Do oral appliances enlarge the airway in patients with obstructive sleep apnoea? A prospective computerized tomographic study

This study evaluated the effect of an anterior mandibular positioning appliance (AMPA) on minimum pharyngeal cross-sectional area (MPCSA) in 32 conscious supine obstructive sleep apnoea (OSA) subjects. The change in MPCSA was measured using low dose computerized tomography, with and without an AMPA in situ. The results showed that the mean presenting respiratory disturbance index (RDI) was 26.6 events/hour, with a body mass index of 28.6 kg/m(2) and mean age of 51.5 years. There was a statistically significant increase in MPCSA of 28.34 mm(2) on appliance insertion (SD = 59.06 mm2; range -145 to +190 mm(2); P= 0.011). The mean mandibular displacement was 5.73 mm (SD = 2.51 mm) in protrusion and 8.27 mm (SD = 4.51 mm) inferiorly. A poor correlation was found between the size of the mandibular displacement and the change in MPCSA (protrusion r= 0.268; inferiorly r= 0.240, P> 0.05). In conclusion, the AMPA significantly increased MPCSA, suggesting that it may be an effective thera py for OSA. There was, however, a wide but unpredictable individual variation of response. As a small number of patients may worsen in their condition with temporary mandibular advancement (TMA), it is essential that all patients treated with TMA should be investigated by polysomnography both before and after treatment.