Class 2 Div 1

Question 1

define class 2 div 1

Answer 1

The lower incisor edges lie posterior to the cingulum plateau of the upper incisors, there is an increase in overjet and the upper central incisors usually proclined or of average inclination

Question 2

Why treat class 2 div 1

Answer 2

• aesthetic concerns
• incisors at risk of trauma
• overjet >9mm x2 as likely to suffer trauma

Question 3

Associated skeletal pattern?

Answer 3

• usually class 2 (sometimes class 1 and possible with class 3 if incisors are proclined)
• usually due to retrognathic mandible

skeletal pattern (vertical)
- found with a range of vertical skeletal patterns

skeletal pattern (transverse)
- no particular assosiation

Question 4

what can an overjet be due to

Answer 4

• skeletal pattern
• tooth inclination
• combination of both

Question 5

What are normal ceph values

not class2, normal

Answer 5

• SNA= 81+/-3 (maxilla to anteiror cranial base)
• SNB= 78+/-3 (mandible to anterior cranial base)
• ANB= 3 +/-2 (difference between the two)
• MxP/MnP= 27 +/-4
• UI/MxP = 109+/-6
• LI/MnP = 93 +/-6
• LAFH/TAFH = 55%

Question 6

ceph landmarks for upper/ lower anterior face height

Answer 6

• nasion
• anterior nasal spine
• menton

Question 7

class 2 div 1 impact on soft tissues

Answer 7

• often incompetent lips
• can have lower lip trap
• if lips incompetent then special effort needed to achieve an anterior oral seal (mentalis muscle could be increased)

Question 8

how is an anterior oral seal achieved

Answer 8

1. lip to lip seal, 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 both

Question 9

class 2 div 1 effect on dental factors

Answer 9

1. increased overjet
2. overbite varies
3. can see good alignment, crowding or spacing
4. molar relationship
5. habitually parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis

Question 10

occlusal features of sucking habit

Answer 10

1. proclination of upper incisors
2. retroclination of lower incisors
3. localised or incomplete AOB
4. narrow upper arch (possible unilateral posterior crossbite)

Question 11

sucking habit tx principles

Answer 11

• stop habit (reinforcement, removable appliance habit breaker, fixed appliance habit breaker)
• allow spontaneous improvement
• treat residual malocclusion if required

Question 12

management options for class 2 div 1

Answer 12

1. accept
2. attempt growth modification
3. simple tipping of teeth
4. camouflague
5. orthognathic surgery

Question 13

when would you accept class 2 div 1 malocclusion

Answer 13

• mildly increased OJ
• significant OJ but not unhappy?
• nb tx might be more difficult when older
• advice re mouthguard

Question 14

in what ways can you attempt growth modification

Answer 14

1. headgear
   - try and restrain growth of maxilla horizontally and/or vertically
2. functional appliance

Question 15

what do functional appliances do + aims

Answer 15

functional appliances utilize, eliminate, or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion
success depends on favourable growth and compliant pt

Aims
- restraint of maxillary growth
- encourage mandibular growth

Question 16

what malocclusions are functional appliances mostly used for

Answer 16

class 2 div 1

can use for 2 div 2 too

Question 17

how do functional applinaces work

Answer 17

by posturing the mandible down and forwards, it encourages the mandible to grow

Question 18

Types of functional appliance

Answer 18

Removable
- tooth-borne = (twin block or activator)
- soft tissue borne (Frankel 2, 2div2)

Fixed
- Herbst

Question 19

what appliance is this

Answer 19

twin block

Question 20

Therapeutic effect of functional appliances

Answer 20

Mostly dento-alveolar changes
- distal movement of uppers
- mesial movement of lowers
- retroclination of upper incisors
- proclination of lower incisors

Minor degree of skeletal changes
- RCTs indicate that degree of max restraint and mandibular growth is usually small

Question 21

what ages are appropriate to use a functional appliance

Answer 21

• should be used during growth
• if possible coincide with pubertal growth spurt
• early use about 10 years old
• later use is late mixed or early permanent dentition

Question 22

potential disadvantages of early treatment with functional appliance

Answer 22

• skeletal effects might not be maintained long term
• overall tx time increased

Question 23

potential benefits of early treatment with functional appliance

Answer 23

• improve appearance earlier (e.g. for bullying reasons)
• reduce risk of trauma
• often better compliance with appliance wear

Question 24

when could you use an URA for tipping of teeth

Answer 24

• v mild class 2 or 1
• OJ due to proclined and spaced incisors
• OB favourable

Question 25

Give a prescription for retroclining anterior teeth with a URA

Answer 25

Active: roberts retractor; 0.5mm ID tubing
Retention: adam’s clasps on 6s; 0.7mm HSSW
Anchorage: ?mesial stops on 3s
baseplate: self cure PMMA + FABP (OJ+3mm)

Question 26

when would you use camouflage with class 2 div 1

Answer 26

• bit older
• not severe enough for surgery

Question 27

how would you camouflague class 2 div1

Answer 27

• take out premolar
• bring uppers back
• procline lowers to reduce OJ

Question 28

when would you consider orthognathic surgery

Answer 28

• when growth is complete (minmum females 16; males 20)
• severe AP discrepancy or vertical direction
• fixed appliances required