Determinants of treatment outcome after use of the mandibular advancement device in patients with obstructive sleep apnea.

OBJECTIVE To determine the predictors affecting treatment outcome after application of the mandibular advancement device (MAD). DESIGN Retrospective analysis. SETTING Tertiary care university hospital. PATIENTS A total of 76 patients (68 men and 8 women) who were treated with the MAD for obstructive sleep apnea (OSA) were included from September 2005 through August 2008. All the subjects underwent cephalometry, nocturnal polysomnography, and sleep videofluoroscopy (SVF) before and at least 3 months after receipt of a custom-made MAD. Sleep videofluoroscopy was performed before and after sleep induction and was analyzed during 3 states of awakeness, normoxygenation sleep, and desaturation sleep. Subjects were divided into success and nonsuccess groups depending on treatment outcome. MAIN OUTCOME MEASURES Multiple variables from cephalometry and SVF including the length of the soft palate, retropalatal space, retrolingual space, and mouth opening angle were evaluated during sleep events with or without the MAD between success and nonsuccess group. RESULTS The soft palate was significantly longer in the nonsuccess group than in the success group. The retropalatal and retrolingual airway spaces and mouth opening angle were not different between 2 groups. Application of the MAD increased the retrolingual space and decreased the length of the soft palate and the mouth opening angle significantly in both success and nonsuccess groups. However, retropalatal space was widened only in the success group, which showed that retropalatal space may be important in determining treatment response of the MAD. CONCLUSION The length of the soft palate showed a difference between success and nonsuccess groups, and widening of retropalatal space might be an important factor for successful outcome with MAD application.