolar nerve block injection, where he deposits anesthetic solution right next to the lingula and mandibular foramen. Which ligament is most likely to get damaged?
The pterygopalatine ganglion is responsible for innervation of the lacrimal gland and other glands of the nasal cavity. The other parasympathetic ganglia include the ciliary, submandibular, and otic.
The nerve fibers pass to the otic ganglion via the tympanic branch of the glossopharyngeal nerve and the lesser petrosal nerve. Postganglionic parasympathetic fibers reach the parotid gland via the auriculotemporal nerve, which lies in contact with the deep surface of the gland. Note: Postganglionic sympathetic fibers reach the gland as a plexus of nerves around the external carotid artery.
The parotid gland is the largest of the major salivary glands and is entirely serous in secretion. The parotids are located below and just anterior to the ear. The gland's capsule is from the deep cervical fascia. About 75% or more of the parotid gland overlies the mas-seter muscle, the rest is retromandibular.
The parotid gland is drained by Stenson duct, which forms within the deep lobe and passes from the anterior border of the gland across the masseter muscle superficially, through the buccinator muscle into the oral cavity opposite the maxillary second molar. The external carotid artery and its terminal branches within the gland, namely, the superficial temporal and the maxillary arteries, supply the parotid gland. The lymph vessels drain into the parotid lymph nodes and deep cervical lymph nodes.
1. Mumps is a viral disease of the parotid gland. Parotitis is the inflammation Notes of the parotid gland.
2. Ebner glands are the only other adult salivary glands that are purely serous. 3. Although it passes through the parotid gland, the facial nerve does not provide any innervation to it.
• sphenomandibular ligament
The sphenomandibular and stylomandibular ligaments are considered to be accessory liga-Len s Therrmer is attached to the lingula of the mandible and the latter at the angle of the mand bl These ligaments are responsible for limitation of mandibular movements (they lunrt excessive opentng). Note: The sphenomandibular ligament is most often damaged m an inferior alveolar nerve block. ThP tPmnnromandibular ligament (also called the lateral ligament) runs from the articular em-men S S S S S condyle. It rovides lateral reinforcement for the capsul. This ligament e v e n t s posterior and inferior displacement of the condyle (it is the mam stabihzmg ligament ^ S Nate: This ligament keeps the head of the condyle in the mandibular fossa if the condyle is fractured. Collateral ligaments (medial and lateral) also referred to as "discal ligaments," are ligaments that arise from the periphery of the disc, are attached to the medial and lateral poles of the condyle re-
ecttve y Z E l S the disc on the top of the condyle. These ligaments restrict movement f the d7sc away from the condyle during function. Note: They are composed of collagenous con-nective tissue; thus they do not stretch. ^
Joint capsule
Sphenomandibular ligament
Spine of sphenoid bone
/ N v Styloid process of temporal bone
Stylomandibular ligament
Angle of mandibular
anat
Which of the following injuries would cause a patient to deviate toward the side of injury when protruding? Select all that apply.
• damage to the lateral pterygoid muscle • ankylosis of the condyle • unilateral condylar fracture
The mandible will also deviate toward the side of injury with: • Ankylosis of the condyle: the most common cause of TMJ ankylosis is trauma • A unilateral condylar fracture
The mandible will deviate away from the affected side with: • Condylar hyperplasia: malocclusion is also a common occurrence with this injury
Remember: The lateral pterygoids (right and left) acting together are the prime protractors of the mandible. Important: In addition to opening and protruding, the lateral pterygoids move the mandible from side to side. For right lateral excursive movements, the left lateral pterygoid muscle is the prime mover and vice versa.
A patient who sustained a subcondylar fracture (unilateral condylar fracture) on the left side would be unable to deviate the mandible to the right (as stated above, the mandible will deviate toward the side of injury with a unilateral condylar fracture, this patient would not be able to deviate the mandible to the right). This is normally treated by a closed procedure involving intermaxillary fixation. This procedure immobilizes the concomitant fractures and corrects the displacement of the jaws associated with the condylar fracture, thereby correcting the shift of the midline toward the side of the fractured condyle and the slight premature posterior occlusion on that side.
• submandibular lymph nodes
The deep cervical lymph nodes are located along the length of the internal jugular vein on each side of the neck, deep to the sternocleidomastoid muscle. The deep cervical nodes extend from the base of the skull to the root of the neck, adjacent to the pharynx, esophagus, and trachea. The deep cervical nodes are further classified as to their relationship to the sternocleidomastoid muscle as being superior or inferior.
The deep cervical lymph nodes are responsible for the drainage of most of the circular chain of nodes, and they receive direct efferents from the salivary and thyroid glands, the tongue, the tonsil, the nose, the pharynx, and the larynx. All these vessels join together to form the jugular lymph trunk. This vessel drains into either the thoracic duct on the left, the right lymphatic duct on the right, or it independently drains into either the internal jugular, subclavian, or brachiocephalic veins.
Some regional groups of lymph nodes: • Parotid lymph nodes - receive lymph from a strip of scalp above the parotid salivary gland, from the anterior wall of the external auditory meatus, and from the lateral parts of the eyelids and middle ear. The efferent lymph vessels drain into the deep cervical nodes. • Submandibular lymph nodes - located between the submandibular gland and the mandible; receive lymph from the front of the scalp, the nose, and adjacent cheek; the upper lip and lower lip (except the center part); the paranasal sinuses; the maxillary and mandibular teeth (except the mandibular incisors); the anterior two-thirds of the tongue (except the tip); the floor of the mouth and vestibule; and the gingiva. The efferent lymph vessels drain into the deep cervical nodes. • Submental lymph nodes - located behind the chin and on the mylohyoid muscle; receive lymph from the tip of the tongue, the floor of the mouth beneath the tip of the tongue, the mandibular incisor teeth and associated gingiva, the center part of the lower lip, and the skin over the chin. The efferent lymph vessels drain into the submandibular and deep cervical nodes.
anat
Which artery descends on the posterior surface of the maxilla and supplies the maxillary sinus and the maxillary molar and premolar teeth?
The external carotid artery supplies most of the head and neck, except for the brain (the brain gets its blood supply from the internal carotid and the vertebral arteries). The external carotid passes through the parotid salivary gland and terminates as the maxillary and superficial temporal arteries. The superficial temporal artery supplies the scalp. The maxillary artery leaves the infratemporal fossa by passing through the pterygomaxillary fissure into the pterygopalatine fossa. Here it splits up into branches that accompany the branches of the maxillary nerve. It supplies the muscles of mastication, the maxillary and mandibular teeth, the palate, and almost all of the nasal cavity.
The mandibular teeth receive blood from the inferior alveolar artery, which is a branch of the maxillary artery. The maxillary teeth also receive blood from branches of the maxillary artery as follows:
• Posterior teeth: from the posterior superior alveolar artery. • Anterior teeth: from the anterior and middle superior alveolar arteries.
Remember: The venous return of both dental arches is the pterygoid plexus of veins.
Branches of the maxillary artery that accompany the branches of the maxillary nerve: 1. The posterior superior alveolar artery descends on the posterior surface of the maxilla and supplies the maxillary sinus and the maxillary molar and premolar teeth. 2. The infraorbital artery enters the orbital cavity through the inferior orbital fissure. It ends by emerging on the face with the infraorbital nerve. 3. The greater palatine artery descends through the greater palatine canal with the greater palatine nerve. It is distributed to the mucous membrane covering the oral surface of the hard palate. 4. The pharyngeal branch passes backward to supply the mucous membrane of the roof of the nasopharynx. 5. The sphenopalatine artery passes through the sphenopalatine foramen into the nasal cavity. It supplies the mucous membrane of the nasal cavity.
• sublingual caruncle
The submandibular glands (formerly called the submaxillary glands) are located in the submandibular triangle of the neck and the floor of the oral cavity. The submandibular duct (Wharton duct) is a long duct that travels along the anterior floor of the mouth. The duct opens into the oral cavity at the sublingual caruncle, a small papilla near the midline of the mouth floor on each side of the lingual frenum. Clinically, the gland is effectively palpated inferior and posterior to the body of the mandible, moving inward from the inferior border of the mandible near its angle as the patient lowers the head. Note: The submandibular gland is a mixed gland, secreting both serous and mucous saliva, but predominantly secreting serous mucous.
The submandibular glands are innervated by efferent (parasympathetic) secretomotor fibers from the facial nerve, which run in the chorda tympani and in the lingual nerve (branch ofCN V3) and synapse in the submandibular ganglion. Note: This is the same as the sublingual glands. The blood supply comes from branches of the facial and lingual arteries. The veins drain into the facial and lingual veins. The lymph vessels drain into the submandibular and deep cervical lymph nodes.
Important: During its course, Wharton's duct is closely related to the large lingual nerve that eventually crosses over it. This is important because, if you incise the mucous membranes of the floor of the mouth, depending on where you cut, you may expose the lingual nerve, Wharton duct, and the sublingual gland.
1. To expose the duct intraorally, only mucous membrane needs to be cut Notes through.
2. Lymphadenopathy is the most common cause of swelling of the tissues in the submandibular triangle.
When a maxillary third molar is displaced into the infratemporal fossa, it is usually displaced through the periosteum and located to the lateral pterygoid plate and to the lateral pterygoid muscle with displacement.
• medial, inferior
• medial, superior
• lateral, inferior
• lateral, superior
• ginglymoarthrodial joint Because the TMJhas characteristics of both a hinge joint and a gliding joint, it is classified as a ginglymoarthrodial joint. A unique feature of the TMJ is that it is rigidly connected to both the dentition and the contralateral TMJ. Components of the TMJ:
• Mandibular condyle (sometimes called the condyloid process of the mandible) - the articulating surface or functioning part of the condyle is located on the superior and anterior surfaces of the head of the condyle. This surface is covered with a dense layer of fibrous connective tissue. • Articular fossa - this fossa is the anterior three-fourths of the larger mandibular fossa. It is considered to be a nonfunctioning portion of the joint. Remember: The mandibular fossa (glenoid fossa) is the temporal component of the TMJ; it is bounded in front by the articular eminence, and behind, by the tympanic part of the temporal bone, which separates it from the external auditory meatus. • Articular eminence (also called the articular tubercle) - is a ridge that extends mediolaterally just in front of the mandibular fossa. It is considered to be the functional portion of the joint. It is lined with a thick dense layer of fibrous connective tissue. • Articular disc (also called the meniscus) - is a biconcave fibrocartilaginous disc interposed between the condyle of the mandible and the mandibular (glenoid) fossa of the temporal bone which provides the gliding surface for the mandibular condyle, resulting in smooth joint movement. The central part is avascular and devoid of nerve tissue. Only the extreme periphery is slightly innervated.
Postglcnoid process
Blood vessels
Condyle v Lateral pterygoid muscle
Upper synovial cavity
Articular eminence
Joint disc
Lower synovial cavity
• lateral, inferior
The infratemporal fossa is an irregular space behind the maxilla. Its roof is formed by the greater wing of the sphenoid. The lateral pterygoid plate of the sphenoid is medial. Laterally, it is limited by the coronoid process and ramus of the mandible. The infratemporal fossa communicates with the pterygopalatine fossa through the pterygomaxillary fissure, which is a cleft between the lateral pterygoid plate and the maxilla. It communicates with the orbit through the inferior orbital fissure, which is found between the maxilla and the greater wing of the sphenoid.
The pterygopalatine fossa is a small space behind and below the orbital cavity. It lies between the pterygoid plates of the sphenoid and palatine bone below the apex of the orbit.
Clinical: If there is good access and adequate light, a single cautious effort to retrieve the tooth with a hemostat can be made. If the effort is unsuccessful, or if the tooth is not visualized, the incision should be closed, the patient should be informed, and prophylactic antibiotics should be prescribed. A secondary surgical procedure is performed 4-6 weeks later after lateral and posteroanterior radiographs are taken to locate the tooth in all three planes. After adequate anesthesia, a long needle is used to locate the tooth. Careful dissection is performed along the needle until the tooth is visualized and subsequently removed. Note: If no functional problems exist after displacement, the patient may elect not to have the tooth removed. Proper documentation of this is critical.
anat The carotid sheath contains which of the following? Select all that apply.
Which nerve may, in some cases, also serve as an afferent nerve for the mandibular first molar, which needs to be considered when there is failure of the inferior alveolar local anesthetic block?
*** The carotid sheath does not contain the sympathetic trunk, which lies posterior to the carotid sheath and anterior to the prevertebral fascia.
The carotid sheath is located at the lateral boundary of the retropharyngeal space at the level of the oropharynx on each side of the neck deep to the sternocleidomastoid muscle. It extends from the base of the skull to the first rib and sternum. It contains the carotid arteries, the jugular vein, and the vagus nerve. Within the carotid sheath, the vagus nerve (CNX) lies posterior to the common carotid artery and internal jugular vein.
The facial vein unites with the retromandibular vein below the border of the mandible and empties into the main venous structure of the neck - the internal jugular vein. The internal jugular vein descends through the neck within the carotid sheath and unites behind the sternoclavicular joint with the subclavian vein to form the brachiocephalic vein. The brachiocephalic veins (right and left) unite in the superior mediastinum to form the superior vena cava, which returns blood to the right atrium of the heart.
• mylohyoid nerve
Just before entering the mandibular canal, the inferior alveolar nerve gives off a motor branch known as the mylohyoid nerve. The inferior alveolar nerve travels along with the inferior alveolar artery and vein within the mandibular canal and divides into the mental and incisive nerve branches at the mental foramen. The inferior alveolar nerve provides sensation to the mandibular posterior teeth. The mylohyoid nerve pierces the sphenomandibular ligament and runs inferiorly and anteriorly in the mylohyoid groove and then onto the inferior surface of the mylohyoid muscle. The mylohyoid nerve serves as an efferent nerve to the mylohyoid muscle and the anterior belly of the digastric muscle. This nerve may, in some cases, also serve as an afferent nerve for the mandibular first molar.
The mylohyoid muscle is an anterior suprahyoid muscle that is deep to the digastric muscle. In addition to either elevating the hyoid bone or depressing the mandible, the muscle also forms the floor of the mouth and helps elevate the tongue. Note: The sublingual gland is located superior to the mylohyoid muscle.
1. When placing the film for a periapical view of the mandibular molars, it is Notes the mylohyoid muscle that gets in the way if it is not relaxed.
2. When the floor of the mouth is lowered surgically, the mylohyoid and ge-nioglossus muscles are detached. 3. An injection into the parotid gland (capsule) when attempting to administer an inferior nerve block may cause a facial expression — paralysis of the forehead muscles, the eyelid, and the upper and lower lips on the same side of the face that the injection was given. Important: If the parotid capsule injection happens, care must be taken to protect the eye from injury and drying using lubrication and an eye patch. 4. Remember: The bone of the maxilla is more porous than that of the mandible. Therefore, it can be infiltrated anywhere.
anat Which of the following provides branches for the most direct blood supply to the temporomandibular joint?
The major arterial blood supply to the TMJ is derived from the superficial temporal artery and from the maxillary artery posteriorly, and from smaller masseteric, posterior deep temporal, and lateral pterygoid arteries anteriorly. The venous drainage is through a diffuse plexus around the capsule and rich venous channels that drain the retrodiscal tissue. Note: The two terminal branches of the external carotid artery are the superficial temporal artery and the maxillary artery.
The fibrous capsule of the TMJ is innervated from a large branch of the auriculotemporal nerve (branch ofCN V3). The anterior region of the joint is innervated from the masseteric nerve (also a branch ofCN V3) and from the posterior deep temporal nerve (also a branch ofCN V3). The sensory innervation of the TMJ is via the trigeminal nerve as well. The nerve fibers primarily follow the vascular supply and terminate as free nerve endings. Thus, the capsule, synovial tissue, and extreme periphery of the disc are innervated. The articular cartilage and the central part of the disc contain no nerves. Both myelinated and nonmyelinated nerves are seen in the TMJ. The retrodiscal bilaminar zone has a rich neurovascular supply and is the source of proprioception.
Remember: Most synovial joints have hyaline cartilage on their articular surface; however, several joints, such as the sternoclavicular, acromioclavicular, and TMJs, are associated with bones that develop from intramembranous ossification. These have fibrocartilage articular surfaces.
• trapezius m. / accessory n. • stylopharyngeus m. / glossopharyngeal n. • sternocleidomastoid m. / accessory n. • cricothyroid m. / superior laryngeal n.
To the organ of Corti for hearing To the semicircular canals for balance
Supplies the stylopharyngeus muscle
Parasympathetic innervation of the smooth muscle and glands of the pharynx, larynx, and viscera of the thorax and abdomen
Carries visceral sensory information from the carotid sinus and body
Provides general sensation information from the skin of the external ear, internal surface of the tympanic membrane, upper pharynx, and posterior one-third of the tongue
Provides taste sensation from posterior one-third of the tongue
Innervates the trapezius and sternocleidomastoid muscles
Innervates all of the intrinsic and most of the extrinsic muscles of the tongue (genioglossus, styloglossus, and hyoglossus muscles)
anat After a stroke on the right side of the brain that affects the right upper motor neurons, the tongue deviates to the:
• left on protrusion
• right on protrusion
• neither of the above, the tongue would not be affected
• left on protrusion — and the left half of the tongue will atrophy
Lesions of the hypoglossal nerve: • Hypoglossal nerve lesions paralyze the tongue on one side • On protrusion, the tongue deviates to the ipsilateral (same) or contralateral side, depending on the lesion site.
Lower motor neuron lesion:
Lesions to the hypoglossal nerve causes paralysis on the ipsilateral (same) side: • Tongue deviates to the paralyzed side on protrusion (the paralyzed muscles will lag, causing the tip to deviate). • Musculature atrophies on the paralyzed side • Tongue fasciculations occur on the paralyzed side Example: With a neck wound that cuts the right hypoglossal nerve, the tongue deviates to the right on protrusion, and the right half of the tongue will later demonstrate atrophy and fasciculations
Upper motor neuron lesion:
Causes paralysis on the contralateral side:
• Tongue deviates to the side opposite the lesion • Musculature atrophies on side opposite the lesion Example: After a stroke on the right side of the brain that affects the right upper motor neurons, the tongue deviates to the left on protrusion, and the left half of the tongue will atrophy
Important: If the genioglossus muscle is paralyzed, the tongue has a tendency to fall back and obstruct the oropharyngeal airway with risk of suffocation.
• mylohyoid muscle
The sublingual glands are located in the floor of the mouth beneath the tongue, close to the midline. It lies between the sublingual fossa of the mandible and the genioglossus muscle of the tongue. The mylohyoid muscle supports the individual sublingual glands in-feriorly. Unlike the submandibular gland, which drains via one large duct, the sublingual gland drains via approximately 12-20 small secretory ducts (ducts ofRivinus ducts), the majority open into the mouth on the summit of the sublingual fold, but a few open into the submandibular duct.
The sublingual gland is innervated by parasympathetic secretomotor fibers from the facial nerve, which run in the chorda tympani and in the lingual nerve (branch ofCN V3) and synapse in the submandibular ganglion. The blood supply comes from branches of the facial and lingual arteries. The veins drain into the facial and lingual veins. The lymph vessels drain into the submandibular and deep cervical lymph nodes.
Important: • The lymph vessels from both the sublingual and submandibular glands drain into the submandibular and the deep cervical lymph nodes • Bartholin duct, a common duct that drains the anterior part of the sublingual gland in the region of the sublingual papilla, may be present • The submandibular duct lies on the sublingual gland • The sublingual gland is a mixed salivary gland, secreting both mucous and serous saliva, but it predominantly secretes mucous
Note: Ebner glands are located around the circumvallate papilla of the tongue. Their main function is to rinse the food away from the papilla after it has been tasted by the taste buds. They are purely serous.
anat The trigeminal ganglion located is located:
• superior to the deep lobe of the submandibular salivary gland
• posterior surface of the maxillary tuberosity of the maxilla
• anterior to the infraorbital foramen of the maxilla
• the apex of the petrous part of the temporal bone in the middle cranial fossa
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anat
The tongue receives its blood supply from which of the following? Select all that apply.
• the apex of the petrous part of the temporal bone in the middle cranial fossa The trigeminal nerve emerges from the anterior surface of the pons by a large sensory and a small motor root, the motor root lying medial to the sensory root. The nerve passes forward out of the posterior cranial fossa, below the superior petrosal sinus, and carries with it a pouch derived from the meningeal layer of dura mater. On reaching the depression on the apex of the petrous part of the temporal bone in the middle cranial fossa, the large sensory root expands to form the trigeminal ganglion. The motor root of the trigeminal nerve is situated below the sensory ganglion and is completely separate from it. The ophthalmic, maxillary, and mandibular nerves arise from the anterior border of the ganglion.
Somatic sensory cell bodies of the ganglion's sensory fibers enter the: • Ophthalmic division (CN VI) to supply general sensation to the orbit and skin of face above eyes • Maxillary division (CN V2) to supply general sensation to the nasal cavity, maxillary teeth, palate, and skin over maxilla • Mandibular division (CN V3) to supply general sensation to the mandible, TMJ, mandibular teeth, floor of mouth, tongue, and skin of mandible
The axons of the neurons enter the pons through the sensory root and terminate in one of the three nuclei of the trigeminal sensory nuclear complex:
Projects to motor nucleus of V to control the jaw jerk reflex and force of bite
Note: Proprioceptive fibers from muscles and the TMJ are found only in the mandibular division. The cell bodies of proprioceptive first order neurons are found in the mesencephalic nucleus, not the trigeminal ganglion. The TMJ, as is the case with all joints, receives no motor innervation. The muscles that move the joint receive the motor innervation.
Branchiomeric motor fibers innervate the temporalis, masseter, medial and lateral pterygoid, anterior belly of the digastric, mylohyoid, tensor tympani, and tensor veli palatini (palati).
• tonsillar branch of the facial artery • lingual artery • ascending pharyngeal artery
The lingual artery arises from the anterior surface of the external carotid artery, and travels obliquely toward the greater cornu of the hyoid bone. It loops upward and then passes deep to the posterior border of the hyoglossus muscle to enter the submandibular region. The loop of the artery is crossed superficially by the hypoglossal nerve. Branches include dorsal lingual artery, suprahyoid artery, and sublingual artery (which supplies sublingual gland). It terminates as the deep lingual artery, which ascends between the genioglossus and inferior longitudinal muscles. Note: The floor of the mouth also receives its blood supply from the lingual artery.
Things to remember about the tongue: • Motor innervation: from the hypoglossal nerve (CNXII). • Sensory innervation: lingual (branch of trigeminal CN V3) supplies the anterior two-thirds, glossopharyngeal (CNIX) supplies the posterior one-third (including vallate papil
lae), vagus (CN X) through the internal laryngeal nerve supplies the area near the epiglottis. Note: Besides the posterior third of the tongue, the glossopharyngeal nerve also supplies sensory innervation to the tonsil, nasopharynx and pharyngeal areas. • Taste: facial (CN VII) via chorda tympani supplies the anterior two-thirds; glossopharyngeal (CNIX) supplies the posterior one-third.
Note: The vertebral arteries arise from the subclavian arteries and join to form the basilar ar
tery. The basilar artery is the main blood supply to the brain stem and connects to the circle of
Willis.
anat
Which of the following nerves exits the skull through the foramen ovale?
anat Which of the following muscle/nerve pairings are correct? Select all that apply.
• lateral rectus m. / abducens n.
• superior oblique m. / trochlear n.
• medial rectus m. / abducens n.
• inferior rectus m. / occulomotor n.
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• mandibular nerve
The ophthalmic nerve (CN VI) enters the middle cranial fossa through the superior orbital fissure and courses within the lateral wall of the cavernous sinus on its way to the trigeminal ganglion. The maxillary nerve (CN V2) enters the middle cranial fossa through foramen rotundum and may or may not pass through the cavernous sinus en route to the trigeminal ganglion. The mandibular nerve (CN V3) enters the middle cranial fossa through foramen ovale, coursing directly into the trigeminal ganglion. The trigeminal ganglion (a.k.a. semilunar ganglion ) lies in a depression known as the trigeminal cave (or Meckel cave). The trigeminal nerve exits the trigeminal ganglion and courses "backward" to enter the mid-lateral aspect of the pons.
The mandibular division is the largest of the 3 divisions of the trigeminal nerve. It has motor and sensory functions. It is created by a large sensory and a small motor root that unites just after passing through the foramen ovale to enter the infratemporal fossa. It immediately gives rise to a meningeal branch and then divides into anterior and posterior divisions.
Anterior Division: Smaller, mainly motor, with 1 sensory branch (buccal): • Masseteric: innervates the masseter muscle and provides a small branch to the TMJ • Anterior and posterior deep temporal: innervates the temporalis muscle • Medial pterygoid: innervates the medial pterygoid muscle • Lateral pterygoid: innervates the lateral pterygoid muscle • Buccal: supplies the skin over the buccinator muscle before passing through it to supply the mucous membrane lining its inner surface and the gingiva along the mandibular molars
Posterior Division: Larger, mainly sensory, with 1 motor branch (nerve to mylohyoid):
• Auriculotemporal: supplies the TMJ, auricle, and external auditory meatus • Lingual: supplies the mucous membrane of the anterior 2/3 of the tongue and gingiva on the lingual side of the mandibular teeth • Inferior alveolar: largest branch of the mandibular division; innervates all mandibular teeth and the gingiva from the premolars anteriorly to the midline via the mental branch • Mylohyoid: supplies the mylohyoid and the anterior belly of the digastric muscle
Remember: The trigeminal nerve contains no parasympathetic component at its origin.
• lateral rectus m. / abducens n. • superior oblique m. / trochlear n. • inferior rectus m. / oculomotor n.
Nerve
Olfactory (CNI)
Optic (CNII)
Oculomotor (CNIII)
Trochlear (CNIV)
Abducens (CN VI)
Facial (CN VII)
Site of Exit from Skull
Cribriform plate of ethmoid bone
Optic foramen
Superior orbital fissure
Superior orbital fissure
Superior orbital fissure
Stylomastoid foramen
Component
Special sensory (special afferent)
Special sensory (special afferent)
Somatic motor (general somatic efferent)
Visceral motor (general visceral efferent)
Somatic motor (general somatic efferent)
Somatic motor (general somatic efferent)
Branchial motor (special visceral efferent)
Visceral motor (general visceral efferent)
General sensory (general somatic afferent)
Special sensory (special afferent)
Function
Sense of smell
Conveys visual information from the retina
Supplies four of the six extraocular muscles of the eye and the levator palpebrae superioris muscle of the upper eyelid
Parasympathetic innervation of the constrictor pupillae and ciliary muscles
Innervates the superior oblique muscle
Innervates the lateral rectus muscle
Supplies the muscles of facial expression; posterior belly of digastric muscle; stylohyoid, and stapedius muscles
Parasympathetic innervation of the lacrimal, submandibular, and sublingual glands, as well as mucous membranes of the nasopharynx and the hard and soft palate
General sensation from the skin of the concha of the auricle and from a small area behind the ear
Provides taste sensation from the anterior two-thirds of the tongue; hard and soft palates
Important: Cranial nerves HI (oculomotor), (vagus) all have parasympathetic activity.
VII (facial), IX (glossopharyngeal), and X
anesth
Which of the following teeth could be removed without pain after administration of an inferior alveolar and lingual nerve block?
• all anterior teeth on the side of the injection
• canine and first premolar on the side of the injection
• all teeth in that quadrant on the side of the injection
• both premolars and first molar on the side of the injection
• canine and first premolar on the side of the injection You need to give a long buccal injection to extract the molars and second bicuspid. For operative procedures, a long buccal injection may not be needed for these teeth. The long buccal injection anesthetizes the soft tissue and periosteum buccal to the mandibular molar teeth. The needle is inserted in the mucous membrane distal and buccal to the most distal molar in the arch.
To anesthetize the lingual nerve: When administering an inferior alveolar nerve block, slowly withdraw the syringe, and when approximately half its length remains within tissues, reaspirate. If negative, deposit a portion of the remaining solution (0.1 mL) to anesthetize the lingual nerve. Incisors may need local infiltration for extractions.
Other Techniques of Mandibular Anesthesia: • Mental nerve block: This nerve block is used when buccal soft tissue anesthesia is necessary anterior to the mental foramen (around the second premolar) to the midline and skin of the lower lip and chin. The needle is inserted in mucobuccal fold at or just anterior to the mental foramen. Target area: mental nerve as it exits the mental foramen (usually located between the apices of the first and second premolars). • Vazirani-Akinosi closed-mouth mandibular block: Although this technique can be used whenever mandibular anesthesia is desired, its primary indication remains those situations in which limited mandibular opening (i.e., patients with trismus) precludes the use of other mandibular techniques. Nerves anesthetized: inferior alveolar, incisive, mental, lingual, mylohyoid nerves. Area of needle insertion: soft tissue overlying the medial (lingual) border of the mandibular ramus directly adjacent to the maxillary tuberosity at the height of the mucogingival junction adjacent to the maxillary third molar. Note: The injection is performed blindly because no bony end points exist, the needle is advanced 25 mm into tissue for an average-sized adult). The distance is measured from the maxillary tuberosity. • The Gow-Gates technique: this technique is a true mandibular nerve block because it provides sensory anesthesia to virtually the entire distribution of CN V3 (inferior alveolar, lingual, mylohyoid, mental, incisive, auriculotemporal, and buccal nerves). Its primary use is when a conventional inferior alveolar nerve block is unsuccessful. Note: Patient must extend his or her neck and open wide for the duration of the technique (the condyle then assumes a more frontal position and is closer to the mandibular nerve trunk). Ex-traoral landmarks: corner of mouth, tragus of ear, and intertragic notch. Area of needle insertion: the needle is positioned so that it is inserted just distal to the maxillary second molar at the height of its mesi-olingual cusp. The needle is then slowly advanced until bone (neck of the condyle) is contacted. The average depth of soft tissue penetration to bone is 25 mm. The needle tip is withdrawn 1 mm, aspirate, and slowly deposit solution.
• middle superior alveolar • posterior superior alveolar
• The posterior superior alveolar (PSA) nerve block, otherwise known as the tuberosity block or the zygomatic block, is used to achieve anesthesia for the pulps of the maxillary third, second, and first molars (entire tooth = 72%; mesiobuccal root of the maxillary first molar not anesthetized = 28%). Target area: PSA nerve — posterior, superior, and medial to the posterior border of the maxilla. Note: Potential for hematoma formation. • The middle superior alveolar (MSA) nerve block is useful for procedures where the maxillary premolar teeth or the mesiobuccal root of the first molar require anesthesia. Target area: maxillary bone above the apex of the maxillary second premolar. Note: The MSA nerve is present in only about 28% of the population. • The anterior superior alveolar (ASA) nerve block or infraorbital nerve block provides profound pulpal and buccal soft-tissue anesthesia from the maxillary central incisor through the premolars in about 72 % of patients. Target area: infraorbital foramen (below the infraorbital notch). Remember: In order to extract the maxillary first molar, you must numb both the PSA and MSA nerves as well as the greater (anterior) palatine nerve for palatal anesthesia (soft tissue).
anesth Which of the following characterize shock? Select all that apply.
