Class 3 malocclusion

Question 1

What can the aetiology of a class 3

Answer 1

Small maxilla

Large mandible

Combination of both

Question 2

What is the definition of class 3 malocclusion

Answer 2

Lower incisor edge occludes anterior to the cingulumplateau of the upper central incisor

The overjet is reduced or reversed

Question 3

What skeletal base does class 3 usually present with

Answer 3

Usually present with a Class 3 skeletal base
relationship

Can present with a Class 1 and rarely a Class 2

Question 4

What relationships are linked in ortho

Answer 4

A-P and transverse relationship linked

Question 5

If a pt has a retrusive maxilla what would that result in

Answer 5

The retrusive maxilla sits on wider part of the mandible resulting in a bilateral crossbite

Question 6

What dental features can be common in class 3

Answer 6

Class III incisor relationship

Class III molar relationship (not always)

Tendency to reverse overjet

Reduced overbite, anterior open bite may be present

Crossbites
-Anterior
-Buccal

Alignment
-Maxilla often crowded
-Mandible often aligned or spaced

Dentoalveolar compensation
-Proclined upper incisors
-Retroclined lower incisors

Tendency for displacements on closing

Question 7

What would make treatment of class 3 more difficult

Answer 7

number of teeth in anterior crossbite

Skeletal element in aetiology
>the A-P discrepancy

Presence of anterior open bite

Question 8

What management options are there for a class3

Answer 8

Accept/monitor

Intercept early with a URA

Growth modification

Camouflage

Combined orthognathic/orthodontic Tx

Question 9

When would you accept and monitor

Answer 9

If no concerns, no dental health indications, mild cases

Question 10

When would you do interceptive Tx

Answer 10

e if Class III incisors have developed due to
early contact on permanent incisors

Only suitable for correcting a lateral incisor crossbite if
permanent canines are high above lateral roots

Question 11

When would you do growth modification Tx

Answer 11

In a growing patient

It’s aimed at reducing and/or redirecting mandibular growth and encourage maxillary growth using functional appliances

Question 12

What functional appliances are used in growth modification

Answer 12

Chin cup

Reverse Twin Block

Frankel III

Question 13

What is the camouflage Tx

Answer 13

When you accept underlying skeletal base relationship
-Aim for class 1 incisors

Question 14

Wha are the favourable features for orthodontic camouflage and what would the extraction pattern be

Answer 14

Favourable features for camouflage:
-Growth stopped
-Mild to moderate Class III Skeletal base ANB not <0˚
-Average or increased overbite
-Able to reach edge to edge incisor relationship
-Little or no dentoalveolar compensation

Extraction pattern:
-Extract further back in the upper arch
-Extract further forward in the lower arch
-Classic pattern-Upper 5’s, lower 4’s

Question 15

When would you do a Orthognathic/ Orthodontic Approach

Answer 15

Pt usually has aesthetic or functional concerns

Growth completed

Moderate/Severe skeletal discrepancy

Question 16

What is orthognathic surgery

Answer 16

Orthognathic surgery is surgical manipulation of the mandible and / or maxilla to produce optimal
dentofacial aesthetics and function

Question 17

When treating class III malocclusion in a patient using a fixed rapid maxillary expansion device , the accompanying headgear needs to be worn for how many hou

Answer 17

14hrs