DR. RAKESH THUKRALPROFESSOR

DEPT OF ORTHODONTICS &

DENTOFACIAL ORTHOPEDIC1

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Module plan

• Topic :

• Subject: Orthodontics

• Target Group:

• Mode:

• Platform:

• Presenter:

Undergraduate Dentistry

Powerpoint – Webinar

Institutional LMS

DR. RAKESH THUKRAL

-:INTRODUCTION:-

The orthodontic speciality deals with treatment ofvarious malocclusion.

Etiology of malocclusion is the study of its cause orcauses.

Malocclusion can occur due to a number of possiblecauses.

Mainly malocclusion are caused by either geneticfactor or by environmental factor .

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Comprehensive orthodontics management involvesidentification of the possible etiology factor and anattempt to eliminate the same,helps in prevention andinterseption.

Development of normal dentition and occlusiondepends on a number of interrelated factors i.e.skeletal,dental,neuromuscular.

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Dental equilibrium

Influence of forces being generated intra orally don’t move the teeth because of dental equilibrium

Teeth and 1.lips 2.cheeks 3.tongue 4.periodontal membrane 5.masticatory muscles

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Classification of etiological factors1.Moyer’s 2.White &Gardiner’s 3.Graber’s

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-:MOYER’S CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION:-

1. Hereditya.neuromuscular systemb.bonec. teethd.soft parts

2. Development defects of unknown origin3. Trauma

a. Prenatal trauma and birth injuriesb. Post natal trauma

4. Physical agenta. Premature extraction of primary teethb. Nature of food

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5. Habita. Thumb sucking and finger suckingb. Tonguec. Lip sucking and lip bitingd. posturee. nail biting

6.Diseasesa. systemic diseaseb. endocrine disorders

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c. local diseases1. nasopharyngeal diseases and disturbed

respiratory function2. gingival and periodontal disease3. tumor4. caries

7. Malnutrition

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-:WHITE AND GARDINER’S CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION:-

A). Dental base abnormalities

1. Vertical malrelationship2. Antero- posterior malrelationship3. Disproportion of size between teeth and basal bone.4. Lateral malrelationship5. Congenital abnormalities

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B ). Pre-eruption abnormalities

1. Abnormalities in in position of developing tooth germ2.Missing teeth3.Supernumerary teeth and teeth abnormal in form4.Prolonged retention of deciduous teeth5.Large labial frenum6.Traumatic injury

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C. Post –eruption abnormalities1. Muscular

a) Active muscle forceb) Rest position musculaturec) Sucking habitsd) Abnormalities in path of closure

2. Pre mature loss of deciduous teeth3. Extraction of permanent teeth

D. Abnormalities in path of closure1. Premature loss of decidious teeth2. Extraction of permanent teeth

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-:GRABER’S CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION:-

GENERAL FACTOR1. Heredity2. Congenital3. Environment

a. Pre-natalb. Post-natal

4. Pre-disposing metabolic climate and diseasea. Endocrine imbalanace

b. Metabolic disturbancec. Infectious diseases

5. Dietary problems(nutritional deficiency)13

6.Abnormal pressure habits and functionalaberrations

a. Abnormal sucking-Thumb and fingersucking,tongue sucking

b. Tongue thrustc. Lip and nail bitingd. Abnormal swallowing habite. Tonsils and adenoidsf. Respiratory abnormalities

g. Speech defects

h. Psychogenitics and bruxism

7. Posture8. Trauma and accidents 14

LOCAL FACTOR

1. Anomalies of number: Supernumerary teeth , Missing teeth2. Anomalies of tooth size3. Anomalies of tooth shape4. Abnormal labial frenum 5. Premature loss of deciduousteeth6. Prolonged retention of deciduousteeth7. Delayed eruption of permanentteeth8. Abnormal eruptive path9. Ankylosis10. Dental caries11. Improper dental restoration

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-Generalfactor(1)HEREDITY:-

Heredity has for long been attributed as one of causes ofmalocclusion.

The child is a product of parents who have dissimilargenetic material.

The child may inherit conflicting traits from both the parentsresulting in abnormalities of the dentofacialregion.

According to Lundstrom there exist a number of human traitthat are influenced by the genes that include:

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Tooth size: Abnormalities of tooth size such asmicrodontia and macrodontia are attributed toheredity.

Arch : The dental arch length and arch width arebelieved to be inherited.

Crowding /spacing : Crowing and spacing of teeth arebelieved to be of genetic origin. most of these conditionsare believed to be a uncoordinated inheritance of archlength and tooth material.

