ETIOLOGY OF MALOCCLUSION LOCAL FACTORS
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LOCAL FACTORS 1.
Anomalies of number a) Supernumerary teeth. b) Missing teeth (congenital absence or loss due to trauma,caries,etc.) 2. Anomalies of tooth size. 3. Anomalies of tooth shape. 4. Abnormal labial frenum. www.indiandentalacademy.com
5.
Premature loss
6.
Prolonged retention
7.
Delayed eruption of permanent teeth
8.
Abnormal eruptive path
9.
Ankylosis
10. Dental caries 11. Improper dental restorations www.indiandentalacademy.com
1) Anomalies of number A) Supernumerary teeth: Supernumerary teeth is a teeth, which is various in size , shape and location when compared to the normal teeth. B)Supplemental teeth : Supplemental teeth is a teeth ,which is closely resembles the particular group of teeth. This is most commonly seen in premolar region www.indiandentalacademy.com and lateral incisor region.
Supernumerary teeth result from disturbances during the initiation and proliferation stages of dental development. Supernumerary teeth occur most commonly in the maxilla.. The most commonly seen supernumerary teeth is mesiodens. Mesiodens is a small tooth with a cone shaped crown and short root. www.indiandentalacademy.com
Supernumerary teeth
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Supernumerary teeth
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It is seen between the two maxillary central incisors. The presence of teeth obviously has great potential to disturb normal occlusal development. The frequency of other supernumerary teeth are paramolars and distomolars. Multiple supernumerary teeth are seen in cleidocranial dysplasia. www.indiandentalacademy.com
Cleidocranial dysplasia Cleidocranial dysplasia is characterized by - Abnormalities of skull,teeth,jaws and shoulder girdle. -The defect of shoulder girdle ranges from complete absence of clavicle to partial absence. - Multiple unerupted supernumerary teeth is also present in this condition. www.indiandentalacademy.com
Cleidocranial dysplasia
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B)Congenitally Missing Teeth Congenital absence of teeth results from disturbances during the intial stages of tooth formation . Anodontia – Total absence of teeth Oligodontia - Absence of many but not all the teeth. Oligodontia showed a tendency for delayed tooth formation*. www.indiandentalacademy.com (* Angle orthodontist vol 63 No:1,1993).
Ectodermal dysplasia Ectodermal dysplasia is characterized by soft , smooth , thin and dry skin with partial or complete absence of sweat glands. The sebaceous glands and hair follicles are absence. The bridge of the nose are depressed. This also manifested with anodontia or Oligodontia. www.indiandentalacademy.com
Frequency of absence(Missing) Maxillary and Mandibular third molars Maxillary lateral incisors Mandibular second premolar Mandibular incisors Maxillary second premolar
Congenitally missing teeth can lead to spacing between teeth and aberrant swallowing pattern. www.indiandentalacademy.com
Congenitally Misssing Lateral Incisors
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2)Anomalies of Tooth Size : A tooth size is determined by heredity .
Anomalies of Tooth Size
Microdontia
Macrodontia
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ďƒ˜True generalized microdontia is usually associated with pituitary dwarfism. ďƒ˜True generalized macrodontia is usually associated with pituitary gigantism. ďƒ˜The most commonly localized microdontia involves the maxillary lateral incisors (peglaterals).
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Microdontia
Macrodontia www.indiandentalacademy.com
3)Anomalies of Tooth Shape :
Intimately related to tooth size is tooth shape.
Abnormal shaped teeth predispose to malocclusion. Presence of maxillary-‘Peg lateral’ incisors spacing will often occur in the maxillary anterior segment. www.indiandentalacademy.com
ďƒ˜ Abnormally large cingulum on the maxillary incisor (Talons cusp) or heavy marginal ridge can force the teeth labially and prevent the establishment of a normal overbite-overjet relationship. ďƒ˜ Mandibular second premolar also shows great variation in shape & size. It may have an extra lingual cusp , which usually serve to increase the mesiodistal dimension of the tooth. www.indiandentalacademy.com
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Anomalies of shape can also occur as a result of amelogenesis imperfecta, hypoplasia, gemination, dens in dente, odontomas , fusion and congenital syphilitic aberration such as Hutchinson‘s incisors and mulberry molars.
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Dilaceration is a condition characterized by an abnormal angulation between the crown and root of a tooth .Dilacerated teeth fails to erupt to normal level and can cause malocclusion.
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Gemination
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Twinning
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Fusion
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4) Abnormal Labial Frenum : ďƒ˜ Abnormalities of the maxillary labial frenum are associated with a midline diastema . ďƒ˜ At birth frenum is attached to the alveolar ridge with fibers running into the incisive papilla. The teeth erupts and as alveolar bone is deposited, the frenum attachment migrates superiorly with the alveolar ridge.
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Abnormal Labial Frenum
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Fibers may persist between the maxillary central incisors and in the ‘V’ shaped intermaxillary suture , attaching to the outer layer of the periosteum and connective tissue of the suture.
