Abstract
The purpose of this study was to compare the skeletal and dentoalveolar changes in skeletal class III patients who underwent only orthodontic treatment, with those in patients who received both orthodontic treatment and orthognathic surgery, and to identify a critical point in the treatment of skeletal class III malocclusion. Fifteen skeletal class III patients who underwent both orthodontic treatment and orthognathic surgery (mean age, 18.4 years; the surgical group), and 14 skeletal class III patients who underwent only orthodontic treatment (mean age, 18.1 years; the orthodontic group), were included in this study. They were treated by the multi-bracket edgewise technique without premolar extraction. Angular and linear cephalometric variables were measured, using lateral cephalograms, for each patient, taken before and at the end of the active orthodontic treatment. Unpaired and paired t-tests were used for statistical analysis. Before treatment, there were no significant differences in any of the cephalometric variables between the surgical and orthodontic groups, except for overjet. Significant changes commonly observed in both groups were a decrease in SNB, an increase in ANB, clockwise rotation of the mandible, counterclockwise rotation of the occlusal plane, and an increase in overjet. On the other hand, a significant increase in U1-FH, and a significant decrease in Ll-Mand. were found only in the orthodontic group. With regard to the extent of the change during treatment, the changes in SNB, ANB, Wits appraisal, and overjet were significantly greater in the surgical group than in the orthodontic group, whereas the changes in U1-FH and the functional occlusal plane angle were significantly greater in the orthodontic group than in the surgical group. Moreover, significant differences were also seen inL1-Mand. and overbite. These results suggest that counterclockwise rotation of the functional occlusal plane is the critical change in the orthodontic treatment of skeletal class III patients without orthognathic surgery, in addition to conventional skeletal and dentoalveolar changes, such as in the anteroposterior jaw relationship and the inclination of anterior teeth.
