Intraoral Vertical Ramus Osteotomy - Objective and Subjective Treatment Outcomes

Abstract

Combined orthodontic and orthognathic surgical treatment is conducted when a jaw discrepancy exceeds what can be treated with orthodontic treatment alone with an acceptable esthetical and functional result. The intraoral vertical ramus osteotomy (IVRO) is one of mainly three different surgical techniques used to move the mandible posteriorly in patients with a skeletal Class III jaw relationship due to excess growth of the mandible. The purpose of this thesis is to evaluate the IVRO procedure with special focus on stability, satisfaction with treatment, oral health-related quality of life (OHRQoL), and impact on respiratory function during sleep. Thirty-six previous skeletal Class III patients operated with an isolated IVRO procedure and subsequent six weeks of intermaxillary fixation were examined 10-15 years after surgery and completed a 37- item structured questionnaire. Pre- and post-surgical orthodontic treatment had been performed in all patients. Skeletal and dental changes were evaluated with lateral cephalograms and dental casts obtained before treatment started, eight weeks, one year and 10-15 years after surgery. OHRQoL was measured with the OIDP index. A prospective cohort study was performed to evaluate the effect of mandibular setback surgery on the respiratory function during sleep. Eight otherwise healthy skeletal Class III patients between 18 and 33 years of age conducted in-home respiratory sleep recordings within two weeks before and at least three months after surgery. Primary outcome variable was apnoea hypopnea index (AHI). In the long-term follow-up study mean mandibular surgical setback was 8.3 mm (range 4.5 - 13.5 mm). The mean skeletal change between eight weeks and 10-15 years after surgery was 1.6 mm in anterior direction. Ninety-two percent had positive horizontal overjet 10-15 years after surgery. Sixty-one percent were very satisfied and the remainder were reasonably satisfied with the treatment. The mean OIDP frequency score was 8.49, indicating that OHRQoL was good. In the group of patients conducting pre- and post-operative sleep recordings, the AHI was below three events per hour before surgery and below four events per hour after surgery in all patients. The mean surgical setback was 4.3 mm (range: 2.5-7.4 mm) in this patient group. In conclusion, 10-15 years after mandibular setback surgery with the IVRO procedure the clinical result was good in most of the patients. All were either reasonably or very satisfied with the treatment, and OHRQoL was reported to be good. In the group of eight young, adult skeletal Class III patients in the prospective study, surgery did not increase AHI above five events per hour, i.e. all were below the threshold for mild obstructive sleep apnoea.