Postoperative stability of two common ramus osteotomy procedures for the correction of mandibular prognathism: A randomized controlled trial

Abstract

The aim of this randomized controlled trial was to compare the skeletal stability between sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) in the treatment of mandibular prognathism. Patients presenting with mandibular prognathism and scheduled for orthognathic surgery were randomized into either the SSRO group or the IVRO group. Changes at B-point were assessed by serial tracing of lateral cephalograms, which were taken preoperatively, and at 2 weeks, 6 months, 1 year, and 2 years postoperatively. Ninety-eight patients were recruited, with 49 patients in each group. Between 2 weeks and 6 months postoperatively, there was significantly more surgical relapse in the horizontal direction (anterior movement) in the SSRO group when compared with the IVRO group (1.83 mm (SD 2.91 mm) vs 0.49 mm (SD 2.32 mm); p = 0.019). At 2 years, there was more surgical relapse in the horizontal direction in the SSRO group than in the IVRO group (0.27 mm (SD 0.34 mm) vs 0.10 mm (SD 0.29 mm); p = 0.014). There were also more absolute changes (irrespective of direction) at B-point in the SSRO group than in the IVRO group at postoperative 6 months, 1 year, and 2 years (p = 0.016, 0.049, and 0.045, respectively). The amounts of change at B-point as percentages of total mandibular setback were 1.3% and 3.5% in the IVRO group and SSRO group, respectively. There were no differences in vertical changes between the two groups at any time points. In conclusion, the horizontal stability at B-point was shown to be superior in the IVRO group compared with the SSRO group in the correction of mandibular prognathism during the 2-year follow-up. Although the exact clinical importance of this difference is unknown at this time, this possible benefit may be an important key factor when deciding which osteotomy technique to employ for mandibular setback.

Keywords: Intraoral vertical subsigmoid osteotomy; Mandibular prognathism; Orthognathic surgery; Sagittal split ramus osteotomy; Stability.