Class III

Question 1

Define Class 3 malocclusion according to BSI ?

Answer 1

• Lower incisor edge occludes anterior to the cingulum of the upper incisor with reduced or reversed overjet

Question 1

2 aetiological factors associated with class 3 maocclusion?

Answer 1

• Genetic - habsburg family
• Environmental factors - cleft lip and palate , Acromegaly

Question 2

What is the aetiology of class 3 skeletal pattern?

Answer 2

• Small maxilla
• Large mandible
• Combination of both

Question 3

Which skeletal base is mainly associated with class 3 malocclusion?

Answer 3

Skeletal class III

Question 4

What two features in the vertical skeletal pattern , that can be complex to treat?

Answer 4

• Increased FMPA and anterior open bite

Question 5

If a retrusive maxilla site on a wider part of mandible in class 3 , what would this lead to?

Answer 5

• Bilateral crossbite

Question 6

4 dental features that can be associated with Class 3 malocclusion?

Answer 6

• Class III incisors
• Class III molars
• Tendency to reverse overjet
• Reduced overbite and anterior open bite
• Anterior and posterior crossbites

Question 7

Regarding crowding , explain how can this be present in class III malocclusion?

Answer 7

• Maxilla often crowded
• Mandible aligned or spaces

Question 8

How would you describe the upper and lower incisors in class 3?

Answer 8

• Proclined upper and retroclined lowers

Question 9

A patient have a class 3 malocclusion, what problem is associated during closure?

Answer 9

tendency to displacements on closing

Question 10

How can the soft tissue affect dentoalveolar compensation in class III?

Answer 10

• Tongue proclines upper incisors
• Lower lip retroclines lower incisors

Question 11

3 reasons to treat a class 3 malocclusion?

Answer 11

• Aesthetics
• Dental health reasons
• Function

Question 12

3 dental health concerns in class 3?

Answer 12

• Attrition
• Gingival recession
• Mandibular displacement

Question 13

4 factors that can make class III malocclusion more difficult to treat?

Answer 13

• increase of number of teeth in anterior crossbite
• increase in anterioposterior discrepency
• Pressence of anterior open bite
• Facial growth

Question 14

Why facial growth might be a problem in treating class III malocclusion?

Answer 14

• Mandibular growth continues for longer leading to worse malocclusion

Question 15

5 treatment options for Class III?

Answer 15

• Accept
• Intercept early with URA
• Growth modification
• Camouflage
• Orthognathic surgery

Question 16

4 indications of accepting class 3?

Answer 16

mild cases where there is no dental health concerns or aesthetic concerns

Question 17

When would intercepting for Class III malocclusion be suitable?

Answer 17

• Class 3 incisors have developed due to early contact of permanent incisors
• For the correction of anterior crossbite in mixed dentition to encounter mandibular growth by dentoalveolar compensation

Question 18

When would correcting a lateral incisor crossbite be suitable in relation to permanent canines?

Answer 18

If the canines are high above the lateral roots as there is a risk of resoption if the canines are in buccal position

Question 19

What would the interceptive treatment with URA do in class III?

Answer 19

• Procline incisors over the bite using a z spring as an active component

Question 20

What is the aim of growth modification in class III cases?

Answer 20

• reducing or redirecting mandibular growth and encouraging maxillary growth

Question 21

4 functional appliances used for growth modification other than protraction headgear with rapid maxillary expansion?

Answer 21

• Chin up
• Reverse twin block
• Frankel III

Question 22

What does chin up do?

Answer 22

• Lingual tipping of lower incisors and rotates the mandible down and forward

Question 23

What does frankel III consist of for the correction of Class III malocclusion and what does it do?

Answer 23

• Shields labial to upper incisors to hold lip away
• Palatal arch to procline the upper incisors
• Lower labial bow to retrocline the lower incisors

Question 24

What is this?

Answer 24

Reverse twin block

Question 25

What is this?

Answer 25

Protraction headgear

Question 26

What are the disadvantages of protraction headgear? and when does it give the best results?

Answer 26

* needs excellent cooperation * needs to be worn for 14 hours per day * 8-10 years in early mixed dentition

Question 27

What are those?

Answer 27

Bollard implants in infrazygomatic crest and lower canine region

Question 28

When would you use bollard implants?

Answer 28

* in later mixed or permanent dentition

Question 29

5 favourable features for camouflage of class 3 malocclusion?

Answer 29

* Growth has stopeed * Mild to moderate class II skeletal base ( ANB not less than 0) * Average or increased overbite * Edge to edge incisor relationship * Little dentoalveolar compensation

Question 30

What would be the extraction pattern for the orthodontic camouflage to treat class III malocclusion ?

Answer 30

* XLA further back in upper * XLA further forward in lowers * Usually upper 5s and lower 4s * Howerever, dental health indicates the extraction pattern

Question 31

What are the aims of camouflage in Class III malocclusion?

Answer 31

* Procline upper incisors * Retrocline lower incisors * Correct the overjet

Question 32

What is orthognathic surgery?

Answer 32

* Surgical manipulation of the mandible or the maxilla or both to produce optimal dento-facial aesthetics and function

Question 33

3 indications of orthognathic surgery in Class III skeletal pattern?

Answer 33

* Growth has stopped * Moderate or severe skeletal discrepancy * Aesthetic and functional concerns

Question 34

4 professionals in the MDT of orthognathic treatment?

Answer 34

* Orthodontist * Maxillofacial surgeon * Technician * Psychologist

Question 35

How long would presurgical ortho treatment last?

Answer 35

18 months to align the arch

Question 36

How long would post surgical ortho treatment last?

Answer 36

6 months for stability