• decreased vascular resistance
• bradycardia
• myocardial ischemia
• mental status changes
• adrenergic response
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anesth
A full E cylinder of oxygen contains approximately:
• myocardial ischemia • mental status changes • adrenergic response
The term "shock" denotes a clinical syndrome in which there is inadequate cellular perfusion and inadequate oxygen delivery for the metabolic demands of the tissues. Important: Reduced cardiac output is the main factor in all types of shock.
In general, shock is characterized by: • Increased vascular resistance: cool mottled skin, oliguria • Tachycardia • Adrenergic response: diaphoresis, anxiety, vomiting, diarrhea • Myocardial ischemia • Mental status changes
The stages of shock include: 1) Compensatory (early) stage: compensatory mechanisms (increased heart rate and peripheral resistance) maintain perfusion to vital organs, 2) Progressive stage: metabolic acidosis occurs (compensatory mechanisms are no longer adequate), 3) Irreversible (refractory stage): organ damage, survival is not possible.
Major categories of shock: • Hypovolemic shock is produced by a reduction in blood volume. Cardiac output will be low due to inadequate left ventricular filling. Causes include severe hemorrhage, dehydration, vomiting, diarrhea, and fluid loss from bums. • Cardiogenic shock is circulatory collapse resulting from pump failure of the left ventricle, most often caused by massive myocardial infarction. • Septic shock is due to severe infection. Causes include the endotoxin from gram-negative bacteria. • Neurogenic shock results from severe injury or trauma to the CNS. • Anaphylactic shock occurs with severe allergic reaction.
• 600 L at a pressure of 2000 psi
Nitrous oxide: • Is a colorless, nonirritating gas with a pleasant, mild odor and taste • Has a blood/gas partition coefficient of 0.47 and is thus poorly soluble in blood • Is excreted unchanged by the lungs • Is the oldest gaseous anesthetic in use today • Is the only inorganic substance used as an anesthetic • As a general anesthetic, the only disadvantage is its lack of potency
1. Nitrous oxide should be stored under pressure in steel cylinders painted blue. Notes 2. Oxygen is stored in green tanks.
3. A full E cylinder of oxygen contains approximately 600 L at a pressure of 2000 psi. 4. At 2 L/min, a full E cylinder will deliver oxygen for approximately 300 min, or 5 hrs.
Advantages and Disadvantages of Nitrous Oxide Analgesia
Advantages
Good analgesia
It is nonflammable
It is suitable for all ages and therapeutic for many medically compromised patients
It has virtually no adverse side effects in the absence of hypoxia
It is titratable and produces euphoria
Disadvantages
There is a "misuse" potential with both patients and dentists
The most common patient complaint is nausea
It is not a complete pain reliever, a local anesthetic is still required to do most dental procedures
Diffusion hypoxia may occur; make sure you give 100% oxygen at the end of dental procedure to prevent it. Important: The inhalation of 100% oxygen is contraindicated for a person who has COPD
Important: Oxygen supplementation should be avoided or used with extreme caution in patients with severe COPD. These patients have an increased incidence of pulmonary bullae or blebs (combined alveoli). Because of nitrous oxide's low blood solubility, it can increase the volume and pressure of these lung defects, which could create an increased risk of barotrauma and pneumothorax.
anesth
According to Guedel's stages of anesthesia, the proper use of nitrous oxide achieves which level of anesthesia?
• stage I
stage II
stage III
. stage IV
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anesth
Which of the following are drugs that help to reduce salivary flow during treatment? Select all that apply.
Stage I (amnesia and analgesia): begins with the administration of anesthesia and continues to the loss of consciousness. Respiration is quiet, though sometimes irregular, and reflexes are still present.
Stage II (delirium and excitement): begins with the loss of consciousness and includes the onset of total anesthesia. During this stage, the patient may move his limbs, chatter incoherently, hold his breath, or become violent. Vomiting with the attendant danger of aspiration may occur. The patient is brought to Stage III as quickly and as smoothly as possible.
Stage III (surgical anesthesia): begins with the establishment of a regular pattern of breathing, total loss of consciousness, and includes the period during which signs of respiratory or cardiovascular failure first appear. This stage has four planes.
Stage IV (premortem): signals danger. This stage is characterized by pupils that are maximally dilated and skin that is cold and ashen. Blood pressure is extremely low, often unmeasurable. Cardiac arrest is imminent. Remember: The eyes appear greatly enlarged in size and nonreactive to bright light when functional circulation to the brain has stopped.
• all answers are correct
Local anesthesia acts by reducing sensitivity which reduces anxiety and stress related to treatment; salivation is also decreased.
Scopolamine, atropine, and benztropine are anticholinergic drugs. Not only do they decrease the flow of saliva, but they also decrease the secretion from respiratory glands during general anesthesia.
1. The duration of action of local anesthetics is directly proportional to protein Notes binding and lipid solubility. Increased protein binding — increased lipid solu
bility = increased duration of action. 2. The lower the pKa (dissociation constant) of the local anesthetic, the faster the onset of action. Important point: a local anesthetic with a low pKa has a very large number of lipophilic free base molecules that are able to diffuse through the nerve membrane. 3. Increased blood flow — shorter duration of action. 4. Metabisulfite is an antioxidant that protects the vasoconstrictor from oxidation. It has a low incidence of allergenicity. 5. The local anesthetic prilocaine can produce methemoglobinemia when administered in larger doses in patients with subclinical methemoglobinemia. The topical anesthetic benzocaine also can induce methemoglobinemia, but only when administered in very large doses. 6. The administration of levonordefrin should be avoided in patients receiving tricyclic antidepressants. There is an increased sensitivity to vasoconstrictors. *** Epinephrine should be used cautiously. 7. The administration of vasoconstrictors in patients being treated with nonselective beta-blockers (i.e., propranolol) increases the likelihood of a serious elevation of the blood pressure accompanied by a reflex bradycardia. Use vasoconstrictors cautiously.
anesth
Epinephrine and levonordefrin are added to local anesthetics because of their:
• ability to increase the potency of the local anesthetic
• ability to decrease the pain (burning) caused by the injection of the local anesthetic
• vasoconstrictive properties
• ability to decrease the possibility of an allergic reaction to the local anesthetic
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anesth
After receiving an injection of a local anesthetic containing 2% lidocaine with 1:100,000 epinephrine, the patient loses consciousness. Which of the following is the most probable cause?
• vasoconstrictive properties Vasoconstrictors (i.e., epinephrine and levonordefrin) are added to local anesthetics because of their vasoconstrictive properties. Vasoconstriction at the site of injection is beneficial because it limits the uptake of the anesthetic by the vasculature, thereby increasing the duration of the anesthetic and diminishing systemic effects (reducing systemic toxicity). Note: The use of a vasopressor-containing local anesthetic also may actually be responsible for the sensation of burning on injection. The addition of a vasopressor and an antioxidant (sodium bisulfite) lowers the pH of the solution to between 3.3 and 4, significantly more acidic than solutions not containing a vasopressor (pH about 5.5). Patients are more likely to feel the burning sensation with these solutions. Note: Malamed's book states that "local anesthetics containing the vasoconstrictor levonordefrin (Neo-Cobefrin) have become impossible to obtain (June 2004)." Important: To minimize the likelihood of intravascular injection, aspiration should be performed before the local anesthetic solution is injected. If blood is aspirated, the needle must be repositioned until no return of blood can be elicited by aspiration. Adverse reactions following the administration of a local anesthetic are, in general, dose-related and may result from high plasma levels caused by excessive dosage, rapid absorption, or unintentional intravascular injection. Systemic toxicities of local anesthetics: Initial clinical signs and symptoms of mild to moderate toxicity include: talkativeness, apprehension, excitability, slurred speech, dizziness, and disorientation. The signs and symptoms of severe toxicity include: seizures, respiratory depression, coma, and death. Important: The excitatory manifestations may be very brief or may not occur at all, in which case the first manifestation of toxicity may be drowsiness merging into unconsciousness and respiratory arrest. Remember: Cardiovascular manifestations are usually depressant and are characterized by bradycardia, hypotension, and cardiovascular collapse, which may lead to cardiac arrest. Note: In local anesthesia, the depression of respiration is a manifestation of the toxic effects of the solution.
1. For a normal healthy (ASA I) patient, the maximum dose of epinephrine is 0.2 mg or 200 Notes m g ; m j s equates to roughly 11 cartridges of 1:100,000 epinephrine. (The maximum dose of
lidocaine is 7mg/kg of body weight. Thus, for healthy adult patients, epinephrine is usually the limiting factor.) 2. In a cardiac risk patient, the maximum dose of epinephrine is 0.04 mg or 40 mg, which equates roughly to two cartridges of 1:100,000 epinephrine.
• syncope
*** Caused by transient cerebral hypoxia
Anxiety-induced events are by far the most common adverse reaction associated with local anesthetics in dentistry. These may manifest in numerous ways, the most common of which is syncope. In addition, they may present with a wide variety of symptoms, including hyperventilation, nausea, vomiting, and alterations in heart rate or blood pressure. Psychogenic reactions are often misdiagnosed as allergic reactions and may also mimic them, with signs such as urticaria, edema, and bronchospasm.
Proper management of syncope: • Place patient in supine position with feet slightly elevated (Trendelenburg position)
• Establish airway (head tilt/chin lift) - Administer 100% oxygen via face mask. 02 is indicated for the treatment of all
types of syncope except for hyperventilation syndrome. • Monitor vital signs and support patient
- Pupils may dilate from brain not getting oxygen. • Maintain your composure. Apply cool, wet towel to patient's forehead. • Follow-up treatment
- Determine factors causing unconsciousness.
Remember: Hyperventilation in an anxious dental patient leads to carpopedal spasm (a spasm of the hand, thumbs, foot, or toes).
Which tooth has a root that
• the maxillary first molar
• the maxillary second molar
• the maxillary third molar
• all of the above
is NOT consistently innervated by the
anesth
PSA nerve?
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anesth
Which of the following are reasons that vasoconstrictors are included in local anesthetics? Select all that apply.
• they prolong the duration of action of the local anesthetic
«they reduce the chance of an allergic reaction to the local anesthetic
• they reduce the toxicity because less local anesthetic is necessary
• they reduce the rate of vascular absorption by causing vasoconstriction
•they help to make the anesthesia more profound by increasing the concentrations of the local anesthetic at the nerve membrane
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• the maxillary first molar
When used to achieve pulpal anesthesia, the PSA nerve block is effective for the maxillary third, second, and first molars in 77% to 100% of patients. However, the mesiobuccal root of the maxillary first molar is not consistently innervated by the PSA nerve. In approximately 28% of patients, the middle superior alveolar nerve provides sensoiy innervation to the mesiobuccal root of the maxillary first molar. Therefore, if anesthesia of this tooth for either restorative dentistry or extraction is required, an infiltration injection also should be performed over the second premolar tooth. Note: Patients experience few subjective signs of anesthesia after receiving a posterior superior alveolar nerve block, as compared to an inferior alveolar nerve block (numb lip).
The risk of a potential complication also must be considered whenever the PSA block is used. Insertion of the needle too far distally may lead to a temporary (10 to 14 days) unaesthetic hematoma. As a means of decreasing the risk of hematoma formation after a PSA nerve block, the use of a "short" dental needle is recommended for all but the largest of patients. One must remember to aspirate several times before and during drug deposition during the PSA nerve block to avoid inadvertent intravascular injection. Important: If a patient's face becomes distended and swollen after a posterior superior alveolar nerve block, the following treatment is recommended:
• Place cold packs and pressure on the affected side • Explain to the patient that he/she may become black and blue on that side
1. Gauge of a needle refers to the diameter of the lumen of the needle: the smaller the num-Notes ber, the greater the diameter of the lumen. A 30-gauge needle has a smaller internal diame
ter than a 25-gauge needle. In the United States, needles are color-coded by gauge: 25-gauge, red; 27-gauge, yellow; and 30-gauge, blue. 2. Positive aspiration is directly correlated to needle gauge. 3. Larger-gauge needles (i.e., 25-gauge) have distinct advantages over smaller ones:
• Less deflection as the needle passes through the tissues • This leads to greater accuracy in needle insertion and, hopefully, to increased success rates • Larger-gauge needles do not break as often
Important: The 25-gauge needle is the preferred needle for all injections presenting a high risk of positive aspiration.
• they prolong the duration of action of the local anesthetic • they reduce the toxicity because less local anesthetic is necessary • they reduce the rate of vascular absorption by causing vasoconstriction • they help to make the anesthesia more profound by increasing the concentrations of
the local anesthetic at the nerve membrane
Vasoconstrictors are invaluable to local anesthesia in dentistry. There are clear indications for their use, of which improving the depth and duration of anesthesia are the most important. Without them, local anesthetics have a very short duration of action intraorally. Vasoconstriction is more important for infiltration techniques in vascular sites than it is for mandibular blocks. The presence of a vasoconstrictor may also reduce systemic toxic effects and can provide hemostasis. The most common agent for this purpose is epinephrine, which is available in formulations of 1:50,000 (0.02 mg/mL), 1:100,000 (0.01 mg/mL) and 1:200,000 (0.005 mg/mh).
There are three main adrenergic receptor subclasses that vasoconstrictors interact with on cardiovascular tissue in the human body. These are classified as alpha receptors (both alpha-1 and alpha-2), beta-1 receptors, and beta-2 receptors. Alpha receptors are densely located on arterioles in the skin and mucous membranes. Stimulation of these receptors leads to vasoconstriction through activation of G proteins and subsequent opening of calcium channels. Beta-1 receptors are located on cardiac tissue, and stimulation of them leads to an increase in heart rate (positive chronotropy) and an increase in contraction force (positive inotropy). Beta-2 receptors, like alpha receptors, are located primarily in vascular beds. However, these receptors are located primarily in vascular beds traversing skeletal muscle. When stimulated, beta-2 receptors activate adenylate cyclase, leading to vasodilation.
Epinephrine is the more potent than levonordefrin. Its affinity for alpha versus beta receptors is roughly equivalent (50:50). Thus, although the primary event that occurs at the site of injection beneath the oral mucosa is vasoconstriction, the relatively low systemic levels achieved after dental local anesthetic injections can cause increases in heart rate and cardiac output, as well as peripheral vasodilation in skeletal muscle beds. Note: Levonordefrin is less potent than epinephrine, its receptor affinity is 75% alpha and 25%> beta. As noted earlier, local anesthetics containing levonordefrin have become impossible to obtain.
anesth
Laryngospasm is an uncontrolled/involuntary muscular contraction (spasm) of the laryngeal cords. It is a well known, infrequent but serious postsurgical complication. In the operating room, it is treated by administering:
Following a local anesthetic injection, anesthetic effects will disappear and reappear in a definite order. Arrange the following sensations in increasing order of resistance to conduction.
A patient under general anesthesia loses the laryngeal reflex. If blood and saliva collect near the vocal cords, this stimulates the patient to go into spasm (laryngospasm), and the vocal cords will close. When this happens, air cannot pass and, hence the problem. The two most important steps in the initial management of a laryngospasm are applying oxygen under positive pressure and administering succinylcholine.
Note: Succinylcholine is a skeletal muscle relaxant that is used when performing endotracheal intubation and endoscopy procedures.
Laryngospasm is frequently cited as an adverse effect of ketamine, but it is rarely observed. Frequently, deep, heavy, loud respirations mistaken for laryngospasm are actually due to airway positioning. Such breathing is managed simply by repositioning the patient's head. True laryngospasm during ketamine sedation is usually caused by stimulation of the vocal cords by instrumentation or secretions.
I.pain 4. touch 2. cold 5. deep pressure 3. warm 6. motor
Local anesthesia causes loss of sensation by first blocking nerve conduction in the smaller unmyelinated fibers that carry pain, and then progressing to the larger myelinated fibers for pressure and motor function. This phenomenon is called differential blockade. Differential blockade may be due to the size of the nerve, the presence or absence of myelin, and firing frequency.
• Size of nerve: local anesthetics preferentially block small fibers because the distance over which such fibers can passively propagate an electrical impulse is shorter. During the onset of local anesthesia, when short sections of nerve are blocked, the small diameter fibers are the first to fail to conduct. • Presence or absence of myelin: For myelinated nerves, three successive nodes of Ranvier must by blocked to halt impulse propagation. The thicker the nerve fiber, the farther apart the nodes tend to be, which explains, in part, the greater resistance to block of large fibers (e.g., motor fibers to skeletal muscle). Myelinated fibers tend to become blocked before unmyelinated fibers of the same diameter. Note: Sodium channels are very dense at the nodes of Ranvier in myelinated fibers, which contributes to them being blocked before unmyelinated fibers of the same diameter. • Firing frequency: sensory fibers, especially pain fibers, have a high firing rate and a relatively long action potential duration (up to 5 msec). Motor fibers fire at a slower rate and have shorter action potential duration (< 0.5 msec). Both A delta and C fibers are small diameter fibers that participate in high-frequency pain transmission. Therefore, they are blocked sooner with lower concentrations of local anesthetics than are A alpha (motor) fibers to skeletal muscle.
Note: Nerves regain function in reverse order.
The extent of anesthesia depends on a variety of factors, including the amount of medication used, body temperature, pH, the amount of protein binding, and dilution by tissue fluids. Local anesthetics work by blocking voltage gated sodium channels, thereby preventing depolarization of the nerve fiber and conduction or transmission of the impulse.
anesth
How will a larger than normal functional residual capacity affect nitrous oxide sedation?
• nitrous oxide sedation will happen much quicker
• nitrous oxide sedation will take longer
• functional residual capacity does not affect nitrous oxide sedation
The functional residual capacity is the amount of air remaining in the lungs at the end of the normal expiration. (It is the sum of Expiratory Reserve Volume (ERV) and Residual Volume (RV)). Note: This air is used to provide air to the alveoli, which will aerate the blood evenly between breaths.
Note: Pulmonary volumes and capacity are about 20 to 25% less in females than in males and are greater in large and athletic individuals. Nitrous oxide sedation will vary accordingly.
Respiratory air volumes during rest and exercise are of physical and clinical interest, and they can be measured using a spirometer. The main volumes of interest are:
• Tidal Volume (TV): amount of air breathed in and out during quiet breathing • Expiratory Reserve Volume (ERV): amount of air forced out of the lungs in a maximal expiration, over and above that expired in normal breathing • Inspiratory Reserve Volume (IRV): amount of air inhaled in a maximal inspiration, over and above that inhaled in normal breathing • Vital Capacity (VC): TV + ERV + IRV • Residual Volume (RV): volume of air that remains in the lungs at all times (can't be measured by spirometry) • Total Lung Capacity (TLC): VC + RV
• very lipid soluble • rapid onset of action
Barbiturates exhibit a dose-dependent CNS depression with hypnosis and amnesia. They are very lipid soluble, which results in a rapid onset of action. They are used most often for induction of anesthesia because they produce unconsciousness in less than 30 seconds.
Barbiturates: • Ultra-short acting: Methohexital (Brevital), thiopental (Pentothal), and thiamylal (Suri-tal) • Short and intermediate acting: Amobarbital (Amytal), pentobarbital (Nembutal), secobarbital (Seconal), and butabarbital (Fioricet, Fiorinal) • Long acting: Phenobarbital (Luminal)
Most commonly used barbiturates for induction of anesthesia: • Thiopental (Pentothal): Usually prepared as a 2.5% solution. An induction dose of 3-5 mg/kg produces a loss of consciousness within 30 seconds and recovery in 5-10 minutes. Because the elimination half-life is 6-12 hours, patients may experience a slow recovery. When injected intravenously, it can be irritating. Usually prepared as 2.5% solution. pH is 10.5. • Methohexital (Brevital): is somewhat less lipid soluble and less ionized at physiologic pH than thiopental. An induction dose of 1-2 mg/kg produces loss of consciousness in less than 20 seconds and recovery in 4-5 minutes. The elimination half-life of methohexital is 3 hours, which allows a clearance rate that is 3 to 4 times faster than that of thiopental. pH is 10.5. The side effect most often seen is hiccups. This is believed to be caused by rapid injection of the Brevital.
1. The most effective agent in the initial treatment of respiratory depression due Notes to the overdose of barbiturates is oxygen under positive pressure.
2. A primary advantage of IV sedation is the ability to titrate individualized dosage.
anesth
Which of the following local anesthetics are available in North America? Select all that apply.
Procaine (Novocaine) was, at one time, the most commonly used ester local anesthetic in dentistry. It is the prototype for the ester group of local anesthetics but is no longer available in dental cartridge form. An easy way to identify amide local anesthetics is to remember that the drug name contains an i plus -caine (lidocaine, mepivacaine, and bupivacaine). Esters such as procaine, benzocaine, and tetracaine contain no i.
Amide-type local anesthetics: Ester-type local anesthetics: • Lidocaine (Xylocaine): most commonly used • Procaine (Novocaine) • Prilocaine (Citanest) . Propoxycaine (Ravocaine) • Articaine (Septocaine): has both amide and ester linkages • Benzocaine (Monocaine) • Mepivacaine (Carbocaine) . Tetracaine (Pontocaine) • Bupivacaine (Marcaine) • Etidocaine (Duranest): removed from the U.S. market in 2002
Topical esters are still commonly used in the practice of dentistry. Most topical local anesthetic ointments and gels contain benzocaine (an ester, e.g., Hurricaine, Cetacaine). Benzocaine gels typically contain 18% - 20% benzocaine. Lidocaine (an amide) is also available in two forms for topical application. EMLA (eutectic mixture of local anesthetic cream), contains both lidocaine and prilocaine. Amides are safe, versatile, and effective local anesthetics. If hypersensitivity to a drug in this group precludes its use, one of the ester-compound local anesthetics may provide analgesia without adverse effect. For patients allergic to both esters and amides, diphenhydramine (Benadryl) is a good choice. Esters are potent local anesthetics slightly different in chemical structure from the amide group. Tetracaine is most commonly used. Allergic reactions are far more common with esters. Important: Lidocaine has an FDA Pregnancy Category rating of B. Lidocaine 2% with epinephrine 1:100,000 is the drug of choice in the treatment of pregnant women. Articaine, bupivacaine, and mepivacaine have an FDA Pregnancy Category rating of C.
Remember: The drug of choice in management of an acute allergic reaction involving bronchospasm (an acute narrowing of the respiratory airway) and hypotension is epinephrine. Note: Allergic reactions to local anesthetic are usually caused by an antigen-antibody reaction.
• place patient in supine position • oxygen administration • place a cold compress on patients • monitor vitals .loosen tight clothing forehead
The most common cause of a transient loss of consciousness in the dental office is vasovagal syncope. This generally is due to a series of cardiovascular events triggered by the emotional stress brought on by the anticipation of or delivery of dental care. Prevention of vasovagal syncopal reactions involves proper patient preparation.
Remember: Any signs of an impending syncopal episode should be quickly treated by placing the patient in a supine position with the feet elevated (Trendelenburgposition), monitoring vital signs, loosening tight clothing and placing a cold compress on the forehead. Oxygen 3-4 L/minute should also be given via nasal cannula. Important: The most common early sign of syncope is pallor.
Vasovagal Syncope: • Most commonly related to injections in younger individuals • Parasympathetic response often followed by sympathetic response secondary to anxiety • Warm feeling, pale, diaphoresis, "feeling faint or sick," nausea, bradycardia, and hypotension
Most Common Medical Emergencies: • Syncope • Asthma attack • Hyperventilation • Acute myocardial infarction • Hypoglycemia • Seizure • Postural hypotension . Allergic reactions • Angina pectoris
Postural Hypotension: Management • Slow to change position from laying to sitting to standing • Need for change in medication? (depends on severity) • Recent change in medication • Rule out precipitating causes
"Hyperventilation syndrome"- most commonly seen in dental office • Related to anxiety/ panic • Associated with lightheadedness, dizziness, chest pain, dysphagia, nausea • Rule out more serious potential conditions including pulmonary (asthma, PE), cardiac (CHF), endocrine (diabetic ketoacidosis)
anesth
For local anesthetics, for every 1 % solution there is:
• 10 mg/mL of anesthetic Use the following to calculate the amount, in milligrams, of anesthetic or vasoconstrictor in a given solution:
a. For local anesthetic, a 1% solution has 10 mg/mL • 100% solution would be 1000 mg/mL
** Total milligrams = (% of the solution) x (lOmg/mL) x (mL of solution) • 34 mg = (2) x (10) x (1.7) for a standard 2% lidocaine solution
b. For vasoconstrictor, 1; 100,000 means 1 gram per 100,000 mL. This equates to 0.01 mg/mL. • Total milligrams = (ratio in mg/mL) x (mL of solution) • .017 mg epi = (.01 mg/mL) x (1.7 mL)
Calculation of Milligrams of Local Anesthetic Per Dental Cartridge (1.7 ml Cartridge)
Local Anesthetic
Articaine
Bupivacaine
Lidocaine
Mepivacaine
Mepivacaine
Prilocaine
Percent concentration
4
0.5
2
2
3
4
mg/ml
40
5
20
20
30
40
x 1.7 ml = mg/Cartridge
68
8.5
34
34
51
68
Maximum Recommended Dosages (MRDs) of Local Anesthetics Available in North America
Local Anesthetic
Articaine With vasoconstrictor
Bupivacaine With vasoconstrictor
Lidocaine No vasoconstrictor With vasoconstrictor
Mepivacaine No vasoconstrictor With vasoconstrictor
Prilocaine No vasoconstrictor With vasoconstrictor
Neuroleptanesthesia is a state of neuroleptanalgesia and unconsciousness, produced by the combined administration of a narcotic analgesic and a neuroleptic agent, together with the inhalation of nitrous oxide and oxygen.
Neuroleptanalgesia only produces an unconscious state if nitrous oxide is also administered (see below).
Under the influence of this combination, the patient is sedated and demonstrates psychic indifference to the environment yet remains conscious and can respond to questions and commands.
Neuroleptanalgesia + nitrous oxide = neuroleptanesthesia in oxygen (unconscious)
Induction of anesthesia is slow, but consciousness returns quickly after the inhalation of nitrous oxide is stopped.
1. Neurolept analgesia is useful for minor surgical procedures, some radiological procedures, Notes burn dressing, and endoscopy.
2. Neuroleptic agents such as droperidol (Inapsine) cause a reduction in anxiety and a state of indifference. 3. Droperidol is an antiemetic and has adrenergic blocking (alpha blocking) activity. 4. Neurolept analgesia/anesthesia may be especially useful in the elderly, debilitated, or seriously ill patient. 5. The combination of droperidol and fentanyl (Sublimaze), is Innovar. 6. Innovar produces slight circulatory effects, but can cause significant respiratory depression. 7. The low incidence of extrapyramidal side effects associated with droperidol use may be effectively treated with the anticholinergic (antimuscarinic) drug, benztropine (Cogentin).
anesth The most common cause of loss of consciousness in the dental office is:
Trauma to muscles or blood vessels in the is the most common etiological factor in trismus associated with dental injections of local anesthetics.
• pterygoid fossa
• temporal fossa
• submandibular fossa
• infratemporal fossa
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• syncope — fainting
Syncope is the most common adverse reaction associated with administration of local anesthesia. Remember: It often occurs when upright, although it can occur when sitting. It will never occur when lying. The patient may complain of feeling generalized warmth with nausea and palpitations.
The initial event in a vasovagal syncope episode is the stress-induced release of increased amounts of catecholamines that cause the following: a decrease in peripheral vascular resistance, tachycardia, and sweating.
As blood pools in the periphery, a drop in blood pressure appears, with a corresponding decrease in cerebral blood flow. The patient will then complain of feeling dizzy or weak. Compensatory mechanisms attempt to maintain adequate blood pressure, but they soon fatigue, which leads to vagally mediated bradycardia. Once the blood pressure drops below levels necessary to sustain consciousness, syncope occurs.
Place the patient in a supine position with the feet elevated (Trendelenburgposition), monitor vital signs, tight clothing should be loosened and a cold compress placed on the forehead. Oxygen 3-4 L/minute should be given via nasal cannula.
Important: The single most important drug to use in any medical emergency, including chronic obstructive pulmonary disease, is oxygen.
Note: The primary airway hazard for an unconscious dental patient in a supine position is tongue obstruction. Remember: Head tilt/chin lift.
• infratemporal fossa
Limited jaw opening, or trismus, is a relatively common complication following local anesthetic administration. In addition to trauma to muscles or blood vessels in the infratemporal fossa, it may be caused by hematoma formation, localized muscle necrosis secondary to the anesthetic drug or vasoconstrictor, infection in the fascial space, or introduction of a foreign body.
Note: In most instances of trismus the patient reports pain and some difficulty opening his or her mouth on the day after treatment in which a posterior superior alveolar or inferior alveolar nerve block was administered.
The main symptom of trismus, is the limitation of movement of the mandible, which is often associated with pain. Symptoms will arise from 1 to 6 days following an injection. The duration of symptoms and their severity are both variable. Note: The medial pterygoid muscle is most often affected.
Management of trismus: • Apply hot, moist towels to the site for approximately 20 minutes every hour • Warm saline rinses • Use analgesics as required • Benzodiazepine (e.g., diazepam) for muscle relaxation if deemed necessary • The patient should gradually open and close mouth as a means of physiotherapy
Following an inferior alveolar nerve block injection or a mental block injection, a prickly or tingling sensation (paresthesia), even complete numbness in the lower lip, may result and persist for a considerable time. This is usually considered to be due to direct trauma or piercing of the nerve trunk by the needle. This happens more often in the case of the mental block injection. The symptoms of paresthesia gradually diminish (may last from 2 weeks to 6 months), and recovery is usually complete.
Remember: The most common cause of paresthesia of the lower lip is the removal of a mandibular third molar (especially horizontally impacted ones).
anesth
There are no contraindications for the use of nitrous oxide sedation in asthmatic patients.
Because anxiety is a stimulus for an asthmatic attack, nitrous oxide sedation is actually beneficial for these patients.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
Nausea and vomiting are the most common adverse effects of nitrous oxide sedation, occurring in 1% to 10% of patients. Fasting is not required for patients undergoing nitrous oxide sedation. The practitioner, however, may recommend that only a light meal be consumed in the 2 hours prior to the administration of nitrous oxide. Diffusion hypoxia can occur as a result of rapid release of nitrous oxide from the blood stream into the alveoli, thereby diluting the concentration of oxygen. This may lead to headache and disorientation and can be avoided by administering 100% oxygen after nitrous oxide has been discontinued.
Remember: The most common complication associated with nitrous oxide sedation is a behavioral problem (laughing, giddy).
Note: Some literature states that nitrous oxide is acceptable for the pregnant patient, however, from a risk management perspective, point it may be prudent not to use nitrous oxide on any pregnant patient. Greater concern lies with office workers, such as dental assistants who might be continually exposed to nitrous oxide. Pregnant assistants should not work in or near rooms where nitrous oxide is being administered.
