Prospective study of posttreatment changes in the temporomandibular joint.

The purpose of this follow-up prospective longitudinal study was to determine what changes occurred in the condyle/fossa relationship after treatment. Orthodontic posttreatment records, including corrected tomograms of 106 white patients (58 Class I and 48 Class II Division 1), from a pretreatment sample of 232 patients, were analyzed. The average pretreatment age was 13.6 +/- 3.0 years. The average length of treatment was 2.3 +/- 0.6 years for the Class I group and 2.8 +/- 0.9 years for the Class II Division 1 group. With orthodontic treatment, the condyle became more concentrically positioned, and a significant (P <.05) decrease in left and right anterior, posterior, and superior joint spaces was observed in most subjects. There was no statistically significant correlation between changes in the condyle/fossa relationship based on age, gender, skeletal or dental variables, signs or symptoms of temporomandibular disorder, headgear use, type of elastics, or nonextraction vs extraction treatment.