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LOCAL ANESTHESIA IN PEDIATRIC DENTISTRY

JEAN MICHAELBatch 4/RDC

Presented By

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PAIN

• It is defined as an unpleasant sensational experience initiated by noxious stimulus & transmitted over a specialized neural network to CNS where it is interpreted as such

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LOCAL ANESTHESIA

Transient loss of sensation in a circumscribed area of the body caused by a depression of excitation in nerve endings or an inhibition of the conduction process in peripheral nerves.

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CONSTITUENTS OF LOCAL ANESTHETIC SOLUTION

1. Local anesthetic agent2. Vasoconstrictors3. Reducing agents4. Preservatives5. Fungicide6. Vehicle

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Local Anesthetic Agent

ESTERSEsters of BENZOIC ACID Cocaine, Butacaine, Benzocaine, Tetracaine etcEsters of PARA-AMINOBENZOIC ACIDProcaine, Chloroprocaine, propoxycaine etc

AMIDESBupivacaine, lidocaine, articaine, prilocaine

QUINOLONESCentbucridine

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Vasoconstrictors

Pyrocatechin derivativeEPINEPHRINE & NOREPINEPHRINEBenzol derivativeLEVONORDEFRINEPhenol derivativePHENYLEPHRINE

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Functions of Vasoconstrictors

• ↓ the blood flow to the injection site• Absorption of LA into CVS is slowed leading to lower

LA level in blood• ↓ the risk of toxicity due to LA• ↑ the duration of action of the LA• ↓ bleeding and are useful when increased bleeding

is anticipated

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• Most commonly used agent – Phenylephrine (1:2500)• Limit – 4 mg at a time (Cardiac patients – 1/4th of normal dose)

• Contraindication – THYROTOXICOSIS

• If the LA solution is exposed to sunlight for a long time before administration, vasoconstrictor in the solution gets degraded by oxidation

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Reducing Agent (Sodium metabisulphite)

Preservative (Xylotox)

Fungicide (Thymol)

Vehicle(Modified Ringer’s solution)

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Mechanism of Action of LASpecific Receptor Theory – 1. Displacement Of Calcium ions from the Sodium

Channel Receptor Site2. Binding of LA molecule to this receptor site3. Blockade of sodium conductance4. Decrease in Sodium Conductance5. Depression in the rate of electrical depolarization 6. Failure to attain the threshold potential level7. Lack of development of propagated action

potentials8. Conduction Blockade

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Biotransformation(Alteration of the drug within the living organism)

• Ester LAs are hydrolyzed in plasma by the enzyme pseudo-cholinesterase. The one that undergoes hydrolysis readily is the least toxic. Allergic reactions are mostly due to the major metabolic product – para-aminobenzoic acid

• Amide LAs are primarily metabolized in the liver. Liver function and hepatic perfusion significantly influence the rate of biotransformation.

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Techniques of Local Anesthesia

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THE TRIGEMINAL NERVE

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Local Infiltration

• Small terminal nerve endings in the area of surgery are flooded with LA solution rendering them insensitive to pain. In this method, incision is made through the same area in which the solution has been deposited.

• This technique is usually successful for treatment of mandibular deciduous canines, incisors and even in molars.

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Field Block

• Here the LA solution is deposited in proximity to the large terminal nerve branches so that the area to be anesthetized is circumscribed to prevent the central passage of afferent impulse

• Maxillary injections administered above the apex of the tooth can be termed field blocks

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Nerve Block

• Method of securing local analgesia in which suitable local anesthetic solution is deposited within close proximity to the main nerve trunk, thus preventing nerve impulses from travelling centrally beyond that point.

