Signs of temporomandibular disorders in girls receiving orthodontic treatment. A prospective and longitudinal comparison with untreated Class II malocclusions and normal occlusion subjects.

The aim of this investigation was to prospectively and longitudinally study signs of temporomandibular disorders (TMD) and occlusal changes in girls with Class II malocclusion receiving orthodontic treatment and to compare them with subjects with untreated Class II malocclusions and with normal occlusion subjects. Three groups of age-matched adolescent girls were examined for clinical signs of TMD and re-examined 2 years later. Sixty-five Class II subjects received orthodontic fixed straight-wire appliance treatment (Orthodontic group), 58 subjects were orthodontically untreated (Class II group), and 60 subjects had a normal occlusion (Normal group). In the Orthodontic group, the prevalence of muscular signs of TMD was significantly less common post-treatment. The Class II and the Normal groups showed minor changes during the 2-year period. Temporomandibular joint clicking increased in all three groups over the 2 years, but was less common in the Normal group. The Normal group also had a lower overall prevalence of signs of TMD than the Orthodontic and the Class II groups at both registrations. Functional occlusal interferences decreased in the Orthodontic group, but remained the same in the other groups over the 2 years. In conclusion, orthodontic treatment did not increase the risk for or worsen pretreatment signs of TMD. On the contrary, subjects with Class II malocclusions and signs of TMD of muscular origin seemed to benefit functionally from orthodontic treatment in a 2-year perspective. The Normal group had a lower prevalence of signs of TMD than the Orthodontic and the untreated Class II groups.