Faust in Weber ,noted that diastema may be due to other factors, the possible causative factors : Microdontia, Macrognathia,Super numerary teeth,Peg laterals,Missing lateral incisors ,Habits as thumb sucking, tongue thrusting & midline pathologies. www.indiandentalacademy.com
Diastema Due to Abnormal Frenum Age
Incidence of Diastema
6 6-7 10-11 12-18
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97% 88% 40% 7%
5)Premature loss of Deciduous teeth : ďƒ˜ Deciduous teeth are the space savers for the permanent teeth. ďƒ˜ They also maintaining the opposing teeth at the proper occlusal level.
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Deciduous cuspids are frequently shed pre-maturely and nature provide more space to align the permanent incisor teeth that have already erupted. Pre mature removal of posterior deciduous teeth because of caries Malocclusion unless space maintainers are placed.
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Lee way Space : In the mandibular arch combined width of the deciduous canine, First & second deciduous molar is on the average of 1.7 mm greater on each side than the permanent successors. In the maxillary arch “lee way space” average is 0.9mm because of the greater size of the permanent canine, first and second pre molar teeth. This space differential is necessary for the occlusal adjustment and final alignment of the incisors. www.indiandentalacademy.com
Pre mature loss (Extraction) of the deciduous second molar will lead to mesial drift of the first permanent molar and blocking of the erupting second premolars. The early loss of permanent teeth should be considered just as severe a ‘Malocclusion maker’ as loss of deciduous teeth.
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6)Prolonged retention of deciduous teeth : Whatever the reason for the prolonged retention of deciduous teeth, they have a significant impact on the dentition. Whichever deciduous teeth may be retained beyond the usual eruption age of their permanent successor is capable of causing buccal / labial or Palatal / Lingual deflection. Impacted in the maxillary arch might lead to the permanent tooth erupting is a cross bite,which might be difficult to treat at a later stage. www.indiandentalacademy.com
Impacted Permanent teeth are more difficult to correct orthodontically, by surgical exposure most commonly impacted tooth is the maxillary canine(3rd molars not in consideration) the reason
It’s the last anterior tooth to erupt.
Space occupied by the deciduous canine is lesser than the mesiodistal width of the permanent canines.
It has longer path of eruption www.indiandentalacademy.com
7 )Delayed eruption of permanent teeth:
Reasons: 1.Early loss of adjacent primary teeth with a consequential flaring or spacing between erupted teeth may lead to decreased space availability for eruption of the succedaneous teeth. 2. Early loss of primary tooth leading to mucosal thickening over the succedaneous tooth . 3. Early loss of the primary tooth might cause excessive bone deposition over the succedaneous tooth. www.indiandentalacademy.com
4. Due to hereditary in certain children teeth erupt much later than established norms.
5.Presence of supernumerary tooth can block the erupting permanent tooth.
6. Presence of odontomas or other cysts and tumors might prevent the permanent tooth from erupting.
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7. Presence of deciduous root fragment that are not resorbed can block these erupting tooth or may deflect it preventing its eruption in an ideal location. 8. Presence of ankylosed deciduous teeth,these might not get resorbed causing a delay in the eruption of the permanent tooth.
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9. The succedaneous tooth might be congenitally missing delaying the loss of the primary tooth.
10. In certain endocrine disorders the eruption of permanent teeth might be delayed. Eg: hypothyroidism.
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8)Abnormal Eruptive path : 1.Tooth bud facing and/or placed or displaced from its ideal location. 2.Presence of a supernumerary tooth may divert a tooth from its eruptive path. 3. Presence of odontomas or a cyst tumour may divert it if not altogether prevent its eruption. www.indiandentalacademy.com
Abnormal Eruptive path(cont..) 4. Un resorbed or retained deciduous teeth might force a tooth to erupt along a path of least resistance rather than in place of the deciduous tooth. 5. Retained root fragments may deflect an erupting permanent tooth. 6.Arch length deficiencies or excess of tooth material may cause one or more teeth to deviate from their eruptive path. www.indiandentalacademy.com
Ectopic Eruption : Malposition of a permanent tooth bud can lead to eruption in wrong place.This condition is called ectopic eruption. Most likely to occur in the eruption of maxillary first molars. Ecotopic eruption may generally be considered a manifestation of arch length deficiency. www.indiandentalacademy.com
9)Ankylosis : ďƒ˜ Ankylosis is the condition which involves the union of the root or part of a root directly to the bone, without the intervening periodontal membrane. ďƒ˜ Ankylosis or partial ankylosis is encountered relatively frequently during the 6 to 12 year age period. www.indiandentalacademy.com
ďƒ˜ Ankylosis of teeth is more commonly associated with certain infections, endocrine disorders and congenital disorders.
Ex : Cleidocranial dysostosis , but there are rare occurrences. ďƒ˜ Ankylosis may be due to past history of trauma. www.indiandentalacademy.com
10)Dental caries ďƒ˜ Dental caries which leads to the premature loss of a deciduous or permanent tooth subsequent drifting of contiguous teeth ,abnormal axial inclination,over eruption and bone loss.
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11)Improper dental restorations : ďƒ˜ Due to improper dental restoration under contoured proximal restoration can lead to a significant decrease in the arch length especially in the deciduous molars.
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Conclusion ďƒ˜
Proper knowledge of preventive and interceptive orthodontics can definitely reduce the occurrence of malocclusion ,if not prevent them from occuring.
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Thank you www.indiandentalacademy.com Leader in continuing dental education
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