Class 2 div 2

Question 1

What is Class 2 div 2?

Answer 1

• lower incisor occludes posterior to the cingulum plateau of upper incisors
• upper incisors are retroclined
• OJ is reduced/ can be increased

Question 2

Incidence of Class 2 div 2

Answer 2

5- 18%

Question 3

Aetiology

Answer 3

1. Skeletal
2. ST
3. Dental
4. Pathology

Question 4

Skeletal A/P

Answer 4

• usually associated with mild/ moderate Sk2 base

Question 5

Skeletal Vertical

Answer 5

• typically reduced
• reduced FMPA
• associated with forward rotational pattern of growth of mandible
• prominent chin (progenia)

Question 6

Soft Tissues

Answer 6

• high resting lower lip line
• secondary to reduced lower face height
• retrocline upper incisors
• marked labio-mental fold
• high masseteric forces
• Upper 2s shorter clinical crowns
• escape effect of lower lip
• trap lower lip

Question 7

Dental Aetiology

Answer 7

• retroclined upper centrals
• upper 2’s often crowded
  1. mesio labially rotated
  2. may be normal/ proclined
• reduced arch length -> crowding
• poor cingulum on lateral incisors
• lower incisors may occlude with upper incisors/ palatal mucosa

Question 8

Developmental dentla anomalies

Answer 8

• 50% have a form of congenital dental anomaly
• 33% have impacted canines

Question 9

Dental features summary

Answer 9

• retroclined upper incisors
• deep OB
• OJ usually reduced
• Class 2 buccal segments
• increased inter- incisal angle
• upper laterals thin with poorly developed cingulum

Question 10

Why treat?

Answer 10

• aesthetics
• traumatic OB (IOTN 4f)

Question 11

Tx options depends on

Answer 11

• Severity of malocclusion
• age and motivation of pt
• dental health
• patient concerns

Question 12

Orthodontic management

Answer 12

• accept
• growth modification
• camouflage
• orthognathic surgery

Question 13

Accept

Answer 13

• acceptable aesthetics
• pt is not concerned
• OB is not a significant problem

Question 14

Growth Modification

Answer 14

• growing pt
• boys 14 +/- 2
• girls 12 +/- 2
• mild to moderate sk pattern
• convert class 2 div 2 into class 2 div 1
• detailed occlusion with fixed appliances

Question 15

Functional Appliances

Answer 15

• Proclination of upper incisors
• Modified twin Block
• Springs/ screw
• upper sectional appliances

Question 16

Modified Twin Block design

Answer 16

Question 17

Camouflage

Answer 17

• accepting underlying skeletal base relationship
• aim to tx to class 1 incisor relationship
• mild to moderate class 2 skeletal pattern
• careful extraction decision

**space closure is difficult in low angle cases

Question 18

How does Fixed appliances correct?

Answer 18

• Overbite reduction
• correction of inter-incisal angle -> reduction
• inter-incisal angle corrected by a combination of
  1. palatal root torque upper incisors
  2. proclination of lower incisors
• upper incisor torqueing
  1. needs adequate palatal cancellous bone palatal to upper incisors
  2. risks of root resorption

Question 19

Difficulty in class 2 div 2

Answer 19

• difficult to treat
• future facial growth can affect stability
• rotated laterals and deep overbite can relapse
• long term bonded retention usually required

Question 20

When to refer?

Answer 20

• deep overbites best corrected when pt is growing
  1. growth modification with functional appliances if A/P discrepancy
  2. URA with FABP