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Other Techniques

• Intraligamentary

• Intraseptal

• Intrapapillary

• Intrapulpal

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The child should never see the injection needleThis creates anxiety and fear towards dental treatment

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Keep the syringe away from the Line of sight of the patient

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Maxillary InjectionTechniques

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• Supraperiosteal (Local infiltration)• Periodontal Ligament Injection• Intraseptal Injection• Intraosseous• Posterior Superior Alveolar Nerve Block• Middle Superior Alveolar Nerve Block• Anterior Superior Alveolar Nerve Block• Greater Palatine Nerve Block• Nasopalatine Nerve Block• Maxillary Nerve Block (Infraorbital Nerve Block)

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Supraperiosteal Injection

• Most frequently used technique for obtaining pulpal anesthesia in maxillary teeth

• Indicated whenever dental procedures are confined to only one or two teeth

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Nerves AnesthetizedLarge terminal branches of dental plexus

Areas Anesthetized• The entire region innervated by the large

terminal branches of dental plexus1. Pulp and root area of the tooth2. Buccal periosteum3. Connective tissue4. Mucous membrane

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INDICATIONS• Pulpal anesthesia of the maxillary teeth when

treatment is limited to only one or two teeth• Soft tissue anesthesia when indicated for

surgical procedures in a circumscribed areaCONTRAINDICATIONS• Infection or acute inflammation in the area of

injection• Dense bone covering the apices of teeth (maxillary central incisors and 1st molars)

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ADVANTAGES• High success rates (>95%)• Technically easy injections• Usually entirely atraumaticDISADVANTAGES• Not recommended for large areas due to

1. Need for multiple needle insertion2. Necessity to administer large total volumes

of local anesthetic

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TECHNIQUE• 25 or 27 gauge needle is used• Area of insertion – height of mucobuccal fold

above the apex of the tooth being anesthetized• Target area – apical region of the tooth to be

anesthetized• Landmarks

1. Mucobuccal fold2. Crown of the tooth 3. Root contour of the tooth

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PROCEDURE• Prepare the tissue at the injection site• Orient the needle so that bevel faces the bone• Lift the lip, pulling the tissue taut• Hold the needle parallel to the long axis of the

tooth• Insert the needle into the height of the

mucobuccal fold over the target tooth

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• Advance the needle until its bevel is at or above the apical region of the tooth

• Aspirate 2 times• If negative, deposit approximate 0.6 ml of LA

over 20 seconds• Slowly withdraw the syringe• Make the needle safe• Wait for 3 to 5 minutes before starting the

dental procedure

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SUPRAPERIOSTEAL INJECTION

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BEVEL ORIENTATION OF NEEDLE

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PAIN

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MINIMAL PAIN

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MANDIBULAR INJECTION TECHNIQUE

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Inferior Alveolar Nerve Block

• Needle Used – 25 Gauge• Nerves Anesthetized –

Inferior Alveolar NerveLingual Nerve

• Site Of Injection – Region where the IAN enters the mandible

through the Mandibular Foramen• Amount of solution deposited – 1 to 1.8 ml

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Area anesthetized• Mandibular teeth of the injected side• Body of the mandible, inferior portion of the ramus• Buccal mucoperiosteum, mucous membrane

anterior to the mandibular 1st molar• Anterior 2/3rd of tongue and floor of the

mouth• Lingual soft tissue and periosteum

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INDICATION• Procedures on multiple mandibular teeth in

one quadrant• When buccal soft tissue anesthesia (anterior

to the first molar) is necessary• When lingual soft-tissue anesthesia is

necessaryCONTRAINDICATION• Infection or acute inflammation in the area of

injection

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TECHNIQUE• 25 gauge needle is used• Area of insertion – Mucous membrane on the

medial side of the mandibular ramus near the mandibular foramen

• Target area – Inferior alveolar nerve as it passes downward towards the mandibular foramen but before it enters the foramen

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• Landmarks 1. Coronoid notch2. Pterygomandibular raphae3. Occlusal plane of the mandibular

posterior teeth

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• Patient position – supine or semisuppine• Operator position –

1. Right IANB – 8 o’clock position2. Left IANB – 10 o’clock

LEFT RIGHT

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PROCEDURE• With the left thumb, palpate the coronoid

notch• With the same finger, pull the buccal soft

tissue laterally to gain visibility and make the tissue taut

• The needle insertion point lies three fourths the anteroposterior distance from the coronoid notch to the deepest portion of pterigomandibular raphae

