Page 14 - REMOVABLE ORTHODONTIC APPLIANCES

6 Removable Orthodontic Appliances
producing a 'functional' effect. (Fixed appli-
ance systems would demand a separate, lower
appliance to achieve such changes.) For such an
improvement to be effective, it is desirable that
facial growth should be taking place.
In a class II division I malocclusion,
proclined upper incisors frequently conceal an
element of over-eruption which will demand
intrusion as well as retraction. This is an indica-
tion for a fixed appliance and any attempts to
Figure 1.6 A bonded attachment on the labial use a removable appliance merely to till the
surface of an upper incisor allows occlusal upper incisors palatally risks producing an
movement with a buccally placed spring. unsatisfactory and 'toothy' appearance.

overbite may be corrected during canine retrac- Lower arch treatment
tion, so allowing the upper incisors to be
retracted on a subsequent appliance (Figure Removable appliances have limited use in the
1.7). In this respect the anterior bite plane is lower arch for a number of reasons:

Figure 1.7 (a) An increased overjet and overbite, (b) An anterior bite plane separates the molars allowing (c)
vertical eruption of the molar teeth, effectively reducing the overbite.