Etiology of malocclusion


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Etiology of malocclusion

  1. 1. Etiology Of malocclusion Presented By: Ritu Agrawal 1
  2. 2. Definition of Malocclusion Malocclusion is defined as a defect in the normal position of the upper and lower teeth when the mouth is closed, as from abnormal development of the jaw or Misalignment between the upper and lower teeth when the jaw is closed, resulting in a faulty bite 2
  3. 3. Classification of etiologic factors of malocclusion 1. Moyer’s classification 2. White &Gardiner’s classification 3. Graber’s classification 3
  4. 4. Moyer’s classification of etiology 1. Heredity • Neuromuscular system • Bone , teeth • Soft part [other than nerves & muscles] 2.Developmental defects of unknown origin 3.Trauma • Prenatal trauma& birth injuries • Post natal trauma 4
  5. 5. 4. Physical agents i. Nature of the food ii. Premature extraction of primary teeth 5. Habits i. thumb sucking, lip sucking ii. tongue thrusting iii. posture iv. Nail biting and other habits 5
  6. 6. 6.Diseases i. Systemic diseases ii. Endocrine disorders iii. Local diseases iv. Nasopharyngeal diseases and disturbed respiratory function v. Gingival and periodontal diseases vi. Tumour vii.caries 7. Malnutrition 6
  7. 7. White & Gardiner’s Classification 1. Dental base abnormalities i. Antero- posterior malrelationship ii. Vertical malrelationship iii. Lateral malrelationship iv. Disproportion of size between teeth & basal bone v. Congenital abnormalities 7
  8. 8. 2. Pre eruption abnormalities i. ii. iii. iv. v. vi. Abnormalities in position of developing tooth germ Missing teeth Supernumerary teeth & teeth in abnormal form Prolonged retention of deciduous teeth Large labial frenum Traumatic injury 8
  9. 9. 3. Post- eruption abnormalities  Muscular - active muscle force -Rest position of musculature -Sucking habits -Abnormalities in path of closure  Premature loss of deciduous teeth  Extraction of permanent teeth 9
  10. 10. Graber’s classification GENERAL FACTORS: 1. Heredity 2. Congenital 3. Environment  Prenatal[ trauma, German measles,maternal diet]  Post natal[ birth injury, cerebral palsy, TMJ injury] 10
  11. 11. 4. Pre disposing metabolic climate & disease  Endocrine imbalance  Metabolic disturbances  Infectious diseases 5. Dietary problems [nutritional deficiency] 6. Abnormal pressure habits & functional aberrrations  Abnormal sucking  Tongue thrust & tongue sucking  Lip and nail biting 11
  12. 12.  Abnormal swallowing habits  Speech defects  Respiratory abnormalities[ mouth breathing etc]  Tonsils & adenoids[compensatory tongue position]  Psychogenic tics & bruxism 7. Posture 8. Trauma & accidents 12
  13. 13. LOCAL FACTORS: 1. Anomalies of number  supernumerary and missing teeth 2. Anomalies of tooth size 3. Anomalies of tooth shape 4.Abnormal labial freenum[ mucosal barrier] 5.Premature loss of deciduous teeth 6.Prolonged retention of deciduous teeth 13
  14. 14. 7. Delayed eruption of permanent teeth 8. Abnormal eruptive path 9. Ankylosis 10. Dental caries 11. Improper dental restorations 14
  15. 15. GENERAL FACTORS 1. Heredity Hereditary causes of malocclusion include all factors that are inherited from parents by the offspring There are no of traits that are influenced by the genes that include a. Tooth size - eg.. microdontia , macrodontia b. Arch dimensions c. crowding 15
  16. 16. d. Abnormalities of tooth shape – eg…. Peg shaped laterals 16
  17. 17. e. Abnormalities of tooth number eg… anodontia, hypodontia , oligodontia f. Interarch variations 17
  18. 18. g.Frenum - include size and shape of the frenum and specially maxillary labial frenum is said to be genetically influenced . for eg …. Midline diastema 18
  19. 19. 2. Congenital factors These defects include malformations that are seen at the time of birth .It can be broadly classified as general and local ….. General factors are – a . Malnutrition b. Endocrinopathies c. Infectious diseases d.Accidents during pregnancy and birth 19
  20. 20. Local factors area. Cleft lip and palate b. Micro and macroglossia c.Cleidocranial dysostosis 3.Enviornmental factors- include Prenatal factors  Abnormal foetal posture during gestation can interfere with the symmetric development of face 20
  21. 21. others are maternal fibroids, amniotic lesions ,maternal diet ,infection such as german measles etc Postnatal factors - include i. Forceps delivery which can result in injury to tmj and can cause ankylosis ,retarded mandibular growth ii.Cerebral palsy , traumatic injuries etc can also cause growth retardation resulting in facial asymmetry 21
