Page 85 - REMOVABLE ORTHODONTIC APPLIANCES

Chapter 9

Class III malocclusions

A class III malocclusion is one in which there is mandible (Figure 9.1). An increased overbite
a reversed overjet on at least one incisor. This is will favour the correction of a reversed overjet
frequently associated with a displacing activity because there will still be a positive overbite
of the mandible where an initial contact causes a after treatment. Cases which have only one or
forward displacement into the reversed overjet. two central incisors in lingual occlusion and
which involve a displacing activity are usually
well suited to removable appliance treatment.
Case selection
Removable appliances are only suitable for
treating the more mild class III cases. They are,
however, particularly useful for interceptive
treatment in the mixed dentition stage.
There are a number of factors to consider in
the selection of cases, which are suitable for
treatment with removable appliances.

Favourable factors
Skeletal pattern
The underlying skeletal pattern is relevant in
the identification of those patients with
reversed overjets who are suitable for treat-
ment with removable appliances. The skeletal
pattern should be class I or only mildly class III
(although it should be remembered that a
displacing activity of the mandible would make
the class III skeletal pattern appear more
severe). The Frankfort mandibular planes
angle should be average or reduced.

Overjet and overbite
Figure 9.1 Forward displacement of the mandible
The reversed overjet should be small and which results in a class III incisor relationship. This
coupled with a forward displacement of the can usually be treated with a removable appliance.