are very light. Functional appliances avoid applying high forces to incisors during
overjet reduction. Mild malocclusions are better left untreated in these circumstances.
992H
Fig. 14.33 Panoramic radiograph showing widespread root resorption during fixed
appliance orthodontic treatment.
14.8.4 Orthodontics and temporomandibular joint (TMJ) disorders
In general, the presence of malocclusion is not associated with an increased
prevalence of TMJ disorders. There is a slightly greater prevalence in subjects with
malocclusions of the type that often have associated occlusal interferences, including
class III cases, cross-bites, and open bites, but the correlation is weak. Even so, simple
orthodontic treatment, often in the mixed dentition, to correct a cross-bite with an
associated mandibular displacement is well worthwhile. In older patients, orthodontic
treatment to remove the interference can be complex and an alternative approach may
be better, such as occlusal adjustment, unless treatment is needed anyway for other
aspects of the malocclusion. Orthodontic treatment should always aim to leave the
occlusion with no interferences.
It has been claimed that many forms of orthodontic treatment cause TMJ disorders,
with premolar extractions coming under the greatest attack. However, extensive
studies have found no evidence of an increased prevalence of TMJ disorders in
subjects who have had orthodontic treatment, including extractions, compared with
untreated controls.
14.9 TEMPOROMANDIBULAR JOINT (TMJ) DISORDERS
Although several studies include children aged 5-7 years, most observations have
been made on the young adolescent. A small number of temporomandibular problems
are associated with functional malocclusion (occlusal interferences) and
morphological malocclusion such as cross-bite and anterior open bites, but bruxism