  22. 22. 4.Pre disposing metabolic climate and disease a. Endocrine imbalance - some disturbances are Disease  Hypothyroidsm Features retarded growth retained deciduous tooth delayed tooth eruption abnormal root resorption irregularites in tooth 22
  23. 23. Hyperthyroidism Hypoparathyroidism Accelerated skeletal growth increase in metabolic rate Premature eruption of dec teeth osteoporosis , open bite tendency changes in Ca metabolism delayed tooth eruption early exfoliation enamel defects 23
  24. 24.  Hyperparathyroidism increase in blood Ca demineralization mobility of teeth due to loss of cortical bone and resorption of alveolar process b.Metabolic disturbancesAcute febrile disease slow down the pace of growth and development and may cause disturbance in tooth eruption and shedding increasing risk of malocclusion 24
  25. 25. c. Infectious diseases- for eg…  Congenital syphillis - transmitted by infected mother to child ,has following features peg shaped lateral incisors mulberry molars enamel hypoplasia dental decay ,narrow max arch ,anterior cross bite depressesd nasal bridge 25
  26. 26. Maternal infection like rubella,rubeola and cytomegalo viruses causes developmental defects like cleft lip and cleft palate 5.Nutritional deficiency During growth this may results in abnormal development Vitamin deficiency states like rickets, scurvy and beriberi predisposes to the development of malocclusion Deficiency of calcium can upsets the development of teeth 26
  27. 27. Abnormal pressure habits and functional aberrations Thumb sucking Tongue thrusting 27
  28. 28. Local factors a)Anomalies in number of teeth The anomalies in the no of teeth can be of two types – 1. supernumerary – teeth that are extra to the normal complement are supernumerary , they may or may not bear resemblance to the adjacent teeth  for eg… distomolars , paramolars 28
  29. 29. Most common is mesiodens These teeth may cause –  Non eruption of adjacent teeth  delay the eruption of adjacent teeth Crowding in dental arch 29
  30. 30. 2. Missing teeth- congenital missing teeth are more common than supernumerary teeth  hypodontia ,anodontia ,oligodontia are eg of congenital missing teeth. Most common missing teeth are third molars , max lateral incisors . 30
  31. 31. Bilateral missing lateral incisors It can lead to – Gaps between teeth Abnormal tilting of adjacent teeth  Aberrant swallowing pattern 31
  32. 32. b.Anomalies of tooth shape – anomalies of tooth shape include fusion, gemination concrescence, talons cusp etc  Congenital syphilis is often associated with the presence of peg shaped laterals 32
  33. 33. c.Premature loss of deciduous teethEarly loss of deciduous teeth can cause migration of adjacent teeth into the space and can prevent eruption of permanent successor In case of anteriors -spacing occur between the erupted anterior teeth – shift in midline Loss of deciduous second molar –mesial migration of 1st permanent molar –loss in the arch length 33
  34. 34. d.Prolonged retention of deciduous teeth Retention of deciduous teeth beyond the usual eruption age of their permanent succesors may cause • buccal /labial or palatal/lingual deflection in its path of eruption OR • Impaction of the permanent tooth Reasons for retention are i. absence of underlying permanent teeth ii.Endocrinal disturbances iii. ankylosed deciduous teeth fail to resorb 34
  35. 35. Labially erupting max canine due to retained deciduous canine 35
  36. 36. e. Delayed eruption of permanent teeth Reasons are i. congenital absence of the permanent tooth ii. presence of supernumerary tooth iii.Premature loss of deciduous tooth iv. endocrinal disorders v.Early loss of adjacent teeth or spacing between erupted permanent teeth 36
  37. 37. f. Ankylosis It is a condition wherein a part or whole of the root surface is directly fused to the bone with the absence of the intervening periodontal membrane More commonly associated with the certain infections , endocrinal disorders ,congenital disorder 37
  38. 38. g. Dental caries and improper dental restorations Caries can lead to premature loss of deciduous or pmt teeth –migration of adjacent teeth-supraeruption of opposing teeth  proximal caries – reduction of arch length 38
  39. 39. Improper dental restorationsOver contoured occlusal restoration -premature contacts - functional shift of mandible Under contoured occlusal restoration-supra eruption of the opposing teeth 39
  40. 40. Thank you 40