Administration of volatile anesthetics (desflurane, enflurane, halothane, isoflurane, and sevoflurane) is not a concern for COPD patients. All volatile anesthetics are bron-chodilators and, therefore, are beneficial to patients with COPD (asthmatic bronchitis, emphysema, and chronic bronchitis).
Important: Sedation with nitrous oxide should be avoided in patients with COPD.
• 150,000 - 450,000/mm3
Thrombocytopenia is defined as a count of <150,0007mrrf. Intraoperative bleeding can be severe with counts of 40 000-70 000/mm\ and spontaneous bleeding usually occurs at counts < 2 0 , 0 0 0 W . The rmntmal recommended platelet count before surgery is 75,000/mm3.
White blood cell count
Red blood cell count
Hemoglobin
Hematocrit
Platelet count
Definition
Percentage of RBC mass in blood volume
Male
5,000-10,000/mm3
4.5-5.9 x 106/mm3 4.5-5.9 x lO'/mm3
14-16 g/dL
42%-52%
150,000-450,000/mm3
Female
5,000-10,000/mm3
12-14 g/dL
36%-48%
150,000-450,000/mm
RBC indices:
Mean corpuscular volume (MCV)
Mean corpuscular hemoglobin (MCH)
Mean corpuscular hemoglobin concentration (MCHC)
Average RBC volumes in fL
Estimates weight of Hgb in average RBC
Estimates average concentration of Hgb in average RBC
80-100 fL
28-33 pg
32-36 g/dL
80-100 fL
28-33 pg
32-36 g/dL
Notes
1. The minimal acceptable value for the hematocrit is 30% for elective surgery.
2. Normal values for coagulation: • Template bleeding time = 1 to 9 minutes • Prothrombin time (PT) = 11 to 16 seconds (compared to normal control) • Partial thromboplastin time (PTT) = activated, 32-46 seconds (compared to normal con-
Important- PT will be increased by warfarin, vitamin K deficiency, fat malabsorption, liver disease DIC and artificially increased tourniquet time. Warfarin works by blocking vitamm K dependent clotting facors, whereas broad-spectrum antibiotics elevate PT by killing normal bowel flora which decreases vitamin K absorption. Heparin in high doses also will increase PT by altering factor X. Note: FFP (fresh frozen plasma) will reverse warfarin effects immediately.
anesth
Which of the following pairings are correct regarding the amount of epinephrine in 1.7cc of solution? Select all that apply.
See card #45 for more detailed explanation of calculations
• 1 mL of 2% lidocaine with epinephrine 1:100,000 contains the following: - 20 mg of lidocaine: Blockade of nerve conduction - 0.01 mg of epinephrine: Increase depth and duration of anesthesia; decrease absorption of
local anesthetic and vasopressor - 6 mg of NaCL: Isotonicity of the solution - 0.5 mg of sodium (meta) bisulfate: Antioxidant - 1 mg of methylparaben: Bacteriostatic agent - Sterile water: A diluent to provide the volume of solution in a cartridge
• 1.7 mL of 2% lidocaine (which is a carpule) with epinephrine 1:100,000 contains the follow-m ^ ' Note: Methylparaben is no longer
- 34 mg of lidocaine: (1.7 mL x 20 mg/mL) m d u d e d m s i n g l e . u s e d e n t a l c a r . - .017 mg of epinephrine: (1.7 mL x .01 mg/mL) t r i d g e s o f , o c a l a n e s t h e t i c ; h o w . - 10.2 mg of NaCl: (1.7 mL x 6 mg/mL) ^ [t {& found m A L L m u l t i d o s e
- 0.85 mg of sodium (meta) bisulfate: (1.7 mL x 0.5 mg/mL)v i a l s o f i n j e c t a b l e d
Calculations of Milligrams per Cartridge
Percent Solution
0.5
1.0
2.0
3.0
4.0
Milligrams (mg) X Volume of Cartridge per Milliliter (mL)
5 X 1.7
10 X 1.7
20 X 1.7
30 X 1.7
40 X 1.7
= Milligrams per Cartridge
8.5
17
34
51
68
• liver A significant difference between the two major groups of local anesthetics, the esters and the amides, is the means by which the body biologically transforms the active drug into one that is pharmacologically inactive. Metabolism (or biotransformation) of local anesthetics is important because the overall toxicity of a drug depends on a balance between its rate of absorption into the bloodstream at the site of injection and its rate of removal from the blood through the processes of tissue uptake and metabolism.
The primary site of biotransformation of amide drugs is the liver. Ester local anesthetics are hy-drolyzed in the plasma to para-aminobenzoic acid (PABA) by the enzyme pseudocholinesterase. Patients with pseudocholinesterase inactivity are unable to detoxify ester type agents at a normal rate. Amide-type anesthetics are recommended in these patients.
Allergic reactions to amide-type local anesthetics are rare but may occur as a result of hypersensitivity to the local anesthetic agent itself or due to an allergy to methylparaben or other preservatives used in many solutions. These reactions are characterized by cutaneous lesions of delayed onset or urticaria, edema, and other manifestations of allergy. Important: For those patients allergic to both ester and amide-type local anesthetics, diphenhydramine is a safe and effective alternative.
The initial clinical signs and symptoms of CNS toxicity for local anesthetics are usually excitatory in nature. However, it is also possible that the excitatory phase of the reaction may be extremely brief or may not occur at all. This is true especially with which local aneshetics? Select all that apply.
lidocaine
tetracaine
• etidocaine
• procaine
• bupivacaine
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anesth
The pH of normal tissue is ; the pH of an inflamed area is .
Local anesthetics readily cross the blood-brain barrier. Their pharmacological action on the CNS is depression. At low (therapeutic, nontoxic) blood levels, there are no CNS effects of any clinical significance. At higher (toxic, overdose) levels, the primary clinical manifestation is a generalized tonic-clonic convulsion.
With a further increase in the blood level of the local anesthetic above its "therapeutic" level, adverse reactions may be observed. Because the CNS is much more susceptible to the actions of local anesthetics than other systems, it is not surprising that the initial clinical signs and symptoms of overdose (toxicity) are CNS in origin. Initial clinical signs and symptoms (slurred speech, dizziness, talkativeness, apprehension, increased anxiety) of CNS toxicity are usually excitatory in nature.
Lidocaine and procaine differ somewhat from other local anesthetics in that the usual progression of signs and symptoms may not be seen. Lidocaine and procaine frequently produce an initial mild sedation or drowsiness (more common with lidocaine).
Sedation may develop in place of the excitatory signs. If either excitation or sedation is observed in the initial 5 to 10 minutes after the intraoral administration of a local anesthetic, it should serve as a warning to the clinician of a rising local anesthetic blood level and the possibility (if the blood level continues to rise) of a more serious reaction, possibly a generalized convulsive episode.
Local anesthetics have a direct action on the myocardium and peripheral vasculature. In general, however, the cardiovascular system appears to be more resistant to the effects of local anesthetic drugs than the CNS.
• Direct action on the myocardium: Local anesthetics produce a myocardial depression that is related to the local anesthetic blood level. Local anesthetics decrease electrical excitability of the myocardium, decrease the conduction rate, and decrease the force of contraction. • Direct action on the peripheral vasculature: All local anesthetics (except cocaine andropi-vacaine) produce a peripheral vasodilation through relaxation of the smooth muscle in the walls of blood vessels.
• 7.4; 5 to 6
It is well known that the pH of a local anesthetic solution (and the pH of the tissue into which it is injected) greatly influences its nerve-blocking action. Acidification of tissue decreases local anesthetic effectiveness. Inadequate anesthesia results when local anesthetics are injected into inflamed or infected areas. Local anesthetics containing epinephrine or other vasopressors are acidified by the manufacturer to inhibit the oxidation of the vasopressor. The pH of solutions without epinephrine is about 5.5; epi-nephrine-containing solutions have a pH of about 3.3. Note: Increasing pH (alkalinization) of a local anesthetic solution speeds the onset of its action, increases its clinical effectiveness, and makes its injection more comfortable. The two factors involved in the action of a local anesthetic are diffusion of the drug through the nerve sheath and binding at the receptor site in the ion channel. Local anesthetics exist in ionized (cation) and non-ionized (base) forms, the proportions of which vary with the pH of the environment. The non-ionized (base) portion is the form that is capable of diffusing across nerve membranes and blocking sodium channels.
Factors Affecting Local Anesthetic Action
Factor
pK.
Lipid solubility
Protein binding
Nonnervous tissue diffusibility
Vasodilator activity
Action Affected
Onset
Anesthetic potency
Duration
Onset
Anesthetic potency and duration
Description
Lower pKa =• more rapid onset of action, more RN (free base form) molecules present to diffuse through nerve sheath; thus onset time is decreased
Increased lipid solubility = Increased potency (example: procaine = 1; etidocaine = 140) Etidocaine produces conduction blockade at very low concentrations, whereas procaine poorly suppresses nerve conduction, even at higher concentrations
Increased protein binding allows anesthetic cations (RNH~) to be more Firmly attached to proteins located at receptor sites; thus duration of action is increased
Increased diffusibility * Decreased time of onset
Greater vasodilator activity * Increased blood flow to region = Rapid removal of anesthetic molecules from injection site; thus decreased anesthetic potency and decreased duration
anesth
Nitrous oxide works on the:
• peripheral nervous system (PNS)
central nervous system (CNS)
• autonomic nervous system (ANS)
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anesth
The primary action of local anesthetics in producing a conduction block is to decrease the permeability of the ion channels to:
• calcium ions
• chloride ions
• potassium ions
• sodium ions
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• central nervous system (CNS)
Nitrous oxide is the only inorganic gas used by the anesthesiologist. Room air contains 21% oxygen; you must make sure that the patient receives at least this much oxygen. The maximum limitation is 60% nitrous oxide and 40% oxygen.
Nitrous oxide is carried in the bloodstream in physical solution. There is no metabolism or degradation of nitrous oxide in the body. It is excreted solely via the lungs, unchanged. High blood levels of nitrous oxide can be achieved quite quickly. It is nontoxic to body tissues. The only toxicity associated with the use of nitrous oxide is the lack of oxygen that could result from the operator's error. The gag reflex is only slightly obtunded with nitrous oxide analgesia. It is believed that nitrous oxide has its main effects on the reticular activating system and the limbic system.
Nitrous oxide is a weak anesthetic. It is used to supplement inhalation agents. It is the only inhalation anesthetic with sympathomimetic activity. It should not be used in doses higher than 60% combined with 40% oxygen. It is known to diffuse into air-containing spaces and to increase the pressure in such cavities. 100% oxygen should be administered during awakening in order to avoid diffusion hypoxia.
Remember: • The first symptom of nitrous oxide analgesia is tingling of the hands. • Nausea is the most common side effect of nitrous oxide analgesia. • The correct total liter flow of nitrous oxide/oxygen is determined by the amount necessary to keep the reservoir bag 1/3 to 2/3 full. • MAC (minimal alveolar concentration) of nitrous oxide is 104. MAC is the concentration of an inhaled anesthetic at 1 atm that prevents skeletal muscle movement in response to a painful stimulus (e.g., surgical skin incision) in 50% of patients.
• sodium ions
Local anesthetics selectively inhibit the peak permeability of sodium, whose value is normally about five to six times greater than the minimum necessary for impulse conduction. The following sequence is a proposed mechanism of action of local anesthetics:
1. Displacement of sodium ions from the sodium channel receptor site, which permits... 2. Binding of local anesthetic molecule to this receptor site, which thus produces... 3. Blockade of the sodium channel, and a... 4. Decrease in sodium conductance, which leads to... 5. Depression of the rate of electrical depolarization, and a... 6. Failure to achieve the threshold potential level, along with a... 7. Lack of development of propagated action potentials, which is called... 8. Conduction blockade
The mechanism whereby sodium ions gain entry to the axoplasm of the nerve, thereby initiating an action potential, is altered by local anesthetics. The nerve membrane remains in a polarized state because ionic movements responsible for the action potential fail to develop. Nerve block produced by local anesthetics is called a nondepolarizing nerve block.
1. Local anesthetics reversibly block nerve impulse conduction and produce Notes reversible loss of sensation at their administration site. The site of action of local
anesthetics is at the lipoprotein sheath of the nerves. 2. Local anesthetics are clinically effective on both axons and free nerve endings. 3. Important: Smallest, unmyelinated nerve fibers that conduct pain and temperature sensations are affected first, followed by touch, proprioception, and skeletal muscle tone. 4. Emergence from a local anesthetic nerve block follows the same diffusion patterns as induction; however, it does so in reverse order. 5. Recovery is usually a slower process than induction because the anesthetic is bound to the drug receptor site in the sodium channel and, therefore, is released more slowly than it is absorbed. 6. Conductance of potassium, calcium, and chloride remains unchanged.
anesth
Which of the following is the phase of anesthesia that begins with the administration of anesthetic and continues until the desired level of patient unresponsiveness is reached?
Volatile liquids require a vaporizer for inhalational administration. Which one additionally requires a heating component to allow delivery at room temperature?
• enflurane
• halothane
• sevoflurane
• desflurane
• isoflurane
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• induction
*** Stage I and Stage II of general anesthesia together are referred to as induction.
The depth of general anesthesia (by inhalation) varies with the partial pressure (tension) of the anesthetic agent in the brain, and the rates of induction and recovery depend on the rate of change of tension in this tissue (also blood supply to the lungs, pulmonary ventilation, and the concentration of the anesthetic influence the rate of induction). The signs and stages of anesthesia are most likely to be seen with anesthetic that has a slow rate of induction.
1. Maintenance is the process of keeping a patient in surgical anesthesia. Notes 2. Recovery is the phase of anesthesia commencing when surgery is complete and
the delivery of the anesthetic is terminated and ending when the anesthetic has been eliminated from the body. 3. The behavior of patients under general anesthesia suggests that the most resistant part of the CNS is the medulla oblongata (cardiac, vasomotor, and respiratory centers of the brain). 4. The most controllable route for administration of a general anesthetic is inhalation. 5. Minimum alveolar concentration (MAC): alveolar concentration of anesthetic at which 50% of the patients are unresponsive to a standard surgical stimulus. 6. Meyer-Overton theory: anesthesia commences when a chemical substance reaches a certain molar concentration in the hydrophobic phase. 7. Second gas effect: this occurs when one gas speeds the rate of increase of the alveolar partial pressure of a second gas. Potent agents are administered with nitrous oxide so that the potent agent will be delivered in increased amounts to the alveoli as gas rushes to replace the nitrous oxide absorbed by pulmonary blood.
• desflurane
Inhalation anesthetics are substances that are brought into the body via the lungs and are distributed with the blood into the different tissues. The main target of inhalation anesthetics (or so-called volatile anesthetics) is the brain. Currently used inhalation anesthetics include five volatile liquids (enflurane, halothane, isoflurane, sevoflurane, desflurane) and one gas (nitrous oxide). The volatile liquids require a vaporizer for inhalational administration. The desflurane vaporizer has a heating component to allow delivery at room temperature.
Some inhalation agents have an unpleasant odor and may irritate the respiratory tract. This irritation may cause coughing and muscle spasms in the voice box, or larynx (laryngospasm), or in the bronchial tubes in the lungs (bronchospasm). Sevoflurane is less irritating to the airway than the others and is preferred for inducing anesthesia in children.
Important: All the potent inhalation agents are capable of triggering malignant hyperthermia (MH), a rare inherited disorder that is potentially fatal.
Administration of an inhalation anesthetic is usually preceded by intravenous or intramuscular administration of a short-acting sedative hypnotic drug, often a barbiturate (thiopental). The procedure almost always requires endotracheal intubation.
1. Administration of volatile anesthetics is not a concern for COPD patients. All Notes volatile anesthetics are bronchodilators and, therefore, are beneficial to patients
with COPD. 2. Volatile anesthetics depress the cardiovascular system, and this depression results in a reduced mean arterial pressure. 3. Desflurane, isoflurane, and sevoflurane are potent vasodilators.
anesth The optimum site for IV sedation for an outpatient is the:
> median basilic vein
• median cephalic vein
• median antebrachial vein
1 axillary vein
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anesth
Dissociative anesthesia is a unique method of pain control that reduces anxiety and produces a trancelike state in which the person is not asleep, but rather feels separated from his or her body. The primary medication used is:
This vein lies in the lateral aspect of the antecubital fossa (anterior to the elbow). Avoid entering the brachial artery. If the artery is entered, the following symptoms will appear: immediate burning at the site of the injection, the arm will appear blotchy, and the pulse in the arm will be weak compared to the other arm.
IV Sedation: • Usually done with a 21-gauge needle • Popular drug is Valium (diazepam) • The rate of injection of Valium is a 1 ml/minute
— 1 mL of injectable Valium contains 5 mg of Valium • Injection is discontinued when the eyelids droop (ptosis)
Cephalic vein
Three common signs indicating when the correct level of sedation has been reached when using Valium:
1. Blurring of vision 2. Slurring of speech 3. 50% ptosis of the eyelids (this is called Ver-rill's sign)
Remember: Valium is contraindicated for use in a patient with a history of narrow-angle glaucoma.
Median cephalic vein
Cephalic vein
Basilic vein
Median cubital vein
Basilic vein
• ketamine
Dissociative anesthesia is useful in emergency situations, such as an injury. It can also be used for short procedures that are painful, such as changing bandages. This method is safe and lasts only a short time. Because a person does not usually recall the procedure, this method is useful in children. The primary medication used is called ketamine. A sedative is often given before ketamine to reduce anxiety.
Note: A person who has had dissociative anesthesia usually does not remember the procedure, especially if a sedative has been given along with the pain medication. Most people feel back to normal within a few hours. As the medication wears off, an individual (particularly adult patients) may have intense dreams and even hallucinations.
Ketamine, a phencyclidine (PCP) derivative, is 10 times more lipid soluble than thiopental, enabling it to cross the blood-brain barrier quickly. It produces dissociative anesthesia, which can be seen on EEG as dissociation between the thalamus and limbic system. Rapid CNS depression with hypnosis, sedation, amnesia, and intense analgesia occurs in 30-60 seconds after administration. The anesthetic induction doses are 1-2 mg/kg IV, with effects lasting 5-10 minutes or 10 mg/kg intramuscular, which acts in 2-4 minutes.
Ketamine: • Increases airway secretions, creating the need for anticholinergics such as glycopyrr-
olate in the preoperative period • Increases BP, heart rate, and cardiac output, but not respirations • Produces bronchial smooth muscle relaxation because of sympathetic stimulation • Is a potent cerebral vasodilator • Side effects include hypertension, increased pulse, and delirium
anesth
Malignant hyperthermia (MH) is a pharmacogenetic disorder in which a genetic variant in the individual alters that person's response to certain drugs. Which of the following describe the major clinical characteristics of MH? Select all that apply.
> rigidity
• fever
• hypermetabolism
• myoglobinuria
•alkalosis
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anesth
The following signs: nausea, pallor, cold perspiration, widely dilated pupils, eyes rolled up, and brief convulsions are indicative of a patient having a
MH is a hypermetabolic state involving skeletal muscle that is precipitated by certain anesthetic agents in genetically susceptible individuals. The incidence of MH is <0.5% of all patients who are exposed to anesthetic agents. Inhalation anesthetic drugs that are known to trigger MH include halothane, enflurane, isoflurane, desflurane, and sevoflurane. Depolarizing neuromuscular blockade agents that can trigger MH include succinylcholine, de-camethonium, and suxamethonium. Classic MH most often manifests in the operating room, but it can also occur within the first few hours of recovery from anesthesia. When exposed to inhalational anesthetics, muscle metabolism increases, and a series of signs and symptoms appear, which, if left untreated, can lead to death. The earliest findings are an increased production of carbon dioxide and signs of increased sympathetic nervous system activity.
Acute clinical manifestations of MH include tachycardia, tachypnea, unstable blood pressure, cyanosis, respiratory and metabolic acidosis, fever, muscle rigidity, and death. Mortality ranges from 63% to 73%. It usually occurs in apparently healthy children and young adults at an average age of 21 years.
When MH is diagnosed early and treated promptly, the mortality rate should be near zero. Whenever anesthesia is administered, dantrolene should be readily available as well as a protocol for management of MH (100% oxygen, cooling procedures, and the correction of acidosis and hyperkalemia). Dantrolene is, at the moment, the only known drug that treats MH. It impairs calcium-dependent muscle contraction and controls hypermetabolic manifestations.
• psychogenic
*** A psychogenic reaction is caused by psychological factors rather than physical factors.
Vasovagal syncope, a psychogenic reaction, is the most commonly experienced complication associated with the use of local anesthetic solutions. The clinical signs closely resemble those of shock. These psychogenic reactions readily respond to placing the patient in a supine position.
The following drugs, when administered 1 hour prior to the dental appointment, are safe and effective ways to allay the fears of an apprehensive adult dental patient and possibly avoid a psychogenic reaction in the dental chair:
These drags are not recommended unless you have experience with them and can handle any complications that may happen from their use.
Note: For a dentist to use "enteral sedation" (the use of a pharmacological method that produces a minimally depressed level of consciousness) some states require special training and registration with the state.
Note: A somatogenic reaction is the development of a reaction from an organic pathophysiologic cause.
anesth Postoperative hypotension is usually due to the effect of:
• transfusion reactions
• a fat embolism
• the anesthetic or analgesics on the myocardium
• liver failure
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anesth
Anesthesia performed with general anesthetics occurs in four stages which may or may not be observable because they can occur very rapidly. Which stage is the one in which skeletal muscles relax and the patient's breathing becomes regular?
Common causes of postoperative hypotension: • Intravascular hypovolemia • Rewarming vasodilation • Hypothyroidism • Myocardial depression
*** Possible treatment options include: • Elevation of the lower extremities • Administration of carefully monitored fluid boluses • Administration of vasopressors (e.g., ephedrine)
The treatment is Narcan (a narcotic antagonist) if hypotension is due to narcotics. Use atropine (an anticholinergic) if bradycardia is present.
Note: Postoperative hypertension is most often due to post-op pain. Treat with narcotics and sedatives. Other common causes include:
• Hypercapnia • Anxiety • Overdistension of the bladder • Hypoxia
• surgical anesthesia
• Stage One (Analgesia): The patient experiences analgesia or a loss of pain sensation but remains conscious and can carry on a conversation. Note: The best monitor of the level of analgesia is the verbal response. • Stage Two (Excitement): The patient may experience delirium or become violent. Blood pressure rises and becomes irregular, and breathing rate increases. This stage is typically bypassed by administering a barbiturate, such as methohexital or thiopental, before the anesthesia. • Stage Three (Surgical Anesthesia): During this stage, the skeletal muscles relax, and the patient's breathing becomes regular. Eye movements slow, then stop, and surgery can begin. • Stage Four (Medullary Paralysis): This stage occurs if the respiratory centers in the medulla oblongata of the brain that control breathing and other vital functions cease to function. Death can result if the patient cannot be revived quickly. This stage should never be reached. Careful control of the amounts of anesthetics administered prevent this occurrence.
1. The medulla is the last area of the brain to be depressed during general anesthesia. Notes This area is the most vital part of the brain and contains the cardiac, the vasomotor,
and respiratory centers of the brain. 2. The most reliable sign of "oxygen want" while monitoring a patient during general anesthesia is an increased pulse rate. Cyanosis may also be present. 3.The emergency most frequently experienced during outpatient general anesthesia is respiratory obstruction. 4. The best anesthetic technique used in oral surgery to avoid aspiration of blood or other debris when a patient is under general anesthesia is endotracheal intubation with pharyngeal packs. 5. A patient with an acute respiratory infection is contraindicated for general anesthesia. 6. The eyes are taped shut prior to draping a patient before surgery to prevent corneal abrasion.
anesth
The recommended gas combination dose for conscious sedation is:
• varies according to the patient response The dose of the gas combination for conscious sedation is variable and is based on patient response. The maximum nitrous oxide limitation is 60% nitrous oxide and 40% oxygen. Nitrous oxide is a weak anesthetic and is used with other agents, such as thiopental, to produce surgical anesthesia. It has the fastest induction and recovery and is the safest because it does not slow breathing or blood flow to the brain.
Nitrous oxide has a low blood-to-gas partition coefficient (0.46) and, therefore, low solubility. It can leave the blood and enter air-filled cavities 34 times more quickly than nitrogen can leave the cavity to enter the blood. The use of nitrous oxide can increase the expansion of compliant cavities, such as a pneumothorax, bowel gas in a bowel obstruction, and an air embolism. Important: The oral and maxillofacial surgeon needs to be cautious when treating the recent trauma patient (e.g., motor vehicle accident victim). An asymptomatic, undiagnosed closed pneumothorax can double in size in 10 minutes after the administration of 70% nitrous. Nitrous oxide sedation should be postponed in patients with gastrointestinal obstructions, middle ear disturbances, and, possibly, sinus infections.
Partition Coefficients for Inhaled Anesthetics
Blood: gas
Brain: blood
Muscle: blood
Fat: blood
Oil: blood
Desflurane
0.42
1.3
2.0
27
18.7
Halothane
2.4
2.9
3.4
51
224
Isoflurane
1.4
1.6
2.9
45
90.8
N20
0.46
1.1
1.2
2.3
1.4
Sevoflurane
0.68
1.7
3.1
48
47.2
Minimal Alveolar Concentration (MAC) of Commonly Used Agents
Agent
Nitrous oxide
Isoflurane
Halothane
MAC
104
1.15
0.77
Agent
Desflurane
Sevoflurane
MAC
6.0
1.71
• phlebitis
Phlebitis is irritation or inflammation of a vein that is sometimes seen after IV administration of valium. This is usually attributed to the presence of propylene glycol in the mixture. Phlebitis is more likely to occur if a vein in the hand or wrist is used and may be more common following repeated injections, especially in heavy smokers, the elderly, and women taking oral contraceptives. Common signs and symptoms of phlebitis:
• Pain • Erythema • Tenderness • Streaking of the limb • Edema
Treatment: Remove the IV catheter, elevate the affected limb, apply warm, moist packs to the infected site, initiate IV antibiotics (preferably cefazolin [Ancef], 1 gm IVbolus push every 8 hours), for appropriate staphylococcus coverage. Thrombosis is the formation of a blood clot that may partially or completely block a blood vessel. A clot located in an inflamed blood vessel is called thrombophlebitis. Virchow triad is the name given to the three chief causes of deep venous thrombosis (DVT): (I) damage to the endothelial lining of the vessel, (2) venous stasis, and (3) a change in blood constituents attributable to postoperative increase in the number and adhesiveness of the patient's platelets. The classical clinical features of DVT are:
A patient who has developed DVT should be started immediately on systemic anticoagulation with elevation of the affected limb. Important: The most frequent respiratory complications following oral and maxillofacial surgery are: pulmonary atelectasis (most often in smokers), aspiration pneumonia (most likely to manifest initially in the patient's right lung), and pulmonary embolus (most originate in the deep venous systems of the lower extremities, especially in nonambulatory patients).
biopsy
When a biopsy is being performed, it is important to:
• incise perpendicular to the long axis of any muscle fibers beneath the lesion
1 incise parallel to the long axis of any muscle fibers beneath the lesion
• incise as deep as possible into muscle fibers beneath the lesion
incise at a 45-degree angle to the long axis of any muscle fibers beneath the lesion
• incise perpendicular to the long axis of any muscle fibers beneath the lesion
*** Whenever possible, the incisions should be oriented parallel to the lines of minimal tension in order to minimize scarring and wound dehiscence. Note: Biopsy incisions on the face should be oriented to follow Langer's lines.
Four major types of biopsy in and around the oral cavity: • Cytology: should be used as an adjunct to, not a substitute for, biopsy. Indications include: when large areas of mucosal change must be monitored for dysplastic change, such as herpes or pemphigus. Technique: the lesion is scraped repeatedly and firmly with a moistened tongue depressor or cement spatula. The cells obtained are smeared evenly on a glass slide, and the slide is immediately immersed in a fixing solution and examined under the microscope. • Aspiration biopsy or fine-needle aspiration (FNA): is the use of a needle and syringe to penetrate a lesion for aspiration of its contents. Indications include: it should be carried out on all lesions thought to contain fluid (with the possible exception of a mucocele) or any intraosseous lesion before surgical exploration. Technique: an 18-gauge needle is connected to a 5- or 10-mL syringe. The area is anesthetized and the 18-gauge needle is inserted into the depth of the mass during aspiration. • Incisional biopsy: removes only a representative portion or portions of a lesion along with a representation of adjacent normal tissue. Indications: if the area under investigation appears difficult to excise because of its extensive size (larger than 1 cm in diameter) or hazardous location, or whenever there is a great suspicion of malignancy. • Excisional biopsy: entails removal of the entire lesion along with at least 2 mm of normal marginal tissue from the sides of the lesion. This technique should be used with smaller lesions (less than 1 cm in diameter) that, on clinical examination, appear to be benign.
Important: It can not be overemphasized that all pertinent clinical information and the findings of other diagnostic modalities must be provided to the pathologist at the time of the initial submission of the specimen.
• 14 days — 2 weeks
Almost all oral ulcers caused by trauma will heal within 14 days. Therefore, any ulcer that is present for 2 weeks or more should be biopsied.
Biopsy is also indicated in the following instances: • Pigmented lesions (black/brown) • When tissue is associated with paresthesia, this is often an ominous sign • If a lesion suddenly enlarges, it should be biopsied
Note: Always aspirate a central bone lesion to rule out a vascular lesion. If a lesion seems compressible, pulsatile, or blue, or if a bruit is heard, beware of a vascular lesion and biopsy only under a controlled hospital setting. *** A stethoscope is used to listen for a bruit.
1. When the entire tumor is removed, it is called an excisional biopsy technique. If Notes o n i y a portion of the tumor is removed, it is called an incisional biopsy technique.
2. Brush biopsies are not recommended due to the number of false positives. 3. After removal, the tissue should be immediately placed in 10% formalin solution (4% formaldehyde) that is at least 20 times the volume of the surgical specimen. The tissue must be totally immersed in the solution, and care should be taken to ensure that the tissue has not become lodged on the wall of the container above the level of formalin. 4. A negative incisional biopsy report of a highly suspicious oral lesion suggests that another biopsy specimen is necessary in view of the clinical impressions. The key is a highly suspicious oral lesion. Tissue samplings should be obtained from multiple sites of the lesion.
Important: Unlike the more common types of oral ulcers, malignant lesions are usually painless, exhibit growth, and do not heal spontaneously. Consequently, biopsy of any ulcer that is present in the mouth for more than 2 weeks is mandatory.
biopsy
An incisional biopsy is indicated for which of the following lesions?
• a 0.5-cm papillary fibroma of the gingiva
• a 2.0-cm exostosis of the hard palate
• a 2.0-cm area of Fordyce disease of the cheek
• a3.0-cm hemangioma of the tongue
• a 3.0-cm area of leukoplakia of the soft palate
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disord/cond
Which of the following symptoms that suggest that your patient is dehydrated? Select all that apply.
