Classification of malooclusion

The classification or description of malocclusion is an essential prerequisite for determining prevalence or severity of malocclusion

1. Supervisor : dR . maher fouda prepare : hawa shoaib Classification of malooclusion

2. The classification or description of malocclusion is an essential prerequisite for determining prevalence or severity of malocclusion .

3. Malocclusions can be broadly classified into following three types (Flow chart 8.1): Intra-arch malocclusions : Malocclusion within the same arch, i.e. either maxillary arch or mandibular arch (Figs 8.1A and B ). Interarch malocclusions : Malocclusions involving both maxillary and mandibular arches (Figs 8.2 A and B ). Skeletal malocclusions : Malocclusion involving underlying skeletal structures (Figs 8.3).

4. Intra-arch Malocclusions (Flow chart 8.2) Malalignment of individual tooth within the same dental arch are referred as intra-arch malocclusions . Intra-arch malocclusion may be in the form of abnormal inclinations , displacement, rotation, transposition or abnormal position of a tooth.

5. Intra-arch malocclusions can be classified into following types: Abnormal Inclinations This condition involves an abnormal tilting of a crown, with the root being in normal position. A tooth may be abnormally inclined in any of the four directions . Buccal Inclination This refers to labial (in case of anteriors ) or buccal (in case of posteriors) tilting of the tooth crown (Fig. 8.4).

6. Lingual Inclination This refers to palatal (maxillary teeth) or lingual (mandibular teeth) tilting of the tooth crown (Fig. 8.5).

7. Mesial Inclination : Refers to tilting of the tooth crown towards the midline (Figs 8.6A and B).

8. Distal Inclination This refers to tilting of the tooth crown away from midline (Fig. 8.7).

9. Displacement This involves bodily movement of the crown, as well as the root of a tooth in the same direction to occupy an abnormal location. A tooth can be displaced in any of the four directions. Buccal Displacement This term refers to bodily movement of the tooth in labial/buccal direction (Fig. 8.8).

10. Lingual Displacement This term refers to bodily movement of the tooth in a lingual direction (Fig. 8.9).

11. Mesial Displacement This term refers to bodily movement of tooth in a mesial direction towards the midline (Fig. 8.10).

12. Distal Displacement This term refers to the bodily movement of the tooth in a distal direction away from the midline (Fig. 8.11).

13. Rotation This term refers to the movement of a tooth around its long axis. A tooth may be rotated in two directions: Mesiolingual (distolabial) or (Fig. 8.12A ) Distolingual ( mesiolabial ) direction (Fig. 8.12B)

14. Transposition This term refers to a condition in which two teeth have exchanged places (Fig. 8.13).

15. Infra/ Supraversion A tooth is said to be in infra/ supraversion , when it is not at the level of occlusion as compared to other teeth in the arch depending on its rate of eruption (Fig. 8.14).

16. Interarch Malocclusions Such m alocclusions can occur in sagittal, vertical or transverse planes of space (Flow chart 8.3).

17. Sagittal Plane Malocclusions This refers to conditions where the upper and lower arches are abnormally related to each other in a sagittal plane. Such malocclusions can be of two types: Prenornml occlusion : Where the lower arch is placed more anteriorly w hen the teeth m eet in centric occlusion (Fig. 8.15 ). Postnormal occlusion : Where the lower arch is placed posteriorly when the teeth meet in centric occlusion (Fig. 8.16).

18. Vertical Plane Malocclusions Vertical plane malocclusions refer to conditions where there is an abnormal vertical relationship between teeth of upper and lower dental arches. They include deep bite and open bite cases . Deep bite/increased overbite : Where there is excessive vertical overlapping of upper anterior over the lower anteriors when teeth are in central occlusion (Figs 8.17A to C ) Open bite : Where there is lack of vertical relationship between upper and lower teeth. Open bite can be presented in the anterior or posterior regions (Fig. 8.18).

19. Anterior open bite : The term refers to conditions where there is no vertical overlap of upper anterior over the lower anterior when teeth are brought to centric occlusion (Fig. 8.19). Posterior open bite : The term refers to a condition where there is a lack of intercuspation between upper and lower posterior teeth, when teeth are in centric occlusion. Posterior open bite can be unilateral or bilateral (Fig. 8.20).

20. Transverse Plane Malocclusions Transverse plane refers to conditions where there is an abnormal transverse relationship between the upper and lower arches. These include various types of crossbites and scissor bites . Crossbite : The term refers to a condition where one/ more teeth may be abnormally malposed buccally , lingually or labially with reference to the opposing tooth or teeth (Fig. 8.21 ). Scissors bite : The term applies to total maxillary buccal (or mandibular lingual) crossbite with the mandibular dentition completely contained in habitual occlusion (Fig. 8.22).

21. Skeletal Malocclusion Skeletal malocclusion can be caused by defects in size, position or relationship between the upper and lower jaws. The skeletal malocclusions can occur in sagittal, vertical and transverse planes (Flow chart 8.4).

