Ortho- Class 3

Question 1

What is a class 3 incisor relationship

Answer 1

Lower incisor edge occludes anterior to cingulum plateau of upper incisor
OJ is reduced or reversed

Question 2

Aetiology

Answer 2

Genetic: hapsburg family, autosomal dominant
Environmental: acromegaly, cleft lip/palate, small maxilla, large mandible

Question 3

Dental features

Answer 3

Class 3 incisor relationship
Class 3 molar relationship
OJ is reduced or reversed
OB reduced
Crossbite: anterior/buccal
Alignment: maxilla often crowded, mandible spaced
Dentoalveolar compensation: proclined upper incisors by tongue, retroclined lower incisor by lip
Tendency for displacement on closing

Question 4

Why treat

Answer 4

Aesthetics
Dental health: attrition, gingival recession, mandibular displacement
Function: mastication/speech

Question 5

Factors which make tx more difficult

Answer 5

> Increased number of teeth in anterior crossbite
a/p discrepancy
Skeletal element in aetiology
AOB/ increased FMPA
Facial growth

Question 6

How to predict puberty

Answer 6

Height/weight charts
Cervical vertebral maturation on lat ceph
Hand wrist radiographs

Question 7

Class 3 management options

Answer 7

Accept and monitor
Intercept early with URA
Growth modification
Camouflage
Combined orthognathic/ortho tx

Question 8

Why accept

Answer 8

No concerns/ dental heath indicators- no displacement/attrition
Mild cases