Class II Div I Malocclusion

Question 1

Define Class II Div I Malocclusion.

Answer 1

Lower incisal edge lies posterior to the cingulum of the upper incisors.
Proclination/average inclination of upper central incisors.
Increased overjet.

Question 2

What is the treatment need of an overjet > 9mm?

Answer 2

IOTN 5a

Question 3

What are the issues with Class II Div I malocclusions?

Answer 3

1. Aesthetics - lip trap
2. Trauma

An OJ > 9mm increases the risk of trauma 2x

Question 4

What causes Class II div I malocclusion?

Answer 4

Class II skeletal pattern.

Soft tissue:
- incompetent lips due to proclamation of upper incisors; lower lip trap; effort needed to achieve anterior seal - mentalist muscle

Dental factors: Tooth inclination; retrognathic mandible.
- increased overjet
- overbite
- alignment, crowding, spacing
- molar relationship tends to be class II (not always)
- habitually parted lips leading to drying of gingiva and exacerbation of pre-existing gingivitis

Digit-sucking habit.

Question 5

What are the normal cephalometric values for SNA, SNB and ANB?

Answer 5

SNA = 81± 3
SNB = 78 ± 3
ANB = 3 ± 2

Question 6

How does a digit sucking habit lead to class II div I malocclusion?

Answer 6

proclination of upper anteriors
retroclination of lower anteriors
localised anterior open bite / incomplete overbite
narrow upper arch

Question 7

How can digit sucking habit be corrected?

Answer 7

stop habit. 9 years and older harder to fix.

reinforcement
removable appliance habit breaker
fixed appliance habit breaker

Question 8

What are the treatment options for a class II div I malocclusion?

Answer 8

1. Accept, do nothing.
   - low IOTN score; mild increased overjet
   - slightly increased overjet but patient not unhappy
2. Growth modification
   - headgear; functional appliance
3. Tipping of teeth
4. Camouflage (fixed appliance)
5. Orthognathic surgery

Question 9

How does a functional appliance work?

Answer 9

utilise, eliminate or guide the forces of muscle function, tooth eruption and growth to correct malocclusion.

Question 10

What are the therapeutic effects of functional appliances?

Answer 10

mostly dentoalveolar changes.

• distal movement upper dentition
• medial movement lower dentition
• retroclination upper incisors
• proclination lower incisors

Question 11

When to use functional appliances?

Answer 11

1. Early use - early mixed dentition; 10 years old; 2 phase treatment
2. Later use - late mixed/permanent dentition; single phase treatment

Question 12

What is the advantage of early use functional appliances?

Answer 12

improves appearance earlier

Question 13

What are the disadvantages of early use functional appliances?

Answer 13

2 phase treatment
little if any difference between those treated early and late

Question 14

What is the expected ANB value for a class II div I malocclusion?

Answer 14

> 5 degrees

average value is 3 ± 2