Etiology of malocclusion

1. “ETIOLOGY OF MALOCCLUSION” Presented by— Hemam Shankar Singh 1

2. CONTENTS 2 ETIOLOGY OF MALOCCLUSION- CONTENTS

3. INTRODUCTION FUNDAMENTAL TO UNDERSTANDING MALOCCLUSION IS THE CONCEPT OF `NORMAL OCCLUSION`. JOHN HUNTER WAS THE FIRST TO DESCRIBE ABOUT NORMAL OCCLUSION. 3 ETIOLOGY OF MALOCCLUSION- INTRODUCTION

4. 4 ETIOLOGY OF MALOCCLUSION-INTRODUCTION

5. Etiology of malocclusion is the study of its causes. Recognition and elimination of the etiological factors is important so that one can prevent and correct the malocclusion and obtain a permanent result. Traditionally, any deviation from "ideal occlusion" has represented what Guilford termed mal-occlusion. of course, ideal occlusion rarely exists in nature and so perhaps it is better to call this concept the "imaginary ideal" 5 ETIOLOGY OF MALOCCLUSION-INTRODUCTION

6. MALOCCLUSION “An occlusion in which there is mal-relationship between the arches in any of the planes of space or in which there are anomalies in tooth position beyond the limits of normal” Sameul S. Flitch was the first to classify malocclusion. 6 ETIOLOGY OF MALOCCLUSION- INTRODUCTION

7. CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION Moyer’s classification White and Gardiner’s classification Proffit’s Classification Graber’s classification 7 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION

8. CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION 8 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. MOYER’S CLASSIFICATION

9. MOYER’S CLASSIFICATION 9 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. HEREDITY NEUROMUSCULAR BONE TEETH SOFT PARTS TRAUMA PRENATAL TRAUMA AND BIRTH INJURIES POSTNATAL TRAUMA

10. MOYER’S CLASSIFICATION 10 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. PHYSICAL AGENTS PREMATURE EXTRACTION OF PRIMARY TEETH NATURE OF FOOD HABITS TUMB SUCKING AND FINGER SUCKING TONGUE THRUSTING LIP SUCKING AND LIP BITING POSTURE NAIL BITING OTHER HABITS

11. MOYER’S CLASSIFICATION 11 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. DISEASES SYSTEMIC DISEASES ENDOCRINE DISEASES LOCAL DISEASES NASOPHARYNGEAL DISEASES & DISTURBED RESPIRATORY FUNCTION GINGIVAL &PERIODONTAL DISEASES CARIES TUMOURS MALNUTRITION DEVELOPMENTAL DEFECTS OF UNKNOWN ORIGIN

12. WHITE & GARDINER’S CLASSIFICATION 12 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O.

13. PROFFIT’S CLASSIFICATION 13 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O.

14. PROFFIT’S CLASSIFICATION 14 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. SPECIFIC CAUSES- 1.Disturbances in embryologic development. 2.Skeletal growth disturbances a.Fetal molding & birth injuries. b.Birth trauma to the mandible. c.Childhood fracture of the jaw. 3.Muscle dysfunction. 4.Acromegaly & hemi- mandibular hypertrophy. 5.Disturbances in dental development . a.Congenitally missing teeth. b.Malformed teeth. c.Supernumerary teeth. d.Interference with eruption. e.Ectopic eruption. f.Early loss of primary teeth. g.Traumatic displacement of teeth

15. PROFFIT’S CLASSIFICATION 15 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. GENETIC INFLUENCES ENVIRONMENTAL INFLUENCES Functional influences on Dentofacial development- a. Masticatory function b. Sucking & Other Habits c. Tongue thrusting d. Respiratory pattern

16. GRABER’S CLASSIFICATION 16 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O.

17. GRABER’S CLASSIFICATION 17 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. GENERAL FACTORS 1. HEREDITY 2. CONGENITAL 3. ENVIRONMENTAL 4. PRE-DISPOSING METABOLIC CLIMATE & DISEASES 5. DIETARY PROBLEMS 6. ABNORMAL PRESSURE HABITS & FUNCTIONAL ABERRATIONS 7. POSTURE 8. TRAUMA AND ACCIDENT

18. GRABER’S CLASSIFICATION 18 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. GENERAL FACTORS 1. HEREDITY 2. CONGENITAL

