ETIOLOGY OF MALOCCLUSION GENERAL & LOCAL FACTORS
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The various classification proposed are:
White and Gardiner Salzmann’s classification Moyer’s classification Graber’s classification
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Graber’s classification General factors 1. Heredity 2. Congenital 3. Environment prenatal postnatal 4. Predisposing metabolic climatic and infectious disease
5. Abnormal pressure habits and functional aberrations— Thumb sucking, Tongue thrust, speech defects etc 6. Dietary problems 7. Posture 8. Trauma and accidents
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Local factors
1. Anomalies in number of teeth 2. Anomalies of tooth size 3. Anomalies of tooth shape 4. Abnormal labial frenum 5 Premature loss of deciduous teeth 6. Prolonged retention of deciduous teeth 7. Delayed eruption 8. Abnormal eruptive pathway 9. Ankylosis 10.Dental caries 11.Improper dental restorations www.indiandentalacademy.com
General factors
Heredity: It includes factors that result in malocclusion and are inherited from the parents by the off springs. These factors can influenceNeuromuscular system Dentition Skeletal structures Soft tissues www.indiandentalacademy.com
Neuromuscular system- There is deformity in neuromuscular co ordination pattern of facial,oral and tongue musculature Dentition- size and shape of the tooth number of teeth primary position of tooth germ shedding of deciduous teeth and sequence of eruption mineralization of teeth www.indiandentalacademy.com
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Skeletal structures- underlying basal bone and other associated cranial bone structures are partially inherited Class III skeletal pattern most commonly show familial tendency
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Soft tisuues (other than neuro muscular) Size and shape of frenum Microstomia Ankyloglossia
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Congenital factors
These malformations are seen at the time of birth Mal development of 1st and 2nd brachial arches Common conditions are: Micrognathism Oligodontia Anodontia Cleft lip and palate congenital syphillis Maternal rubella infections Cleidocranial dystosis Cerebral palsy
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Micrognathism ( small jaw) ď‚Ą congenital variety is usually seen with congenital heart disease and Pierre Robin syndrome. ď‚Ą
Micrognathia of maxilla is due to deficiency in the pre maxilla
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Mandibular retrognathism is characterized by severe retrusion of the chin www.indiandentalacademy.com
Oligodontia : different teeth seem to be affected by different degree with the third molar being most affected Anodontia absence of teeth very rare condition Cleft lip & palate :generally associated with under developed maxilla and related dental disturbances www.indiandentalacademy.com
Congenital syphills- syphills of congenital origin is transmitted from the infected mother to the child: Hutchinson’s molar Mulberry molar Enamel deficiency Extensive dental decay Small maxilla Ant cross bite
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Maternal rubella infections: dental hypoplasia retarded eruption of teeth extensive caries
Cleidocranial dystosis - unilateral/bilateral partial/ complete absence of the clavicle - max retrusion and mandibular protrusion -over retained deciduous teeth and retarded eruption of permanent teeth -presence of supernumerary teeth www.indiandentalacademy.com
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Cerebral palsy aberrant muscle activity resulting in malocclusion
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Environment Prenatal factors • Abnormal fetal posture : -Interferes with symmetric development of face -Not directly associated with malocclusion but may be associated with abnormal pressure or imbalance. -Most of the deformities are temporary and disappears with time www.indiandentalacademy.com
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Maternal infections such as German measles and use of certain drugs during pregnancy like thalidomide can cause congenital deformities like cleft
Post natal factors - Trauma - Forceps delivery can result in injury to the TMJ area which can undergo ankylosis retarded mandibular growth ď‚Ą
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Predisposing metabolic climate and disease Endocrinal imbalance: Diseases hypopitutarism
Hyperpitutarism
Features - delayed tooth eruption - incomplete root formation -large mandible -enlarged tongue - accelerated dental development
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Hypothyroidism
- Growth retardation - Delayed eruption of the teeth - Maxillary protrusion - Spacing
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Hyperthyroidism
- Accelerated skeletal growth - Irregular eruption of the teeth -Mild prognathism
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Hypoparathyroidism
- retarded eruption -early exfoliation -enamel defects
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Hyperparathyroidism
- demineralization -disappearance of lamina dura -mobility of teeth
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Metabolic disturbances ď‚Ą
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Acute febrile diseases may also affect the dentition and its surrounding hard and soft tissue. If severity and duration is not prolonged the child is able to recoup and catch up growth is possible www.indiandentalacademy.com
Infectious diesease
Bacterial infection
Osteomyelitis - Bone response to force is altered Congenital syphillis –under developed maxilla - narrow maxillary arch - enamel hypoplasia -Defect in shape of teeth
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Viral infection Mumps
Measles
-airway obstruction
Rubella
-retarded eruption of teeth -congenital malformations including cleft lip and palate
-dental hypoplasia -retarded eruption -extensive caries -Inflammation/ congestion of gingiva
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Dietary problems
Protein deficiency
Vitamin A deficiency
- delayed eruption -calcification of teeth is affected - retarded eruption
Vitamin B complex
- cheilosis - retarded growth - pernicious anaemia
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Vitamin C deficiency
Vitamin D
- disturbed collagen fibre formation - bleeding gums - loosening of teeth -disturbed calcification of teeth -poor quality of teeth - narrow maxillary arch - High palatal vault -Under developed mandible
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Hypervitaminosis D - poorly calcified teeth -decalcification of bones -Increased osteoclastic activity
