Classification of malocclusion
FINAL YEAR BDS
FMHCM&D , LAHORE
Before going to malocclusion or abnormal
occlusion lets ask first , what is normal
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 ridge
occludes with the mesial marginal ridge of the lower
- 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).
Mesiolingual or distbuccal
Distolingual or mesiobuccal
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:
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
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
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