• pale or gray skin color
• dry mouth
• decreased skin turgor
• modified state of consciousness
• high blood pressure
• rapid pulse
• reduced urine output
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• a 3.0-cm area of leukoplakia of the soft palate
Leukoplakia is a premalignant lesion. This means that if left untreated, some of the lesions progress to carcinoma. It is because of this chance of malignant transformation that all leukoplakic lesions should be biopsied.
Biopsy Technique and Surgical Principles: • Anesthesia: Block local anesthetic techniques are employed when possible; if not, infiltration may be used but the solution should be injected at least 1 cm away from the lesion • Tissue stabilization: Use fingers or clamps • Hemostasis: Gauze compresses (avoid high speed suction) or gauze-wrapped suction tip on a low-volume suction device • Incision: Sharp scalpel • Extent of tissue: Obtain some normal tissue adjacent to lesion if possible • Handling of tissue: Use a traction suture through the specimen, not tissue forceps, to avoid specimen trauma. Traction sutures can also mark a point on the specimen so that the lesion can be oriented should there be a positive margin. • Specimen care: After removal, the tissue should be immediately placed in 10% formalin solution that is at least 20 times the volume of the surgical specimen. Note: No other solution is acceptable. • Wound management: Requires either a primary closure (preferably) or placement of periodontal dressings in cases of gingival or palatal biopsies where secondary healing will be necessary • Records: A Biopsy Data Sheet should be accurately filled out
The Method of Tissue Removal Varies Among the Type of Biopsies: 1. In a needle (percutaneous) biopsy, the tissue sample is simply obtained by use of a syringe. A needle is passed into the tissue to be biopsied, and cells are removed through the needle. 2. In an open biopsy, an incision is made in the skin, the organ is exposed, and a tissue sample is taken. 3. A closed biopsy involves a much smaller incision than open biopsy. The small incision is made to allow insertion of a visualization device, which can guide the physician to the appropriate area to take the sample.
• pale or gray skin color • dry mouth • decreased skin turgor • modified state of consciousness • rapid pulse • reduced urine output
Dehydration is the loss of water and important blood salts like potassium (K+) and sodium (Na+). Vital organs, such as the kidneys, brain, and heart, can't function without a certain minimum amount of water and salt. Causes include decreased intake (lack of water) and/or increased output (vomiting, diarrhea, loss of blood, drainage from burns, diabetes melli-tus, diuretic use, or a lack of ADH owing to diabetes insipidus).
Initially, a patient suffering from dehydration will clinically demonstrate only dryness of the skin and mucous membranes.
However, as dehydration progresses, the turgor (or fullness) of the skin is lost. If dehydration persists, oliguria (reduced urine output) occurs as a compensation for the fluid loss. More severe degrees of fluid loss are accompanied by a shift of water from the intracellular space to the extracellular space, a process that causes severe cell dysfunction, particularly in the brain. Systemic blood pressure falls with continuous dehydration, and declining perfusion eventually leads to death.
Fluids in several forms should be continually urged on the patient. In severely dehydrated individuals, they must get to the hospital right away. IV fluids will quickly reverse dehydration and are often life saving in young children and infants.
disord/cond
Patients with a fasting plasma glucose level higher than or a random plasma glucose of greater than have diabetes mellitus.
Your 60-year-old patient presents with congestive heart failure. They note cardiac symptoms with mild activity but are asymptomatic at rest. What is the functional classification of heart failure in your patient?
Diabetes mellitus is an absolute or relative insulin insufficiency caused either by a low output of insulin from the pancreas or by unresponsiveness of peripheral tissues to insulin. Diabetes is the leading cause of blindness, end-stage renal disease, and nontraumatic limb amputation in the United States. Diabetes increases risk for cardiovascular, cerebral, and peripheral vascular disease.
Many patients with diabetes mellitus have no symptoms, and the diagnosis is made because of abnormal blood glucose levels detected on a routine screening. Some patients may develop polydipsia, polyuria, polyphagia, and weight loss. In patients with severe insulin deficiency, development of ketoacidosis may cause nausea, vomiting, lethargy, confusion, and coma.
The major concern for the dentist treating a patient who has diabetes mellitus is hypoglycemia. This most often occurs when the medications used to reduce high blood glucose cause levels to drop beyond what is physiologically needed for the body to function. Symptoms of hypoglycemia: weakness, nervousness, excessive sweating, tremulousness, and palpitations. The symptoms may progress from confusion and agitation to seizures and coma without intervention.
1. The treatment of choice for hypoglycemia in a conscious diabetic is the administration of Notes an oral carbohydrate (packets of table sugar, orange juice, cola beverages, candy bars, etc.)
2. The treatment of choice for hypoglycemia in an unconscious diabetic patient: EMS should be contacted. Then 1 mg of glucagon can be injected IM, or 50 ml of 50% glucose solution can be given by rapid IV infusion. The glucagon injection should restore the patient to a conscious state within 15 minutes; then some form of oral sugar can be given. 3. People with well-controlled diabetes are no more susceptible to infections than people without diabetes, but they have more difficulty containing infections (this is caused by altered leukocyte function). 4. Patients who take insulin daily and check their urine regularly for sugar and ketones (controlled diabetics) usually can be treated in the normal manner without additional drugs or diet alterations. Important: If any doubt exists as to the patient's medical status, consultation with the patient's physician is indicated. Do not assume anything!
• class III
Class I congestive heart failure is defined as no cardiac symptoms with activity, Class II is symptoms with marked activity, Class III is symptoms with mild activity, and Class IV is symptoms at
rest Congestive heart failure (CHF) results from impaired pumping ability by the heart. A ventricular ejection fraction below 50% is indicative of CHF. Valvular heart disease, coronary artery disease, arrhythmias, hypothyroidism, high cardiac output syndromes, and hypertension can lead to heart failure. Note: Usually the left ventricle fails first, soon followed by right-sided failure. The presenting symptoms include dyspnea, orthopnea, paroxysmal nocturnal dyspnea, fatigue, exercise intolerance, and edema. Note: The most common sign of left-sided heart failure is pulmonary edema, whereas right-sided heart failure causes pedal (peripheral) edema or abdominal swelling. Pharmacologic therapy: goals are to control fluid retention, control neurohormonal activation, and control symptoms.
• Diuretics (e.g., Lasix, Aldactone, Zaroxolyn), are used to control fluid retention • ACE inhibitors (e.g., captopril, lisinopril), which interfere with the renin-angiotensin system, are required of all patients with cardiac failure unless contraindicated • Vasodilators, including hydralazine and nitrates, are used when the use of ACE inhibitors is
not possible • Beta blockers (e.g., carvedilol, bisoprolol, metoprolol, atenolol), should be used in patients with left ventricular dysfunction, unless contraindicated • Digitalis can improve symptoms and exercise tolerance by increasing cardiac contractility • Other medications include oxygen and morphine • Aspirin, NSAIDs, and calcium channel blockers should be avoided
Patient treatment and dental management considerations: • Prolonged rest, administration of oxygen • Digitalis (patients are prone to nausea and vomiting) • Diuretics/vasodilators (patients are prone to orthostatic hypotension; avoid excessive epinephrine) • Dicumarol (patients may have bleeding problem,)
The unpleasant sensation of difficulty in breathing
Increase in depth of respiration
Permanent cessation of breathing (unless corrected)
An increase in both rate and depth of respiration
A reduced rate and depth of respiration
1. Hyperventilation results in the loss of carbon dioxide (COf) from the blood Notes (hypocapnia), thereby causing a decrease in blood pressure and sometimes fainting.
2. Hypoventilation results in an increased level of carbon dioxide (CO2) in the blood (hypercapnia). 3. The respiratory rate is 10-20 breaths/min in normal adults and 44 breaths/min in infants. A respiratory rate of >20/min is considered tachypnea, and a respiratory rate <10/min is bradypnea. 4. Kussmaul respiration is an increase in both rate and depth of respiration and is synonymous with hyperventilation. 5. Cheyne-Stokes breathing is alternating hyperpnea, shallow respiration, and apnea. Children and the elderly normally show this pattern in sleep. In normal adults, causes of this pattern of breathing include heart failure, uremia, drug-induced respiratory depression, and brain damage. 6. Stridor is a high-pitched respiratory sound, such as the inspiratory sound heard often in acute laryngeal obstruction.
• atelectasis
Atelectasis occurs when mucus or a foreign object obstructs airflow in a main stem bronchus causing collapse of the affected lung tissue into an airless state. It typically occurs 36 hours postoperatively and presents with mild dyspnea, low-grade fever, and hypoxia. Note: Prolonged atelectasis can lead to pneumonia.
The treatment of postoperative atelectasis is aimed at expansion of the lung, and, for most patients, incentive spirometry (encouraging the patient to take long, slow, deep breaths) is adequate. However, in patients with severe atelectasis, endotracheal suction and even bronchoscopy may be warranted.
Pneumothorax occurs when air leaks into the pleural space causing the lung to recoil from the chest wall. In an awake patient, a pneumothorax typically presents with dyspnea, chest pain, absence of breath sounds on the affected side, and evidence of pneumothorax on a chest x-ray. Tracheal deviation may be present.
The objective of treatment for a pneumothorax is to remove the air from the pleural space, allowing the lung to re-expand. In an emergency, a small needle (such as a standard Intravenous needle) may be placed into the chest cavity through the ribs to relieve the excessive pressure. The definitive treatment is a chest tube - a large plastic tube that is inserted through the chest wall between the ribs to remove the air completely.
1. Pneumonitis (inflammation of the lung) and atelectasis are two of the most Notes common causes of fever in a patient who has had general anesthesia.
2. The most common post-op complication of outpatient general anesthesia is
nausea.
disord/cond
A 55-year-old male presents to your office with a long history of a productive cough. The patient states that the cough has been present for 6 months during each of the last 3 years. The patient is afebrile and chest x-ray is unremarkable.
Which of the following acid-base abnormalities will develop in a patient with recurrent vomiting of gastric contents?
respiratory acidosis
respiratory alkalosis
• metabolic acidosis
• metabolic alkalosis
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• chronic bronchitis
COPD is a disease due to persistent airway obstruction. Two diseases account for the bulk of the patients with COPD: emphysema and chronic bronchitis. There is continuing debate as to whether this term also includes acute asthma. As a general rule, it is not included because it is partly reversible and is more generally considered a restrictive lung disease. In most cases, bronchitis and emphysema occur together. Note: Secondary pulmonary hypertension is most often caused by COPD.
Comparison of Emphysema and Chronic Bronchitis
Description
Major complaint
Age of onset
Body habitus
Lung exam
Peripheral edema
Hemoglobin
Blood gases
Chest X-ray
Emphysema
"Pink puffer"
Dyspnea
After age 50 years
Thin
No adventitious sounds
Negative
Normal
PO, normal or reduced PCO, normal or elevated
Hyperinflated with flat diaphragms
Chronic Bronchitis
"Blue bloater"
Chronic cough
Late 30s and 40s
Overweight
Rhonchi arc present
Positive
Elevated
P02 reduced PC02 elevated
increased interstitial markings and normal diaphragms
Important : 1. Drugs with antiplatelet activity (aspirin) should be prescribed to COPD patients with caution. Hemoptysis has been reported after the use of aspirin in patients with COPD. 2. COPD patients taking theophylline should not be prescribed erythromycin. Erythromycin increases the metabolism of theophylline and may cause toxicity.
Acidosis vs Alkalosis • If pH is less than 7.35, the patient is acidemic • If pH is greater than 7.45, the patient is alkalemic
Determine primary process • After evaluating pH, look at PC02 and bicarbonate
- If pH is acidemic and PC02 is greater than 45 mmHg, the primary process is respiratory; if bicarbonate is less than 22, the primary process is metabolic
- If pH is alkalemic and the PC02 is less than 35 mmHg, the primary process is respiratory; if bicarbonate is greater than 26, the primary process is metabolic.
Metabolic acidosis: Etiologies- diabetic or starvation ketoacidosis, lactic acidosis, uremia, severe
dehydration. Clinical manifestations: Dyspnea on exertion and nausea and vomiting are common
Clinical manifestations: CNS symptoms such as confusion, delirium, and coma. Cardiac arrhythmias and hypotension may be noted
Respiratory acidosis: Etiologies- COPD, asthma, severe pneumonia or pulmonary edema, CNS depression (drugs, CNS event), acute airway obstruction, pneumothorax
Clinical manifestations: Related to degree and duration of acidosis and presence of hypoxia. In acute disease, CNS symptoms such as confusion, anxiety, psychosis, and seizures may be noted; In chronic disease, there is lethargy, fatigue, and confusion
Respiratory alkalosis: Etiologies- anxiety, hypoxia, CNS disease, drug use (salicylates), preg
nancy, sepsis Clinical manifestations: May cause dizziness, perioral paresthesias, confusion, hypotension, siezures, and coma
disord/cond
Which statement below is true regarding type 2 diabetes?
• was formally known as insulin-dependent diabetes
• patients have little or no insulin secretion capacity
• symptoms appear abruptly and include polyuria, polydipsia, polyphagia, and weight loss
• accounts for 90% of all cases of clinical diabetes
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disord/cond
The clinical presentation of acute asthma includes which of the following?
• accounts for 90% of all cases of clinical diabetes
Diabetes is the most common pancreatic endocrine disorder. It is a metabolic disease involving mostly carbohydrates (glucose) and lipids. It is caused by absolute deficiency of insulin (type 1) or resistance of insulin's action in the peripheral tissues (type 2). The classic triad of symptoms includes polydipsia, polyuria, and polyphagia.
= „ . _ - , , . *~uiujiausuu oi • ype i ana lype L uiaueies ivieuitus
Characteristic
Level of insulin
Typical age of onset
Percentage of diabetes
Basic defect
Associated with obesity
Speed of development of symptoms
Development of ketosis
Treatment
Type 1 Diabetes
None
Childhood
10-20%
Destruction of beta cells
No
Rapid
Common if untreated
Insulin injections, dietary management
Type 2 Diabetes
May be normal or exceed normal
Adulthood
80-90%
Reduced sensitivity of insulin's target cells
Usually
Slow
Rare
Dietary control and weight reduction; occasionally oral hypoglycemic drugs
Asthma is a condition characterized by episodic reversible narrowing of the airways. The most common symptoms include episodic wheezing, cough, chest tightness, and shortness of breath. The disease can begin at any age, but about half of patients develop asthma before the age of 10. There are three basic pathophysiologic changes: (1) airway inflammation (2) airway obstruction and (3) airway hyperresponsiveness
Important: An acute asthmatic attack is best treated by administration of supplemental oxygen with an in-halaled betan-adrenergic agonist (albuterol, terbutaline). If the patient is resistant to beta agonists, theophylline should be considered. In a severe asthmatic attack that is unresponsive to the above treatment, 0.3 mg of 1:1000 epinephrine should be administered subcutaneously.
Important: There are no contraindications for the use of nitrous oxide sedation in asthmatic patients. Because anxiety is a stimulus for an asthmatic attack, nitrous oxide sedation is actually beneficial for these patients. If patient is taking steroids, consult physician for the possible need for corticosteroid augmentation.
General guidelines for the management of patients with asthma:
• Minimize stress: short appointments, use sedation techniques (nitrous, diazepam or other oral antianxiety medications). • Avoid antihistamines • Minimize epinephrine use (local anesthesia up to 2 carpules of 2% lidocaine with 1:100,000 epinephrine may be used) • Avoid erythromycins and clarithromycin in patients on theophylline • Be aware of aspirin sensitivity: there is a clinical triad of asthma, nasal polyps, and aspirin sensitivity. It is important to be sure that the patient with asthma does not have this triad when aspirin-containing preparations are prescribed.
Status asthmaticus is the most severe clinical form of asthma, usually requiring hospitalization, that does not respond adequately to ordinary therapeutic measures. If not managed properly, chronic partial airway obstruction may lead to death from respiratory acidosis (which is produced by hypoxemia and hypercapnia).
disord/cond Which of the following coagulation factors is deficient in hemophilia B?
A history of rheumatic fever, IV drug abuse, or heart murmur should alert the dentist to the possibility of:
•diabetes mellitus
• AIDS
• valvular disease
• end-stage renal disease
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• IX Hemophilia A and B are inherited as a sex-linked recessive trait by which males are affected and females are carriers. The majority of people afflicted with hemophilia have type A, and it presents under the age of 25. The signs, symptoms and clinical manifestations include excessive bleeding from minor cuts, epistaxis, hematomas, and hemarthroses. Classifications of Hemophilia:
• Hemophilia A: considered the classical type, caused by a deficiency of coagulation factor VIII (antihemophilic factor). • Hemophilia B (also called Christmas disease): due to a deficiency in factor IX (Christmas factor) • Hemophilia C (also called Rosenthal syndrome): not sex-linked, less severe bleeding. Due to a deficiency of factor XI. Rare disorder but more common in Ashkenazi Jews.
Important: A true hemophiliac is characterized by having the following: • Prolonged partial thromboplastin time (PTT) • Normal prothrombin time (PT) • Normal platelet count • Normal bleeding time
Note: von Willebrand disease is inherited as an autosomal dominant bleeding disorder, it occurs with equal frequency in both sexes. Due to the absence of von Willebrand factor (VWF), which results in failure to form a primary platelet plug. Laboratory, features include a prolonged PTT and prolonged bleeding time. Thrombocytopenia:
• Idiopathic thrombocytopenic pupura (ITP): autoimmune bleeding disorder in which patients develop antibodies against their own platelets. Signs and symptoms: no splenomegaly, superficial bleeding of the skin, mucous membranes, and genitourinary tract. • Thrombotic thrombocytopenic purpura (TTP): characterized by severe thrombocytopenia, microangiopathic hemolytic anemia (have presence of schistocytes), and neurologic abnormalities. Signs and symptoms: fever, neurologic abnormalities, including headache, aphasia, or stupor.
Important: Patients with valvular heart disease are also at risk for bacterial endocarditis.
Rheumatic fever is a sequela of a previous Group A , beta-hemolytic streptococcal infection, usually of the upper respiratory tract. The disease involves the heart, joints, central nervous system skin and subcutaneous tissues. It is characterized by an exudative and proliferative inflammatory lesion of the connective tissue, especially that of the heart, joints, blood vessels, and subcutaneous tissue.
Heart inflammation (carditis) disappears gradually, usually within 5 months. However, it may permanently damage the heart valves, resulting in rheumatic heart disease. The valve between the left atrium and ventricle (mitral valve) is most commonly damaged. Note: The pulmonary valve is rarely involved.
Remember: A heart murmur may have no pathological significance or may be an important clue to the presence of valvular, congenital, or other structural abnormalities of the heart.
disord/cond
A tall, thin patient presents to your office with shortness of breath. On examination, you note the patient is breathing through "pursed" lips, his expiratory phase is prolonged, and lung sounds are distant. Which of the following is the most likely diagnosis?
• asthma
• bronchiectasis
• cystic fibrosis
• emphysema
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disord/cord
Special considerations must be taken when treating a patient on renal dialysis. Which of the following should be considered? Select all that apply.
• treat the day before dialysis
• treat the day after dialysis
• NSAIDs are the best analgesic to use
• morphine is acceptable for use as an analgesic
• be aware of shunts when taking the patients blood pressure
• consider that the patient may be on steroid therapy
The emphysema or "pink puffer" patient is typically thin and presents with dyspnea, pursed-lip breathing and pink skin color. Arterial blood gases reveal hypoxia and hypercapnia. Emphysema is defined as destructive changes to the alveoli walls and enlargement of air spaces. It affects the lung parenchyma distal to terminal bronchioles. Cigarette smoking is major risk factor (increases risk by 10 to 30 times compared to nonsmokers). Note: Alpha-1-antitrypsin deficiency should be suspected in patients who develop emphysema in their late 30s.
Bronchiectasis: abnormal dilatation of the large conducting pathways, due to congenital structural abnormalities or acquired processes. Congenital causes include cystic fibrosis and alphal-antitrypsin deficiency. Acquired processes include viral and bacterial infections, foreign bodies, and tumors. The major symptom is a cough, which is daily and productive with purulent sputum. Hemoptysis may accompany the cough. As disease progresses, exercise intolerance and dyspnea develop.
Cystic fibrosis: an autosomal recessive disease that is the most common lethal inherited disease in American whites. Most patients are diagnosed in the preteen years. It is due to a defect in cystic fibrosis transmembrane conductance regulator. Symptoms are due to development of thick secretions that block the airways and ductal system in other organs (usually pancreas and liver). Common symptoms include chronic cough with sputum production and dyspnea.
Remember: Patients with chronic bronchitis (or any COPD) can have difficulty during oral surgery. Many of these patients depend on maintaining an upright posture to breathe adequately. They frequently experience difficulty breathing if placed in an almost supine position or if placed on high-flow nasal oxygen.
Important: Patients with chronic bronchitis may be predisposed to lung cancer (bronchogenic carcinoma).
• treat the day after dialysis • be aware of shunts when taking the patients blood pressure • consider that the patient may be on steroid therapy
Fr,d staae renal disease (ESRD) is a condition in which there is a permanent and almost L l l e t e los" of kdney function. The kidney functions at less than 10% of its normal c a a c S In end-stage renal disease, toxins slowly build up in the body. Normal kidneys remove these S , urea and creatinine) from the body through urine. In chronic renal disease, there is a slow, progressive decline in kidney function (low glomerular filtration rate [GFR] and fall in urine output). Creatinine clearance is a measure of GFR:
Patients with ESRD: • Are often on steroid therapy • Are more susceptible to post-op infections • Have an increased tendency to bleed
*** When oral surgical procedures are undertaken on these patients, meticulous attention to good surgical technique is necessary to decrease the risks of excessive bleeding and infection.
Some important points to remember when treating patients with renal insufficiency and those on he-
^ N e l e ' r measure the patient's blood pressure on the arm where the dialysis shunt has been created • Avoid the use of drugs that are metabolized or excreted by the kidney . Avoid the following analgesics: aspirin, acetaminophen, NSAIDs, meperidine, and morphine • Perform oral surgery the day after dialysis • Consult physician for possible prophylatic antibiotics
drugs Codeine, a widely used analgesic in dentistry:
• is a natural constituent of opium
• may be given only by injection
• has a calming effect on gastric mucosa
• is stronger than morphine, more addictive, and more constipating
• is a natural constituent of opium Next to morphine, codeine is the most important alkaloid of opium. Codeine has two primary therapeutic effects: analgesic and antitussive. Codeine is relatively less potent than morphine and does not have the abuse potential of morphine. It is more likely than other opioids, other than morphine, to cause constipation and nausea. Codeine is usually combined with other drugs, for example, Empirin (aspirin + codeine), and Tylenol #2, 3, and 4 (acetaminophen + codeine). Note: Morphine is effective in providing relief of moderate to severe pain but is associated with the adverse effects of constipation, nausea, and vomiting. Opioid analgesics are thought to inhibit painful stimuli in the substantia gelatinosa of the spinal cord, brain stem, reticular activating system, thalamus, and limbic system. Opiate receptors in each of these areas interact with neurotransmitters of the autonomic nervous system, producing alterations in reaction to painful stimuli. Actions of opioid analgesics can be defined by their activity at three specific receptor types:
• Kappa receptors: analgesia, sedation, dysphoria, psychomimetic effects • Delta receptors: analgesia, modulates activity at the mu receptor
Pharmacokinetics of Selected Oral Opioid Analgesics
Drug
Opioid Agonists
Morphine
Codeine
Hydrocodone (Vicodin, Lorcet, Lortab)
Oxycodone (Percodan, Percocet)
Oxycodone, time-release formula (OxyContin)
Hydromorphone (Dilaudid)
Meperidine (Demerol)
Fentanyl (Duragesic transdermal)
Methadone
Propoxyphene (Darvon)
Onset of Action
15-60 min
10-30 min
10-20 min
15-30 min
1 hr
15-30 min
10-15 min
12-24 hr
30-60 min
15-60 min
Duration of Action
4-5 hr
4-6 hr
4-8 hr
3-4 hr
12 hr
4-5 hr
2-4 hr
3 days
4-7 hr
4-6 hr
• lorazepam
Anterograde amnesia, minimal depression of ventilation and the cardiovascular system, and sedative properties make benzodiazepines favorable preoperative medications. Clinical uses for benzodiazepines include: preoperative medication, IV sedation, induction of anesthesia, maintenance of anesthesia, and suppression of seizure activity. Benzodiazepines act by potentiating the action of GABA, an amino acid and inhibitory neurotransmitter, which results in increased neuronal inhibition and CNS depression. Benzodiazepines bind to specific benzodiazepine receptor sites, which are found on postsynaptic nerve endings in the CNS. Benzodiazepines are the most effective oral sedative drugs used in dentistry. The most common benzodiazepines used as amnesties in anesthesiology are midazolam (most common), lorazepam, and diazepam.
• Midazolam (Versed): is the most lipid soluble of the three and, as a result, has a rapid onset and a relatively short duration of action. Is prepared as a water-soluble compound that is transformed into a lipid-soluble compound by exposure to the pH of blood upon injection. This unique property of midazolam improves patient comfort when administered by the IV or IM route. This prevents the need for an organic solvent such as propylene glycol, which is required for diazepam and lorazepam. • Diazepam (Valium): is water-insoluble and requires the organic solvent propylene glycol to dissolve it. The onset time is slightly slower than that of midazolam. • Lorazepam (Ativan): is the least lipid soluble of the three main benzodiazepines, resulting in a slow onset of action but long duration of action. It requires propylene glycol to dissolve it, which increases its venoirritation. Lorazepam is a more powerful amnestic agent than midazolam, but its slow onset and long duration of action limit its usefulness for preoperative anesthesia.
1. Chloral hydrate is a sedative and hypnotic that is widely used for pediatric se-
Notes dation. 2. Emotional stress decreases the rate of absorption of a drug when given orally.
drugs Which of the following drugs would be BEST given to a patient with a history of gastric ulcers?
Acetaminophen (Tylenol) is the only over-the-counter non-antiinflammatory analgesic commonly available in the USA. It is a weak cyclooxygenase inhibitor in peripheral tissues, thus accounting for its lack of antiinflammatory effect. It may be a more effective inhibitor of prostaglandin synthesis in the CNS, resulting in analgesic and antipyretic action. Acetaminophen does not produce gastric ulceration like aspirin does. The combination of acetaminophen and propoxyphene (called Darvocet-N or Wygesic) is used to treat moderate to severe pain due to dental procedures. Note: Propoxyphene (Darvon) is an oral synthetic opioid analgesic structurally similar to methadone. Darvon compound-65 is a combination of aspirin, caffeine, and propoxyphene.
1. Acetaminophen does not affect clotting time as does aspirin — it does not Notes have significant antiplatelet effects. It is effective for the same indications as in
termediate-dose aspirin. It is, therefore, useful as an aspirin substitute, especially in children with viral infections (who are at a risk for Reye syndrome if they take aspirin). 2. Aspirin is an antiinflammatory, antipyretic, and analgesic agent that is used to relieve headaches, toothaches, minor aches and pains, and to reduce fever. The GI tract rapidly absorbs it. 3. Talwin compound combines the strong analgesic properties of pentazocine and the analgesic, antiinflammatory, and fever-reducing properties of aspirin. It is used for the relief of moderate pain. It does not produce euphoria. 4. The most appropriate time to administer the initial dose of an analgesic to control postoperative pain is before the effect of the local anesthetic wears off. 5. Remember: the following analgesics should be avoided in patients with renal disease: aspirin, acetaminophen, NSAIDs, meperidine and morphine.
• thiopental
Barbiturates exhibit a dose-dependent central nervous system depression with hypnosis and amnesia. Barbiturates are very lipid soluble, which results in a rapid onset of action. They are used most often for induction of anesthesia because they produce unconsciousness in less than 30 seconds.
Barbiturates inhibit depolarization of neurons by binding to the GAB A receptors, which enhances the transmission of chloride ions. Note: Barbiturates are potent cerebral vasoconstrictors resulting in decreases in cerebral blood flow, cerebral blood volume, and intracranial pressure (ICP).
Ultra-short-acting barbiturates: • Thiamylal (Surital) • Methohexital (Brevital) • Thiopental (Pentothal) -no longer available in the United States
Long-acting barbiturates: • Phenobarbital (Luminal): generally not used in oral surgery
Important: Barbiturates are contraindicated in patients with respiratory disease or those who are pregnant.
Note: Physical dependence is likely to develop with barbiturates if abused. The dependence has a strong psychological as well as physical basis. Sudden withdrawal from high doses can be fatal.
drugs
should be used cautiously in the elderly. It should never be given to patients on monoamine oxidase inhibitors for psychiatric disease and is generally contraindicated in patients receiving phenytoin (Dilantin) for seizure disorders.
• meperidine Meperidine (Demerol) is a synthetic opioid analgesic with less potency than morphine. It is used for the relief of moderate to severe pain, for preoperative sedation, for postoperative analgesia, for obstetric anesthesia, and, when given IV, for supportive anesthesia. It is probably the most widely used narcotic in American hospitals. It should be used with particular caution, if at all, in the elderly. It is the drug of choice among drug abusers and must be used with extreme caution. Meperidine is the most abused drug by health professionals. The onset of action is more rapid, but the duration of action is shorter, than that of morphine. Note: It produces slight euphoria but no miosis.
Meperidine is often prescribed as 50 mg every 4 hours as needed for pain. It is often simultaneously prescribed with the drug promethazine (Phenergan) in 25-50 mg doses every 4 hours. The promethazine is a sedative and enhances the effect of meperidine. Therefore, less meperidine yields more analgesia when in combination with promethazine. In addition, promethazine is an antiemetic, which helps negate some of the side effects of meperidine, namely, nausea.
Important: Concomitant administration of meperidine and MAO inhibitors has resulted in life-threatening hyperpyrexic reactions that may culminate in seizures or coma. Monoamine oxidase (MAO) inhibitors are a class of drugs used for depression and Parkinson disease. Examples of MAO inhibitors include isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and selegiline (Eldepryl).
Mechanism of action: thought to act by increasing endogenous concentrations of norepinephrine, dopamine, and serotonin through inhibition of the enzyme monoamine oxidase, responsible for the breakdown of these neurotransmitters.
Note: There is a decreased effectiveness of meperidine in the presence of phenytoin (Dilantin)
Remember: Morphine is the standard drug to which all analgesic drugs are compared. It causes euphoria, analgesia, and drowsiness along with miosis and respiratory depression.
• mydriasis • cycloplegia • reduction of salivation • prevention of cardiac slowing during general anesthesia
The cholinergic blocking (anticholinergic) drugs competitively inhibit the action of acetylcholine at parasympathetic postganglionic neuroeffector sites. The principal drags in this category are atropine and scopolamine, which are useful in dentistry as agents to control salivary secretion and as preanesthetic medication. The desirable clinical effects of the anticholinergics are mydriasis, antispasmodic actions, and reduction in gastric and salivary secretions.