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• Prepare the tissue of injection site• Place the barrel of the syringe in the corner of

the mouth on the contralateral side• Penetrate the tissue with the needle and

slowly advance till bony resistance is felt

JM 43ABOVE 12 YEARS

6 – 12 YEARS

BELOW 6 YEARS

PEDIATRIC PATIENT

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• Average depth of penetration is 20 – 25 mm• When bone is contacted, withdraw 1 mm to

prevent sub-periosteal injection• Aspirate• If negative, slowly deposit 1.5 ml of anesthetic

over a period of 1 minute• Slowly withdraw the syringe till half of its

length remains in the tissue

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• Re-aspirate• If negative, deposit a portion of remaining

anesthetic (.1 ml) to anesthetize lingual nerve• Withdraw the syringe slowly and make the

needle safe• After about 20 seconds, return the patient to

upright or semi-upright position• Wait for 3 to 5 minutes before commencing

the dental procedure

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Buccal Nerve Block

• Needle used – 25 Gauge• Nerve Anesthetized – Buccal Nerve (branch of anterior division of

mandibular nerve)• Site of injection – Mucous membrane distal and buccal to the

most distal molar tooth in the arch• Amount of LA required - .3 ml

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Area Anesthetized• Soft tissue and periosteum

buccal to the mandibular molar teeth

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INDICATION• When buccal soft tissue anesthesia is

necessary for dental procedures in the mandibular molar region

CONTRAINDICATION• Infection or acute inflammation in the area of

injection

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TECHNIQUE• 25 Gauge long needle is recommended• Area of insertions – mucous membrane distal

and buccal to the most distal molar tooth in the arch

• Target area – Buccal Nerve as it passes over the anterior border of the ramus

• Landmarks – mandibular molars & mucobuccal fold

• Orientation of bevel – towards the bone

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PROCEDURE• Operator position

Right BNB – 8 o’clock positionLeft BNB – 10 o’clock position

• Patient position – supine or semisupine• Prepare the tissue for needle penetration• With left index finger, pull the buccal soft

tissues in the area of injection laterally to improve visibility and make the tissue taut

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OPERATOR AND PATIENT POSITIION FOR BNB

LEFT RIGHT

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• Align the needle parallel to the occlusal plane and buccal to the teeth and direct it towards the injection site

• Penetrate the mucous membrane at the injection site, distal and buccal to the last molar

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• Advance the needle until mucoperiosteum is gently contacted

• Depth of penetration – 1 to 2 mm• Aspirate• Slowly deposit .3 ml of LA over 10 seconds• Withdraw the syringe slowly and immediately

make the needle safe• Wait for approximately 1 minute before

commencing the dental procedure

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IANB & BUCCAL NERVE BLOCK

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INTRAPULPAL INJECTION

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• Here local anesthetic solution is delivered directly to the pulp using a bent needle

• mostly used to anesthetize mandibular 1st molar which may be sometimes difficult to achieve using other procedures like nerve blocks in case of inflammation in the site of infection

• Advantages of Intrapulpal injection – • Requires minimum volumes of LA solution• Immediate onset of action• Very few post operative complications

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• Nerve anesthetized – Terminal nerve endings at the site of injection

in the pulp chamber and canals of the involved tooth

• Areas anesthetized – tissues within the injected toothINDICATION when pain control is necessary for pulpal

extirpation or other endodontic treatment in the absence of adequate anesthesia from other technique

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TECHNIQUE• Insert a 25 or 27 gauge short or long needle

into the pulp chamber or the root canal • Wedge the needle firmly into the pulp

chamber or root canal• Deposit .2 to .3 ml of anesthetic solution

under pressure• Resistance to the injection of the drug should

be felt Bend the needle, if necessary, to gain access to the canal

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• When the intrapulpal injection is performed properly, a brief period of sensitivity (ranging from mild to very painful) usually accompanies the injection

• Pain relief occurs immediately thereafter, permitting instrumentation to proceed atraumatically

• Instrumentation may begin approximately 30 seconds after the injection

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TOPICAL ANESTHESIA

• It is the method of obtaining anesthesia by the application of suitable agent to an area of either the skin or mucous membrane through which it penetrates to anesthetize superficial nerve endings

• It is commonly used to obtain anesthesia of the mucosa prior to injection

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Topical anesthetic Sprays

Active ingredient – 10% Lignocaine HydrochlorideOnset of Action – 1 minuteDuration of Action – 10 minutesAvailable in different fruit flavors