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Abnormalities of tooth shape: Anomalies of toothshape such as the presence of peg shaped lateral isanother trait that shows high genetics predisposition.

Abnormalities of tooth number : Presence of eithermore or less number of teeth can also be inherited .

Overjet :The horizontal overlap upper and lowerdentition referred to as the overjet is believed to begenetically influenced.

Inter –arch variations: Discrepancies in the transvers ,sagittal and vartical plane between upper and lower jawscan be inherited.

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-General factors – (2) congenital

Congenital defects or development defects aremalformations seen at the time of birth.

It may be caused by a variety of factors including genetic,radiologic, chemical, endocrine , infection and mechanicalfactors.

The causes that cause congenital abnormalities can bebroadly classified as general and local causes forcongenital defects-

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-:General causes of congenital defects-

a.Abnormal state of mother during pregnancyb. Malnutritionc. Endocrinopathiesd. Infectious diseasese. Metabolic and nutritional distrubancesf. Accidents during pregnancy and at the time of childbirthg. Intra- uterine pressureh. Accidental traumatisation of the foetus by external forces

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Local causes of congenital defects-

a. Abnormalities of jawdevelopment due to intra-uterine position

b. Clefts of the face and palate

c. Macro and microglossia

d. Cleidocranial dysostosis

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Frequently seen congenital conditions-:1-clefts of lip & palate:- Clefts involving the lip and palate are the most

commonly seen congenital defects that occur as a resultof non-fusion between the various embryonic processes.

Cleft patients may exhibit a number of dental problemincluding missing teeth , mobile teeth , rotation, crossbiteetc.

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2 – Congenital syphilis:-Syphilis of congenital origin istransmitted from the

infected mother to the child.The child exhibits one or more of thefollowing features:

a. Hutchinson’s incisorsb. Mulberry molarsc. Enamel deficienciesd. Extensive dental decaye. The maxilla may be smaller in

size relative to the mandiblef. Anterior crossbite

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3 – MaternalRubella infection :-

Matrenal rubella infectionduring pregnancy believed tocause widespread congenitalmalformation in the child .

The following are some of thefeature that can be seen:

a) Dental hypoplasiab) Retarded eruption of

teethc) Extensive caries- all can

lead to malocclusion 24

4-Cleidocranial dysostosis:- This is a congenital condition

characterized by unilaterl or bilateral,partial or complete absence of theclavical.

The patient may exhibit thefollowing features:

a. Maxillary retrusion andpossible mandibularprotrusion

b. Over retained deciduousteeth and retarded eruptionof permanent teeth

c. Presence of supernumeraryteeth

d. Presence of short and thinroots of the teeth 25

5 –Cerebral palsy:-(brain injury during birth)

This is a condition where in the patient lacksmuscular co-ordination.

The uncontrolled and aberrant muscle activity upsetsmuscle (dental equilibrium) balance resulting inmalocclusion.

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General Factors-(3)Environment:- Various prenatal and postnatal environmental factors

can cause malocclusion:

1. Prenatal factors: The foetus is well protectedagainst injuries and nutritional deficiencies duringpregnancy in its amniotic sac, but there are certainfactor , the presence of which can result in abnormalgrowth of the oro-facial region thereby predisposing tomalocclusion.

Abnormal fetal posture during gestastion is said tointerfere with symmertric development of the face.

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The other prenatal influences include maternal fibroids, ,amniotic lesions , maternal diet and metabolism.

Maternal infection such as German measles and useof certain drugs during pregnancy such as Thalidomidecan cause gross congenital deformities including clefts.

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2.Postnatal factors: The following are some of thepostnatal factors that can cause malocclusion:

a)Forceps delivery can result in injury to thetemporomandibular joint joint area, which canundergo ankylosis. Such patients show retardedmandibular growth and thus have a hypoplasticmandible.

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b) Cerebral palsy is a condition characterized by muscleincoordination . This may occur due to birth injuries . Thepatient can exhibit malocclusion due to loss of musclebalance.c) Traumatic injuries that cause condylar fracture cancause growth retardation resulting in marked facialasymmetry.d) Milwaukee braces are used for treatment of scoliosis.These braces derive support from the mandible.

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General factors (4)-Pre-disposing metabolic climate & disease:-

A number of endocrinal disorders , infectious conditions and metabolic disturbances can predispose to malocclusion.

(1).Endocrine imbalance:• Certain endocrinal disorders may result in malocclusion .• The following are some of the endocrinal

disturbances that can cause malocclusion:a. Hypothyroidismb. Hypoparathyroidismc. Hyperthyroidismd. hyperparathyroidism

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(2). Metabolic disturbance:

• Acute febrile diseases are believed to slow down the pace of growth and development .