The pharmacologic actions of atropine and scopolamine are similar in many respects. Atropine, in the usual dose used in dentistry, does not show a CNS response. Scopolamine, however, has a depressant effect on the CNS, which accounts for its usefulness as a preanesthetic agent and perhaps its use in motion sickness in several over-the-counter preparations. Both drags will reduce salivary flow and in large doses, block the cardiac-slowing effect of the vagus nerve.
Anticholinergic drags should be used with considerable caution in patients with cardiovascular disease and are contraindicated in patients with glaucoma, prostate hypertrophy, and intestinal obstruction.
Side effects are common with the anticholinergic drags and include blurred vision, tachycardia, urinary retention, constipation, decreased salivation, sweating, and dry skin.
Note: Atropine and scopolamine are also extremely useful in therapy and examination of the eye. These drugs produce dilation (mydriasis) and paralysis of accommodation for distance vision and light (cycloplegia). Such effects are generally long-lasting and can also be manifested by larger systemic doses of the drags.
drugs A sedative dose of a barbiturate should be expected to produce:
Impacted maxillary third molars are occasionally displaced into two areas: • Maxillary sinus (antrum): from which they are removed via a Caldwell-Luc approach • Infratemporal space: during elevation of the tooth the elevator may force the tooth posteriorly through the periosteum into the infratemporal fossa. If access and light are good, the tooth may be retrieved with a hemostat. If the tooth is not retrieved after a short amount of time, the area should be closed. The patient should be informed that the tooth has been displaced and will be removed by an oral surgeon who will use a special technique to remove it.
Note: To minimize the chance of dislodging an impacted maxillary third molar into the infratemporal fossa during its surgical removal, (1) develop a full-thickness mucope-riosteal flap, bringing the incision anterior to the second molar (add a releasing incision if necessary), to improve visualization of the impacted tooth, and (2) place a broad retractor distal to the molar while elevating it. Remember:
1. When performing a surgical removal of a mandibular molar, do not section through the entire tooth. The lingual plate is often thin, and complete sectioning may perforate the plate and injure the lingual nerve. 2. The inferior alveolar nerve most often lies buccal and slightly apical to the roots of a mandibular third molar. 3. Buccal-to-lingual movement is not efficient when removing mandibular posterior teeth because mandibular bone is too dense and does not expand in a similar fashion to that of the maxillary bone.
• at the same height of the operator's shoulder
The chair usually has to be repositioned to be satisfactory for exodontics. For mandibular extractions, the patient should be positioned so that the occlusal plane of the mandibular arch is parallel to the floor when the mouth is opened. The chair should be as low as possible. For maxillary extractions, the upper jaw of the patient should be at the height of the operator's shoulder. These positions allow the upper arm to hang loosely from the shoulder girdle and obviate the fatigue associated with holding the shoulders in an unnaturally high position during the course of the day. The low positions allow the operator to bring the back and leg muscles into the operation to assist the arm. The chair can be tipped backward slightly for maxillary extractions.
The fingers of the left hand (for a right-handed dentist) serve to: • Retract the soft tissue • Provide the operator with sensory stimuli for the detection of expansion of the alveo
lar plate and root movement under the plate • Help guide the forceps into place on the tooth • Protect teeth in the opposite jaw from accidental contact with the back of the forceps • Support the mandible while performing mandibular extractions
Remember: recommended sequence of extraction: • Maxillary teeth before mandibular teeth • Posterior teeth before anterior teeth
exo Which of the following are contraindications to tooth extraction. Select all that apply.
An acute apical abscess should not be a contraindication to extraction. It has been shown that these infections can resolve very quickly when the affected tooth is removed. However, it may be difficult to extract such a tooth, either because the patient is unable to open sufficiently wide enough or because adequate local anesthesia cannot be obtained.
There are few true contraindications to the extraction of teeth. Note: In some instances, the patients' health may be so compromised that they cannot withstand the surgical procedure.
Examples of contraindications include: • End-stage renal disease • Severe uncontrolled metabolic diseases (i.e., uncontrolled diabetes mellitus) • Advanced cardiac conditions (unstable angina) • Patients with leukemia and lymphoma should be treated before extraction of teeth • Patients with hemophilia or platelet disorders should be treated before extraction of teeth • Patients with a history of head and neck cancer need to be treated with care because even minor surgery can lead to osteoradionecrosis. Note: These patients are often treated with hyperbaric oxygen therapy prior to dental surgery. • Pericoronitis: infection of the soft tissues around a partially erupted mandibular third molar Note: This infection should be treated prior to removal of the maxillary third molar. • Acute infectious stomatitis and malignant disease are relative contraindications • Treatment with IV bisphosphonates increases the risk of osteonecrosis of the jaw
Note: Causes of excessive bleeding after dental extractions include: injury to the inferior alveolar artery during extraction of a mandibular tooth (usually the third molar), a muscular arteriolar bleed from a flap procedure, or bleeding related to the patient's history (i.e., patients who are on warfarin or drugs for platelet inhibition, patients who have hemophilia or von Willebrand disease, or who have chronic liver insufficiency).
• close the wound in layers to minimize the postoperative void • apply pressure dressings • use drains to remove any bleeding that accumulates
Dead space in a wound is any area that remains devoid of tissue after closure of the wound. It is created by either removing tissues in the depths of a wound or by not reapproximating tissue planes during closure. Dead space in a wound usually fills in with blood, which creates a hematoma with a high potential for infection. This is more likely to happen in closed wound incisions or in an open wound that has closed over at the top too quickly, leaving "dead space" open underneath. Some of these may resolve themselves, but most need to have the fluid drained, and the "dead space" needs to be closed, either by deep suturing or by reopening the top of the wound and packing until it heals from the bottom up.
Ways in which you can eliminate dead space: • Close the wound in layers to minimize the postoperative void • Apply pressure dressings • Use drains to remove any bleeding that accumulates • Place packing into the void until bleeding has stopped
Important: Infections are uncommon in healthy patients. However, whenever a mu-coperiosteal flap is elevated for a surgical extraction, there is a possibility for a subperiosteal abscess. Thus, all surgical flaps should be irrigated liberally prior to closing with sutures. Note: The treatment for a subperiosteal abscess is drainage of the abscess and antibiotic treatment.
exo Which of the following is the primary direction of luxation for extracting maxillary deciduous molars?
*** As opposed to the buccal direction in adults. This is because the deciduous molars are more palatally positioned and the palatal root is strong and less prone to fracture.
In general, the removal of deciduous teeth is not difficult. It is facilitated by the elasticity of young bone and the resorption of the root structure. Do not use the "cowhorn" forceps for extraction of lower primary molars because the sharp beaks of these forceps could cause damage to the unerapted permanent premolar teeth.
1. If the preoperative radiograph shows that the permanent premolar is Notes wedged tightly between the bell-shaped roots of the primary tooth, the best treat
ment is to section the crown of the primary molar and remove the two portions separately. This will help in not disturbing the permanent tooth. 2. After extraction of mandibular teeth on a child in which mandibular block was given, always advise child not to bite on his/her lip while he or she is numb. Inform parents to watch the child so this does not occur.
• smooth the sharp edges of the remaining bone and suture the remaining soft tissue
A fracture of the maxillary tuberosity most commonly results from extraction of an erupted maxillary third molar— or a second molar if it happens to be the last tooth in the arch.
If the tuberosity is fractured but intact, it should be manually repositioned and stabilized with sutures.
The complications most often seen after extraction of an freestanding, isolated maxillary molar are:
• Fracture of the tuberosity • Alveolar process fracture
Important: "Beware of the lone molar"— it is often ankylosed to the bone. Remember: The ankylosed tooth emits an atypical, sharp sound on percussion.
Key point to remember: Tuberosity fractures may occur and should be treated at the time of surgery. If the operator is unable to do this, he/she must arrange an immediate referral.
1. For denture construction, at the correct vertical dimension, the distance from Notes the crest of the tuberosity to the retromolar pad should equal at least 1 cm.
2. If there is inadequate intermaxillary distance at the tuberosity, a tuberosity reduction can be performed to remove excess tuberosity. An elliptic incision is made over the tuberosity and carried down to bone. This wedge is resected. The buccal and palatal tissues are undermined subperiosteally. Submucous wedges are removed from each flap, and the wound is closed. This decreases the vertical and horizontal dimensions of the tuberosity.
exo Which of the following can be safely excised in preparing the edentulous mandible for dentures? Select all that apply.
The genial tubercles are situated on the lingual surface of the mandible at a point about midway between the superior and inferior borders. There are four of them, two of which are situated on each side and adjacent to the symphysis. Although usually relatively small, they may be fairly large and extend outward from the surface as spinous processes. These tubercles are the area of muscle attachment for the suprahyoid muscles.
Important: If the genial tubercles were removed, the tongue would be flaccid.
1. When removing the mylohyoid ridge, be careful to protect the lingual Notes nerve.
2. When removing a mandibular exostosis (mandibular torus), it is recommended that an envelope flap design, which has no vertical components, be used.
• when the root is approximately two-thirds formed
• Patient would be around the age of 17-21. • At this time, the bone is more flexible and the roots are not formed well enough to have developed curves and rarely fracture during extraction.
When the root is fully formed, the possibility increases for abnormal root morphology and for fracture of the root tips during extraction.
Complications of Surgery
Complication
Tearing of the flap
Puncture wounds
Orai-antral communications
Root fracture
Injury to adjacent teeth
Tooth displacement
Alveolar process and maxillary tuberosity fractures
Trauma to inferior alveolar nerve
Dry socket
Comment
Can be avoided by initially creating an adequately sized incision
Caused by too much force; treated with pressure to stop bleeding and left open to heal by secondary intent.
Managed with a figure-eight suture over the socket, sinus precautions, antibiotics, and a nasal spray to prevent infection and keep the ostium open
Most common complication; removed with elevators (i.e., straight, Cryer, Stout) and root tip picks.
Fracture of teeth or restorations
For example, maxillary molar root into the maxillary sinus
From too much force used to remove teeth
May occur in the area of the roots of the mandibular third molars. Lingual nerve travels very close to the lingual cortex of the mandible in this area.
Can occur in 3% of mandibular third molar extractions. Will heal with irrigation and local treatment for pain control
1. Patients who are young tolerate surgery very well. Postoperative complications are Notes usually minimal.
2. Older individuals have the most postoperative difficulties. The bone is more dense and usually the patient responds more slowly to the entire process (anesthesia and surgery).
exo When would you place a suture over a single extraction socket?
routinely
• never
• if the patient requests it
• when there is severe bleeding from the gingiva or if the gingival cuff is torn or loose
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exo
The most commonly impacted teeth are the mandibular third molars, maxillary
• when there is severe bleeding from the gingiva or if the gingival cuff is torn or loose
Normal postextraction procedure: • All loose bone spicules and portions of the tooth, restoration, or calculus are removed from the socket as well as from the buccal and lingual vestibules and the tongue • The socket must be compressed by the fingers to reestablish the normal width present before the buccal plate was surgically expanded. Note: The natural recontouring of the residual ridge occurs primarily by resorption of the labial-buccal cortical bone. • Sutures are usually not placed unless the papillae have been excised • The socket is covered with a gauze sponge that has been folded and moistened slightly at its center with cold water • The patient is instructed to bite down on the pressure dressing for 30-60 minutes • A printed instruction sheet is given to the patient • A prescription for pain is given if the need is anticipated
If bleeding persists for some time following an extraction, it may be helpful to instruct the patient to bite on a tea bag. The tannic acid in the tea bag will help promote hemo-stasis.
Remember: The most common cause of postextraction bleeding is the failure of the patient to follow postextraction instructions.
• maxillary canines
Classifications of impacted teeth Angulation: Mesioangular (least difficult to remove for mandibular impactions), distoangular (most difficult to remove for mandibular impactions), vertical and horizontal Pell - Gregory Classification: relationship to anterior border of the ramus
• Class 1: normal position anterior to the ramus • Class 2: one-half of the crown is within the ramus
• Class 3: entire crown is embedded within the ramus
Relationship to occlusal plane: • Class A: tooth at the same plane as other molars • Class B: occlusal plane of third molar is between the occlusal plane and the cervical line of the second molar • Class C: third molar is below the cervical line of the second molar
Factors That Make Impaction Surgery Less Difficult
Mesioangular position
Class 1 ramus
Class A depth
Roots one third to two thirds formed*
Fused conic roots
Wide periodontal ligament*
Large follicle*
Elastic bone*
Separated from second molar
Separated from alveolar nerve*
Soft tissue impaction
* Present in young patients
Factors That Make Impaction Surgery More Difficult
Distoangular position
Class 3 ramus
Class C depth
Long, thin roots*
Divergent curved roots
Narrow periodontal ligament*
Thin follicle*
Dense, inelastic bone*
Contact with second molar
Close to inferior alveolar canal
Complete bony impaction
* Present in older patients
of impacted teeth:
• Compromised medical status • Likely damage to adjacent structures • Extremes of ages (preteen or an asymptomatic full bony impaction in a patient > 35 years of age
All of the following are cardinal signs of a EXCEPT one. Which one is the EXCEPTION?
• a mandibular torus, if present, should be removed
• a stent should be fabricated
• a biopsy should be taken
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• bilateral lymphadenopathy
The etiology of dry socket is not absolutely clear, but is thought to develop because of increased fibrinolytic activity causing accelerated lysis of the blood clot. It is most common following extraction of the mandibular molars. Smoking, premature mouth rinsing, hot liquids, surgical trauma, and oral contraceptives all have been implicated in the development of a dry socket. Note: Careful technique and minimal trauma reduce the frequency of patients developing dry socket.
Treatment for dry socket:
• Flush out debris with slightly warmed saline solution — gently!!! • Place a sedative dressing in socket (eugenol). The dressing should be removed within 48 hours and replaced until the patient becomes asymptomatic. Note: (1) The gauze provides an attachment for the obtundent paste so it stays in the socket (2) Eugenol is the active component in most sedative dressings (3) If gel foam or another resorbable material is used then, the dressing does not need to be removed (4) The medical term for dry socket is alveolar osteitis • Nonsteroidal antiinflammatory analgesics should be prescribed if necessary. *** Antibiotics are generally not indicated.
1. Dry socket is the most common complication seen after the surgical removal Notes of a mandibular molar.
2. Curetting a dry socket can cause the condition to worsen because healing will be further delayed, any natural healing already taking place will be destroyed, and there is a risk of causing the localized inflammatory process to be spread to the adjacent sound bone.
• a stent should be fabricated
Maxillary tori present few problems when the maxillary dentition is present and only occasionally interfere with speech or become ulcerated from frequent trauma to the palate.
Indications for the removal include a large, lobulated torus with a thin mucoperiosteal cover extending posteriorly to the vibrating line of the palate that prevents seating of a denture and also prevents a posterior seal at the fovea palatini. Other indications for the removal of maxillary tori are chronic irritation, interference with speech, rapid growth and in patients that have a cancer phobia.
Technique for removal: . • A stent should be fabricated prior to removal of a palatal torus. This is done on a study model that has had the exostosis removed. • A double-Y incision should be made over the midline of the torus • After careful elevation of the flaps, the torus should be scored multiple times in the anterior, posterior, and transverse dimensions • An osteotome can be used to remove each of these small portions • A large bur or bone file is used to smooth the area
• After thorough irrigation, the wound is closed loosely with horizontal mattress su
tures • The stent is placed to prevent hematoma formation and to support the flap
Important: The maxillary torus should not be excised en masse to prevent entry into the nose (the palatine bone will come out with torus).
exo For impacted mandibular third molars, place the following in their correct order from the least difficult to most difficult to remove.
• vertical
1 horizontal
distoangular
mesioangular
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exo
Which two major forces are used for routine tooth extractions?
exo The Caldwell-Luc procedure eliminates blind procedures and facilitates the recovery of large root tips or entire teeth that have been displaced into the maxillary sinus. When performing this procedure, an opening is made into the facial wall of the antrum above the:
Important: If an entire tooth or a large fragment of one is displaced into the sinus, it should be removed. If the tooth fragment is irretrievable through the socket, it should be retrieved through a Caldwell-Luc approach ASAP. However, only perform this if you know what you are doing. If not, refer patient to an oral surgeon. Note: If a small communication is made with the maxillary sinus during extraction of a tooth, the best treatment is leave it alone and allow the blood clot to form.
Postoperative instructions to patient: • Avoid nose blowing for 7 days • Open mouth when sneezing • Avoid vigorous rinsing • Soft diet for 3 days
If a sinus communication should occur, the following medications may be prescribed for 1 week:
1. If the opening is of moderate size (2-6 mm), a figure-eight suture should be Notes placed over the tooth socket.
2. If the opening is large (7 mm or larger), the opening should be closed with a flap procedure.
Remember: The integrity of the floor of the maxillary sinus is at greatest risk with surgery involving the removal of a single remaining maxillary molar. The fear here is possible ankylosis.
• maxillary premolar roots
If a large root fragment or the entire tooth is displaced into the maxillary sinus (antrum), it should be removed. The usual method is a Caldwell-Luc approach. This is a surgical procedure in which an opening is made into the maxillary sinus by way of an incision into the canine fossa above the level of the premolar roots. The tooth or root is then removed. Postoperative management includes a figure-eight suture over the socket, sinus precautions, antibiotics, a nasal spray, and a systemic decongestant to keep the sinus ostium open and infection-free. Important: An oral surgeon to whom the patient should be referred should perform this procedure.
If the root tip is small (2 or 3 mm), noninfected, and cannot be removed through the small opening in the socket apex, no additional surgical procedure should be performed through the socket, and the root tip should be left in the sinus. If the root tip is left in the sinus, measures should be taken similar to those taken when leaving any root tip in place. The patient must be informed of the decision and given proper follow-up instructions.
Remember: The palatal root of the maxillary first molar is most often dislodged into the maxillary sinus during an extraction procedure.
Note: If a root tip of a mandibular third molar disappears from site while trying to retrieve it, its most likely location is the submandibular space. Other possible locations would be the inferior alveolar canal or the cancellous bone space.
exo Which suture grading below is the thickest?
•2/0
•3/0
•4/0
5/0
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exo Which of the following events are correctly paired with the stages of wound healing? Select all that apply.
• fibroblasts lay a bed of collagen / proliferative phase
• platelet aggregation / inflammatory phase
> contraction of the wound / remodeling phase
> thromboplastin makes a clot / inflammatory phase
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• 2/0
Suture size is based on strength and diameter. The gauge or thickness of the suture material is denoted by O gradings. As the thickness of the material decreases, the O grading rises. Hence 2/0 is thicker than 3/0, which is thicker than 4/0 and so on.
Because suture material is foreign to the human body, the smallest-diameter suture sufficient to keep the wound closed properly should be used. Most oral and maxillofacial surgical procedures (intraoral suturing) require the use of 3/0- or 4/0 gauge material, but on extraoral skin surfaces, finer gauge is preferred such as 6/0 or even finer. This helps reduce scar visibility.
Note: The primary function of sutures is to help to stabilize the flap during the healing phases without imposing needless traction on the soft tissue.
• fibroblasts lay a bed of collagen / proliferative phase • platelet aggregation / inflammatory phase • thromboplastin makes a clot / inflammatory phase
Contraction of the wound occurs during the proliferative phase of wound healing, which is one of three phases:
1. Inflammatory Phase (initial lag phase) • Immediate to 2-5 days • Hemostasis
- Vasoconstriction - Platelet aggregation - Thromboplastin makes clot
• Inflammation - Vasodilation - Phagocytosis
2. Proliferative phase (fibroblastic phase) • 2 days to 3 weeks • Granulation
- Fibroblasts lay bed of collagen - Fills defect and produces new capillaries
• Contraction - Wound edges pull together to reduce defect
• Epithelialization
3. Remodeling Phase (maturation phase) • 3 weeks to 2 years • New collagen forms, which increases tensile strength to wounds • Scar tissue is only 80% as strong as original tissue
Factors that impair wound healing: diabetes, protein deficiencies, older age, infections, foreign material, necrotic tissue, ischemia, and tension on the wound. Remember: 3% hydrogen peroxide is the agent of choice for the debridement of intraoral wounds.
exo Sutures placed intraorally are normally removed:
1-2 days postoperatively
5-7 days postoperatively
9-11 days postoperatively
13-15 days postoperatively
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exo Regardless of the flap design used, certain principles should be followed while incising and reflecting the gingiva. With this in mind, the termination of a vertical incision at the gingival crest must be:
The two basic categories of sutures are (1) resorbable and (2) nonresorbable: • Resorbable: These sutures are resorbed after a certain time, which usually coincides with healing of the wound. These sutures are made of gut or vital tissue (catgut, collagen, fascia, etc.) and are plain or chromic, or of synthetic material, e.g., polyglycolic acid (Dexon). Plain catgut sutures are resorbed postsurgically over 8 days, chromic sutures in 12-15 days, and synthetic (Dexon) sutures in approximately 30 days. These types of sutures are used for flaps with little tension, in children and mentally handicapped patients, and generally for patients who cannot return to the office to have the sutures removed.
• Nonresorbable: These sutures remain in the tissues and are not resorbed, but have to be cut and removed about 5-7 days after their placement. They are fabricated of various materials, mainly surgical silk (monofilamentous or multifilamentous) in many diameters and lengths) and surgical cotton suture. Silk sutures are the easiest to use, are the most economical, and have a satisfactory ability to hold a knot. One of the disadvantages of silk sutures is that they wick bacteria due to their braided nature. Although much more expensive, many surgeons prefer the use of Vicryl sutures.
Note: Resorbable sutures evoke an intense inflammatory reaction. This is the main reason neither plain gut nor chromic gut are used for suturing the surface of a skin wound. When suturing an extraction site in the anticoagulated patient, a nonresorbable suture is recommended. Resorbable sutures are accompanied by an inflammatory response and increasing fibrinolytic activity,which may potentially result in clot breakdown.
Two basic methods of wound healing (soft tissue):
1. Primary intention (also called primary closure): involves minimal re-epithelialization and collagen formation, allowing the wound to be "sealed" within 24 hrs. Healing occurs more rapidly with a lower risk of infection and with less scar formation and less tissue loss than wounds allowed to heal by secondary intention. Examples include: well-repaired and well-reduced bone fractures. 2. Secondary intention (also called secondary closure): involves re-epithelialization via migration from the wound edges, collagen deposition in the connective tissue, contracture, and remodeling. The site fills in with granulation tissue. Healing is slower and results in scarring and wound depression. Examples include: extraction sockets, poorly reduced fractures, and large ulcers.
• at the line angle of the tooth
Regardless of the flap design used, certain principles should be followed while incising and
reflecting the gingiva. These include: • Incision should be made with a firm, continuous stroke
• Incision should not cross underlying bony defect that existed prior to surgery or were produced
by the surgery • Vertical incisions are made in the concavities between bony eminences • Termination of vertical incision at the gingival crest must be at the line angle of the tooth • Vertical incision should not extend beyond the depth of the mucobuccal fold
• Base of the flap must be as wide as the width of the free edge (supraperiosteal vessels running
vertically should not be transected) • Periosteum must be reflected as an integral part of the flap
Important: The correct position for ending a vertical releasing incision is at a tooth line angle not over the buccal surface of a tooth. If it ends over a buccal surface, the edges are difficult to approximate and this may lead to periodontal problems. Incision should never cross bony prominences as this increases the chance for wound dehiscence. Three types of incisions used in oral surgery:
1 Linear: straight line incision used for apicoectomies.
2. Releasing: used when adding a vertical leg to a horizontal creation incision. For extractions,
augmentations, etc. 3. Semilunar: curved incision mostly used for apicoectomies.
The basic principles of oral surgical flap design: • Flap design should ensure adequate blood supply; the base of the flap should be larger than
the apex • Reflection of the flap should adequately expose the operative field • Flap design should permit atraumatic closure of the wounds • Flap should be closed over bone if possible
exo While attempting to remove a grossly decayed mandibular molar, the crown fractures. What is the recommended next step to facilitate the removal of this tooth?
• use a larger forcep and luxate remaining portion of tooth to the lingual
• separate the roots
• irrigate the area and proceed to remove the rest of the tooth
*** This can be done with a chisel, elevator, or most easily with a bur.
Teeth with two or more roots often need to be sectioned into single entities prior to successful removal. A popular method of sectioning is to make a bur cut between the roots, followed by inserting an elevator in the slot and turning it 90° to cause a break.
Roots can be removed by closed technique. The surgeon should begin a surgical removal if the closed technique is not immediately successful.
Indications for surgical extractions: • After initial attempts at forceps extraction have failed • Hypercementosis or widely divergent • Patients with dense bone roots • In older patients, due to less elastic bone • Extensive decay which has destroyed • Short clinical crowns with severe attrition (bruxers) most of the crown
Teeth are resistant to crush but are not resistant to shear. Therefore: • Place the beaks of the forceps opposite to each other at the same level on the tooth. • The beaks should be applied in a line parallel with the long axis of the tooth.
Remember: When luxating a tooth with forceps, the movements should be firm and deliberate, primarily to the facial with secondary movements to the lingual. The maxillary first bicuspid is least likely to be removed by rotation forces due to its root structure (obviously molars are not removed by rotation).
1. It is recommended to use a bite block when removing mandibular teeth to diminish Notes pressure on the contralateral TMJ.
2. Distilled water is not used for irrigation because it is a hypotonic solution and will enter cells down the osmotic gradient, causing cell lysis and rapid death of bone cells. 3. Buccal to lingual movement is not efficient when removing mandibular posterior teeth because mandibular bone is too dense and does not expand in a fashion similar to that of maxillary bone. 4. The root of the zygoma can interfere with efficient removal of a maxillary first molar.
• in the submandibular space
Important: To prevent this, avoid all apical pressures when removing the roots or root tips of all mandibular molars. If a mandibular molar root tip is displaced inferiorly, it may either be in the mandibular canal or through the lingual cortical plate. The mandibular canal is generally found buccal to the roots of the mandibular third molar.
The submandibular space is a potential space of the neck bounded by the oral mucosa and tongue anteriorly and medially; the superficial layer of deep cervical fascia laterally; and the hyoid bone inferiorly. The mylohyoid muscle, stretching across the floor of the mouth, serves as the inferior boundary of the sublingual space and the superior boundary of the submaxillary spaces.
Note: The submaxillary, submental and sublingual spaces are collectively referred to as the submandibular space. The submaxillary space usually drains infections from the mandibular bicuspids and molars because their apices lie below the mylohyoid muscle attachment.
The submental space is the medial part of the submaxillary space. It is however, important to note that it lies above the mylohyoid unlike the submaxillary space. It contains the submental lymph nodes that drain the median parts of the lower lip, tip of the tongue, and the floor of the mouth. It usually drains infections from the mandibular incisors and canines because their apices lie above the mylohyoid muscle attachment.
The sublingual space is the superior part of the submandibular space, containing the sublingual gland and loose connective tissue surrounding the tongue.
Remember: Ludwig angina is the most commonly encountered neck space infection (involves the sublingual, submandibular, and submental spaces).
exo Arrange the following five phases of healing of an extraction site in their correct order.
• replacement of the connective tissue by fibrillar bone
• hemorrhage and clot formation
• replacement of granulation tissue by connective tissue and epithelialization of the site
• recontouring of the alveolar bone and bone maturation
Five phases of healing of an extraction site: 1. hemorrhage and clot formation 2. organization of the clot by granulation tissue 3. replacement of granulation tissue by connective tissue and
epithelialization of the site 4. replacement of the connective tissue by fibrillar bone 5. recontouring of the alveolar bone and bone maturation
Note: Glucocorticoids have been shown to have the greatest effect on granulation tissue — they retard healing. This is believed to be due to the fact that:
• Glucocorticoids interfere with the migration of neutrophils and mononuclear phagocytes into a site of inflammation; the phagocytic and digestive ability of macrophages is also reduced. • Glucocorticoids inhibit formation of granulation tissue by retarding capillary and fibroblast proliferation and collagen synthesis.
The same stages that occur in normal wound healing of soft tissue injuries also occur in the repair of injured bone. However, osteoblasts and osteoclasts are also involved in repairing damaged bone tissue.
Bone healing occurs by 2 ways: • Healing by first intention (Primary union) • Healing by second intention (Secondary union)
In case of healing by primary intention, there is not much loss of cells and tissues. The ends of the flap will approximate in some time and the tooth extraction recovery will occur in some time whereas in case of healing by secondary intention, there is extensive loss of cells and tissues. The ends of the flap don't approximate and the healing occurs from bottom to the top and from margins inwards. Healing by secondary intention is slow as compared to faster healing by primary intention.
• lateral pterygoid muscle
Muscles involved in displacing mandibular fractures include the medial and lateral pterygoid, temporalis, masseter, digastric, geniohyoid, genioglossus, and mylohyoid. The lateral pterygoid displaces the condyle anteriorly and medially because of its insertion on the pterygoid fovea. Muscles attached to the ramus (i.e., temporalis, masseter, and medial pterygoid) result in superior and medial displacement of the proximal segment. As fractures progress anteriorly toward the canine region, the digastric, geniohyoid, genioglossus, and mylohyoid exert a posterior-inferior force on the distal segment.
The lateral pterygoid muscle is the only muscle that inserts directly on the neck of the mandibular condyle. In subcondylar fractures, the forces of this muscle frequently result in anterior and medial displacement of the condyle. In higher condylar fractures and in intracapsular fractures above the insertion of the lateral pterygoid, the small fragment can occasionally be seen displaced in a pure horizontal or vertical direction.
Note: Displacement of the proximal segment of the condyle usually occurs in an an-teromedial direction because of the pull of the lateral pterygoid muscle. The patient will deviate to the side of the fracture on opening because of the unopposed action of the contralateral lateral pterygoid muscle.
fractures
are second only to nasal fractures in frequency of involvement.
• le fort I
• le fort II
• le fort III
1 zygomatic fractures
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fractures
The most frequent complication associated with mandibular fracture management is:
• hematoma
• wound dehiscence
• facial or trigeminal nerve injury
• infection
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• zygomatic fractures Zygomaticomaxillary complex (ZMC) fractures involve four major processes: the zygomaticofrontal region, infraorbital rim, zygomatic buttress, and zygomatic arch. Zygomatic fractures are commonly encountered in facial trauma because of their prominent position on the facial skeleton. The most common mechanism producing facial fractures is auto accidents. About 70% of auto accidents produce some type of facial injury, although most are limited to soft tissue. The face seems to be a favorite target in fights or assaults, which are the next most common mechanism. Specific terminology is used to describe the different types of fractures that occur. Simple fractures are closed, while compound fractures are open and exposed through a wound. A comminuted fracture occurs when the bone has broken into multiple pieces.
Fracture type prevalence: • Zygomaticomaxillary complex: 40 % •LeFortI: 15%
II: 10% III: 10%
• Zygomatic arch: 10% • Alveolar process of maxilla: 5% • Smash fractures: 5% • Other: 5%
Signs of a Bone Fracture
Notes
Pain
Contour deformity
Ecchymosis
Abnormal mobility of the bone
Numbness
Hematoma
Crepitation
1. The maxilla and mandible are in a critical relationship to the upper airway; therefore displacement of fractures can cause obstruction of the airway resulting in respiratory arrest. Control of the airway is vital to any treatment of a patient with facial fractures. 2.Maxillary fractures have a greater tendency toward the production of facial deformity than do mandibular fractures.