19. GRABER’S CLASSIFICATION 19 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. GENERAL FACTORS 5. DIETARY PROBLEMS 7. POSTURE 8. TRAUMA AND ACCIDENT 6. ABNORMAL PRESSURE HABITS & FUNCTIONAL ABERRATIONS a. ABNORMAL SUCKING b. THUMB & FINGER SUCKING c. TONGUE THRUST & TONGUE SUCKING d. LIP & NAIL BITING e. ABNORMAL SWALLOWING HABITS f. SPEECH DEFECT g. RESPIRATORY DEFECT h. TONSILS & ADENOIDS i . PSYCHOGENIC TICS & BRUXISM

20. GRABER’S CLASSIFICATION 20 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS 1. ANOMALIES OF NUMBER 2. ANOMALIES OF TOOTH SIZE 3. ANOMALIES OF TOOTH SHAPE 4. ABNORMAL LABIAL FRENUM: MUCOSAL BARRIERS 5. PREMATURE LOST OF DECIDUOUS TEETH 6. PROLONGED RETENTION OF DECIDUOUS TEETH 7. DELAYED ERUPTION OF PERMANENT TEETH 8. ABNORMAL ERUPTIVE PATH 9. ANKYLOSED 10. DENTAL CARIES 11. IMPROPER DENTAL RESTORATION

21. GRABER’S CLASSIFICATION 21 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. GRABER’S CLASSIFICATION-GENERAL FACTORS HEREDITY Heredity has for long been attributed as one of the causes of malocclusion Another reason attributed for genetically determined malocclusion is the Racial, ethical & regional inter-mixture

22. GRABER’S CLASSIFICATION 22 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. HEREDITY Number of human traits that are influenced by the genes include (according to Lundstrom): Tooth size Arch dimension crowding/spacing Abnormalities of tooth shape Abnormalities of tooth number Overjet Inter-arch variations Frenum

23. GRABER’S CLASSIFICATION 23 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. HEREDITY Genuine Class II malocclusion in three brothers

24. GRABER’S CLASSIFICATION 24 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS They are malformations seen at the time of birth Its causes can be broadly classify as General congenital factors Local congenital factors

25. GRABER’S CLASSIFICATION 25 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS General congenital factors Abnormal state of mother during pregnancy Malnutrition Endocrinopathies Infectious disease Metabolic and nutritional disturbances Accidents during pregnancy and child birth Intra-uterine pressure Accidental traumatization of the fetus by external forces

26. GRABER’S CLASSIFICATION 26 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS Local congenital factors Abnormalities of jaw development due to intra-uterine position Clefts of the face and palate Macro and microglossia Cleidocranial dysostosis

27. GRABER’S CLASSIFICATION 27 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS The following are some of the congenital conditions frequently encountered by orthodontist Clefts of the lip and palate Congenital syphilis Maternal rubella infections Cleidocranial dysostosis Cerebral palsy

28. GRABER’S CLASSIFICATION 28 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS CLEFTS OF THE LIP AND PALATE Cleft Palate can be defined as a furrow in the palatal vault or Breach in continuity of palate. Most commonly seen congenital deformity at the time of birth . Both dental & skeletal components affected Such patients exhibit following Missing Mobile teeth Rotations Cross bite Impacted teeth Supernumerary teeth, etc.

29. GRABER’S CLASSIFICATION 29 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS CONGENITAL SYPHILIS The child exhibits one or more of the following features: Hutchinson’s incisors Mulbery molars Enamel def Extensive dental decay The maxilla may be smaller in size relative the mandible Anterior cross bite MATERNAL RUBELLA INFECTIONS Maternal rubella infections during pregnancy show some features Dental hypoplasia Retarded eruption of teeth Extensive caries

30. GRABER’S CLASSIFICATION 30 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS CLEIDODOCRANIAL DYSOSTOSIS This is a congenital condition characterized by unilateral or bilateral, partial or complete absence of the clavicle The patient may exhibit the following features Maxillary retrusion & possible Mandibular protrusion Over retained deciduous teeth & retarded eruption of permanent teeth Presence of supernumerary teeth Presence of short & thin roots

31. GRABER’S CLASSIFICATION 31 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. CONGENITAL DEFECTS CLEIDODOCRANIAL DYSOSTOSIS

