Bimaxillary Orthognathic Surgery Does Not Induce Obstructive Sleep Apnea in Skeletal Class III Patients

Abstract

Since the relationship between mandibular setback surgery and obstructive sleep apnea (OSA) occurrence still remains controversial, the aim of this study was to assess the impact of bimaxillary orthognathic surgery on the probability of OSA development, using a home sleep test (HST) device. The authors implemented a double-blinded prospective cohort study. All healthy patients with skeletal class III deformity were included in this study. Subjects were candidates for bimaxillary orthognathic surgery. OSA monitoring was performed by the pulmonologist, week 1 preoperatively (T0), 1 and 6months postoperatively (T1, T2), with a specific brand of a HST device. The predictor variables were the amount of mandibular setback and maxillary advancement, separately. Changes in apnea-hypopnea index (AHI) and SpO2 1 and 6months after surgery relative to T0 were the outcome variables. OSA severity was measured using AHI, and classified as mild (5<AHI<15), moderate (15<AHI<30), and severe (AHI>30). Age, sex, and body mass index were the study covariates. The outcome assessor (pulmonologist), and the data analyzer were blind in this study. The significance level was set at 0.05, using the SPSS19. The sample was composed of 30 patients, (15 females, 15 males) with an average age of 25.73±5.26years and a mean body mass index of 19.90±3.6kg/m2. The mean amount of mandibular setback was 4.5±1.1 (ranged from 2-7mm), while the average maxillary advancement was 2.9±1.2mm (ranged 1-5mm). Mean AHI at T0, T1, and T2 was 1.8±1.0, 3.4±1.5, and 1.9±0.9 events per hour events, respectively. The AHI scores increased from T0 to T1 but again decreased until T2, which were statistically significant (P<.001). The mean amount of SpO2 at T0, T1, and T2 was 96.7±0.9, 94.0±1.3, 96.7±0.7%, respectively. Postoperative AHI in T1 and T2 had direct statistical significant relationships with the amount of mandibular setback (Rsp=.404, .574, respectively and P<.05). Postoperative AHI scores were lower in patients with <5mm mandibular setback in comparison to subjects who underwent ≥5mm setback (P<.05). Bimaxillary orthognathic surgery (concomitant maxillary advancement and mandibular setback) did not increase the incidence of OSA in young healthy non-obese class III patients, in the case of mandibular setback up to 7mm.