22. Skeletal Malocclusions in Sagittal Planes These include conditions where the upper and lower jaws are abnormally related to each other in a sagittal plane The term prognathism refers to forward placement of a jaw and term retrognathism is used for backward placement of a jaw . Sagittal plane malocclusion can occur in one or both the jaws or as various combinations (Figs 8.23 A to C).

23. Skeletal Malocclusions in Vertical Plane These malocclusions include open bite and deep bite conditions (Fig. 8.24).

24. Skeletal Occlusions in Transverse Plane Narrowing or widening of the jaws may result in an abnormal relationship between upper and lower jaws in a transverse plane. These include skeletal crossbite and scissor bite conditions, which may be unilateral/ bilateral (Fig. 8.25).

25. Classification of Incisor Relationship British standard classification of incisor relationship includes following three classes (Flow chart 8.5):

26. Class I Incisors Relationship Lower incisal edges occlude with or lie immediately below the cingulum plateau of the upper incisors (Fig. 8.26A).

27. Class II Incisors Relationship The lower incisal edge lies posterior to the cingulum plateau of the upper incisors. Class II Division 1 Incisor Relationship : The upper central incisors are proclined or of average inclination. There is an increase in overjet (Figs 8.26Bi and iii ). Class II Division 2 Incisor Relationship : The upper central incisors are retroclined . The overjet is usually minimal but may be increased (Figs 8.26Bii and iv).

28. Class III Incisors Relationship The lower incisal edges lies anterior to the cingulum plateau of the upper incisor (Fig. 8.26C).

29. Factors influencing Incisor Relationship The overjet is determined partly by the skeletal pattern and partly by the inclination of the incisors. The overbite depends on the incisor classification. If the overjet is normal, the depth of overbite will depend on the angle is about 135 degree. If the inter-incisal angle is much greater than this, the overbite will be deep because the incisors can erupt past one another. When the overjet is increased, the overbite will be usually increased as well unless some other factors, such as a thum bsucking habit, prevents full eruption of incisors.

30. Canine Relationship

31. Canine Relationship Canine relationships are classified into following three classes (Flow chart 8.6).

32. Class I Canine Relationship It means mesial inclination of the cusp of the upper canine, which overlaps the distal incline of the cusp of lower canine (Fig. 8.27A).

33. Class II Canine Relationship Distal incline of the cusp of upper canine, which overlaps the mesial incline of the cusp of lower canine are termed as class II canine relationship (Fig. 8.27B).

34. Class III Canine Relationship Lower canine is forwardly placed as compared to upper canine. Hence, there is no relationship between upper and lower canine that exist and is referred as class III canine relationship (Fig. 8.27C).

35. Molar Relationship

36. Molar Relationship There are 12 permanent molars — six upper and six lower. The six permanent molar in each arch are the first, second, and third molars on either side of the arch. The permanent molars play a major role in the mastication of food (chewing and grinding to pulverize) and are the most important in maintaining the vertical dimension of the face (preventing a closing of the bite or vertical dimension, appearance ). They are also important in maintaining continuity within the dental arches, thus keeping other teeth into proper alignm ent . Molar relationships are classified into following three classes (Flow chart 8.7).

37. Class I Molar Relationship Mesiobuccal cusp of the permanent maxillary first molar occludes in mesiobuccal developmental groove of first permanent mandibular molar, referred as Class I molar relationship (Fig. 8.28A).

38. Class II Molar Relationship Distobuccal cusp of the maxillary first permanent molar occludes in the mesiobuccal development groove of first permanent mandibular molar, termed as class II molar relationship (Fig. 8.28B).

39. Class III Molar Relationship Mesiobuccal cusp of maxillary first permanent molar occludes interdentally between first and second mandibular molar are said to be class III molar relationship (Fig. 8.28C).

40. Angle's Classification of Malocclusion

41. Angle classified malocclusion based on the anteroposterior relationship of the teeth in the year 1898. He used Roman numerical I, II, III to designate the main classes, whereas Arabic numerical , 1, 2, denote the divisions of the classification. Unilateral deviations were termed as subdivisions Angle's classes o f malocclusion are given as follows: Angle's class I malocclusion Angle's class II malocclusion Angle's class III malocclusion

42. Angle's class II malocclusion is further subdivided into the following two types: Angle's class II division 1 malocclusion Angle's class II division 2 malocclusion Angle's class II is classified into folloiving types, based on subdivisions: Angle's class II subdivision division 1 malocclusion Angle's class II subdivision division 2 malocclusion Angle's class III is classified into following two types : True class III malocclusion Pseudo class III malocclusion Angle's class III is classified based on subdivisions: Angle's class III subdivision

43. Angle's Class I Malocclusion Angle's class I malocclusion, where the mesiobuccal cusp of the maxillary permanent first molar occludes with the mesiobuccal groove of the mandibular first permanent molar (Fig. 8.29).

44. Extraoral features of Angle's class I malocclusion are listed in Table 8.1 . Intraoral features of Angle's class I malocclusion are listed in Table 8.2.