32. GRABER’S CLASSIFICATION 32 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ENVIRONMENT PRE-NATAL FACTORS Fetus is well protected against injuries & nutritional def during pregnancy But there are certain factors, presence of which can result in abnormal growth of oro -facial region thereby predisposing to malocclusion Pressure against rapidly growing areas leads to distortion Arm pressed against the face- maxillary deficiency Head flexed against the chest- Mandibular deficiency. Decreased amniotic fluid- small mandible Cleft palate results due to upward displacement of tongue. Growth catches-up when pressure is released except when cartilage is affected- Stickler syndrome Thalidomide – gross congenital deformities including cleft

33. GRABER’S CLASSIFICATION 33 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ENVIRONMENT STICKLER SYNDROME

34. GRABER’S CLASSIFICATION 34 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ENVIRONMENT Teratogens affecting dentofacial development Contemporary Orthodontics: William R Proffit

35. GRABER’S CLASSIFICATION 35 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ENVIRONMENT 2. POST-NATAL FACTORS Birth injuries Trauma to mandible Most mandibular deformities-due to congenital anomalies-but thought to be due to birth trauma. Forceps delivery–TMJ damage . Ankylosis : develop ankylosis of TMJ, may be due to birth injury. A high incidence of cross-bite is seen in a group of children who were born with forceps delivery. An increased asymmetric molar occlusion was observed with traumatic breech delivery.

36. GRABER’S CLASSIFICATION 36 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ENVIRONMENT vi. A tendency for abnormal dental arch dimension, larger height of the maxilla and greater length of the mandibular arch was observed to occur as a result of forceps delivery. vii. Palatal grooves and cleft formation : A prolonged oro -tracheal intubation of pre term infants is seen to be associated with airway damage, palatal groove formation, defective primary incisors and an acquired cleft palate. viii. Delayed eruption of primary teeth : Viscardi (1994) found that first primary teeth eruption at the usual chronologic age in healthy premature infants, but eruption may be delayed in premature infants who require a prolonged mechanical ventilation for neonatal illness/or who experience inadequate nutrition

37. GRABER’S CLASSIFICATION 37 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. PREDISPOSING METABOLIC CLIMATE & DISEASE Hypopituitarism : Dwarf Delayed eruption of permanent teeth and delayed shedding of primary teeth. Crowding due to smaller arch size. Mandibular growth more affected than maxilla.

38. GRABER’S CLASSIFICATION 38 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. PREDISPOSING METABOLIC CLIMATE & DISEASE Hyperpituitarism : Gigantism- large teeth and jaws. Acromegaly - occurs after growth and ossification is complete. Lips thick, tongue enlarged, shows scalloping. Accelerated condylar growth-large mandible. Teeth tipped buccally due to large tongue.

39. GRABER’S CLASSIFICATION 39 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. PREDISPOSING METABOLIC CLIMATE & DISEASE Hypothyroidism: Delayed eruption. Abnormal resorption pattern. Retained deciduous teeth. Malposed teeth-deflected from eruption path. Gingival disturbances. Hyperthyroidism: Early shedding and eruption Atrophy of alveolar bone.

40. GRABER’S CLASSIFICATION 40 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. DIETARY PROBLEMS NUTRITIONAL DEFICIENCY Disturbances in the developmental timetable. Rickets, scurvy and beri-beri can produce severe malocclusions. Premature loss of teeth/Prolonged retention. Abnormal eruptive path. Poor tissue health Poor absorption-hormonal/enzymatic deficiency. Decreased fluoride intake-loss of teeth due to caries-malocclusion.

41. GRABER’S CLASSIFICATION 41 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ABNORMAL PRESSURE HABITS AND FUNCTIONAL ABERRATION EQUILIBRIUM THEORY If an object is acted upon by a set of forces but remains in the same position, then the forces must be in balance. Dentition is in equilibrium. Movement occurs when equilibrium is disturbed. 4 PRIMARY FACTORS IN EQUILIBRIUM: Intrinsic forces of tongue and lips. Extrinsic forces- habits & orthodontic appliances. Forces from dental occlusion. Forces from periodontal membrane

42. GRABER’S CLASSIFICATION 42 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. POSTURE Frequently suggested that poor posture can lead to malocclusion. Stooping with chin on the chest- mandibular retrusion. Child resting head on hand or sleeping on arm or fist- possible development of malocclusion. May accentuate existing malocclusion. Role as primary etiological factor to be proved conclusively.

43. GRABER’S CLASSIFICATION 43 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. ACCIDENT OR TRAUMA Undiscovered traumatic experiences- significant in malocclusion. Eruptive abnormalities. Abnormal resorption . Loss of vitality. Both prenatal trauma & postnatal injuries- Dentofacial deformity:

44. GRABER’S CLASSIFICATION 44 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS ANOMALIES IN NUMBER OF TEETH: In order to achieve good occlusion, normal number of teeth should be present. Presence of extra teeth or absence of one or more teeth predisposes to malocclusion. Heredity plays a strong part in anomalies in number of teeth.

