SKELETAL STABILITY AFTER MANDIBULAR ADVANCEMENT - A COMPARISON OF 2 RIGID INTERNAL-FIXATION TECHNIQUES

Objective: To compare two different methods of rigid fixation for any difference in postoperative stability after mandibular advancement. Ma terial and Methods: Thirty-eight patients with Class II malocclusion t reated by bilateral sagittal split osteotomy (BSSO) and mandibular adv ancement were selected for this retrospective study. Group A (n = 16) had noncompressive bicortical screws inserted in the genial area throu gh a transcutaneous approach and Group B (n = 22) had the bone segment s fixed with unicortical screws and miniplates on the lateral surface of the mandibular body. Cephalograms were taken preoperatively, 2 days postoperatively, and 6 months after the operation, and a computer pro gram was used to superimpose the three cephalograms and register the a dvancement and postoperative instability. Results: There was a minimal difference in advancement of the mandible in the two groups. Statisti cal analysis showed no significant difference in postsurgical stabilit y. However, positive correlation between the amount of advancement and the amount of postsurgical instability was demonstrated using a linea r multiple regression test (P = .0002). Conclusion: This study indicat es that the two different methods of internal rigid fixation of the se gments after surgical advancement of the mandible give equal stability postoperatively and their use is a matter of surgical choice.