3. Maxillary Le fort fractures, orbital fractures, and zygomatic fractures usually require internal rigid fixation. 4. The highest incidence of fractures occurs in young males between the ages of 15 and 24. These fractures are usually the result of trauma.
infection
Common Complications Associated with Mandibular Fracture Management
Infection
Malocclusion
Damage to tooth roots
Wound dehiscence
Osteomyelitis
Delayed union or nonunion
Facial or trigeminal nerve injury
Hematoma
Tooth injury
Of these, infection is one of the most problematic; it is the most frequent complication and is an important cause of nonunion. The most common cause of postoperative infection is movement at the fracture site due to mobile hardware, such as a loose screw in an otherwise stable plate.
Four reasons that a fracture does not heal: 1. Ischemia: the navicular bone of the wrist, the femoral neck, and the lower third of the tibia are all poorly vascularized and, therefore, are subject to ischemic necrosis after a fracture. 2. Excessive mobility: healing is prevented and pseudoarthrosis or a pseudo-joint may occur. 3. Interposition of soft tissue: occurs between the fractured ends. 4. Infection: compound fractures have a tendency to become infected.
*** Important: a fat embolism is most often a sequela of fractures.
Inappropriate healing (three types): 1. Delayed union: satisfactory healing which requires greater than the normal 6-week period. May be caused by infection, interposition of soft tissue or muscle between the fracture segments. 2. Non union: failure of the fracture segments to unite properly. May be caused by infection, improper immobilization, or interposition of soft tissue. 3. Mai union: can be either delayed or complete union in an improper position. May be caused by improper immobilization or imperfect reduction.
fractures
What determines whether muscles will displace fractured segments from their original position?
In general, mandibular fractures are less common in children than in adults. When mandibular fractures occur in children, fractures of the mandible, particularly in the condylar region, are relatively common.
• line of fracture The line of fracture will determine whether muscles will be able to displace the fractured segments from their original position. Favorability is determined by the forces exerted by the masticatory muscles on the fracture segments. A favorable fracture is one that is not displaced by masticatory muscle pull, and an unfavorable fracture occurs when the line of fracture permits the fragments to separate.
The four muscles of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid. After discontinuity of the mandible due to fracture, these muscles exert their actions on the fragments, leading to malocclusion. Signs and symptoms that may be associated with mandibular fractures:
• Pain and tenderness at the fracture site • Changes in occlusion • Ecchymosis of the floor of the mouth or skin • Crepitation on manual palpation • Changes in mandibular range of motion • Soft tissue bleeding • Sensory disturbances (numbness of the lower lip) • Deviation of the mandible on opening • Soft tissue swelling • Trismus • Palpable fracture line intraorally or at the inferior border of the mandible
Approximately 43% of all patients with mandibular fractures have associated systemic injuries. Cervical spine fractures were found in 11% of this group of patients. It is imperative to rule out cervical neck fractures, especially in patients who are intoxicated or unconscious and in patients who are involved in vehicular accidents. Posteroanterior and lateral films and CT of the neck should be reviewed with the radiologist before treatment is initiated in these patients.
• greenstick The ossification capability of children allows faster healing and distinguishes it from the adult mandible. As a result, many mandibular fractures in children can be treated with immobilization for a shorter time or may simply require observation and a soft diet. Note: Open reduction and internal fixation in children are reserved for severely displaced fractures. In an adult, the location of facial fractures is influenced by both the resistance of the bone to fracture and the prominence of its position on the facial skeleton. Adult facial fractures are most commonly seen in the nasal bones followed by the zygoma, mandible, and maxilla. In children, early growth in the cranium and orbits predisposes young children to frontal bone and orbital fractures.
The following categories classify mandibular fractures by describing the condition of the bone fragments at the fracture site and possible communication with the external environment:
• Simple: divides a single bone into two distinct parts with no external communication. These are closed fractures with no lacerations of the oral mucosa or facial tissues. • Compound: fracture communicates with the outside environment (open fracture). This may occur by laceration of the oral tissues exposing the bone fragments, fracture of the maxilla into the sinuses, or by way of skin lacerations that would expose the fracture segments. Infection is common. • Comminuted: are multiple fractures of a single bone. They may be simple or compound. • Greenstick: fracture that extends only through the cortical portion of the bone without-complete fracture of the bone. Greenstick fractures are closed fractures involving incomplete fractures with flexible bone. Most often seen in children.
Remember: (1) The most common complication of an open fracture is infection. (2) Any jaw fracture extending through tooth-bearing bone is considered an open fracture due to potential tears in the PDL and exposure of the fracture to the oral flora.
fractures
Computed tomography (CT) scan is the gold standard for evaluation of which of the following? Select all that apply.
• mandibular fractures at the angle
• fractures of the mandibular condyle
• le fort I fractures
• zygomatic fractures
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fractures
Closed reduction is best used in the treatment of:
• favorable, nondisplaced fractures
• displaced and unstable fractures, with associated midface fractures, and when MMF is contraindicated
• either of the above
• none of the above
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• mandibular fractures at the angle • fractures of the mandibular condyle • le fort I fractures • zygomatic fractures
Note: For a long time in the past, a posteroanterior oblique Waters view or a reverse Waters view together with a posteroanterior and submental vertex view of the skull were used for evaluating zygomaticomaxillary complex (ZMC) fractures. However, the CT scan (both axial and coronal orientations) is currently the diagnostic tmaging modality of choice for evaluating these fractures as well as the other fractures listed. This imaging modality shows the location of the fractures, degree of displacement of the bones, and status of surrounding soft tissues.
Important: Dysfunction of the infraorbital nerve is common in a patient with a ZMC fracture An ophthalmologic examination is of paramount importance. Also, fractures of the facial bones, particularly the zygomatic complex, may, on rare occasions, be complicated by damage to the contents of the superior orbital fissure.
Other possible complications of the zygomatic complex (ZMC) fracture include: • Paresthesia (most common): usually subsides • The antrum (sinus) may be filled with a hematoma, which usually evacuates itself • Ocular muscle balance may be impaired because of fracture of the orbital process
Note: Fracture of the infraorbital rim presents with the following symptoms: • Numbness of the following areas on the affected side: upper lip, cheek, and nose
Note: The most feared, but fortunately rare, complication of ZMC fractures is blindness. Remember: By definition, the four articulating sutures (ZF, ZT, ZM, and ZS) are disrupted in this fracture. Therefore, the commonly applied term "tripod fracture" is a misnomer and does not correctly describe this fracture.
Most practitioners consider CT scanning to be the gold standard imaging modality for evaluation of mandibular fractures. A CT scan allows the entire face to be evaluated in one study. Despite the popularity of CT imaging, in many facilities the initial imaging studies may consist of panoramic radiography or a plain view series of the mandible i.e., posteroanterior, Waters, reverse Towne, or submentovertex projections. Many rural hospitals still use a plain view series of the mandible. Therefore familiarity with plain radiographs is important.
• favorable, nondisplaced fractures
Treatment options of mandibular fractures can be divided into rigid fixation, semirigid fixation, and nonrigid or closed reduction. Methods considered rigid fixation are the lag screw technique, compression plating, reconstruction plates, and external pin fixation. Miniplate fixation and wire fixation are types of semirigid fixation. Maxillomandibular fixation ([MMF] with ivy loops, arch bars, or transalveolar screw), gunning splints, and lingual splints are considered nonrigid fixation. Rigid fixation allows for primary bone healing without callous formation. Nonrigid fixation allows for secondary bone formation with inflammatory infiltration and callous formation. Semirigid fixation allows for areas of primary and secondary bone formation.
• Closed reduction is best used in the treatment of favorable, nondisplaced fractures. It is also used in situations in which Open Reduction Internal Fixation (ORIF) is contraindicated. Maxillomandibular fixation (MMF) is obtained by applying wires or elastic bands between the upper and lower jaws, to which suitable anchoring devices can be attached, such as arch bars or skeletal screws. The standard length of (MMF) is 4-6 weeks.
• Open reduction involves direct exposure of the fracture site and placement of internal fixation to prevent movement of the fracture site. Open reduction is used in displaced and unstable fractures, with associated midface fractures, and when MMF is contraindicated. In addition, some surgeons advocate ORIF for patient comfort and for expedited return to activity and work. Arch bars are always placed first to establish occlusion, then ORIF is performed. The plates can be placed intrao-rally, extraorally via a cervical incision, or percutaneously. Dynamic compression plates (DCP) can be used for most body, angle, symphyseal, or parasymphyseal fractures.
Note: Initial management of mandibular fractures starts after the patient has been stabilized. All fractures of tooth-bearing areas of the mandible are considered open and should be treated with antibiotics that cover mouth flora, specifically gram-positive and anaerobic organisms. Mouth rinses with Peridex solution or half strength hydrogen peroxide in water are useful to keep the mouth clean. Timing of repair is controversial. Several studies have shown a decreased incidence of infection if compound fractures are repaired within 48 hours. Other studies have shown no change if fractures are repaired in less than a week. Regardless of infection rates, patient comfort dictates that the earliest date for repair is the best as displaced fractures are painful.
fractures
The process of fracture healing can occur in:
• one way: by direct or primary bone healing which occurs without callus formation
• one way: by indirect or secondary bone healing which occurs with a callus precursor stage
• two ways: by direct or primary bone healing, which occurs without callus formation, and indirect or secondary bone healing, which occurs with a callus precursor stage
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fractures
The most common pathognomonic sign of a mandibular fracture is:
• nasal bleeding
• exophthalmos
• malocclusion
• numbness in the infraorbital nerve distribution
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• two ways: by direct or primary bone healing, which occurs without callus formation, and indirect or secondary bone healing, which occurs with a callus precursor stage
Primary bone healing involves a direct attempt by the cortex to reestablish itself after interruption. Bone on one side of the cortex must unite with bone on the other side of the cortex to reestablish mechanical continuity. Under these conditions, bone-resorbing cells on one side of the fracture show a tunneling resorptive response, whereby they reestablish new haversian systems by providing pathways for the penetration of blood vessels.
Secondary bone healing involves the classical stages of fracture healing.
Stages of fracture healing: • Stage 1: Inflammation (Immediately following fracture) - bleeding from the fractured bone and surrounding tissue causes the fractured area to swell. This stage begins the day you fracture the bone and lasts about 2 to 3 weeks. • Stage 2: Soft callus (2 to 3 weeks after fracture) - the pain and swelling will decrease. At this point, the site of the fracture stiffens and new bone begins to form. The new bone cannot be seen on radiographs. This stage usually lasts until 4 to 8 weeks after the injury. • Stage 3: Hard callus (4 to 8 weeks after fracture) - the new bone begins to bridge the fracture. This bony bridge can be seen on radiographs. By 8 to 12 weeks after the injury, new bone has filled the fracture. • Stage 4: Bone remodeling (8 to 12 weeks after fracture) - the fracture site remodels itself, correcting any deformities that may remain as a result of the injury. This final stage of healing can last for several years.
The rate of healing and the ability to remodel a fractured bone vary tremendously for each person and depend on the patient's age, health, type of fracture, and the bone involved. For example, children are able to heal and remodel their fractures much faster than adults.
Compartment syndrome: Severe swelling after a fracture can put so much pressure on the blood vessels that not enough blood can get to the muscles around the fracture. The decreased blood supply can cause the muscles around the fracture to die, which can lead to long-term disability.
• malocclusion
Other signs and symptoms of a mandibular body or angle fracture include: • Lower lip numbness • Mobility, pain, or bleeding at the fracture site
The important points in treating mandibular fractures are immobilization of the fractures, the appropriate use of antibiotics, and restoration of form and function. The usual treatment for mandibular fractures that are displaced and mobile is with open reduction and internal fixation using titanium bone plates and screws. If the patient has teeth, the occlusion is used as a guide for the surgeon to repair the fracture. Other methods of repair include splinting (for pediatric patients) and maxillo-mandibular fixation (see below).
• Establishing a proper occlusal relationship by wiring the teeth together is termed maxillo-mandibular fixation (MMF) or intermaxillary fixation (IMF). The most common technique includes the use of a prefabricated arch bar that is adapted and wired to teeth in each arch; the maxillary arch bar is wired to the mandibular arch bar, thereby placing the teeth in their proper relationship. Other wiring techniques such as Ivy loop or continuous loop wiring have also been used for the same purpose.
More recently, techniques for rigid internal fixation (RTF) have gained popularity for treatment of fractures. These use bone plates, bone screws, or both to fix the fracture more rigidly and stabilize the bony segments during healing. Even with rigid fixation, a proper occlusal relationship must be established before reduction stabilization and fixation of the bony segments. Advantages of RIF for treatment of mandibular fractures include decreased discomfort and inconvenience to the patient because IMF is eliminated or reduced, improved postoperative nutrition, improved postoperative hygiene, and frequently better postoperative management of patients with multiple injuries.
Note: Mandibular angle fractures are generally more prone to the development of complications compared with the body or symphyseal areas. Multiple complications may arise but most commonly include loose hardware necessitating removal, infection, malocclusion, delayed union, and fibrous union. Damage to the inferior alveolar nerve (or lingual nerves) can be a complication of the initial injury or a consequence of treatment.
fractures
Which type of Le Fort fracture is often referred to as a pyramidal fracture?
• le fort I
• le fort I
• le fort I
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fractures
The least common site for a mandibular fracture to occur is the:
Types of Le Fort's fractures: • Le Fort I: the fracture line traverses the maxilla through the piriform aperture above the alveolar ridge, above the floor of the maxillary sinus, and extends posteriorly to involve the pterygoid plates. This fracture allows the maxillae and hard palate to move separately from the upper face as a single detached block. Le Fort I fracture is often referred to as a transmaxillary fracture. • Le Fort II: superiorly, this fracture traverses the nasal bones at the frontonasal sutures. It extends laterally through the lacrimal bones, crossing the floor of the orbit, fracturing the medial and inferior orbital rims, and fracturing the pterygoid plates posteriorly. In this fracture, the attachment of the zygomatic bones to the skull at the lateral orbital rims and at the zygomatic arches is preserved. As a result of this fracture, the maxillary and nasal regions are movable relative to the rest of the midface and skull. Because of its triangular pattern, this fracture is often referred to as a pyramidal fracture. • Le Fort III: this fracture line involves fracture of all the buttress bones linking the maxilla to the skull. This fracture allows the entire upper face (nasal, maxillary, and zygomatic regions) to move relative to the skull. In this fracture, there is a craniofacial disjunction with a separation at the frontozygomatic suture, nasofrontal junction, orbital floor, and zygomatic arch laterally.
Clinical manifestations of midface fractures: • Clinical diagnosis of midface fractures is relatively easy to make when there is a displacement of the fracture, which is often manifested by the presence of malocclusion (most often presenting as anterior open bite). • Mobility of the midface • Nasal bleeding, subconjunctival ecchymosis, maxillary hypoesthesia, and tenderness of the bony buttresses.
Important: The first step in the treatment of these fractures is to reestablish the correct occlusal relationship between then maxilla and mandible.
• coronoid process -1.3% of mandibular fractures
The location and extent of mandibular fractures are determined largely by the direction and intensity of the blow and the specific points of weakness in the mandible.
Anatomic Distribution of Mandibular Fractures
Area of Mandible
Condyle
Angle
Symphysis
Body
Alveolar process
Ramus
Coronoid Process
% of Fractures
29.1
24.5
22
16
3.1
1.7
1.3
The condylar neck (29.1% of fractures') is a safety feature that allows the blow to the jaw to be dispersed at this point rather than driving the condyle into the middle cranial fossa. Bilateral dislocated fractures of the condylar necks will cause an anterior open bite and the inability to protrude the mandible. A unilateral fracture through the neck may cause forward displacement of the head of the condyle due to pull of the lateral pterygoid muscle.
The symphysis (22% of fractures) is usually where blows are sustained. These blows often result in fractures of the subcondylar region.
Remember: The patient's mandible will deviate to the side of injury on opening.
Note: Mandibular fractures can almost always be identified on a panoramic radiograph. If a fracture is suspected, at least two different radiographs should be taken for comparison (i.e., panoramic, posteroanterior, Waters, reverse Towne, or submentovertexprojections).
gen info
Patients with hypocalcemia have an ionized calcium level below 2.0 or serum calcium concentration lower than 9 mg/dL. Some of the most common causes are:
Whether a bone cyst or other cysts are completely enucleated or treated by marsupialization depends on the:
• duration
• origin
• color
• size and location to vital structures
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• renal failure and hypoalbuminemia
Calcium levels are regulated by parathyroid hormone and, to some extent, by the kidney tubules and GI mucosa. Other causes of hypocalcemia are vitamin D deficiency, hypoparathyroidism, pancreatitis, rhabdomyolysis, severe hypomagnesemia, multiple citrated blood transfusions, and drugs (antineoplastic agents, antimicrobials, agents used to treat hypercalcemia). Chronic hypocalcemia can be asymptomatic. Clinical manifestations are paresthesias of the lips and extremities due to increased excitability of nerves, tetany, cramps, and abdominal pain due to spasm of skeletal muscle, and convulsions.
Note: Chvostek and Trousseau signs are seen in hypocalcemia. Chvostek is twitching of the facial muscles as a result of tapping over the facial nerve in the preauricular area, and Trousseau sign is carpopedal spasm due to occlusion of the brachial artery when a blood pressure cuff is applied above systolic pressure for 3 minutes.
Hypercalcemia is an abnormally high level of calcium in the blood, usually more than 10.5 mg/dL. The most common causes of hypercalcemia are hyperparathyroidism and cancer.
Mnemonic for symptoms of hypercalcemia: • Stones: renal calculi • Bones: bone destruction • Moans: confusion, lethargy, fatigue, weakness • Abdominal groans: abdominal pain, constipation, polyuria, and polydipsia
1. Renal failure with oliguria is the most common cause of true hyperkalemia (too Notes much potassium in the blood). Some signs and symptoms include nausea, vomiting,
diarrhea, and ventricular fibrillation leading to cardiac arrest. 2. Usually the first sign of hypokalemia is skeletal muscle weakness or cramping. 3. The major extracellular cation is sodium. 4. The major intracellular cation is potassium.
• size and location to vital structures
Treatment of Cysts of the Jaws
Technique
Enucleation
Marsupialization, decompression, and the Partsch operation
Marsupialization followed by enucleation
Description
Shelling out without rupture
Creating a surgical window in the wall of the cyst, evacuating the contents of the cyst; and maintaining continuity between the cyst and the oral cavity
Indications
Treatment of choice; should be used when it can be safely be done without sacrificing adjacent structures
When enucleation would damage adjacent structures
Enucleation with curettage
Marsupialization is done first. After initial healing secondary enucleation may be undertaken without injury to adjacent structures
After enucleation a curette or bur is used to remove 1 to 2 cm of bone around the entire periphery of the cystic cavity
If cyst is not totally obliterated after marsupialization heals
When removing a keratocystic odontogenic tumor (KOT) Any cyst that recurs after what was deemed thorough removal
1. Marsupialization, decompression, and the Partsch operation all refer to creating a sur-Nor.es gical window in the wall of the cyst. The cyst is uncovered or "deroofed" and the cys
tic lining made continuous with the oral cavity or surrounding structures. The cyst sac is opened and emptied. 2. Cysts and cyst-like lesions can be classified as fissural or odontogenic. Keratocystic odontogenic tumors (KOT) have a higher rate of recurrence than do fissural and cysts of odontogenic inflammatory origin.
At what point should the EMS be activated with adult victims?
• after 1 minute of CPR
• after 2 minutes of CPR
• after 3 minutes of CPR
• immediately when an adult is found to be unresponsive
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The normal value for blood urea nitrogen (BUN) is:
• 2-5 mg/dL
• 7-18mg/dL
• 23-30 mg/dL
• 33-50 mg/dL
gen info
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• immediately when an adult is found to be unresponsive
*** For a victim less than 8 years of age, the EMS should be activated after 1 minute or 5 cycles of CPR. This is because, in younger patients, the most likely cause of arrest is respiratory. Cardiopulmonary Resuscitation:
A= Airway • Place victim flat on his/her back on a hard surface. • Shake victim at the shoulders and shout "are you okay?" • If no response, call emergency medical system — 911 then, • Head-tilt/chin-lift: open victim's airway by tilting their head back with one hand while lifting up their chin with your other hand.
B = Breathing • Position your cheek close to victim's nose and mouth, look toward victim's chest, and • Look, listen, and feel for breathing (5-10 seconds) • If not breathing, pinch victim's nose closed and give 2 full breaths into victim's mouth • If breaths won't go in, reposition head and try again to give breaths. If still blocked, perform abdominal thrusts (Heimlich maneuver)
C = Circulation • Check for carotid pulse by feeling for 5-10 seconds at side of victim's neck. • If there is a pulse but victim is not breathing, give rescue breathing at rate of 1 breath every 5-6 seconds or 10-12 breaths per minute • If there is no pulse, begin chest compressions as follows:
- Place heel of one hand on midposition of victim's sternum. With your other hand directly on top of first hand, depress sternum 1.5 to 2 inches. - Perform 30 compressions to every 2 breaths (rate of compressions: 100/min). - Check for a pulse after the first minute and every few minutes thereafter.
*** Continue uninterrupted until advanced life support is available.
• 7-18 mg/dL
Blood Chemistry Tests and Hematology Reference Values
Test
Blood urea nitrogen (BUN)
Carbon dioxide (includes bicarbonate)
Chloride
Creatinine
Glucose
Potassium
Sodium
Calcium
Phosphorus
Protein
Alkaline phosphatase
Normal Value
7-18 mg/dL
23-30 mmol/L
98-106 mEq/L
0.6-1.2 mg/dL
Fasting: 70-110 mg/dL Random: 85-125 mg/ dL
3.5-5 mEq/L
101-111 mEq/L or 135-148 mEq/L (depending on test)
8.8-10.0 mg/dL
2.7-4.5 mg/dL
6-8 g/dL
20-70 U/L
Clinical Significance
Increased in renal disease and dehydration; decreased in liver damage and malnutrition
Elevated in vomiting and pulmonary disease; decreased in diabetic acidosis, acute renal failure and hyperventilation
Increased in dehydration, hyperventilation, and CHF; decreased in vomiting, diarrhea, and fever
Increased in kidney disease
Increased in diabetes and severe illness; decreased in insulin overdose or hypoglycemia
Increased in renal failure and acidosis; decreased in vomiting and diarrhea
Increased in dehydration and diabetes insipidus; decreased in burns, diarrhea, or vomiting
Increased in excess PTH production and in cancer; decreased in alkalosis
Elevated in kidney disease; decreased in excess PTH
Increased in dehydration, multiple myeloma; decreased in kidney disease, liver disease, poor nutrition and severe burns
Increased in liver disease and metastatic bone disease
gen info
Which of the following are stages of hemostasis? Select all that apply:
There are three phases of hemostasis: 1. Vascular phase
• Vasoconstriction • Begins immediately after injury
2. Platelet phase • Platelets and vessel walls become sticky • Mechanical plug of platelets seals off openings of cut vessels • Begins seconds after injury
3. Coagulation phase • Blood lost into surrounding area coagulates through extrinsic and common pathways • Blood in vessels in area of injury coagulates through intrinsic and common pathways • Slower than other phases
Important: If a patient is taking aspirin, anticoagulants, broad-spectrum antibiotics, alcohol, or anticancer medications, you should be prepared to take special measures in order to control the bleeding. Note: Patients with specific systemic diseases will also have a prolonged bleeding time. These include nonalcoholic liver disease, hepatitis, cirrhosis, and hypertension. Five means of obtaining wound hemostasis:
1. By assisting natural hemostatic mechanisms —usually accomplished by placing a cotton sponge with pressure on bleeding vessels or the use of a hemostat directly on the vessel. 2. By the use of heat on the cut vessels (called thermal coagulation) 3. By suture ligation of the vessel 4. By the placement of a pressure dressing over the wound—most bleeding from oral surgery can be controlled this way. 5. By using vasoconstrictive substances (epinephrine) in local anesthetics
• once every 3 seconds - (20 breaths/min)
* When an adult has a pulse but is breathless, the recommended rate of rescue breathing is once every 5-6 seconds (10-12 breaths/minute). * A victim whose heart and breathing have stopped has the best chance for survival if emergency medical services are activated and CPR is begun within four minutes. * 5-10 seconds is used to assess the pulse. The brachial pulse is assessed in infants, whereas the carotid pulse should be assessed in children and adults. * The best indicator of effective ventilation is seeing the chest rise when delivering breaths. * If chest compressions are interrupted, the blood flow and blood pressure will drop to zero. * At least 1 sec/breath is the length of time recommended to deliver each breath to an adult victim. * Time is not as critical with the new guidelines concerning the length of time recommended to deliver each breath to an infant or child. Now it is important to deliver breaths that make the victim's chest rise.
CPR Ready Reference
Rescue breathing, victim has a pulse, give breath every:
No pulse, locate compression landmark
Compressions are preformed with:
Compression rate
Compression depth
Compression Ventilation ratio
Adults 8 years and up
5-6 seconds
In the center of the breast bone, between the nipples
Heal of 1 hand, second hand on top
Child 1 to 8 years
3 seconds
In the center of the breast bone, between the nipples
Heel of one hand
Infants Under 1 year
3 seconds
One finger width below the nipple line
Two fingers
About 100/min
1.5—2 inches About 1/3 to 1/2 t le depth of the chest
30:2
gen info
The American Society of Anesthesiologists would give what classification to a patient with a severe systemic disease that is a constant threat to life?
What is the most frequent cause of airway obstruction in an unconscious
person?
• chewing gum
• cigarette
•tongue
• hard candy
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• class 4
The ASA classification was first established in 1940 for the purpose of statistical studies and hospital records. It is useful for both outcome comparisons and as a convenient means of communicating the physical status of a patient among anesthesiologists. The five classes, as last modified in 1961, are:
Class 1 — Healthy patient, no medical problems
Class 2 — Mild systemic disease
Class 3 — Severe systemic disease, but not incapacitating
Class 4 — Severe systemic disease that is a constant threat to life
Class 5 — Moribund, not expected to live 24 hours regardless of operation
*** An organ donor is usually designated as a class 6
•tongue
The first step when initiating CPR is to establish unresponsiveness (shake and shout - "Are OK"). Then:
C A L L
you
CALL 911
PUMP
1 , r
BLOW
POSITION HANDS IN THE CENTER OF THE CHEST
CONTINUE WITH TWO BREATHS AND 30 PUMPS UNTIL HELP ARRIVES
Important points to remember in CPR: • The first maneuver the rescuer should use to open the airway in an otherwise uninjured patient is the head tilt with chin lift • If efforts are effective, the pupils will constrict • If too much pressure is incorrectly applied directly over the xyphoid process, the liver may be injured
Remember, you should stop CPR only under the following conditions: • If another trained person takes over CPR for you • If EMS personnel arrive and take over care of the victim • If you are exhausted and unable to continue • If the scene becomes unsafe
gen info Which of the following is a calculated value developed to normalize the reporting of prothrombin time (PT)?
• IMR
•IGR
ITR
INR
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gen info
Which of the following is the most common error in blood pressure measurement?
The accuracy of the prothrombin time (PT) is known to be very system-dependent. The World Health Organization has addressed this system variability problem by (1) the establishment of primary and secondary international reference preparations of thromboplastin and (2) the development of a statistical model for the calibration of thromboplastins to derive the International Sensitivity Index (ISI) and the INR.
INR (international normalized ratio): • Developed to improve consistency of oral anticoagulant therapy • Converts the PT ratio to a value that would have been obtained using a standard PT method • INR is calculated as (PT p a t i e n t / PT n o r m a l )« .
x** (ISI is the international sensitivity index assigned to the test system) • The recommended therapeutic ranges for standard oral anticoagulant therapy and high-dose therapy, respectively, are INR values of 2.0-3.0 and 2.5-3.5.
Other tests used to measure a patient's clotting mechanisms: • Prothrombin Time (PT): the normal range is 11 to 13.5 seconds. To be a good candidate for surgery, the PT time should be within 5-7 seconds of the control sample • Partial Thromboplastin Time (PTT): detects coagulation defects of the intrinsic system. Basic test for hemophilia. Normal value is 25-36 seconds. • Bleeding Time (Ivy method): normal value is less than 9 minutes • Platelet Counts: normal value is 150,000 - 450,000 per 1 cu mm of blood. The minimal platelet count for oral surgery is 50,000
Important: Perhaps the single most important consideration in ruling out hemorrhagic disorder is history.
• the use of too large or too small cuffs Important: Use of the wrong cuff size can result in erroneous readings. A normal adult blood pressure cuff placed on an obese patient's arm will produce falsely elevated readings. This same cuff applied to the very thin arm of a child will produce falsely low readings.
• Before performing a blood pressure reading, the patient should be comfortably seated with the back and arm supported, the legs uncrossed, and the upper arm at the level of the right atrium. • Proper cuff size selection is critical to accurate measurement. The bladder length and width of the cuff should be 80% and 40%, respectively, of the arm circumference. Blood pressure measurement errors are generally worse in cuffs that are too small vs those that are too big. • Blood pressure measurement in sitting and recumbent positions is acceptable. The diastolic blood pressure can be expected to be about 5 mm Hg higher in the sitting position. • A difference in blood pressure between the two arms can be expected in about 20% of patients. The higher value should be the one used in treatment decisions. • When measuring blood pressure, the cuff should be inflated to 30 mm Hg above the point at which the radial pulse disappears. The sphygmomanometer pressure should then be reduced at 2 to 3 mm/second. Two readings should be performed at least 1 minute apart.
Category
Normal
Prchypertension
High blood pressure
Stage 1
Stage 2
Systolic
Less than 120
120-139
And
Or
Diastolic
Less than 80
80-89
140-159
160 or higher
Or
Or
90-99
100 or higher
grafts
Which of the following is the gold standard for bone regenerative grafting materials for several reasons, including the capability to support osteogenesis and having osteoinductive and osteoconductive properties?
An autogenous bone graft is the transplantation of bone from one site to another site within the same person. These grafts may be of cancellous, cortical, or a combination of cortical and cancellous bone. Autogenous bone is the only graft that possesses all of the following properties: osteoinduction, osteoconduction, and osteogenesis. Additionally, there are no immunogenic complications. The downsides to autograft are the finite quantity available and donor site morbidity. Types of autogenous bone grafts:
• Cortical grafts: advantages are due to its structural capabilities. Also has a higher concentration of BMP (bone morphogenetic protein). The disadvantages are due to the lamellar architecture. Common donor sites: iliac crest, ribs, anterior cortex of the chin, lateral cortex of the ramus/external oblique ridge. • Cancellous grafts: advantages are mostly based on its rich cellular capability. The most abundant supply can be harvested from the anterior or posterior iliac crest. The only disadvantage arises from the fact that they do not possess any macroscopic structural integrity. Thus, the graft cannot be rigidly fixed and will deform, migrate, or resorb if placed under tension or compressive functional forces.