45. GRABER’S CLASSIFICATION 45 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS SUPERNUMERARY TEETH: Teeth that are extra to the normal complement are termed supernumerary teeth . These teeth have abnormal morphology and do not resemble normal teeth. Extra teeth that resemble normal teeth are called supplemental They result from disturbances during the initiation and proliferation stages of dental development. no definitive time when supernumerary teeth may develop. may form prior to birth or as late as 10- 12 years of age. usually develop from a 3 rd tooth bud arising from the dental lamina near the permanent tooth bud teeth.

46. GRABER’S CLASSIFICATION 46 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS Supernumerary teeth can cause: 1. Non-eruption of adjacent teeth 2. Delay the eruption of adjacent teeth 3. Deflect the erupting teeth into abnormal locations 4. Crowding in the dental arches.

47. GRABER’S CLASSIFICATION 47 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS ANOMALIES OF TOOTH SIZE: There should be harmony between the tooth size and the arch length, and also between the maxillary and mandibular tooth size, in order to have normal occlusion. An increase in size of teeth results in crowding while, smaller sized teeth predispose to spacing. Anomalies of size of teeth can be of 2 types: 1.Microdontia 2. Macrodontia

48. GRABER’S CLASSIFICATION 48 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS ANOMALIES OF TOOTH SHAPE: Anomalies of tooth size and shape are often interrelated. Abnormally shaped teeth predispose to malocclusion. Anomalies of tooth shape include: The presence of peg shaped maxillary lateral incisors is often accompanied by spacing and migration of teeth. Abnormally large cingulum on maxillary incisors- Prevent establishment of normal overbite and Overjet. The involved tooth is usually in labio -version due to the forces of occlusion. 3. Additional lingual cusp of mandibular 2 nd premolars- Increase the mesio -distal dimension of tooth

49. GRABER’S CLASSIFICATION 49 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS 4. Fusion- Fused teeth arise through the union of 2 normally separated tooth germs. 5. Gemination - Results from attempt at division of single tooth germ

50. GRABER’S CLASSIFICATION 50 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS 6. Congenital syphilis – It is often associated with hypoplasia of maxillary and mandibular anteriors . Characteristics of congenital syphilis are “Hutchinson’s incisors” and “mulberry molars”.

51. GRABER’S CLASSIFICATION 51 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS 7. Dilaceration – Dilacerated tooth often fails to erupt to proper level and can thus interfere with normal occlusion. They may also complicate extraction of teeth and may interfere with tooth movement and alignment.

52. GRABER’S CLASSIFICATION 52 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS 8. Dens evaginatus – A developmental condition that appears clinically as an accessory cusp or a globule of enamel on the occlusal surface between the buccal and lingual cusps mainly of premolars. It may result in incomplete eruption, displacement of teeth and may interfere with normal occlusion.

53. GRABER’S CLASSIFICATION 53 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS ABNORMAL LABIAL FRENUM: shows spacing between the maxillary central incisors due to presence of the fibrous tissue ,labial frenum .

54. GRABER’S CLASSIFICATION 54 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS PREMATURE LOSS OF DECIDUOUS TEETH: Specifically, it refers to the stage of development of the permanent tooth that will succeed the lost primary tooth. Premature loss can occur due to: 1. Caries 2. Trauma 3. Endocrinal disturbances like hyperthyroidism 4. Metabolic disturbances like hypophosphotasia When a primary tooth is lost before the permanent successor has started to erupt, bone may reform atop the permanent tooth, delaying its eruption. When its eruption is delayed, more time is available for other teeth to drift into space that would have been occupied by the permanent tooth.

55. GRABER’S CLASSIFICATION 55 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS PROLONGED RETENTION OF DECIDUOUS TEETH Can occur because of :- Absence of underlying permanent teeth Endocrinal disturbances such as hypothyroidism and hypopituitarism Ankylosed deciduous teeth that fail to resorb Malposition of erupting permanent teeth Prolonged retention of deciduous anteriors usually results in lingual or palatal eruption of their permanent successor Prolonged retention of buccal teeth results in eruption of the permanent teeth either buccally or lingually or may remain impacted within the jaws.