• These condition may cause a disturbance in tooth eruptionand shedding thereby increasing the risk of malocclusion.

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General factor (5)-Dietaryproblems:- Nutritional deficiencies during growth may result in

abnormal development , causing malocclusion.

These problems are more common in the developingcountries than in the development world.

Nutritional related disturbances such as rickets, scurvy andberiberi can produce severe malocclusion and may upset thedental developmental timetable.

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General factors (6)-Abnormal pressure habits &functional aberrations-thumb sucking,tonguethrusting,lip &nail biting,abnormalswallowing oral breathing,tonsils&adenoids,psychogenic tics &bruxism

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General factor (7)-Posture :- Poor postural habits are said to be a cause for

malocclusion.

They may be associated with abnormal pressure andmuscle imbalance thereby increasing the risk ofmalocclusion.

Children who support their head by resting chin on theirhand and those who hand their head so that the chin restsagainst the chest are observed to have mandibulardeficiency.

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-General factor (8)-Accidents & trauma:-

Children are highly prone to injuries of the dento-facial regionduring the early years of life when they learns to crawl, walkor during play.

Most of these injuries go unnoticed and may be responsible fornon- vital teeth that do not resorb & cause defelction of eruptingpermanent teeth into abnormal position

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LOCAL ETIOLOGICAL FACTORS

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-:ANOMALIES IN NUMBER OF TEETH:-• Presence of extra teeth or absence of one or more

teeth predisposes to malocclusion:1].Supernumerary teeth:Teeth that are extra to the normal complement are termedsupernumerary teeth. Teeth have abnormal morphology.Extra teeth that resemble normal teeth are calledsupplemental teeth.

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-:CLASSIFICATION OF SUPERNUMERARY TEETH BASED ON ITS MORPHOLOGY:-

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1)Peg shaped conical supernumerary teeth:They usually present with conical or triangular –

shaped crown and compete root formation. They areusually found between the maxillary central incisor .They may remain unerupted and cause midline diastemaand cause rotation of incisor and non-eruption ofcentral incisor

2.Barrel shaped or tuberculate supernumerary:• The tuberculate supernumerary has a barrel-shaped

apperance and a crown consisting of multiple tubercles.• It may be invaginated.• Tuberculate type have either incomplete or absent root

formtion.• They are generally larger than conical supernumerary

teeth and are usually found in a palatal position relativeto the maxillary incisor.

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3.Supplemental teeth:

•Supplemental supernumerary teeth resemble theirrespective normal teeth.•They form at the end of a tooth series.•The most common supplemental tooth is the permanentmaxillary lateral incisor, although supplemental premolarand molar also occur.

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4. Odontomes:•These are benign ,disordered overgrowth of mature tissue comprising all dental tissues and appearing radiographically as well demarcated ,mostly radio-opaque lesions in tooth bearing areas.•They can be compound or complex.•Compound odontomes comprise many separate, small tooth- likestructues.•A complex odontome is a single, irregular mass of dental tissue that has no morphologocal resemblance to a tooth.

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Problem associated with supernumerary teeth:they can cause 1. Failure of eruption

2. Displacement or rotation of permanent teeth

3. Crowding

4. Pathology and other complication

5. Incomplete space closure during orthodontic treatment

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Missing teeth Congenitally missing teeth are by far more common than

supernumerary teeth and can occur in either of the jaws. Congenitally absence of teeth is referred to as

hypodontia if some teeth are missing from the arch oranodontia if all of teeth are absent . If six or morepermanent teeth are missing, the term ‘oligodontia’ isused.

Hypodontia usually affects the last teeth in each series ,i.e. third molars, upper laterals , second premolars.

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• The following are some of the commonly missing teeth in decreasing order of frequency:

a. Third molarsb. Maxillary lateral incisorc. Mandibularsecond premolard. Mandibular incisore. Maxillary second premolar

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Hypodontia or oligodotia can be classified as:

1. Isolated or non-syndromic hypodontia

2. Syndromic hypodontia

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-:ANOMALIES OF TOOTH SIZE:- The normal occlusion requires a good harmony between

the tooth size and arch length and also between themaxillary and mandibular tooth size.

Macrodontia refers to a tooth or teeth larger than normalfor partocular tooth type.

Frequency of Macrodontia in permanent dentition is 1.1%while in primary dentition it is unknown.

Affects most frequently upper central incisior, secondpremolar and lower third molar.

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Microdontia refers to teeth that appear smaller in sizecompared to normal .

