Class II malocclusion

Class II Malocclusion
Copyright (c) Department of Orthodontics
University of Dental Medicine, Yangon

1. Class II malocclusions
Class II division 1
Class II division2

2. Class II malocclusion
• Class II malocclusion includes those anomalies where
the mesiobuccal cusp of maxillary first permanent molar
occludes mesial to the buccal developmental groove of
the lower first permanent molar.
• This may or may not associated with alignment ,
dentitional and spaced problems.
• Class II malocclusion usually occurs on the skeletal II
dental base, but may also occur on skeletal I base

3. Class II malocclusion is divided into
Class II, division 1 - if the incisors are proclined
Class II, division 2 - if the incisors are retroclined.

4. Class II, div 1 malocclusion
Class II, div 2 malocclusion

5. Class II division 1 malocclusion
 Most common type of malocclusion demanding
orthodontic treatment because of the prominence of the
upper incisors affecting facial aesthetics.

6. Occlusal features
Incisal relation
 Class II incisor relation with increased overjet.
The upper incisors are usually proclined or of
average inclination if the underlying cause is
maxillary skeletal protrusion.
 The overbite is usually deep and complete.
 Incomplete overbite may be associated with
abnormal swallowing or soft tissue behavior.

11. Buccal segment relation.
 First permanent molar relation is usually class II ,
reflecting the underlying skeletal pattern II.
 The molar relation may be class I if the skeletal pattern
is class I or if associated with early loss of primary
molars leading to mesial drift of the lower molars.
 Crowding , spacings , rotations , crossbites , openbites
and other dental anomalies may be associated with
class II division 1 malocclusions.

12. Skeletal relation
Anteroposterior relation
 The skeletal pattern is generally class II.
 In which case the anteroposterior arch discrepancy
(overjet) reflects the severity of the underlying skeletal
discrepancy.
 The skeletal pattern may be class I, in which case, the
anteroposterior arch discrepancy is caused by finger
sucking habit or alveolar dental protrusion.

13. Vertical
There is wide variation of vertical relationship.
Anterior facial height may be average or reduced.
In some cases there may be increased lower facial height
with high mandibular plane angle.
The lower incisors may be proclined to compensate the
severity of the underlying skeletal discrepancy.

14. Facial growth
 Associated with varying patterns of facial growth.
 Anteriorly directed mandibular growth with signs of
anterior mandibular growth rotation.
 This growth direction is usually favourable as the
continuing facial growth improves the facial profile.

15. Vertically directed mandibular growth with signs of
posterior growth rotation.
This growth direction is usually unfavourable as the
continuing facial growth further exacerbate the
overjet and anterior facial height.
Lips are grossly incompetent and does not improve
with treatment.
 Such growth direction can be predicted by :
- mandibular plane angle,
- gonial angle and
- Y axis.

16. Soft tissues
 The level and action of lips and adaptation of the tongue
is determined by the severity of the anteroposterior and
vertical skeletal dysplasia.
 In mild skeletal discrepancy, the lips are usually
competent or potentially competent and can obtain an
anterior oral seal without undue effort.

17. In severe skeletal discrepancy, the lips are grossly
incompetent and the tongue has to move forward
to reach the lower lip and obtain an anterior oral
seal.
 Thus the eruption of the lower incisors will be
impeded resulting in incomplete overbite.

19. Path of mandibular closure and mandibular position
 In moderately severe class II division 1 cases , the
mandible is usually positioned forward in an attempt to
achieve anterior oral seal without undue effort and to
improve the facial esthetics.(habitual rest position)
 In this position the mandibular condyle is not in centric
relation position.
 During closure from the habitual rest position to centric
occlusion position the mandible has to move upward and
backward into centric relation position.

20. This mandibular deviation during closure from rest
to centric relation position should be detected
clinically to correctly diagnose the severity of both
skeletal and occlusal discrepancy.
In patients with small or narrow maxilla , the
mandible may be displaced laterally, due to
premature occlusal contact.

21. Class II division 2 malocclusion
• The clinical features of class II division 2 malocclusion is
characterized by the interaction of both the
anteroposterior and vertical dimensions of the skeletal
bases .

22. Occlusal features
Incisal relation
 Class II incisal relation – the lower incisor edge occludes
posterior to the cingulum plateau of the upper incisor.
 The angulation of upper incisors are retroclined.

23. In crowded arch , the lateral incisors are usually proclined ,
mesiolabially rotated and overlap the centrals.
 The overbite is usually deep and complete.
 In some cases traumatic to the labial or palatal gingiva or
with gingiva recession.
The severe the discrepancy in anteroposterior relation of
incisors, the greater the depth of the overbite

24. Buccal segment relation
Molar relation
 Full unit class II molar relation is rare.
 Mild class II molar relation is common.
 May be class I cases in cases with bimaxillary
retroclination.
 Transversely, there may be a crossbite which is usually
confined to premolar region.

25. Skeletal relation
Anteroposterior relation
 The skeletal pattern is usually mild class II but could be
class I.

26. Vertical relation
The lower facial height is often reduced.
Low mandibular plane angle, maxillomandibular plane angle
and the gonial angle is acute and well developed.
 Forward growth rotation of the mandible resulting in well
developed chin and pleasing facial profile.
 In extremely low angle class II division 1 cases, forward
growth rotation of mandible could result in protrusive chin.

27. Transverse relation
 The maxillary basal bone is usually broad and well
developed relative to mandibular basal bone.
 In severe transverse discrepancy, there may be crossbite
usually in premolar region.
 In mild to moderate discrepancy, the upper molars and
premolars may be lingually inclined to compensate
transverse skeletal discrepancy.

28. Soft tissues
 The lips are usually competent and relax.
 The lip line is high relative to upper incisor crowns.
 The greater the retroclination of incisors, the higher the
lip line.
 The labiomental fold is usually deep with prominent chin.

29. Path of mandibular closure and mandibular position
In cases with deep overbite, protruding lip and prominent
chin , the patient may adopt the habitual mandibular
posture in a slightly forward and opened position.
This may lead to mandibular backward deviation during
closure from rest to centric position.
There may be limitations in mandibular lateral movement in
cases with deep overbite and mandibular backward
deviation.