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Etiology of malocclusion

Etiology of malocclusion. Fengshan Chen Tongji university. Systems of Classification. Inherited (predetermined)(genetic) Acquired(environmental). Systems of Classification. 1) McCoy and Shepard(1956) a) Direct(determining) b) Indirected(predisposing) 2) Moyers(1972)

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Etiology of malocclusion

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  1. Etiology of malocclusion Fengshan Chen Tongji university

  2. Systems of Classification • Inherited (predetermined)(genetic) • Acquired(environmental)

  3. Systems of Classification • 1) McCoy and Shepard(1956) • a) Direct(determining) • b) Indirected(predisposing) • 2) Moyers(1972) • a)Heredity • b)Developmetal Defects • c)Trauma • d) Physical agents • e) Habits • f) Diseases • g)malnutrition

  4. Classification • 3.Salzman • a) Prenatal • b) Postnatal • 4.Graber • a) General (extrinsic) factors • b) Local (intrinsic) factors

  5. Graber General factors • Heredity • Congenital defects • Environment • Predisposing metabolic climate &disease • Diet • Abnormal pressure habits • Posture • Trauma

  6. Heredity • Two Facts • 1.For each individual there is a basic pattern or blueprint for dentofacial development not really which may be masked but not really changed.(unless by surgery). • 2.Racial and familial characteristics repeat

  7. Facial Typing • Brachycephalic-short, broad • Dolicocephalic-narrow, tapering, long • Mesocephalic-round, oval

  8. Facial Typing-profile • Convex-Class Two (protrusive maxilla or retrusive mandible) or Class 1 bimaxillary • Concave-Class Three (protrusive mandible or retrusive maxilla) • Flat-Class One (denture bases in harmony)

  9. Affected by Heredity • Tooth size • Arch length and width • Height of the palatal vault • Crowding or spacing • Overbite and overjet • Position and configuration of muscles • Tongue size and shape • Character of the oral mucosa

  10. Heredity also plays a role in: • Congenital deformities • Facial asymmetry • Size and position of the jaws • Oligodontia and anodontia • Supernumerary teeth • Variations in tooth shape

  11. Examples of Congenital Defects • Clefts of the lip and palate • Cerebral Palsy • Crouzons syndrome • Cleido-Cranial Dysostosis • Cranial Synostosis

  12. Crouzon´s Syndrome

  13. Surgery to reopen cranial sutures

  14. Results of Surgery & Orthodontics

  15. Results of Surgery & Orthodontics

  16. Results of Surgery & Orthodontics

  17. Environmental Factors • Prenatal • trauma • maternal diet • maternal metabolism & diseases • fetal posture • maternal consumption of alcohol & drugs

  18. Environmental Factors • Postnatal • Birth injuries • TMJ injuries • Accidents, fractures • Avulsion or displacement of teeth

  19. Metabolic Factors & Diseases • Acute febrile disease- e.g. measles, mumpes, chicken-pox,etc. • Diseases of muscle dysfunction-e.g. muscular dystrophy, cerebral palsy, polio. • Endocrine disorders-e.g. pituitary,thyroid,parathyroid.

  20. Diet • Poor diet may cause deficiency diseases such as richetts, beri scurvy etc. • These may cause severe malocclusion due to interference with craniofacial growth and development in addition Periodontal problems associated with significant bone loss

  21. Posture • Not an important factor • May be a contributing factor • Seldom considered a primary cause

  22. Habits • Thumb or finger sucking • Foreign objects • Tongue thrusting • Lip or cheek biting • Mentalis muscle strain

  23. Thumb Sucking

  24. Treatment Phase 1

  25. progress

  26. Treatment Phase 2

  27. Post Treatment

  28. Tongue Thrusting

  29. Treatment

  30. progress

  31. Hyperactive mentalis muscle

  32. Local factors • Congential absence of teeth • Anomalies of tooth size • Anomalies of tooth shape • Abnormal labiel frenum • Premature loss of deciduos teeth • Supernumerary teeth

  33. Local Factors • Abnormal resorption of deciduous teeth • Delayed eruption of permanent teeth • Abnormal eruptive path • Ankylosis of deciduous teeth • Proximal caries • Improperly contoured restorations

  34. Congenital absense of teeth

  35. Missing and peg-shaped lateral

  36. Space adjusted

  37. Retention

  38. Temporary Restorations

  39. Congenitally Missing Laterals

  40. Spaces Opened

  41. Temporary Restorations

  42. Mandibular retrusion

  43. Mandibular Prognathism and facial asymmetry

  44. Mandibular Prognathism & facial asymmetry

  45. Bilateral Clefts

  46. Expansion

  47. Pre-grafting

  48. Ideopathic Root Resorption

  49. Dilantin Hyperplasia

  50. Tooth Size

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