1. The bone marrow for grafting defects in the mandible and maxilla is generally ob-Notes tained from the iliac crest (anterior and posterior). Also used for ridge augmen
tation. 2. BMP is a protein complex responsible for initiating osteoinduction. BMP is part of the cytokine family of growth factors, which occurs in the organic portion of bone called the bone matrix. 3. A costochondral rib graft may be employed with the cartilaginous portion simulating the TMJ and condyle. When used for ridge augmentation, there is a great deal of shrinkage. 4. Bone plates, biphasic pins, titanium mesh, and intraosseous wires are used in the fixation of bone grafts. Sutures are not generally used.
• freeze-dried
Allogeneic bone is nonvital, osseous tissue harvested from one individual and transferred to another of the same species. Three forms of allogeneic bone include: fresh frozen, freeze-dried, and demineralized freeze-dried bone. Fresh frozen bone, however, is rarely used due to the concern related to transmission of disease.
• Freeze-dried bone is osteoconductive, however, it has no osteogenic or osteoinductive capabilities. Freeze-dried allogeneic grafts are usually placed in conjunction with autogenous grafts. • Demineralized freeze-dried allogeneic bone lacks mechanical strength, but has osteoconductive and osteoinductive capabilities. Demineralizing the freeze-dried bone exposes the bone morphogenetic proteins, which has been shown to induce bone formation.
The three processes by which bone can be repaired or regenerated are: • Osteogenesis (osteogenic potential) is the formation of new bone from osteoprogenitor cells. Spontaneous osteogenesis is the formation of new bone from osteoprogenitor cells in a wound. Transplanted osteogenesis is formation of new bone from osteoprogenitor cells placed into the wound from a distant site. Osteogenic grafts include the advantages of osteoinductive and osteoconductive grafts, in addition to the advantages of transplanting fully differentiated osteocompetent cells that will immediately produce new bone. • Osteoconduction is the formation of new bone from host-derived or transplanted osteoprogenitor cells along a biologic or alloplastic framework, such as along the fibrin clot in tooth extraction or along a hydroxyapatite block. Osteoconductive grafts provide only a passive framework or scaffolding. The grafted material, therefore, does not have the ability to actually produce bone. This type of graft simply conducts bone-forming cells from the host bed into and around the scaffolding. • Osteoinduction refers to new bone formation from the differentiation of osteoprogenitor cells, derived from primitive mesenchymal cells, into secretory osteoblasts. Such grafts help produce the cells that are necessary to produce new bone.
grafts Which of the following refers to a horizontal osteotomy of the anterior mandible?
> blepharoplasty
•genioplasty
• cervicofacial rhytidectomy
rhinoplasty
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grafts
Match the term on the left with the correct description on the right.
• autograft tissue removed from an animal donor and surgically transplanted to a human
«allograft tissue surgically removed from one area of a person's body, such as the iliac crest, and transplanted in another site on the same person
• xenograft tissue surgically transplanted from an individual of the same species who is genetically related to the recipient
• isograft tissue surgically transplanted from one individual to a genetically nonidentical individual of the same species
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• genioplasty
Genioplasty refers to a horizontal osteotomy of the anterior mandible. Chin implant refers to either an alloplastic implant or an autogenous implant. Alloplastic implants and sliding genioplasty represent the two currently accepted methods of chin augmentation.
A sliding genioplasty involves removing a horseshoe-shaped piece of the chin bone and sliding it either backward or forward, finally fixing it in place using titanium screws. The most common complication after genioplasty surgery is a neurosensory disturbance, followed by hematoma and infection.
Alloplastic augmentation can also be considered for the treatment of a genial deficiency. The materials most commonly used include high-density polyethylene, hard tissue replacement polymer, polyamide mesh, solid medical grade silicone rubber, hydroxyapatite, and Gore-Tex.
Problems that are frequently encountered when using alloplastic materials for the treatment of a genial deficiency:
1. Migration from the position in which they were placed at the time of surgery 2. Erosion of the chin prominence contiguous with the implant 3. Unpleasant sensation in the implant region when exposed to cold temperatures
Remember: Alloplastic grafts are inert, man-made synthetic materials. The modern artificial joint replacement procedures use metal alloplastic grafts. For bone replacement a man-made material that mimics natural bone is used. Most often, this is a form of calcium phosphate (i.e., tricalciumphosphate, calcium carbonate, or hydroxyapatite).
• autograft: tissue surgically removed from one area of a person's body, such as the iliac crest, and transplanted in another site on the same person
• allograft: tissue surgically transplanted from one individual to a genetically non-identical individual of the same species
• xenograft: tissue removed from an animal donor and surgically transplanted to a human
• isograft: tissue surgically transplanted from an individual of the same species who is genetically related to the recipient
Classification of grafts (or implants): • Autogenous grafts (also called autografts) are composed of tissues taken from the same individual. Most frequently used in oral surgery. • Allogeneic grafts (also called allografts) are composed of tissues taken from an individual of the same species who is not genetically related to the patient (usually cadaver bone). • Isogeneic grafts (also called isografts) are composed of tissues taken from an individual of the same species who is genetically related to the recipient. • Xenogeneic implants (also called xenografts or heterografts) are composed of tissues taken from a donor of another species, for example, animal bone grafted to man. Rarely used in oral surgery.
Note: Rejection of the graft is most common when allografts or xenografts of bone and cartilage are used in oral surgery. Autogenous grafts, although frequently presenting surgical and technical problems, do not, as a rule, involve rejection (or immunological complications).
The ideal graft should: • Be replaced by the host bone • Withstand mechanical forces • Produce no immunologic response (or rejection) • Actively assist osteogenic (bone-forming) processes of the host. The greatest osteogenic potential occurs with an autogenous cancellous graft and hemopoietic marrow.
grafts
The term alloplastic is synonymous with:
• original
• natural
• synthetic
• genuine
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implants
In reference to the bone-implant interface, which of the following yields the most predictable long-term stability?
The term alloplastic is synonymous with synthetic. This indicates that the material is produced from inorganic sources and contains no animal or human components. Alloplastic materials offer a prepackaged solution to common reconstructive surgical problems without the need for autogenous grafting and donor site morbidity.
For bone replacement, a man-made material that mimics natural bone is used. Most often hydroxyapatite (HA) is used for augmentation of the mandible. Hydroxyapatite is a dense, biocompatible material that can be produced synthetically or obtained from biologic sources such as coral. The granular or particle form is most commonly used for alveolar ridge augmentation. Note: When placed in a subperiosteal environment, HA bonds both physically and chemically to the bone.
Some advantages and disadvantages of restructuring an atrophic ridge with hydroxyapatite granules:
• Advantages: - It is a simple surgical technique suitable as an office procedure - No donor site is required to obtain autogenous bone graft material - Hydroxyapatite is totally biocompatible and nonresorbable
• Disadvantages: - Migration of the hydroxyapatite granules - Poor ridge form (inadequate height) - Abnormal color under the mucosa - Mental nerve neuropathy - usually occurs from excessive augmentation - Cannot participate in phase 1 osteogenesis since no viable osteogenic cells are
present
• osseointegration
The bone-implant interface: Fibro-osseous integration
• Connective tissue-encapsulated implant within bone • Not seen often with newer materials
Osseointegration • A direct structural and functional connection between living bone and the surfaces of a load-carrying implant without soft-tissue
• Yields most predictable long-term stability • Several important factors involved: materials, surface characteristics, bone, timing
Biointegration • Implant interface that is achieved with bioactive materials, such as hydroxyapatite
(HA) or bioglass, that bond directly to bone. • HA-coated implants appear to develop bone faster than do non-coated implants but, after a year, there is little difference between coated and non-coated implant.
Important principles for success of dental implants: primary stability, amount of bone, anatomic structures (i.e., adjacent natural teeth, maxillary sinus, nasal cavity, inferior alveolar canal).
1. To ensure the development of keratinized tissue around a dental implant, the best Notes time to augment the soft tissue is Stage II surgery.
2. Guided tissue regeneration is a surgical procedure used to eliminate a bony defect around a dental implant. This process decreases the connective tissue growth while increasing the growth of bone in the defect. 3. A gentle surgical technique requires that you do not heat bone above 47°C. Above this temperature, bone tissue damage occurs.
implants
Which of the following is found between the bone and implant of an endosseous dental implant?
The histologic definition of osseointegration is best described by the following: The direct connection between living bone and a load-bearing endosseous implant at the light microscopic level. Only endosseous and transosseous implants are considered true osseointegrated implants.
Criteria for success of a dental implant: • Clinical immobility under load-bearing conditions • Symptom free • Minimal loss of crestal bone • No peri-implant radiolucency
1. For an implant to be successful, you need adequate transfer of force and bio-Notes compatibility.
2. Handpieces for preparation of dental implant receptor sites are low speed/high torque. 3. In the event an endosseous dental implant is mobile, the proper procedure is to remove the failed implant, debride the socket, and consider placing a bone graft with a resorbable membrane. 4. You need a minimum of 10 mm of bone height to place an endosseous (rootform) dental implant. 5. The minimum required distance from the apex of a mandibular posterior implant to the superior aspect of the inferior alveolar canal is 2 mm. 6. Titanium and titanium alloy are the most common materials used today for two-stage endosseous implants.
• smoking
*** Because smoking affects the healing of bone and overlying tissue, it should be considered a relative contraindication to implant placement.
Any toothless area can be considered for dental implants. Determining whether implants are an option and the type of implants to use include: the patient's requirements and expectations, the amount of additional work needed (i.e., bone grafting), the dentist's skill level, and the long-term prognosis.
Some indications for implant placement: • Fixed restoration of single or multiple teeth in a partially edentulous jaw • Retention of a removable prosthesis in a partially edentulous jaw • Retention of a prosthesis in a completely edentulous jaw • Retention of a fixed prosthesis in a completely edentulous maxilla or mandible
Important: In patients with uncontrolled systemic diseases such as diabetes, immunocompromised patients, and patients with bleeding disorders, implant placement should be considered with extreme caution.
Remember: 1. The highest failure rate is seen in the posterior maxilla where the bone is the softest (D4) quality. 2. Mobility of the implant is regarded as the most common sign of implant failure. 3. A dental implant supported prosthesis should fit passively on the dental implant. 4. The minimum space required for a 4.0-mm diameter implant is 7.0 mm— 1.5 mm on each side of the implant plus the diameter of the implant 5. The maximum amount of taper to allow for proper draw on an overdenture attachment, such as an "O" ring, is 15 degrees.
implants Currently, the most popular used implants are:
misc. To prevent infective endocarditis in patients at risk for such infections, the American Heart Association (AHA) frequently issues guidelines for prophylactic antibiotic coverage during dental procedures. In accordance with the most recently revised AHA guidelines, which of the following are acceptable antibiotic options for the prevention of infective endocarditis? Select all that apply.
misc. The roots of the third, second, and first molars are all below the level of the mylohyoid. Infection of these teeth pass through the root, directly into the
The mandibular left second molar of a 14-year-old boy is unerupted. Radiographs show a small dentigerous cyst surrounding the crown. What is the treatment of choice?
surgically extract the unerupted second molar
• uncover the crown and keep it exposed
• prescribe an antiinflammatory medication and schedule a follow-up appointment in 6 months
• submaxillary space Remember: The mylohyoid muscle, stretching across the floor of the mouth, serves as the inferior border of the sublingual space and the superior border of the submaxillary space.
Fascial Spaces and Infection
Space
Maxillary Spaces
Canines space
Buccal Space
Infratemporal space
Mandibular Spaces
Buccal space
Submental space
Sublingual space
Submaxillary space
Pterygomandibular space
Masseteric space
Temporal space
Masticator space
Usual Source of Infection
Canines
Maxillary molars, premolars
Maxillary third molars
Mandibular molars, premolars
Mandibular incisors
Mandibular molars, premolars
Mandibular molars
Mandibular molars, premolars
Mandibular third molars
Other spaces (infratemporal, masseteric, and pterygomandibular)
Other spaces (pterygomandibular and temporal spaces)
Important: Anatomic variability exists and the descriptions given above represent the space in which an infection from a tooth is most likely to drain. Note: Penicillin V is often the preferred drug to treat odontogenic infections. It is effective against streptococci and oral anaerobes. For penicillin-allergic patients, clindamycin or clarithromycin can be used. Narrow-spectrum antibiotics are preferred over broad-spectrum antibiotics, and bacteriocidal agents are preferred over bacteriostatic agents.
• uncover the crown and keep it exposed
Dentigerous cysts are those associated with the crowns of unerupted teeth. Some literature refers to these cysts as "follicular" or "primordial" cysts. Note: They are probably the result of degenerative changes in the reduced enamel epithelium.
Remember: If cysts form when a tooth is erupting, they are called eruption cysts. These cysts interfere with normal eruption of the teeth. Eruption cysts are more commonly found in the child and young adult and may be associated with any tooth. If treatment is indicated, simple incision or "deroofing" is all that is needed.
Dentigerous cyst
Eruption cyst
misc. Which of the following are considered primary fascial spaces? Select all that apply.
Fascial spaces: layers of fascia "create" potential fascial spaces (they are called potential because in health, there is no space); all are filled by loose areolar connective tissue. The hyoid bone is the most important anatomic structure in the neck that limits the spread of infection. Infections or other inflammatory conditions spread by the path of least resistance to reach the fascial spaces. The most common space involved is the vestibular space.
The spaces directly adjacent to the origin of the odontogenic infections are the primary fascial spaces. Infections spread from the origin into these spaces, which are buccal, canine, sublingual, submaxillary, submental, and vestibular. Note: Canine space infections and deep temporal space infections can result in cavernous sinus thrombosis via the ophthalmic veins.
Fascial spaces that become involved following spread of infection to the primary spaces are the secondary fascial spaces.The secondary spaces are pterygomandibular, infratemporal, masseteric, lateral pharyngeal, superficial and deep temporal, retropharyngeal, masticator, and prevertebral. Note: Lateral pharyngeal infections can traverse the retropharyngeal and prevertebral spaces and spread into the mediastinum.
Factors that influence the spread of odontogenic infection: (1) Thickness of bone adjacent to the offending tooth (2) Position of muscle attachment in relation to root tip (3) Virulence of the organism and (4) Status of patient's immune system.
1. The masticator space contains the contents of the pterygomandibular space and is continuous Notes with the temporal space.
2. The most definite clinical sign indicating extension of an odontogenic infection into the masticator space is trismus. Trismus is difficulty in opening the mouth due to a tonic spasm of the muscles of mastication. 3. Trismus may also result from passing the needle through the medial pterygoid muscle during an inferior alveolar nerve block. 4. Other symptoms of fascial space infection include pain, dysphagia, and dysphonia. 5. The submandibular space is continuous with the lateral pharyngeal space. The mylohyoid muscle divides this space and serves as the inferior border of the sublingual space and the superior border of the submaxillary space.
• rectally ***Axillary is the least accurate
General considerations when checking vital signs: • The patient should not have had alcohol, tobacco, caffeine, or performed vigorous exercise within 30 minutes of the exam • Ideally, the patient should be sitting with feet on the floor and their back supported. The examination room should be quiet and the patient comfortable • History of hypertension, slow or rapid pulse, and current medications should always be obtained
Routine Vital Signs: • Blood pressure: normal 120/80 • Pulse rate: normal 72 • Respiration rate.- normal 15 • Temperature can be measured in several different ways:
- Oral with a glass, paper, or electronic thermometer (normal 98.6°F/37°C) - Axillary with a glass or electronic thermometer (normal 97.6°F/ 36.3°C) - Rectal or "core" with a glass or electronic thermometer (normal 99.6°F/37.7°C) - Aural (the ear) with an electronic thermometer (normal 99.6°F/37.7°C)
*** For every 1°C rise in body temperature, there is a corresponding 9-10 beats/min increase in the patient's heart rate.
Note: Abnormalities of vital signs are often clues to diseases, the alterations in vital signs are used to evaluate a patient's progress. Five major areas to be discussed when taking a patient history: 1. Chief complaint 2. History of present illness 3. Specific drug allergies 4. Review of systems (heart, liver, kidney, brain, etc.) 5. Nature of systems. Important: In complicated cases, don't be hesitant to call patient's physician, previous dentists, or other health professionals.
misc. Osteomyelitis usually begins in the medullary space involving the
, Cardiac Conditions Stratification for Risk of Endocarditis
Endocarditis Prophylaxis Recommended
High Risk
Prosthetic heart valves
Surgically constructed systemic pulmonary shunts or conduits
Complex cyanotic congenital heart disease
Prior bacterial endocarditis
Moderate Risk
Most other congenital cardiac malformations
Acquired valvular dysfunction
Hypertrophic cardiomyopathy
Mitral valve prolapse with regurgitation and/ or thickened leaflets
Endocarditis Prophylaxis Not Recommended
Negligible Risk
Isolated secundum atrial septal defect
Surgical repair of atrial septal defect, ventricular septal defect, or patent ductus arteriosus
Prior coronary artery bypass graft
Mitral valve prolapse
Physiologic, functional, or innocent heart murmurs
Previous Kawasaki disease without valvular dysfunction
Previous rheumatic fever without valvular dysfunction
Cardiac pacemakers and implanted defibrillators
• cancellous bone
Osteomyelitis is a relatively rare inflammatory process within the medullary (trabecular) portion of bone that involves the marrow spaces. Osteomyelitis is generally classified into two major groups: suppurative and nonsuppurative. Suppurative osteomyelitis is classified into acute, chronic, or infantile osteomyelitis. Nonsuppurative osteomyelitis is classified into chronic sclerosing (focal and diffuse), Garre osteomyelitis, and actinomycotic osteomyelitis. Infection, inflammation, and ischemia are the mechanisms by which osteomyelitis spreads. The most common initiating causes are odontogenic infection and trauma. The infection usually begins in the medullary space involving the cancellous bone. Eventually the cortical bone, periosteum, and soft tissues become involved.
Note: Garre osteomyelitis is characterized by localized, hard, nontender, bony swelling of the lateral and inferior aspects of the mandible. It is primarily present in children and young adults and is usually associated with a carious molar and low-grade infection.
Important: Acute osteomyelitis occurs more frequently in the mandible as opposed to the maxilla. The primary reason for this is that the blood supply to the maxilla is much richer and is derived from a number of different arteries, while the mandible tends to draw its primary supply from the inferior alveolar artery. The dense overlying cortical bone of the mandible prevents penetration of periosteal blood vessels, thus the mandibular cancellous bone is more likely to become ischemic and, therefore, infected. Important point: a reduced blood supply will predispose bone to osteomyelitis. The most frequently found bacteria in patients with osteomyelitis of the jaws include Gram-positive cocci (i.e., streptococci, Staphylococcus aureus), anaerobic cocci, and gram-negative rods. The treatment of osteomyelitis of the jaws usually includes both surgical intervention and medical management of the patient, as well, as sensitivity testing. Medical management involves administration of empirical antibiotics, performing a Gram stain, and the administration of culture-guided antibiotics. Surgical treatment includes removal of loose teeth and foreign bodies; sequestrectomy; debridement; decortication; resection; and reconstruction, if necessary.
misc. Why is a conventional handpiece that expels forced air contraindicated when performing dentoalveolar surgery?
• too much bone will be removed
• these handpieces can cause tissue emphysema or an air embolus, which can be fatal
• these handpieces are not high-powered enough to remove bone
Anyone scheduled for general anesthesia should have a chest x-ray and patients over 40 years old should also have a/an:
• ECG
• MRI
• panorex
• biopsy
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• these handpieces can cause tissue emphysema or an air embolus, which can be fatal
Very important: Most high-speed turbine drills used in routine restorative dentistry are totally unacceptable for oral surgery. The air exhausted from these drills goes into the wound and may be forced deeper into tissue planes and produce tissue emphysema, a potentially dangerous situation.
Rongeur forceps are the most commonly used instruments for removing bone. However, the technique that most oral surgeons use when removing bone is the bur and handpiece.
Irrigation of the surgical wound during and after the cutting of bone cannot be emphasized enough. Copious amounts of coolant spray are crucial in minimizing osseous necrosis caused by heat generated from the bur. Irrigation serves also to cleanse the crypt and areas beneath the flap of bony debris, tooth fragments, and blood. Distilled water is not used for irrigation because it is a hypotonic solution and will enter cells down the osmotic gradient causing cell lysis and rapid death of bone cells.
Note: An acute infected tissue emphysema is usually caused by the indiscreet use of: 1. Air pressure syringes: In drying out a root canal with a compressed air syringe, septic material may be forced through the apical foramen into the cancellous portion of the alveolar process and ultimately out through the nutrient foramina into adjacent soft tissues, resulting in formation of a septic cellulitis and tissue emphysema. 2. Atomizing spray bottles activated by compressed air: A similar condition can be induced by the use of a compressed-air spray bottle for irrigation of wounds, particularly in the retromolar region. It is safer to use a hand-activated syringe when irrigating wounds or drying root canals since it is unlikely that a tissue emphysema would be produced under these circumstances.
• ECG
Routine Admission Tests • A complete blood count that includes an evaluation of the hemoglobin and hemat
ocrit indices • A total white blood cell count with a differential count • A gross and microscopic urinalysis
*** Anyone scheduled for general anesthesia should have a chest x-ray, and patients over 40 years old should also have an ECG.
Factors to be considered in the decision to hospitalize a patient for an elective procedure:
• Medical problems compromising treatment (diabetes, hemophilia, etc.) • Difficulty and extent of surgery • Consideration of the individual patient (emotionally disturbed, handicapped, etc.) • Cost of hospitalization (time and money)
misc.
Incision for drainage (l&D) in an area of acute infection should only be performed after:
• a culture for antibiotic sensitivity has been performed
Physiologically, it is at this time that nature has constructed a barrier around the abscess, walling it off from
the circulation and making it possible to palpate the presence of purulent material within the abscess cavity
(known as fluctuance).
The important components in treatment of odontogenic infection are:
• Determining the severity of infection • Determining whether the infection is at the cellulitis or abscess stage • Evaluating the state of the patient's host defense mechanisms. Compromised host defenses include severe diabetes, alcoholism, malnutrition, uremia, leukemia, malignant tumors, lymphoma, or someone on cancer chemotherapeutic or immunosuppressive agents. • Determine whether patient should be treated by a general dentist or an oral surgeon. Criteria for referral to an oral surgeon include rapidly progressive infection, difficulty in breathing or swallowing, fascial space involvement, elevated temperature (>101°F), severe jaw trismus (<10 mm), toxic appearance, or compromised host defenses. • Treating the infection surgically. Removal of the source of infection and drainage of purulence.
- Methods of drainage of odontogenic infections: endodontic treatment, extraction of the offending tooth, or incision and drainage of the soft tissue.
• Support the patient medically: airway maintenance, rehydration, analgesia, nutrition, etc. • Prescribe appropriate antibiotics. Indications for the use of antibiotics include rapidly progressive swelling, diffuse swelling, compromised host defenses, involvement of fascial spaces, severe pericoronitis, and osteomyelitis. Penicillin VK. is often the preferred drug. If the patient is penicillin-allergic, use clindamycin.
Surgical principles of incision and drainage: • Before incision, obtain fluid for culture • Incise the abscess in healthy skin or mucosa and in a cosmetically or functionally acceptable place, using blunt dissection and thorough exploration of the involved space • Use one-way drains in intraoral abscesses; use through-and-through drainage in extraoral cases • Remove the drain gradually from deep sites
1. For odontogenic infections, the most common organisms are aerobic gram-positive cocci, Notes anaerobic gram-positive cocci, and anaerobic gram-negative rods.
2. Streptococcus species (which are highly virulent and aerobic) initiate the infectious process, a cellulitis then occurs, followed by proliferation of anaerobic organisms.
• v-y advancement
When a frenum is positioned in such a way as to interfere with the normal alignment of teeth or results in pulling away of the gingiva from the tooth surface causing recession, it is often removed using a surgical process known as a frenectomy.
Three surgical techniques used for a frenectomy:
• Diamond excision \ are effective when the mucosal and fibrous tissue band is rela-• Z-plasty / tively narrow. These techniques relax the pull of the frenum.
• V-Y advancement is often preferred when the frenal attachment has a wide base. This technique is good for lengthening tissue and usually results in less scarring.
Note: Local anesthetic infiltration is usually sufficient for surgical treatment of frenal attachments. Care must be taken to avoid excessive infiltration directly in the frenum area since it may obscure the anatomy that must be visualized at the time of excision.
misc. An orofacial infection can reach the cavernous sinus through two routes: an anterior route via the and , and a posterior route via the
Cavernous sinus thrombosis is an uncommon but potentially lethal extension of odontogenic infection. Valveless veins in the head and neck allow retrograde flow of infection from the face to the sinus. The pterygoid plexus of veins and angular and ophthalmic veins may contribute to retrograde flow. Note: Canine space infections and deep temporal space infections can result in cavernous sinus thrombosis via the ophthalmic veins.
The first clinical signs of cavernous thrombosis include vascular congestion in periorbital, scleral, and retinal veins. Other clinical signs include periorbital edema, proptosis (exophthalmos), thrombosis of the retinal vein, ptosis, dilated pupils, absent corneal reflex, and supraorbital sensory deficits.
Important: The infection is life-threatening and requires prompt and aggressive treatment, consisting of elimination of the source of infection, drainage, parenteral antibiotic therapy, and neurosurgical consultation.
Remember: Cranial nerves III, IV, V (ophthalmic division ofV), and VI pass through the cavernous sinus.
Differences Between Cellulitis and Abscess
Characteristic
Duration
Pain
Size
Localization
Palpation
Presence of pus
Degree of seriousness
Bacteria
Cellulitis
Acute
Severe/generalized
Large
Diffuse borders
Doughy to indurated
No
Greater
Aerobic
Abscess
Chronic
Localized
Small
Well circumscribed
Fluctuant
Yes
Less
Anaerobic
• alveoloplasty
An alveoloplasty is the surgical preparation of the alveolar ridges (i.e., removing undercuts and sharp edges from areas such as the mylohyoid ridge) for the reception of dentures or shaping and smoothing the socket margins after extractions of teeth with subsequent suturing to insure optimal healing.
The objectives of this recontouring should be to provide the best possible tissue contour for prosthesis support, while maintaining as much bone and soft tissue as possible.
Remember: 1. In some cases, the bone is well-contoured for denture or partial denture construction, but the soft tissues may interfere with the fit or function of the prosthesis. These soft tissues areas include the mandibular retromolar pad, the maxillary tuberosity, excessive alveolar ridge tissue, labial and lingual freni, or a condition called inflammatory fibrous hyperplasia. 2. A closed reduction is the closing of the space between fractured bone without cutting through the soft tissue or surrounding bone. 3. A gingivoplasty is a surgical procedure to reshape the gingivae to create a normal, functional form. 4. An operculectomy is the removal of the operculum, which is the flap of tissue over an unerupted or partially erupted tooth.
misc. While there are many reasons for autotransplanting teeth, tooth loss as a result of dental caries is the most common indication, especially when:
First molars erupt early and are often heavily restored. Autotransplantation in this situation involves the removal of a third molar which may then be transferred to the site of an unrestorable first molar. Other conditions in which transplantation can be considered include tooth agenesis (especially of premolars and lateral incisors), traumatic tooth loss, atopic eruption of canines, root resorption, large endodontic lesions, cervical root fractures, localized juvenile periodontitis, as well as other pathologies.
Patient selection is very important for the success of autotransplantation. Candidates must be in good health, able to follow postoperative instructions, and available for follow-up visits. They should also demonstrate an acceptable level of oral hygiene and be amenable to regular dental care. Most importantly, the patients must have a suitable recipient site and donor tooth. Note: If surgery is done on a diabetic patient, antibiotic coverage should be considered particularly if the diabetes is not well controlled or uncontrolled.
The most important criteria for success involving the recipient site is adequacy of bone support. There must be sufficient alveolar bone support in all dimensions with adequate attached keratinized tissue to allow for stabilization of the transplanted tooth.
The donor tooth should be positioned such that extraction will be as atraumatic as possible. Abnormal root morphology, which makes tooth removal exceedingly difficult and may involve tooth sectioning, is contraindicated for this surgery. Teeth with either open or closed apices may be donors; however, the most predictable results are obtained with teeth having between one-half to two-thirds completed root development. Note: The most likely cause of failure will be a chronic, progressive external root resorption.
Important: An allogeneic tooth transplant refers to a situation in which a tooth from one individual is placed in another individual. The almost universal sequelae of an allogeneic tooth transplant is ankylosis and progressive root resorption. Remember: The change in continuity of the occlusal plane observed after ankylosis of a tooth is caused by the continued eruption of the other non-ankylosed teeth and growth of the alveolar process.
• blood dyscrasias (i.e., hemophilia, leukemia) • addison disease or any steroid deficiency • fever of unexplained origin • nephritis • any debilitating disease • cardiac disease
*** Uncontrolled diabetes mellitus is a systemic contraindication to elective surgery. Important: Patients with these systemic conditions can be treated, but you need to consult with the patient's physician before treatment. In most cases, these patients are best treated in the hospital by an oral surgeon. Examples of contraindications include:
• End-stage renal disease • Severe uncontrolled metabolic diseases (i.e., uncontrolled diabetes mellitus) • Advanced cardiac conditions (unstable angina) • Patients with leukemia and lymphoma should be treated before extraction of teeth • Patients with hemophilia or platelet disorders should be treated before extraction of teeth • Patients with a history of head and neck cancer need to be treated with care because even minor surgery can lead to osteoradionecrosis. Note: These patients are often treated with hyperbaric oxygen therapy prior to dental surgery. • Pericoronitis: infection of the soft tissues around a partially erupted mandibular third molar. Note: This infection should be treated prior to removal of the maxillary third molar. • Acute infectious stomatitis and malignant disease are relative contraindications • Treatment with IV bisphosphonates increases the risk of osteonecrosis of the jaw
Note: Cardiac disease, such as coronary artery disease, uncontrolled hypertension, and cardiac decompensation can complicate exodontia. Usually a postinfarction patient is not subjected to oral surgery within 6 months of his infarction. However, emergency procedures can be performed, provided the patient's physician has been consulted.
Important: 1. Infected maxillary molars and mandibular molars will usually drain into the buccal space which lies between the buccinator muscle and overlying skin and superficial fascia. 2. The submaxillary space, which lies inferior to the mylohyoid muscle, is primarily infected by the mandibular first, second, and third molars.
***Stridor is a high-pitched, noisy respiration, like the blowing of the wind. It demands immediate attention. It is caused by partial obstruction of the airway at the level of the larynx or trachea.
Because total airway obstruction usually occurs during inspiration, there is usually adequate oxygen left in the cerebral blood to permit up to 2 minutes of consciousness. If the obstruction is not recognized and managed and if oxygen is not delivered to the victim's lungs, blood, and brain, permanent neurologic damage occurs within 3 to 5 minutes.
