What Are the Factors Associated with Longevity of Mandibular Advancement Oral Appliances?

Background/Objectives: Mandibular advancement oral appliances (MAOAs) for obstructive sleep apnea syndrome treatment can be rendered more convenient by adopting a separate and movable design; however, concerns regarding possible weakening of effect have been raised. This study had the aim to clarify the factors associated with the longevity of separate and movable MAOAs. Methods: Information on 466 MAOAs from 230 patients was collected from medical records, including baseline information, apnea–hypopnea indexes, transcutaneous oxygen saturation, component connection method, and initial fabrication status (new fabrication or repair). MAOAs were evaluated in clinical practice, and breakage was considered a failure. Failures were classified into three types: Type A, breakage anywhere in MAOA; Type B, connector breakage (thermoplastic component breakage was censored); and Type C, thermoplastic component breakage (connector breakage was censored). Survival time of MAOA for all types was analyzed using a shared frailty model. Hazard ratios and 95% confidence intervals were determined, with the statistical significance at p < 0.05. Results: Type A failures were significantly linked to patient sex, age, and connection method; Type B failures were associated with sex and age; and no variables were linked to Type C failures. Younger male patients showed lower survival rate except for Type C, with no correlation between apnea symptom severity and survival status. Conclusions: MAOA connector strength was significantly associated with the MAOA survival rate. Connectors were more likely to break in younger patients, and this tendency was particularly pronounced in males. Therefore, age and sex should be considered when choosing the MAOA connection method.