Complication after extraoral vertical and intraoral oblique osteotomy have been reported but not in a comprehensive manner. Although intuitively the profile of complications after Intraoral Vertical Ramus Osteotomy (IVRO) would be similar to subcondylar osteotomy, the technique of the two procedures are different, and thus unfavorable outcome after surgery also may differ. The purpose of this study was evaluate the morbidity and complications following correction of mandibular prognathism by IVRO.

Materials and methods: A prospective study was undertaken of 208 consecutively treated orthognathic surgical patients with mandibular prognathism. Each patient was treated by bilateral IVRO within 2–3 weeks of maxillo-mandibular fixation and no interosseous fixation of proximal segment.

Method and data analysis: Postoperative stability, immediately after surgery, at 6 months, and at 12 months after surgery were made. Complications were assessed by retrospective individual chart review. The average follow-up 58 months, ranging 2–7 years.

Results: Severe wound haemorrhage was no encountered. There was no wound infection after surgery. Nerve injury occurred at 1 (0.5%) operative site but was not permanent. Condylar dislocation did not occur.

Conclusion: Our studies indicated that surgical correction of mandibular prognathism by IVRO had a beneficial effect not only on dental occlusion but also upon complication after surgery.