An orthodontic study of temporomandibular joint disorders. Part 2: Clinical research in orthodontic patients.

The purpose of this survey was to investigate the symptoms of temporomandibular joint disorders (TMD) in orthodontic patients and to define the relationships between symptoms and malocclusion and/or orthodontic treatment. The subjects were 532 patients, 6 to 38 year old Japanese, in the orthodontic department of Tokyo Dental College Hospital. They were examined for past or recent TMJ sounds, pain in the TMJ area, and abnormal jaw movements. The prevalence of TMJ symptoms was 33.8%. Sex differences were not statistically significant. The prevalence of TMD symptoms increased with age. TMD symptoms in young orthodontic patients (6-18 years old) were more common than in untreated subjects. Posterior crossbite and open bite patients had a high prevalence of symptoms.