Class 2 Div 1

Question 1

What is the BSI definition of class 2 div 1

Answer 1

The lower incisor edges lie posterior to the Cingular plateau of the upper incisors
There is an increased overjet
The upper central incisors are proclined or of average inclination

Question 2

What is the trauma risk of an increased overjet

Answer 2

Overjet >9mm twice as likely to suffer trauma

Question 3

What is the aetiology of class 2 div 1?

Answer 3

Skeletal pattern- usually class 2, commonly due to retrognathic mandible.

Soft tissues- often incompetent lips due to prominence of incisors/ underlying skeletal pattern. Lower lip trap is a factor for increased OJ.

Dental factor- increased OJ, OB varies, alignment varies, usually class 2 molar relationship

Sucking habits- effects depend on duration/ intensity

Question 4

How is an oral seal created in class 2 div 1?

Answer 4

Activity of facial muscles/ posturing mandible forward to allow lips to meet
Or
Lower lip being drawn up behind upper incisors and tongue placed forwards behind incisors to lower lip

Question 5

what are the occlusal features of a sucking habit?

Answer 5

Proclination of upper anteriors
Retroclination of lower anteriors
Localised AOB or incomplete OB
Narrow upper arch (may also see unilateral posterior cross bite)

Question 6

How is an AOB created when caused by digit sucking?

Answer 6

Increased FWS, tongue is pushed downwards leaving buccinator muscles unopposed
Masseter pulls in upper arch (making it narrow)
Causes continued eruption of molars

Question 7

What determines the effects of the lips/tongue on the incisors?

Answer 7

The skeletal pattern and the means by which an oral seal is achieved

Question 8

What is the lower face height commonly when there is lip incompetence/ class 2

Answer 8

LAFH reduced

Question 9

What is the effect of a lip trap?

Answer 9

Lower lip lies under the upper incisors to create an oral seal.
Upper incisors become proclined
Lower incisors become retroclined

Increases overjet

Question 10

What is the effect of incompetent lips on the gingiva

Answer 10

Will cause drying of gingivae which can aggravate gingivitis

Question 11

What is the IOTN for OJ >9mm

Answer 11

5a

Question 12

What are the management options for breaking a digit sucking habit?

Answer 12

Stop habit
- reinforcement
- bitter tasting nail polish
- gloved finger
- removable appliance habit breaker (URA with goal post)
- fixed appliance habit breaker

Question 13

What are the 5 management options for class2 div1?

Answer 13

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

Question 14

What factors should be considered when treatment planning?

Answer 14

Skeletal pattern and profile- surgery may be required if marked discrepancy

Mandibular growth- forward mandibular growth is favourable (LAFH reduced), whereas backwards mandibular growth is not favourable (LAFH increased, risk of incompetent lips post tx)

Form and relationship of lips and tongue- consider whether stable correction is likely

Space requirements- treatment may be started with functional appliance to correct molar relationship to class 1 and then extractions to relieve crowding

Question 15

What is the method of growth modification for class2 div1

Answer 15

Headgear- restrain growth of maxilla

Functional appliance- almost always twin block- postured the mandible down and forwards. Restrains maxillary growth and encourages mandibular growth (small- 1-2mm)
However, mostly dento-alveolar changes

Question 16

What is the definition for functional appliances?

Answer 16

Functional appliances utilise, eliminate or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion
Mostly used for class 2 div 1

Question 17

What are the dento alveolar changes that take place due to a functional appliance

Answer 17

Distalise upper dentition (molars)
Mesial movement of lower dentition
Retrocline upper incisors
Procline lower incisors

Question 18

When should functional appliances be considered?

Answer 18

During growth- F- 11-13 years, M- 13-15 years old.

Question 19

What are the disadvantages of functional appliances?

Answer 19

Overall treatment time increased (2 phase treatment)
Patient compliance determines outcome

Question 20

What a re benefits of functional appliances?

Answer 20

Improves aesthetics early
Reduces trauma risk

Question 21

What is involved with the simple tipping of teeth for class 2 div1 patients?

Answer 21

URA can be used to treat increased OJ
Used when mild class 2, if OJ is due to proclined and spaced upper incisors, OB present.

Use of roberts retractor (0.6mm HSSW with 0.5 ID tubing) and FABP

Question 22

What is orthodontic camouflage?

Answer 22

Correction of the incisor relationship, without correcting underlying skeletal base
Usually involves upper arch extractions (eg 4’s) and fixed appliance to bodily retract the incisors.

Used when not severe class 2 and vertical proportions are adequate

Extraction spaces are used for crowding relief

Question 23

What can be used to achieve anchorage with fixed appliances?

Answer 23

Palatal arch

Question 24

When is orthognathic surgery considered?

Answer 24

Carried out when growth is complete and there is severe AP/ vertical discrepancy.
Usually mandibular surgery
Fixed appliances used before surgery to along arches, during and after surgery.

Usually when OJ >10mm