Both CPAP and MAD are effective in treating all severities of OSA. There is a trend for better success with CPAP amongst severe OSA patients.30 MAD can reduce AHI in mild-moderate OSA cases 76%; and in severe cases 79%.27 The surgical cure rate (AHI <5) is 43%.27 Even in severe OSA cases with the AHI in the 80s, MAD treatment significantly reduced AHI to the 1.7 – 11 range.24
Adherence to nightly use of 4 hours or greater is an issue with both MAD and CPAP therapies. MAD adherence ranges from 76-98% while it is 30-80% amongst CPAP users.27 In a crossover study of 108 OSA patients, CPAP users used their machines 5.3 hours per night while MAD users wore their appliances for 6.5 hours per night.31 Research has shown that adherence is better with MAD than CPAP.
A reasonable question to ask is what is the overall morbidity and mortality of OSA between CPAP vs. MAD treatment when adherence is taken into consideration? In a one month study of with respect to outcome measures of mean arterial pressure, blood pressure and sleep quality, MAD was not inferior to CPAP.32
In regards to effectiveness between titratable (adjustable) and non-titratable (fixed) MAD appliances, the titratable appliances are superior. Non-titratable appliances have a fixed mandibular position, thus protrusion cannot be further increased for therapeutic effect, nor can it be decreased to relieve TMJ discomfort or other side effects should they occur. In a study of 180 OSA patients treated with 2 titratable proprietary MAD appliances and a fixed appliance, the titratable appliances significantly improved OSA (AHI <5) in 72% of cases compared to 52% in the fixed group.33
A final thought in regard to MAD appliance design: early appliances assumed that increasing the vertical dimension (VD) in addition to protrusion would add further benefit. While some increase in VD is inherent in these appliances, excessive VD can actually have adverse airway effects.34