Class 2 Div 1

Question 1

Definition of class 2 div 1

Answer 1

• lower incisor edge lies posterior to cingulum plateau of upper incisors
• increased overjet
• upper central incisors proclined or of average inclination

Question 2

What % of malocclusion are class 1

Answer 2

67-72

Question 3

What % of malocclusion are class 2 div 1

Answer 3

15-20

Question 4

What % of malocclusion are class 2 div 2

Answer 4

10

Question 5

What % of malocclusion are class 3

Answer 5

3

Question 6

Why treat class 2 div 1?

Answer 6

1. Aesthetics
2. Dental health: trauma risk

Question 7

What skeletal pattern are class 2 div 1 usually?

Answer 7

Class 2 due to retrognathic mandible- maxillary protrusion less common

Question 8

Soft tissue features?

Answer 8

• lips often incompetent due to prominence of incisors and/or underlying skeletal pattern
• lower lip trap can be cause of increased overjet
• if lip’s incompetent then special effort needed to achieve anterior oral seal

Question 9

How to achieve anterior oral seal?

Answer 9

3 separate ways
1. Lip to lip seal by activity of circum-oral musculature- mandible postured to allow lips to meet
2. Lower lip drawn up behind upper incisors- tongue placed forwards between incisors to lower lip
3. Combination of these

Question 10

Dental factors of class 2 div 1?

Answer 10

• increased overjet
• overbite varies
• potentially good alignment, crowding or spacing
• molar relationship
• habitually parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis

Question 11

What habit can cause class 2 div 1?

Answer 11

Sucking habit

Question 12

Occlusal features of sucking habit?

Answer 12

Proclination of upper anteriors
Retroclination of lower anteriors
Localised AOB/ incomplete OB
Narrow upper arch +/- unilateral posterior crossbite

Question 13

Management options of class 2 div 1

Answer 13

1. Accept
2. Attempt growth modification
3. Simple tipping of teeth
4. Canouflage
5. Orthognathic surgery

Question 14

What should u consider when thinking of accepting class 2 div 1

Answer 14

• mildly increased overjet
• significant overjet but patient not unhappy
• will tx options be more difficult in future?
• advice re mouthguard

Question 15

2 ways in which u can attempt growth modification?

Answer 15

1. Headgear- try and restrain growth of maxilla horizontally and/or vertically
2. Functional appliance

Question 16

How do functional appliances work?

Answer 16

• FAs utilize, eliminate or guide forces of muscle function, tooth eruption and growth to correct malocclusion
• mandible postured downwards and forwards
• aim to restrain maxillary growth and promote mandibular growth
• success depends on favourable growth and enthusiastic patient
• used mostly for class 2 div 1, can use for 2 div 2, limited use for div 3

Question 17

Types of functional appliances?

Answer 17

1. Removable:
   - Tooth borne e.g. twin block, activator/bionator
   - soft tissue borne- frankel
2. Fixed- herbst

Question 18

When should functional appliances ideally be used?

Answer 18

Pubertal growth spurt
Can be used earlier - about 10 (2 phase tx)

Question 19

Potential disadvantage of early treatment with FA?

Answer 19

• early skeletal effect from FA not maintained in long term
• 2 phase tx, longer tx time- 1st phase early functional appliance plus retention- 2nd phase- fixed appliance in early permanent dentition

Question 20

Potential benefits of early Tx with FA

Answer 20

• improve appearance earlier (psychological benefit)
• reduced risk of trauma
• better compliance

Question 21

How would u use a URA to tip teeth in class 2 div 1

Answer 21

Active: roberts retractor 0.5mm in tubing
Retention: Adams clasp 6/6 0.7mm HSSW
Anchorage: Mesial stops 3/3
Baseplate: FABP

Question 22

How can camouflage help with class 2 div 1

Answer 22

• upper arch extraction to create space for OJ reduction
• non extraction OJ reduction and molar correction

Question 23

Features of orthognathic surgery

Answer 23

• when growth is complete
• severe skeletal discrepancy in A/P and/or vertical direction
• mostly mandibular surgery
• fixed appliances required before, during and after surgery