Classification of malocclusion

ABDULLAH KARAMATFINAL YEAR BDSFMHCM&D , LAHORE

Before going to malocclusion or abnormal occlusion lets ask first , what is normal occlusion ??!!

Andrew’s six keys to normal occlusion : 1- Molar inter-arch relationship :

-The mesiobuccal cusp of the upper first molar should within the groove between the mesial and middle buccal cusps of the lower first permanent molar

-The crown of the upper first molar must be angulated so that its distal marginal ridgeoccludes with the mesial marginal ridge of the lower second molar.

- The mesio-lingual cusp of the upper first molar should occlude in the central fossa of the lower first molar.

2- Mesio-distal crown angulation : The gingival part of the long axis of the clinical

crown must be distal to the occlusal part of line passing through long axis of tooth.

3- Labiolingual crown inclination :• When viewed from mesial or lingual side if

gingival area of crown is more lingually placed than the occlusal position , it is referred to as positive crown Inclination and vice versa.

• The maxillary incisors exhibit a positive crown inclination , mandibular incisors show a slightly negative crown inclination

• The maxillary and mandible posterior teeth both have negative crown inclinations.

4- Rotations :

• In order to achieve correct occlusion, none of the teeth should be rotated.

• Rotated molars and premolars occupy more space in the dental arch than normal.

• Rotated incisors may occupy less space than those correctly aligned.

• Rotated canines adversely affect esthetics and may lead to occlusal interferences

5- Tight contacts :

To consider an occlusion normal , there should be tight contact between adjacent teeth

6-Curve of Spee : A normal occlusion has a flat occlusal plane

(the mandibular curve of Spee should not be deeper than 1.5mm).

Malocclusion : -Intra arch -Inter arch: Saggital plane Vertical plane Transverse plane

1- Intra arch malocclusions : Distal inclination or tipping Mesial inclination Lingual inclination Buccal inclinationMesial displacementDistal displacementLingual displacementBuccal displacement

infraversion suparversion rotations Mesiolingual or distbuccalDistolingual or mesiobuccalTransposition

2- Inter arch :

A- Saggital plane : Edward Angle created a classification of different

malocclusions based on the relative antero-posterior (A-P) position of the maxillary first molar regarding the mandibular first molar which may be perceived in a sagittal plane.

Class I : When the mesio-buccal cusp of the upper first

molar occludes in the mesio-buccal groove of the lower first molar, but there are problems like spacing or crowding.

Class II : The upper molars are in a Class II position,

which is anterior to the mesiobuccal groove of the lower first molar. There are two subtypes:

division 1 division 2

Class II Division 1: The molar relationships are like that of Class II

and the upper anterior teeth are protruded/proclined resulting in an increased overjet.

Class II Division 2: The molar relationships are Class II, but the

central are retroclined (inclined towards the palate) and the lateral or canine teeth are proclined (inclined towards the lip). A deep bite is commonly found.

Class III : In this case the upper molars are placed

posteriorly to the mesiobuccal groove . It can be related to a decreased or reversed overjet. When there is a reversed overjet the lower anterior teeth are found ahead of the upper anterior teeth. The normal occlusion involves the upper teeth overlapping the lower.

B- vertical plane : 1. Deep bite or overbite : It is a condition in

which there is excessive vertical overlap between upper and lower anteriors

2-Open bite : it is a condition where there is no vertical

overlap between upper and lower teeth

C- Transverse plane : The transverse arch

malocclusions include various types of cross bites

Incisor classification :

Canine classification :