56. GRABER’S CLASSIFICATION 56 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS DELAYED ERUPTION OF PERMANENT TEETH Probable causes for delayed eruption of permanent teeth :- Early loss of a primary tooth might cause formation of a bony crypt over the succedaneous tooth. Presence of supernumerary tooth can block the eruption of permanent tooth. Presence of a heavy mucosal barrier can prevent the permanent tooth from emerging into the oral cavity. Presence of odontomas or other cysts and tumors might prevent the permanent tooth from erupting. Presence of deciduous root fragments that have not resorbed may block the erupting permanent tooth. Presence of ankylosed deciduous teeth may cause delay in eruption of permanent teeth. Congenital absence of permanent teeth

57. GRABER’S CLASSIFICATION 57 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS ABNORMAL ERUPTIVE PATH: This is usually a secondary manifestation of a primary disturbance. Some causes of abnormal eruptive pathway are: In cases of arch length deficiency, deflection of the erupting tooth may be merely an adaptive response to the condition present. Presence of supernumerary teeth, retained deciduous teeth, root fragments, bony barrier or mucosal barrier may result in abnormal eruptive pathway. Traumatic displacement of tooth buds– A deciduous tooth may be driven into the alveolar process, and though it may erupt later, it may displace the developing successor in an abnormal direction. 1 st and 2 nd permanent molars are occasionally impacted; 3 rd are frequently impacted by an abnormal path of eruption. Coronal cysts can also cause abnormal eruptive paths.

58. GRABER’S CLASSIFICATION 58 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS ANKYLOSIS: Ankylosis is encountered relatively frequently during the 6 –12 year age period. It may result due to an injury of some sort as a result of which a part of the periodontal membrane is perforated and a bony “bridge” forms joining the lamina dura and cementum . The “bridge” need not be large to stop the normal eruptive force of a tooth. The most commonly affected tooth is mandibular 2 nd deciduous molar. Accidents or trauma, infections, certain congenital disorders like cleidocranial dysostosis predispose to ankylosis of teeth.

59. GRABER’S CLASSIFICATION 59 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS DENTAL CARIES: Caries can lead to premature loss of deciduous or permanent teeth thereby causing migration of contiguous teeth, abnormal axial inclination and supra-eruption of opposing teeth. Proximal caries that has not been restored can cause migration of adjacent teeth into the space leading to a reduction in arch length. A substantial reduction in arch length can be expected if several adjacent teeth involved by proximal caries are left un-restored.

60. GRABER’S CLASSIFICATION 60 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. LOCAL FACTORS IMPROPER DENTAL RESTORATIONS: Malocclusion can be caused due to improper dental restorations. Undercontoured proximal restorations result in loss of arch length due to drifting of adjacent teeth to occupy the space. Overcontoured proximal restorations might bulge into the space to be occupied by a succedaneous tooth and result in a reduction in this space. Overhang or poor proximal contacts may predispose to periodontal breakdown around these teeth. Premature contacts on an overcontoured occlusal restoration can cause a functional shift of the mandible during jaw closure, whereas, under- contoured occlusal restorations can lead to the supra-eruption of the opposing teeth.

61. CONCLUSION 61 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. No longer can conscientious orthodontists look at a child’s mouth, observe a space deficiency and then attribute it to the premature loss of teeth or prolonged retention of teeth. In the past, local “causes” were stressed but today we know the importance of general factors in etiology of malocclusion along with the local causes. Knowledge·of the contribution of genetic and environmental causes of malocclusion obligates clinicians to differentiate between patients whose malocclusions are primarily of genetic origin from patients whose malocclusions are primarily of environmental origin. Abnormal morphologic structures in the face and dentition that have a high degree of heritability require different treatment approaches from those structures that are influenced primarily by environmental factors.

62. CONCLUSION 62 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. For most patients the differentiation between genetic and local environmental factors is of great importance when choosing the appropriate treatment and retention plans. Retention of a treated malocclusion is a challenge because the genetic and environmental etiologic factors responsible for the malocclusion may continue to draw the treated teeth back into malocclusion.(AJO 81,82,83,84,85) Stability of treated malocclusions appears to be similar in growing and adult patients.(AJO 94) Addressing known etiologic factors during treatment can produce more stable occlusions after treatment. Prevention of genetic causes for malocclusion is not possible at this time. In contrast, the prevention of environmental causes holds much promise.

63. 63 ETIOLOGY OF MALOCCLUSION-C. OF ETIO M/O. THANK YOU