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Abnormal pressure habits and functional aberrations
Thumb sucking Tongue thrust Lip and nail biting Abnormal swallowing habits Speech defects Respiratory abnormalities Tonsils and adenoids Pshychogenic habits and bruxism www.indiandentalacademy.com
All these habits are functional aberrations which produces forces that are abnormal and these forces are capable of bringing about a permanent deformity in the developing musculo skeletal unit ď‚Ą
Deformity depends upon the- Intensity - Duration - Frequency ď‚Ą
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Posture
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Poor postural habit It may be associated with maloclusion though not proved
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Accidents and Traumas Injuries of the dento alveolar region may get unnoticed during the early years of life ď‚Ą Responsible for - Non vital teeth - Ankylosed teeth - Injuries at condylar region ď‚Ą
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Local factors—anomalies in number Supernumerary teeth –Teeth extra to normal complement -Most common mesiodens -may closely resemble the teeth of the group they belong or bear no resemble supplemental teeth- teeth that bear close resemble to a particular group of teeth and erupt close to original site of these teeth Most common are-premolar region or the lat region www.indiandentalacademy.com
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supplemental teeth-Teeth bear close resemble to a particular group of teeth - Erupt close to original site of these teeth -Most common are-premolar region or the lateral incisor region
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Supernumerary teeth can cause-Non eruption of adjacent teeth -Delay the eruption of adjacent teeth -Deflect the erupting tooth into abnormal locations -Crowding
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Missing teeth –more common condition than supernumerary teeth
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Oligodontia- absence of many teeth Anodontia-absence of all the teeth Hypodontia-presence of few teeth eg-hypo hydrotic ectodermal dysplasia www.indiandentalacademy.com
This condition can lead to - Spacing between the teeth - Aberrant swallowing patterns -Abnormal axial inclination of adjacent teeth
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Anomalies of tooth size
Microdontia- True generalized form of microdontia is rare Usually seen in cases of pitutary dwarfism Most common form of localized microdontia is- max lat incisors called-peg lateral
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Anomalies of tooth shapeFusion - tooth arises through the union of two normally seperated tooth bud -may lead to spacing Gemination Twinning Concrescence Dilaceration
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Abnormal of labial frenum
- Often associated with maxillary mid line spacing
A heavy fibrous frenum is found attached to inter dental papilla
Can prevent the two max central incisors from approximating each other www.indiandentalacademy.com
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Blanch test- is used to determine the role of frenum as a casuative factor for mid line test Step 1. The lip is pulled superiorly and anteriorly Step 2. Any blanching indicates fibres of the frenum crossing the alveolar ridge An IOPA will show notching in the inter dental alveolar ridge region
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Premature loss of deciduous teeth-Decrease in total arch length as the posterior teeth move mesially -Ectopic eruption of teeth -Shift in the midline
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Prolonged retention of deciduous teeth ď‚Ą
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Reasons for prolonged retention of tooth areAbsence of any underlying permanent teeth Endocrinal disturbancesHypothyroidism Ankylosed deciduous teeth Non vital teeth that do not resorb www.indiandentalacademy.com
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Prolonged retention of deciduous teeth result in lingual or palatal eruption of their successors.
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Delayed eruption of permanent teeth May result in ectopic eruption of permanent teeth ď‚Ą The reasons for delayed eruption are-Congenital absence of the permanent tooth -Presence of supernumerary teeth ď‚Ą
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-Presence of heavy mucosal barrier can prevent the permanent tooth from emerging into the oral cavity - Presence of deciduous root fragments - Endocrinal disturbances - Ankylosed teeth
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Abnormal eruptive path Causes for this are: - Tooth bud displaced from its ideal position - Presence of supernumerary teeth , odontomas, retained tooth may divert a tooth from its eruptive path ď‚Ą
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Retained deciduous teeth might force a tooth to erupt along a path of least resistance rather than in place of deciduous teeth ď‚Ą Arch length deficiency or excess of tooth material may cause one or more teeth to deviate from their eruptive path - Most common is max canine ď‚Ą
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Various reasons for this behavior are-Travels the longest distance, from near floor of the orbit to cover the arch - It is the last anterior tooth to erupt and loss in arch length- anterior or posterior teeth may impinge on the space required for it to erupt
- Abnormal position of the tooth bud www.indiandentalacademy.com
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Ankylosis -Union of the root or part of a root directly to the bone without the intervening periodontal ligament -Associated with certain infections, endocrine disorders, and congenital diseases
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Dental caries -Proximal caries may result in reduction of arch length -Loss of E space -Migration/ tilting of teeth in the space available -Supra eruption of the teeth in opposing arch
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Malocclusions caused due to caries
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Improper dental restoration -Under contoured proximal restoration- decrease in arch length -Over contoured restoration- may bulge into the space to be occupied by the succadenous tooth -Overhang or poor proximal contact- periodontal breakdown -Occlusal prematurities due to over contoured occlusal restoration can cause a functional shift of the mandible www.indiandentalacademy.com
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