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Technique

• Dry the area of application (mucous membrane)• Spray an appropriate quantity of the solution

into a small cotton roll• Place the cotton role on the site of injection in

the sulcus• Wait for 1 minute before inserting the needle to

allow the topical anesthetic to act

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Topical Anesthetic Ointments & Jelly• Ointments – 5% Lignocaine (onset of action is 3-4 minutes)• Emulsions – 2% Lignocaine

BENZOCAINE – • Odorless white crystalline powder

(soluble in alcohol and fatty oils)• Safe – due to its low aqueous solubility, It is

very slowly absorbed from the oral tissues and wounds

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RECENT ADVANCES IN LA

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EMLA (Eutectic Mixture of LA)

• Mixture of LIGNOCINE & PRILOCAINE• EMLA cream is used for numbing the skin

before inserting the needle• It is designed to go through intact skin• Potential for toxic effects of LA is minimal• Use in children under 6 months is

contraindicated due to the possibility for developing methemoglobinemia due to prilocaine

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Intraoral lignocaine patch

• Contains 10% or 20% lignocaine • Placed for 15 minutes on the buccal mucosa of

the maxillary or mandibular premolar area, 2 mm apical to the mucogingival junction

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Electronic Dental Anesthesia

• Uses the principle of Transcutaneous Electrical Nerve Stimulation (TENS)

• Requires good patient co-operation• It increases salivary blood flow

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Complications Of LA(Pediatric Patient)

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NUMB FEELING• Invites the possibility of an unnecessary

emotional upset of the child

How to Avoid ?• The dentist should explain beforehand to the

child that he/she will experience the numbness after the administration of LA

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LIP BITING

How to avoid ?• Warning should be given immediately following

injection procedure. Warning should be repeated before the child leaves the dental chair.

• Parents should also be warned about this possible complication if not attended properly

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Complication due to Injection of LOCAL ANESTHETIC SOLUTION

3 TYPES –

1. Method of deposition of the drug2. Drug dosage dependent reactions3. Hypersensitivity reactions

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Method of deposition of drug

VASOVAGAL SYNCOPE• Due to peripheral pooling of blood and

reduction in cerebral blood flow

• Rarely encountered in children due to constant movement of extremities coupled with crying out loud which prevents the peripheral pooling of blood

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BROKEN NEEDLE• Due to sudden movement during administration

of the LA solution

FAILURE TO ACHIEVE ANESTHESIA• This may be due to

1. Improper Technique of administration2. Normal anatomic Variation

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FACIAL NERVE PARALYSIS

• Encountered during IANB• Due to injection of LA solution into parotid

gland• Facial Nerve gets temporarily paralyzed• Effects wears off over a period of time during

which the eye needs to be protected

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TRISMUS• Due to trauma to muscles or blood vessels of

infra temporal fossa• Intramuscular or supramuscular injection of

LA• Hemorrhage• Hematoma and scar formation

How to Avoid ?• Avoid repeated injections or multiple

insertions into the same area• Use only minimum effective volume of LA

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Drug Dosage Dependent Reactions• At Low levels - ↑ Heart rate and Cardiac Output• At High levels - ↓ Cardiac Output & Circulatory

Failure• Methemoglobinemia – Caused by Benzocaine & PrilocainHow To Avoid ?• Use Of Aspiration Technique• Keeping the amount of agent administered

below toxic limit

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CAUSES OF TOXICITY• Use of excessive dose of LA• Inadvertent intravascular injection• Slow detoxification or biotransformation• Slow elimination or redistributionMajority of the toxic reactions to LA are

immediate, mild and transientThey can be avoided by closely monitoring

during the injection, injecting slowly and withdrawing the needle at the first signs of an adverse response

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TOXICITY DUE TO VASOCONSTRICTORS• They causes local ischemia and thus retard

their own absorption• Patients with ischemic heart diseases and

hypertension are at high risk of toxicity if administrated intravascularly

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Manifestation Of Toxicity

• Cardiac Depression• Coma• Convulsions• Unconsciousness• Muscular twitching• Visual and auditory disturbances,

light headedness, numbness of tongue

Conc

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LA i

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Hypersensitivity (rare)

Manifests as • Utricaria • Facial edema• Breathlessness

Methyl paraben (protein) is the main allergent• It has been replaced in recent times

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