DENTAL CHANGES IN THE MANDIBLE DURING INITIAL BASS APPLIANCE THERAPY

The aim of this study was to analyse movements of lower molars and inc isors during 6 months of Bass appliance therapy and to evaluate the de ntal arch space attained. The sample consisted of 53 patients with sev ere Class II, division 1 malocclusions. The analyses were performed on lateral cephalograms and dental casts. Sixteen of the patients were f ollowed for 6 months before treatment. Dental space in the lower jaw d ecreased 0.7 mm (n = 16) during the observation period and increased 1 .8 mm (n = 53) during the 6 months of treatment. The molars moved post eriorly a total of 0.7 mm and tipped distally 2.4 degrees during treat ment. The incisors moved anteriorly 0.3 mm and tipped mesially 0.5 deg rees.