Noninvasive Procedures for Obstructed Airway: • Back blows, manual thrusts, Heimlich maneuver, chest thrust, and finger sweep
Invasive Procedures for Obstructed Airways:
*** These procedures should only be performed by persons trained in these techniques andonly if proper equipment is available.
•Tracheotomy: Is used more for long-term airway maintenance and not for emergency airways • Cricothyrotomy: Is a procedure for establishing an emergency airway where other methods are unsuitable or impossible. The access site is the cricothyroid membrane of the trachea, located on the anterior neck, between the cricoid and thyroid cartilages.
Important: A cricothyrotomy may be lifesaving in an anaphylactic reaction in which a patient shows signs of laryngeal obstruction. If a patient shows signs of laryngeal obstruction, that is, stridor (crowing sounds), epinephrine should be given and oxygen administered. If a patient loses consciousness and appears to be unable to breathe, an emergency cricothyrotomy may be required to bypass the laryngeal obstruction.
• tongue and floor of the mouth
The most common sites of oral cancer are the tongue and the floor of the mouth. The other common sites are the buccal vestibule, buccal mucosa, gingiva, and rarely, the hard and soft palate. This cancer is extremely malignant and, even if there is slight delay it spreads to lymph nodes of the neck.
Squamous cell carcinoma (epidermoid carcinoma) is the most common form of oral cancer. Oral SCC usually presents as an indurated ulcer with poorly defined borders. The lesion is characteristically painless, unless inflammation from superinfection or chronic mechanical irritation is present. An indolent clinical presentation in the form of a small superficial ulceration, leukoplakia, or erythroplakia is also likely, especially in the early stages of development.
Remember: SCC usually affects the lower lip, and it rarely the upper lip. This occurrence has been attributed to greater exposure of the lower lip to sunlight. Lip carcinoma commonly presents as an ulcer. In many cases, a keratin crust covers the ulcer. The rest of the lip vermilion may show actinic changes.
Important: Carcinoma in situ is an epithelial dysplasia that includes all the layers of the epithelium but does not extend beyond the basal layer. Once the malignant cells have penetrated the basal layer into the lamina propria, early invasive squamous cell carcinoma has been established. If tumor invasiveness extends deeper into the tissues, involving fat, muscle, or other structures, then true invasive squamous cell carcinoma has evolved.
The degree of histologic differentiation best describes the degree of malignancy of a tumor. Malignant neoplasms are histologically classified as (1) well differentiated (2) moderately differentiated, or (3) poorly differentiated (anaplastic) tumors. From a histologic point of view, poorly differentiated tumors have the highest degree of malignancy.
1. The salivary glands, blood vessels, lymphatics, muscle, bone, and other connective tis-Notes sue can also give rise to primary malignancies of the head and neck.
2. Cancer of the breast, prostate, lung, kidney, thyroid, hematopoietic system, and colon can metastasize to the head and neck region.
misc. Pericoronitis is acute inflammation of the tissue overlying and surrounding a partially erupted or erupting tooth. The most commonly involved tooth is a:
Bleeding that consists of pinpoint dots of blood is called . Larger flat areas where blood has collected under the tissue, up to a centimeter in diameter, are called . A very large area is called a/an .
• purpura, petechiae, ecchymosis
• petechiae, ecchymosis, purpura
• ecchymosis, purpura, petechiae
• petechiae, purpura, ecchymosis
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• mandibular third molar — See picture below
The clinical picture is that of a markedly red, swollen, suppurative lesion. The involved tissue is very tender and often accompanied by pain radiating to the ear, throat, and floor of the mouth. Excruciating pain is produced when the opposing tooth impinges on the inflamed tissue during mastication. There may be trismus of the masticator muscles on the affected side. Involvement of the cervical nodes, fever, and malaise are common. If this occurs, antibiotic therapy is indicated.
The principal etiologic factors in pericoronitis are food debris and bacterial waste products that have accumulated under the soft tissue flap, overlying a partially erupted tooth. This tissue is often traumatized during mastication, which further exacerbates the situation. Satisfactory emergency treatment is as follows:
1. Carefully cleanse beneath the tissue flap using a dental scaler if available. Then flush thoroughly with an irrigating syringe, warm saline and/or chlorhexidine gluconate. 2. Instruct the patient to rinse with warm saline hourly. 3. Prescribe a soft diet and instruct the patient to refrain from chewing on the affected side of the mouth. 4. Repeat treatment daily until the inflammatory reaction subsides.
Important: The maxillary third molar is the most frequent contributing factor to pericoro-nal infections found around mandibular third molars. Always examine the maxillary third molar, it may be supererupted or malaligned.
• petechiae, purpura, ecchymosis
Postoperative ecchymosis is a result of trauma to the underlying blood vessels. Blood escapes from the vascular tree and accumulates in the tissues. It is common after extractions in elderly patients due to the fragility of the vessel walls. All patients should be warned that it may occur following extractions. Note: Sometimes the patient will complain of a diffuse, nonpainful, yellowish discoloration of the skin. Moist heat often speeds the resolution of postoperative ecchymosis.
Most common adverse effects of radiation therapy on the oral and paraoral tissues: • Rampant caries • Difficulty in swallowing • Radiation mucositis • Varying degree of trismus • Xerostomia • Radiation dermatitis
Important: Osteoradionecrosis does not develop unless the patient's oral condition is not optimized before radiation therapy, and postirradiation dental procedures are performed without proper precautions.
Note: Hyperbaric oxygen therapy must be considered if surgery is to be performed on an irradiated mandible.
Remember: • Petechiae - <2 mm • Purpura -2-10 mm • Ecchymosis - >10 mm
misc. Thrombocytopenia (low platelet count) that is less than is an absolute contraindication to elective surgical procedures because of the possibility of significant bleeding.
characteristics raise the suspicion of malignancy?
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• 50,000/mm3
Patients with less than 10,000 - 20,000 platelets have been known to bleed spontaneously. Platelet counts between 50,000 and 100,000 have not been associated with significant bleeding, provided platelet function is normal.
1. Normal platelet count is 150,000 - 450,000. Notes 2. Emergency procedures may be done with as few as 30,000 platelets if the
dentist is working closely with the patient's hematologist and uses excellent techniques of tissue management 3. Bleeding time is a screening test that assesses platelet number and function. 4. Aspirin irreversibly blocks cyclooxygenase function, inhibiting platelet aggregation for their 7 to 10 day life span. Because approximately 10% of platelets are replaced each day, it takes an average of 2-3 days for bleeding time to normalize, but most experts recommend allowing 7 days without aspirin before surgery. Other NSAIDs will alter platelet function only temporarily.
Characteristics of lesions that raise the suspicion of malignancy: • Erythroplasia: lesion is totally red or speckled red and white • Ulceration: lesion is ulcerated or is an ulcer • Duration: more than two weeks • Rapid growth • Bleeding: Bleeds on gentle manipulation • Induration: lesion and surrounding tissue is firm to the touch • Fixation: feels attached to adjacent structures
A red but not ulcerated area on mucous membrane is called erythroplasia. The texture may be normal or roughened. Size is variable, some being so small as to virtually escape detection, whereas large areas are conspicuous to casual inspection. There are usually no symptoms. Being neither elevated nor depressed, they present as quiet, unpretentious lesions. The border may be sharp or blend imperceptibly into surrounding normal mucosa. It must constantly be kept in mind that early carcinoma frequently appears as an area of erythroplasia. There are certain areas of the oral mucosa that seem more prone to develop malignancy. Additionally, oral cancer is more often seen in those over age 40. Because of this, an area of erythroplasia in a cancer-prone area in a patient past 40 is highly suspicious for malignancy and should be biopsied on the day it is seen. This is especially true for those lesions with a duration exceeding 2 weeks.
Note: Local spread of oral carcinoma is achieved by direct invasion and infiltration of adjacent structures. Perineural invasion and spread is particularly important because it can adversely influence the actual extent of the tumor. Regional spread to the neck lymph nodes occurs by the lymphatic route.
misc. Which of the following is the most common technique used for mandibular advancement?
The mandibular ramus sagittal split osteotomy has become one of the most commonly performed mandibular orthognathic procedures. The mandible is split sagittally and can either be used to advance the mandible (in the case ofretrognathia,) or to set back the mandible (in treating prognathiaj. It is the standard procedure used today. Note: The position of the condyle is unchanged during correction of mandibular prognathism or retrog-nathism.
Vertical ramus osteotomy: can be used to set the mandible posteriorly. Used for the correction of prognathism.
Vertical body osteotomies: procedures that involve extracting mandibular teeth bilaterally (usually bicuspids). Apiece of bone is also removed from the mandible and you slide everything back. Used for prognathism.
The step osteotomy: may be indicated in cases of mandibular prognathism, retrognathism, asymmetry, and apertognathia. By performing bilateral step-shaped cuts in the body of the mandible, the lower jaw is divided into three separate, independently moveable pieces.
Note: Maxillary surgeries are referred to as Le Fort I osteotomies. The maxilla can be moved forward and down more easily than it can be moved up or back. Distraction osteogenesis (DO) involves cutting an osteotomy to separate segments of bone and the application of an appliance that will facilitate the gradual and incremental separation of bone segments. Used for patients with cleft lip and palate as well as other deformities of the facial skeleton.
' trigeminal neuralgia
Classifications of Orofacial Pain
Pain Type
Somatic (increased stimulus yields increase in pain)
Neuropathic (pain independent of stimulus intensity)
Neuropathic pain: • Trigeminal neuralgia: prototypic neuropathic fascial pain; Typically there is a trigger point and the pain presents as electrical, sharp, shooting, and episodic (seconds to minutes in duration). Most commonly seen in patients over 50 years of age. Carbamazepine (Tegretol) is still the mainstay of treatment. • Odontalgia secondary to deafferentation (atypical odontalgia): occurs as a result of trauma or surgery (root canal or extraction). Results from damage^to the afferent pain transmission system. • Postherpetic neuralgia: is a potential sequela of a herpes zoster infection. Pain is described as burning, aching, or electric shock-like. Treated with antidepressants, anticonvulsants, or sympathetic blocks. Ramsay Hunt syndrome is a herpes zoster infection of the sensory and motor branches of CN VII and CN VIII. • Neuromas: may occur after nerve injury. This area (neuroma) can become very sensitive to stimuli and cause chronic neuropathic pain. • Burning mouth syndrome: is most commonly seen in postmenopausal females. Chief complaints are pain, dryness, and burning of the mouth and tongue. Some complain of altered taste sensation. Half of patients get better without treatment during a 2-year period. • Chronic headache: categorized as being either migraine, tension-type, or cluster • Temporal arteritis (giant cell arteritis): is the most common form of vasculitis that occurs in adults. Almost all patients are over the age of 50. Commonly causes headaches, joint pain, facial pain, fever, and difficulties with vision, and sometimes permanent visual loss in one or both eyes. Often difficult to diagnose.
tmj
What is the best way to palpate the posterior aspect of the mandibular condyle?
• intraorally
• externally over the posterior surface of the condyle with the mouth open
• externally over the posterior surface of the condyle with the mouth open
The temporomandibular joint should be evaluated for tenderness and noise. When checking for joint noises (clicking and crepitus), the joint is palpated laterally (in front of the external auditory meatus) while the patient opens and closes the mandible.
Tenderness can be assessed by palpating the lateral aspects of the joints when the mouth is closed and during opening of the mouth. The joint should also be palpated for tenderness while the patient opens maximally, and the fingertip should be positioned slightly posterior to the condyle to apply force to determine if there is inflammation of the retrodiscal tissue.
Note: By placing fingertips in the patient's external auditory meatus, this technique can produce false joint sounds during mandibular function because of pressure against the thin ear canal cartilage.
Remember: (1) The posterior aspect of the condyle is rounded and convex, whereas the anteroinferior aspect is concave. (2) The condyles are not symmetrical nor identical
Temporomandibular disorders: • Myofascial pain disorder (MPD): most common cause of masticatory pain and compromised function. The symptoms are diffuse and poorly localized in the preauricular region, often involving the muscles of mastication. The pain and tenderness develop as a result of abnormal muscle function and hyperactivity. It can be the result of disc displacement disorders or degenerative arthritis. • Disc displacement disorders: are seen with and without reduction (the return of the normal disc-to-condyle relationship). See card 170. • Systemic arthritic conditions: include rheumatoid arthritis, systemic lupus, and pseudogout. Patients with these conditions usually have other clinical systemic signs and symptoms. • Chronic recurrent dislocation: occurs when the mandibular condyle translates anterior to the articular eminence and requires mechanical manipulation to achieve reduction. It is associated with pain and muscle spasm. • Ankylosis: can occur intracapsularly or extracapsularly, and can be fibrous or bony. Bony ankylosis results in more limitation of motion. Trauma is the most common cause of ankylosis. These patients have a severely restricted range of motion that may be accompanied by pain.
• anteromedially In a healthy temporomandibular joint (TMJ), the articular disc is seated on the condyle and is held in place by the collateral ligaments (also called "discal ligaments") that are attached to the medial and lateral poles of the condyle. Attached to the anterior portion of the articular disc are muscle fibers from the lateral pterygoid muscle. When the collateral ligaments become elongated or torn, they become loose which allows the lateral pterygoid muscle to pull the articular disc out of place. When this occurs, it is called a disc displacement. Because of the anteromedial direction of the lateral pterygoid muscle, the articular disc is usually displaced anteromedially. Note: When the articular disc is displaced anteromedially to the condyle, a click sound is usually demonstrated when the mouth is opened and the condyle moves past the thick posterior band of the articular disc. There can also be a clicking sound when the mandible moves to the opposite side as the condyle again moves past the thick posterior band of the articular disc. Often another click will be demonstrated when the mouth is subsequently closed and the condyle moves from the thin central area of the disc and then past the thicker posterior band as the articular disc once again becomes displaced. A crepitation sound (also known as "crepitus " — multiple scraping or grating sounds) is usually associated with a degenerative process (osteoarthritis) of the condyle, the dull thud is usually associated with a self-reducing subluxation of the condyle, and tinnitus is described as ear ringing. Nonsurgical therapy for TMJ dysfunction:
• Patient education: parafunctional habits (e.g., nail and pencil biting) and stress can be associated with myofascial pain disorder (MPD). These habits or stress should be dealt with by a trained professional. • Medications: for TMJ disorders include NSAIDs, steroids, narcotic and nonnarcotic analgesics, antidepressants, and muscle relaxants. • Physical therapy: treatment may include biofeedback, ultrasound, transcutaneous electrical nerve stimulation (TENS), massage, thermo-treatment, exercise, and iontophoresis. • Occlusal splints: can be classified as either autorepositioning (for muscle or joint pain when no specific anatomically based pathologic entity can be identified) or anterior repositioning. The anterior repositioning splint protrudes the mandible into a forward position, hypothetically recapturing the normal disc-to-condyle relationship. Occlusal modification may be accomplished via equilibration, full mouth reconstruction, orthodontics, and orthognathic surgery. • Arthrocentesis: for patients with internal derangement. A few milliliters of saline or lactated ringer solution are injected into the superior joint space.
tmj
Which surgical approach is the best to expose the TMJ?
Surgical approaches to the TMJ: • Preauricular: the best incision to expose the TMJ. A perpendicular incision is made just anterior the external ear parallel to the superficial temporal artery. The incision extends from one inch abo the zygomatic arch to the lower extremity of the ear. The condyle is approached from behind. Not With this approach, care must be taken not to damage either the facial nerve or the vessels that ricr. supply this area. •Submandibular approach (Risdon approach): this is one standard surgical approach to the ram of the mandible and neck of the condyle. It is not the best approach for procedures within the jo: space itself.
Patients with pain and dysfunction whose signs and symptoms do not respond satisfactorily to nonsi gical therapy within 3 months may be candidates for surgery, particularly if they are diagnosed with a vanced internal derangement caused by ankylosis, rheumatoid arthritis, or severe degenerati osteoarthritis. Patients with no improvement in range of motion and mouth opening despite conservati treatment are also candidates for surgical therapy.
Surgical treatments: • Arthroscopy allows direct visualization of the anatomic structure of the TMJ, biopsy of patholoj tissue, and removal of osteoarthritic fibrillation tissue, as well as direct injection of steroid into i flamed synovial tissues. • Disc repositioning surgery (open arthroplasty): is used in patients with painful, persistent clickii popping, and closed lock. The disc is mobilized and a posterior wedge may be removed, with suti ing used to reposition the disc in a better anatomic position. • Disc repair or removal (discectomy): is indicated when the disc is severely damaged. Results vi widely as to whether it is a viable option for patients. Replacement materials have been problemat so there is a tendency to favor autogenous materials (i.e., temporalis muscle and fascia). • Condylotomy: is accomplished by performing an intraoral vertical ramus osteotomy. It has been us for the treatment of internal derangement with and without reduction and chronic dislocation. • Total joint replacement: is indicated in the severely pathologic joint, as seen in rheumatoid arth tis, severe degenerative joint disease, ankylosis, and neoplasia. Costochondral bone graft reconstn tion is the most common autogenous material used.
• reciprocal clickini
The most common form of pain and discomfort associated with TMJ disorders is masticatoi myalgia or myofascial pain. This is a disorder characterized by pain and masticatory mu cle spasm and limited jaw opening. The condition is characterized by a unilateral dull, achii pain which increases with muscular use.
Internal derangement of the articular disc: • First stage: reciprocal clicking is considered pathognomonic. In the first stage of interr derangement, clicking begins suddenly and spontaneously or after an injury. The noise often loud and may be audible to others, but it is rarely associated with severe pain. • Second stage: the second stage of disc derangement is reciprocal clicking with inte mittent locking. The typical patient complains that the jaw becomes locked and there usually, but not always, severe pain over the affected joint. • Third stage: is associated with limited opening and has been termed closed lock. A lb ited opening of <27 mm and severe pain over the affected joint are characteristic findinj Note: In contrast to the second stage, few patients are able to unlock or relocate their clos lock and restore normal function. • Fourth stage: the final stage is characterized by an increase in opening and crepitus c curring within the joint during movement due to degenerative changes in the disc and art ular surfaces. Note: This stage appears to be less painful than previous stages, because t neurovascular tissue is no longer impinged between the condyle and the glenoid fossa.
The occurrence of TMJ pain caused by rheumatoid arthritis depends on the severity of 1 systemic disease. Most studies show that about one-third of the patients with rheumatoid arth tis will experience pain in the joint at some time, with nearly 60% of patients suffering fn bilateral joint dysfunction. Note: The target tissue of rheumatoid arthritis is the synovial me brane. Progression in the TMJ follows a general scheme with exudation, cellular infiltratit and pannus formation. The articular surfaces of the temporal and condylar components ; destroyed, the disc becomes grossly perforated, and the subchondral bone is resorbed.
• preauricular Surgical approaches to the TMJ:
• Preauricular: the best incision to expose the TMJ. A perpendicular incision is made just anterior to the external ear parallel to the superficial temporal artery. The incision extends from one inch above the zygomatic arch to the lower extremity of the ear. The condyle is approached from behind. Note: With this approach, care must be taken not to damage either the facial nerve or the vessels that richly supply this area. • Submandibular approach (Risdon approach): this is one standard surgical approach to the ramus of the mandible and neck of the condyle. It is not the best approach for procedures within the joint space itself.
Patients with pain and dysfunction whose signs and symptoms do not respond satisfactorily to nonsurgical therapy within 3 months may be candidates for surgery, particularly if they are diagnosed with advanced internal derangement caused by ankylosis, rheumatoid arthritis, or severe degenerative osteoarthritis. Patients with no improvement in range of motion and mouth opening despite conservative treatment are also candidates for surgical therapy.
Surgical treatments: • Arthroscopy allows direct visualization of the anatomic structure of the TMJ, biopsy of pathologic tissue, and removal of osteoarthritic fibrillation tissue, as well as direct injection of steroid into inflamed synovial tissues. • Disc repositioning surgery (open arthroplasty): is used in patients with painful, persistent clicking, popping, and closed lock. The disc is mobilized and a posterior wedge may be removed, with suturing used to reposition the disc in a better anatomic position. • Disc repair or removal (discectomy): is indicated when the disc is severely damaged. Results vary widely as to whether it is a viable option for patients. Replacement materials have been problematic, so there is a tendency to favor autogenous materials (i.e., temporalis muscle and fascia). • Condylotomy: is accomplished by performing an intraoral vertical ramus osteotomy. It has been used for the treatment of internal derangement with and without reduction and chronic dislocation. • Total joint replacement: is indicated in the severely pathologic joint, as seen in rheumatoid arthritis, severe degenerative joint disease, ankylosis, and neoplasia. Costochondral bone graft reconstruction is the most common autogenous material used.
• reciprocal clicking
The most common form of pain and discomfort associated with TMJ disorders is masticatory myalgia or myofascial pain. This is a disorder characterized by pain and masticatory muscle spasm and limited jaw opening. The condition is characterized by a unilateral dull, aching pain which increases with muscular use. Internal derangement of the articular disc:
• First stage: reciprocal clicking is considered pathognomonic. In the first stage of internal derangement, clicking begins suddenly and spontaneously or after an injury. The noise is often loud and may be audible to others, but it is rarely associated with severe pain. • Second stage: the second stage of disc derangement is reciprocal clicking with intermittent locking. The typical patient complains that the jaw becomes locked and there is usually, but not always, severe pain over the affected joint. • Third stage: is associated with limited opening and has been termed closed lock. A limited opening of <27 mm and severe pain over the affected joint are characteristic findings. Note: In contrast to the second stage, few patients are able to unlock or relocate their closed lock and restore normal function. • Fourth stage: the final stage is characterized by an increase in opening and crepitus occurring within the joint during movement due to degenerative changes in the disc and articular surfaces. Note: This stage appears to be less painful than previous stages, because the neurovascular tissue is no longer impinged between the condyle and the glenoid fossa.
The occurrence of TMJ pain caused by rheumatoid arthritis depends on the severity of the systemic disease. Most studies show that about one-third of the patients with rheumatoid arthritis will experience pain in the joint at some time, with nearly 60% of patients suffering from bilateral joint dysfunction. Note: The target tissue of rheumatoid arthritis is the synovial membrane. Progression in the TMJ follows a general scheme with exudation, cellular infiltration, and pannus formation. The articular surfaces of the temporal and condylar components are destroyed, the disc becomes grossly perforated, and the subchondral bone is resorbed.
anat The arises from the anterior surface of the external carotid artery and then passes near the greater cornu of the hyoid bone.
It loops upward and then passes deep to the posterior border of the hyoglossus muscle to enter the submandibular region. The loop of the artery is crossed superficially by the hypoglossal nerve. The lingual artery supplies structures of the floor of the mouth and the posterior and inferior surface of the tongue. Major branches include the :
• Suprahyoid artery: supplies the suprahyoid muscles • Dorsal lingual artery: supplies the tongue, tonsils, and soft palate • Sublingual artery: supplies the floor of the mouth, mylohyoid muscle, and sublingual gland • Deep lingual artery: supplies the tongue
Important: The lingual artery does not accompany the corresponding nerve throughout its course.
Remember: The inferior alveolar nerve, artery, and vein along with the lingual nerve are found in the pterygomandibular space between the medial pterygoid muscle and the ramus of the mandible. The inferior alveolar nerve passes lateral to the sphenomandibular ligament. The submandibular duct is crossed twice by the lingual nerve. If the lingual nerve is cut after the chorda tympani joins, there will be loss of both taste and tactile sensation.
Note: The lateral pterygoid muscle forms the roof of the pterygomandibular space.
• pterygomandibular raphe
O n eooh side, the P - O ^ - T ^ E ^ ^ ^ S S * riorly to attach to the posterior end of the n , » » l « m y l o » b u C e i n a t o r
passively increased.
The pterygomandibular raphe is noted in the oral cavity as the pterygomandibular fold
1. The buccinator muscle is pierced by the needle when performing an inferior
"0 t C S f-rt^ndofof the temporalis muscle and the superior pharyngeal con-
be incised.
drugs A sedative dose of a barbiturate should be expected to produce:
Properties of barbiturates: • CNS depressants: CNS depression with barbiturates is additive with alcohol and opioids • Have no significant analgesic effect even at doses that produce general anesthesia • Have anticonvulsant effects
Mechanism of action of barbiturates: • Barbiturates inhibit depolarization of neurons by binding to the GABA receptors, which enhances the transmission of chloride ions.
Characteristics of barbiturates: • Well absorbed orally, distributed widely throughout the body • Metabolized in the liver to inactive metabolites that are excreted in the urine
Therapeutic uses of barbiturates: • Anesthesia: influenced by duration of action. Thiopental is an ultra short-acting barbiturate used IV to induce surgical anesthesia. Note: After IV administration, the last tissue to become saturated as a result of redistribution is fat (as compared to liver, brain, and muscle tissue) • Anticonvulsant: phenobarbital used in long-term management of tonic-clonic seizures, status epilepticus, and eclampsia • Anxiety: can be used as mild sedatives to relieve anxiety and insomnia
Drug interactions: CNS depressants, alcohol, and opioid analgesics enhance the CNS depression of barbiturates.
Important: Barbiturates can lead to excessive sedation and cause anesthesia, coma, and even death. Barbiturate overdoses may occur because the effective dose of the drug is not too far away from the lethal dose (this is known as a small therapeutic window).
Note: The barbiturates can produce fetal damage when administered to a pregnant woman.
• tissues should be closed under tension
*** j m s j s fai s e ; sutures should not be overtightened or closed under tension.
The interrupted suture is the most common suture method. Because each suture is independent, this procedure offers strength and flexibility in placement. Due to this advantage, if one suture is lost or becomes loose, the integrity of the remaining sutures is not compromised. The major disadvantage is the time required for placement of this pattern of sutures. (See figure #1 below)
Advantages of a continuous pattern or method (See figure #2 below): • Ease and speed of placement • Distribution of tension over the whole suture line • A more watertight closure than the interrupted pattern or method
Figure #1 Figure #2
exo For impacted mandibular third molars, place the following in their correct order from the least difficult to most difficult to remove.
• mesioangular - 43% of mandibular impactions • horizontal - 3% of mandibular impactions • vertical - 38% of mandibular impactions • distoangular - 6% of mandibular impactions
Important: This is the exact opposite of impacted maxillary third molars, where the mesioangular impactions (12%) are the most difficult and the vertical (63%) and distoangular impactions (25%) are the easiest to remove.
Surgical principles for removing impacted teeth: 1. Adequate exposure (adequate-sizedflap): an envelope flap is most often used, but releasing incisions are common. Note: The base portion of the flap should always be wider than the apex portion of the flap to maintain adequate blood supply to the released soft tissues. 2. Bone removal: a trough of bone on the buccal aspect of the tooth down to the cervical line should be removed initially; more bone removal may be required depending on the particular tooth. Important: Bone is rarely, if ever, removed on the lingual aspect of the mandible because of the likelihood of damaging the lingual nerve. 3. Tooth sectioning: sectioning of the tooth may also be needed. This is most often performed with a straight bur, such as a No. 8 round bur, or with a fissure bur, such as a No. 557 or 703. 4. Copious irrigation of the wound is very important, and replacement of the soft tissue flaps completes the procedure.
• rotation • luxation
Luxation is the loosening of the tooth in the socket by progressive severing of the periodontal ligament fibers. Patience and controlled force are needed, not brute strength. The force should be applied as low down the root as possible when extracting teeth. You should support the jaw with your other hand and have a thumb and finger on either side of the tooth being extracted. Note: Rotation forces can be used on single rooted teeth. Teeth are extracted by luxation forces perpendicular to the long axis of the tooth, not by pulling along the long axis. The fulcrum is as close to the apex of the tooth as possible.
Remember: The beak of the extraction forcep is designed so that most of the pressure exerted during an extraction is transmitted to the root of the tooth.
Important: When using dental elevators, one should always have respect for the forces generated. Due to the large amount of leverage, dental elevators can generate tremendous forces during normal use and have potential to cause iatrogenic damage.
Note: A Class II lever is used during tooth extractions (seepictures below)
Class I Lever Class II Lever Class III Lever
Effort
— L m f A i 1 j...,.,, , ,,i | Fulcrum - J .
Fulcrum or or
Pivot Point Pivot Point
Effort Pivot Point
implants Currently, the most popular used implants are:
misc. To prevent infective endocarditis in patients at risk for such infections, the American Heart Association (AHA) frequently issues guidelines for prophylactic antibiotic coverage during dental procedures. In accordance with the most recently revised AHA guidelines, which of the following are acceptable antibiotic options for the prevention of infective endocarditis? Select all that apply.
Dental implants are divided into three categories based on their relationship to the oral tissues:
1. Endosseous implants are implants that are surgically inserted into the jawbone. They are the most frequently used implants today. They are further subdivided into root form and blade (plate) form. 2. Subperiosteal implants are frameworks specifically fabricated to fit on top of supporting areas in the mandible or maxilla under the mucoperiosteum. This type of implant "rides on" bone. 3.Transosseous implants are implants that are similar to endosseous implants in that they are inserted into the jawbone. However, these implants actually penetrate the entire jaw so that they actually emerge opposite the entry site, usually at the bottom of the chin. Note: Their primary indication is in the very atrophic mandible where root form implants may further compromise the strength of the jaw.
Remember: Osseointegrated implants are anchored directly to living bone. This determination is made by radiographic and light microscopic analysis. Only endosseous and transosseous implants are considered true osseointegrated implants.
• Root form implants: cylindrical in shape, can be smooth, threaded, perforated, and solid or hollow, vented, coated, or textured. They are available in various widths (3.2 mm to 7 mm) and lengths (8 mm to 18 mm). Typically made of titanium. Treatment with root form implants is divided into three phases; surgical, healing and prosthetic. Note: These implants are the most popular. • Blade implants (also known as plate form implants): are flatter in appearance and are utilized when there is insufficient width of bone but adequate depth. They are available in single and two-stage forms. Typically made of titanium.
Two basic types of implant placement: 1. Submerged: requires a second surgical procedure (two-stage) to uncover the fixture. 2. Nonsubmerged: does not require a second surgical procedure (one-stage).
In adults, the new antibiotic regimen recommended for the prevention of infective endo
carditis is: • Amoxicillin: 2.0 grams, 30-60 minutes prior to the procedure (four 500-mg
tablets)
For those patients allergic to penicillin, • Clindamycin: 600 mg, 30-60 minutes to the procedure (four 150-mg tablets)
The guidelines for children are: • Amoxicillin: 50 mg/kg, 30-60 minutes prior to the procedure
For those patients allergic to penicillin, • Clindamycin: 20 mg/kg, 30-60 minutes prior to the procedure
These new guidelines involve a number of changes from the previous set of guidelines: • Only one antibiotic dosage is required • The recommended antibiotic for penicillin-allergic patients is clindamycin not erythromycin • Prophylaxis is no longer required for many dental procedures
Alternatives for patients who are allergic to penicillin and who cannot take clindamycin include cephalexin, clarithromycin, and azithromycin.