It is important to note that the teeth affected are usuallythe ones that are also most often congenitally absent.

Microdontia is frequently seen associated with Downssyndrome and various type of ectodermal dysplasia,frequency in permanant dentition is 5% while in primarydentition less than 1%.

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-:ANOMALIES OF TOOTH SHAPE:-• Anomalies of tooth size and shape are very interrelated.

Abnormally shaped teeth predispose to malocclusion.• The following are some of the examples of frequently seen

tooth shape anomalies:

a. The presence of peg shaped maxillary lateral incisorsis often accompanied by spacing and migration ofteeth.

b. Another example is presence of an abnormallylarge cingulum on a maxillary incisor.

c. The mandibular second premolars may rarely havean additional lingual cusp, thereby increasing themesio-distal dimension of tooth.

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-:ABNORMAL LABIAL FRENUM:- Abnormalities of the maxillary labial frenum are quite often

associated with maxillary midline spacing . Prior to the teeth , the maxillary labial frenum is attached to

the alveolar ridge with some fibers crossing over linguallyto the region of the incisive papilla.

This may prevent approximation of central incisors anddiastema,confirm by blanch test.

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-:PREMATURE LOSS OF DECIDUOUS TEETH:-

It refer to loss of a tooth before its permanent successor issufficiently advanced in development and eruption tooccupy its place.

Early loss of deciduous teeth can cause migration ofadjacent teeth into the space and can therefore prevent theeruption of the permanent successor.

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The severity of malocclusion caused due to early loss of adeciduous tooth depends on the following factors:

A].Location of the missing tooth.

B]. The earlier the deciduous teeth are extracted before thesuccessional teeth are ready to erupt , the greater is thepossibility of malocclusion.

C]. In a parson having arch length deficiency or crowdingthe early loss of deciduous teeth may worsen theexisting malocclusion.

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-:PROLONGED RETENTION OF DECIDUOUSTEETH:-

This refer to a condition where thereis undue retention of deciduousteeth beyond the usual eruptionage of their permanent successors.

Prolonged retention of deciduousanteriors usually result in lingualor palatal eruption of theirpermanent successors.

Certain parts of the deciduous rootswhich are away from the path oferuption of the permanent teeth fail toget resorbed thereby leaving smallfragment of the root within the jaw . 53

The following are some of the reasons for prolongedretention of deciduous teeth:

a. Absence of underlying permanent teeth .

b. Endocrinal disturbances such ashypothyroidism.

c. Ankylosed deciduous teeth that fail to resorb.

d. Non – vital deciduous teeth that do not resob.

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-:DELAYED ERUPTION OF PERMANENT TEETH:-can cause migration of adjacent teeth and a malocclusion There are a number of reasons that can delay the eruption

of permanent teeth. The following are some of them:

a) Congenital absence of the permanent toothb) Presence of supernumerary tooth or pathology such as

odontomes can block the erupting permanent tooth.c) Premature loss of deciduous teeth can result in

delayed eruption of the underlying permanent teethdue to formation of thick cortical bone over theerupting permanent tooth.

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d. Endocrinal disorders such as hypothyroidism can causea delay in eruption of the permanent teeth.

e. Presence of deciduous root fragments that are notresorbed can block the erupting permanent teeth.

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-:ABNORMAL ERUPTIVE PATH:- One of the causes of malocclusion is an abnormal path of

eruption , which could be due to arch length deficiency ,presence of supernumerary teeth, impacted teeth , retainedroot fragment , or formation of a bony barrier.

The maxillary canines develop almost near the floor ofthe orbit and travel down to their final position in themaxilla .

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-:ANKYLOSIS:-

Ankylosis is a condition wherein apart or whole of the root surface isdirectly fused to the bone with nointervening periodontalmembrane.

Anlylosis can also be associatedwith certain infections, endocrinaldisorders and congenital disordersuch as cleidocranial dysostosis.

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-:DENTAL CARIES:- Caries can lead to premature loss of deciduous or

permanent teeth thereby causing migration of contiguousteeth , abnormal axial inclination and supra-eruption ofopposing teeth.

Proximal caries that has not been restored can causemigration of the adjacent teeth into the space leadingto a reduction in arch length.

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-:IMPROPER DENTAL RESTORATIONS:- Improper dental restorations may predispose to malocclusion. Over- contoured occlusal restorations cause prematuer contacts

leading to functional shift of the mandible during jaw closure. Under –contoured occlusal restorations can permit the

opposing dentition to undergo supra eruption Proximal restorations that are under- contoured invariably

result in loss of arch length due to drifting of adjacent teeth tooccupy the space.

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