Vertical Ramus Versus Sagittal Split Osteotomies: Comparison of Stability After Mandibular Setback

Abstract

Intraoral vertical ramus osteotomy (IVRO) offers some advantages over sagittal split ramus osteotomy (SSRO) for treatment of the prognathic patient. The purpose of this study was to compare the postoperative changes of proximal and distal segments after IVRO and SSRO with semirigid internal fixation. Thirty Japanese adults with a diagnosis of prognathic mandible were randomized to undergo either IVRO (n = 15) or SSRO (n = 15) according to an adaptive random assignment procedure. The postoperative changes of the proximal and distal segments were assessed with posteroanterior and lateral cephalograms. Compared with the SSRO group, the B-point and pogonion moved significantly posteriorly and inferiorly in the IVRO group from 1 month to 3 months after surgery. At 1 year after surgery, there was no significant difference between the 2 groups in the horizontal and vertical stability of the B-point and the pogonion. In the IVRO group, the gonion deviated significantly laterally from 1 week until 1 month after surgery as compared with that of the SSRO group. There was a significant correlation between the amount of setback and the amount of lateral gonial deviation in the IVRO group from 1 week to 1 year after surgery. Although in IVRO cases, distal segments moved posteriorly and inferiorly immediately after the release of maxillomandibular fixation, the stability after IVRO is equal to that after SSRO with semirigid internal fixation.