45. Angle Class II Malocclusion Angle class II malocclusion is characterized by class II molar relation, where the distobuccal cusp of the maxillary permanent first molar occludes with the buccal groove of the mandibular first permanent molar (Fig. 8.30).

46. Angle's class II malocclusion has been sub-classified into the following divisions: Angle class II division 1 malocclusion Angle class II division 2 malocclusion

47. Angle's Class II Division 1 Malocclusion Angle's class II division 1 malocclusion is characterized by class II molar relation on either side with proclined maxillary anteriors (Figs 8.31A to C).

48. Angle's Class II Division 2 Malocclusion Angle's class II division 2 malocclusion is characterized by class II molar relation with retroclined maxillary anteriors (Figs 8.32A and B).

49. Extraoral features Angle class II division 1 m alocclusion are listed in Table 8.3 . Intraoral features Angle class II division 1 malocclusion are listed in Table 8.4

50. Extra and intraoral features of Angle's class II division 2 malocclusion are listed in Tables 8.5 and 8.6.

51. Angle's Class II Subdivision Angle's class II subdivision may be: Angle's class II subdivision division 1 malocclusion Angle's class II subdivision division 2 malocclusion

52. Angle's Class II Subdivision Division 1 Malocclusion If the class II molar relation on one side of the arch and class I molar relation on the other side of the dental arch with proclined maxillary anteriors , it is termed as Angle's class II subdivision division 1 malocclusion.

53. Angle's Class II Subdivision Division 2 Malocclusion If the class II molar relation on one side of the arch and class I molar relation on the other side of the dental arch with retroclined m axillary anteriors , it is termed as Angle's class II subdivision division 2 malocclusion.

54. Angle's Class III Malocclusion Angle's class III malocclusion is characterized by class III molar relationship where the mesobuccal cusp of the permanent maxillary first molar occludes into the interdental space between mandibular first and second perm anent molar . True class III is due to the malrelationship of either the dental arches or skeletal structure of the m axillary retrognathism that is the prognathism of the mandible (Figs 8.33A and B).

55. Pseudo Class III Malocclusion Angle's class III pseudo malocclusion is characterized by class III molar relationship, which is mainly due to habit. It is also called as habitual or postural malocclusion.

56. Extra and intraoral features of A ngle's class III malocclusion are listed in the Tables 8.7 and 8.8.

57. Class III Subdivision Class III molar relationship on one side and class I on the other side of the dental arch is termed as class III subdivision (Figs 8.34A and B).

58. Limitation of Angle's Classification

59. Dewey's Classification Dewey's Modification for Angle's Classification (Flow chart 8.8)

60. Dewey's modified the A n gle's classificatio n of malocclusions with modifications in Angle's class I and class III malocclusions . He divided Angle's class I malocclusion into five types and class III into three types. Since Angle's class II malocclusion was already well defined, Dewey did not give any modification for it.

61. Lischer's Classification for Modification of Angle's Classification (Flow chart 8.9)

62. Lischer's replaced the terms class I, II, III in Angle's classification of malocclusion, with the terms neutroocclusion , disto - occlusion and Mesio -occlusion (Fig. 8.43), respectively. In addition, he described other possible malpositions of a tooth or a group of teeth as listed below (Figs 8.44A to C).

63. Neutron-Occlusion Neutron-occlusion is the normal retention step of dental arches . Disto -Occlusion Disto -occlusion is the postnormal occlusion . Mesio -Occlusion Mesio -occlusion is the prenormal occlusion.

64. For Individual Teeth : Labioverison of tooth— Movement of tooth/teeth towards the lip or cheek. Linguoversion of teeth—Lingual to normal position Mesioversion - —Mesial to the normal position Distoversion —Distal to normal position Supraversion of tooth—Crossing the line of occlusion . Infraversion of tooth—Away from the line of occlusion ° Transversion —Transposition-Wrong position in the arch Torsi version— Rotated on its long axis

65. Simon's Classification (Flow chart 8.10)

66. Simon's classification is based on anterior posterior , transverse and vertical plane relationships of the dental arches. Simon's system of classification made use of three anthropometric, which are: I . Frankfort horizontal plane (FH plane ) II. Orbital plane III . Midsagittal plane. Simon's classification of malocclusion is based on abnormal relationship of the dental arches from their normal position in relation to anteroposterior, transverse and vertical planes.

67. Ballard's Classification

68. Ballard's classification of m alocclusion is based on skeletal relationship on the jaws (Flow chart 8.11).

69. Bennett's Classification of Malocclusion

70. Sir Norman Bennett's classification of malocclusion is based on its etiology. B ennett's classification of malocclusion is as follows (Flow chart 8.12):

71. Ackerman-Profit System of Classification

72. Ackerman and Profit is the most recent of all the classifications. It is based on Venn-Diagrams. It has got 9 groups as shown in the Figure 8.49. Ackerman and Profit gave an all-inclusive method of diagramming and categorizing malocclusions to overcome the limitations of the Angle's classification system in which five characteristics and their interrelationships are assessed, using a modified Venn diagram.