Class II Division 1 Malocclusion

Question 1

BSI Classification of Class II Div 1 Malocclusion

Answer 1

Lower incisor edges lie posterior to the cingulum plateau of the upper incisors
The upper incisors are proclined of normal inclination

Question 2

Skeletal pattern of Class II Div 1 Malocclusions

Answer 2

• Usually skeletal 2 with retrognathic mandible
• May be class I skeletal relation with proclined upper incisors and retroclined lower incisors due to habits or soft tissues
• Associated with a range of vertical skeletal patterns

Question 3

Influence of soft tissues on class II division 1 malocclusion

Answer 3

• Mainly mediated by the skeletal pattern - lips are incompetent due to the prominence of the upper incisors and/or skeletal pattern

Question 4

If the lips are incompetent in pt with Class II div 1, how will they try to achieve an anterior oral seal?

Answer 4

1. Circumoral muscular activity for lip-to-lip seal
2. Mandible is postured forwards to allow lips to meet at rest
3. Lower lip is drawn up behind upper incisors (lower lip trap)
4. Tongue placed forward between the incisors to contact the lower lip causing incomplete overbite

Question 5

In Class II div 1, how does circumoral muscular activity for lip-to-lip seal and mandible is postured forwards to allow lips to meet at rest affect skeletal pattern?

Answer 5

Moderates skeletal pattern by dent-alveolar compensation

Question 6

How does a lower lip trap affect the perception of the underlying skeletal pattern in class II div 1 cases?

Answer 6

Lower lip proclines upper incisors and retroclines lower incisors so the incisor relationship is more severe than the skeletal relationship

Question 7

How does the tongue being placed forward between the incisors to contact the lower lip causing incomplete overbite compensate for the underlying skeletal pattern in class II div 1 cases?

Answer 7

Tongue may procline the lower incisors compensating for the skeletal pattern?

Question 8

What effects does digit sucking habit have (more than 6h/day)?

Answer 8

• Proclination of upper incisors and retroclination of lower incisors causing increased OJ
• Incomplete overbite or AOB (asymmetric)
• Narrowing of upper arch - tongue at lower posture and increased action of buccinator muscles causing buccal Crossbite (unilateral due to cusp to cusp and mandibular deviation)
• Class II buccal segment relationship

Question 9

What is the management of increased OJ in class I or mild class II skeletal pattern? How does crowding affect management?

Answer 9

1. assess upper incisor angulation, if OJ can be reduced by tilting then can use upper removable appliance, if not possible then fixed appliance needed for bodily movement
2. if lower arch is well aligned and molar relationship is class II, space for OJ reduction by xla upper 4s or distal movement of upper buccal segment (if molar relationship is less than 1/2 unit class II to begin with)
3. If xla needed in lower and upper arch to relieve crowding, upper 4s and lower 5s then fixed appliance
4. If xla needed in lower and upper to relieve severe crowding then xla upper and lower 4s then fixed appliance