Class II Div I

Question 1

How long should patients wearing headgear where it for and with how much force?

Answer 1

Px must wear for 14hrs with a force of 500g per side

Question 2

How can digit sucking lead to class II div I?

Answer 2

• Proclination of upper anterior teeth
• Retroclination of lower anterior teeth
• Increased overjet
• Anterior open bite (usually asymmetric)
• Narrow upper arch +/- Unilateral posterior crossbite

Question 3

What is a class II buccal relationship?

Answer 3

The buccal groove of the mandibular first permanent molar occludes posterior to the mesio-buccal cusp of the maxillary first molar

BSI Classification (british standards institute classifcation)

Question 4

What is Orthognathic surgery?

Answer 4

Jaw surgery combined with fixed appliances

Usually mandibular

Question 5

Define a Class II Div I

Answer 5

The lower incisor edges occlude behind the cingulum plateau of the upper incisors and the upper incisors are normally inclined or proclined

Always an increased overjet

Question 6

What soft tissue factors contribute to the aetiology of class II div I malocclusion?

Answer 6

• Teeth erupt into a zone of equilibrium where they are controlled by the lips, tongue and cheek. If the lower lip does not control the upper teeth this can lead them to become proclined
• Increased mentalis activity leads to Retroclined lowers

Question 7

Describe a pt that would require orthognathic surgery to treat class II div I

Answer 7

1. Non growing px
2. Severe Skeletal II (severe AP or VD)
3. Poor facial appearance

Fixed appliances needed before, during & after surg

Question 8

What teeth are traditionally removed in the upper and lower arch for camoflague tx of class II div I?

Answer 8

Upper 4s
Lower ideally none or 5s

Question 9

Define functional appliance

What is the mode of action of a functional appliance?
What is the difference between myotonic and myo-dynamic?

Answer 9

Appliances that use forces generated by the oral and facial musculature to produce dental and skeletal changes

Forces are generated by stretching the facial musculature by holding the mandible in a postured position

Myotonic = Passive muscle stretching
Myo-dynamic = Muscular stretching during functional movement

Question 10

Describe an ideal pt for camoflague tx of class II div I

Answer 10

• Mild – Mod Skeletal II pattern
• Px happy with facial profile

Question 11

What is the gold standard functional appliance used in the UK?

Answer 11

Twin block

Question 12

What dental changes would you expect to see with fixed appliances?
(Class II Div I Patient)

Answer 12

o Upper incisors retrocline
o Lower incisors procline
o Lower molars erupt mesially
o Upper molars tip distally

70% of changes observed are dental

Question 13

What skeletal changes would you expect to see with fixed appliances?
(Class II Div I Patient)

Answer 13

Mandibular growth – 1-2 mm

*Maxillary restraint – 0.7mm

*Anterior repositioning of glenoid fossa

Question 14

Give an example of a soft tissue bourne functional appliance

Answer 14

Frankel appliance

Question 15

Describe what an ideal patient for orthodontic treatment (interceptive) for a class II div I malocclusion

Answer 15

1. Well motivated (will wear)
2. Actively growing
3. Moderate – Severe A-P discrepancy
4. Increased overjet
5. Increased overbite
6. Low FMPA (or normal)
7. Reduced LAFH
8. Lip trap px
9. Proclined upper incisors & retroclined lower incisors

FMPA Frankfort-Mandibular Plane Angle / LAFH lower anterior face height

Question 16

What is camoflague treatment for class II div I?

Answer 16

Accept the malocclusion and work around it
Normally XLAs in upper arch and use of fixed appliances (braces)
Can be done without XLA if there is adequate spacing
Normally only if there is mild/moderate skeletal II pattern

Question 17

What would you say to a patient if they do not want treatment for their class II div I?

Answer 17

Explain risks (trauma) & give/advise mouthguard for contact sports

Question 18

Why do we treat class II div I?

Answer 18

• For aesthetics
• There is an increased risk of trauma
• Psychological well being
• An Overjet of >9mm = IOTN 5a

Risk of trauma increases with increasing overjet

Question 19

What are the treatment options for class II div I?

Answer 19

1. No treatment
2. Growth Modification (Interceptive)
3. Camouflague
4. Orthognathic Surgery (Comprehensive)

Question 20

How does headgear help treat class II div I?

Answer 20

Force to maxilla to restrict A-P growth
Allows ‘catch up’ growth of the mandible
Can direct force to intrude or extrude molars to control vertical dimension

Question 21

Name a passive and active tooth bourne functional appliance

Answer 21

Twin block (active)
Bionator (passive)

Question 22

What skeletal changes would you expect to see with fixed appliances? (3)
(Class II Div I Patient)

Answer 22

o Mandibular growth at condyles (~1-2mm)
o Little restraint of the maxilla (~0.7mm)
o Glenoid fossa remodels to be more anterior

Question 23

How may crowding lead to a class II div I malocclusion?

Answer 23

Crowding in upper arch (labial segment) leads to Proclination

Question 24

Describe an poor patient for orthodontic treatment for class II div I malocclusion

Answer 24

1. Poorly motivated
2. Poor OH
3. Non-growing (or towards end of growth spurt)
4. Mild skeletal discrepancy
5. High FMPA with reduced overbite
6. Retroclined upper incisors
7. Proclined lower incisors

Question 25

What are the skeletal factors of the aetiology of class II div I malocclusion?

Answer 25

Most Px are skeletal II with a retrognathic mandible (80%) Maxillary hyperplasia - large maxilla LAFH most commonly reduced but varies Vertical discrepancies- backwards growth rotations | retrognathic mand = small mand / LAFH = Lower anterior face height

Question 26

What is the lower lip trap?

Answer 26

When the lips get trapped behind the upper teeth and cause proclination

Question 27

What environmental factors can lead to class II div I?

Answer 27

Trauma to condyle Habits - digit sucking Dental factors (Crowding, pathological teeth migration forward leading to class II buccal segments) Soft tissues, (mediated by the underlying skeletal pattern) Lower lip trapping, hyperactive mentalis, and lip incompetence due to short upper lip. Decreased muscle tone in cerebral palsy

Question 28

Which values of a ceph would be different when considering a class II div I would be

Answer 28

Increased ANB Reduced gonial angle Normal, reduced or increased MMP angle and lower face height Proclined upper incisors Depending on the aetiology B-point may be reduced or A-point may be increased

Question 29

State the incidence of trauma of different overjets

Answer 29

Question 30

When would be accept a class II div I? If this is accepted, what should be done?

Answer 30

*Acceptable aesthetics *Patient not concerned *Oral hygiene not good enough for treatment *Overbite not a significant problem Due to the high risk of trauma they should be advised to use a mouthguard for all contact sport.