Class 2 Div 1

Question 1

Types of malocclusion

Answer 1

Class 2 div 1 - 15-20%

Question 2

Definition of Class 2 div 1

Answer 2

• lower incisor edges lie posterior to the cingulum plateau of upper incisors
• increased OJ
• upper central incisors are proclined or average inclination

Question 3

Why treat class 2 div 1?

Answer 3

• aesthetics
• dental health
• prominent incisors at risk of trauma especially if incompetent lips
• OJ > 9mm twice as likely to suffer trauma
• OJ > 9mm, IOTN 5a

Question 4

What includes in aetiology and features?

Answer 4

• skeletal pattern (A/P, vertical, transverse)
• soft tissues
• dental factors
• habits

Question 5

Skeletal pattern of class 2 div 1 (A/P)

Answer 5

• associated with class 2 sk pattern
• due to retrognathic mandible
• less common to have maxillary protrusion
• can happen in skeletal class 1
• rarely in class 3

Question 6

OJ might be due to?

Answer 6

• sk pattern
• tooth inclination
• combination of both

Question 7

Sk pattern - Vertical

Answer 7

• found in association with a range of vertical sk pattern

Question 8

Sk pattern (transverse)

Answer 8

• no particular association with transverse

Question 9

Normal values for SNA

Answer 9

81 +/- 3

Question 10

Normal values of SNB

Answer 10

78 +/- 3

Question 11

Normal values of ANB

Answer 11

3 +/- 2

Question 12

Normal values of UI/MxP

Answer 12

109 +/- 6

Question 13

Normal values of LI/ MnP

Answer 13

93 +/- 6

Question 14

Lateral ceph labelling

Answer 14

Question 15

Normal values for LAFH/ TAFH

Answer 15

55%

Question 16

Presentation of Soft tissues

Answer 16

• lips are often incompetent due to prominence of incisors and/ or underlying Sk pattern
• lower lip trap can be aetiological factor in increased OJ
• if lips incompetent, then special effort needed to achieve anterior oral seal

Question 17

Achieving an anterior oral seal

Answer 17

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. combi of both

Question 18

Dental factors of Class 2 div 1

Answer 18

• increased OJ - incisors proclined/ average
• Overbite varies
• good alignment, crowding or spacing
• molar relationship
• parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis

Question 19

Sucking habits

Answer 19

• thumb
• fingers
• blanket
• lip
• combination of all
• NNSH - non nutritive sucking habits

** depends on duration and intensity

Question 20

Occlusal Features of Sucking Habits

Answer 20

• proclination of upper anteriors
• retroclination of lower anteriors
• localised AOB/ incomplete OB
• narrow upper arch
• may see unilateral posterior crossbite

Question 21

How to stop habits?

Answer 21

1. Stop habit
   - reinforcement
   - removable appliance habit breaker
   - fixed appliance habit breaker
2. allow spontaneous improvement
3. treat residual malocclusion if required

Question 22

Types of Management Options

Answer 22

1. Accept
2. Growth Modification
3. Simple tipping of teeth
4. Camouflage
5. Orthognathic surgery

Question 23

Accept conditions

Answer 23

• mildly increased OJ
• significant OJ but not unhappy
• will future tx options be more difficult in the future?
• advise on mouthguard

Question 24

Growth Modification

Answer 24

• Headgear to try and restrain growth of maxilla horizontally and vertically
• functional appliance

Question 25

What is Functional appliance?

Answer 25

- utilize, eliminate, guide the forces of muscle function, tooth eruption and growth to correct malocclusion - used mostly in class 2 div 1

Question 26

Types of functional appliances

Answer 26

Removable - tooth borne: twin block, activator/ bionator - ST borne: Frankel 2 Fixed - Herbst

Question 27

Twin Block Appliances

Answer 27

Question 28

GM with Functional appliances

Answer 28

- produce restraint of maxillary growth and encourage mandibular growth - depends on favourable growth and enthusiastic pt

Question 29

Therapeutic effect of Functional Appliances

Answer 29

Mostly dento-alveolar changes - distal movement of upper dentition - mesial movement lower dentition - retroclination of upper incisors - proclination of lower incisors Minor degree of skeletal changes - degree of maxillary restraint and mandibular growth is usually small (1-2mm)

Question 30

When to use functional appliances?

Answer 30

- during growth - early use about 10 yrs old (2 phase tx) - later use for late mixed/ early permanent dentition (1 phase)

Question 31

Disadvantages of early tx

Answer 31

- early skeletal effects from functional appliance/ headgear therapy not maintained in long term - overall tx time increased, 2 phase tx 1. early functional appliances + retention 2. fixed appliances in early perm dentition

Question 32

Benefits of Early tx

Answer 32

- improve appearance earlier from teasing - reduce trauma - better compliance with appliance wear

Question 33

When to use simple tipping of teeth?

Answer 33

- simple URA has limited role in tx of increased OJ Unless - very mild class 2/1 - OJ due to proclined and spaced incisors - OB favourable - after specialist assessment

Question 34

Retroclining anterior teeth

Answer 34

Question 35

Camouflage with fixed appliances

Answer 35

- reduce OJ - may need upper arch extractions to give space/ distal movements

Question 36

Orthognathic surgery

Answer 36

- when growth is complete - sk discrepancy is severe in A/P or vertical direction - usually involves mandibular surgery, but may involve maxillary surgery - fixed required before, during and after surgery