Background: Obstructive sleep apnoea-hypopnoea is a syndrome characterised by recurrent episodes of partial or complete upper airway obstruction during sleep that are usually terminated by an arousal. Nasal continuous positive airway pressure is the primary treatment for obstructive sleep apnoea-hypopnoea, but many patients are unable or unwilling to comply with this treatment. Oral appliances are an alternative treatment for sleep apnoea.

Objectives: The objective was to review the effects of oral appliance in the treatment of sleep apnoea in adults.

Search strategy: We searched MEDLINE 1966-2003, and the Cochrane Airways Group Sleep Apnoea RCT Register. Searches were current as of July 2003. Reference lists of articles were also searched.

Selection criteria: Randomised trials comparing oral appliance with control or other treatments in adults with sleep apnoea.

Data collection and analysis: Trial quality was assessed and two reviewers extracted data independently. Study authors were contacted for missing information.

Main results: Twelve trials involving 509 participants were included. All the studies had some methodological shortcomings. Oral appliances improved apnoea-hypopnoea index compared with inactive control (-13.17 AHI [-18.53 to -7.80] parallel group data - four studies). Oral appliances reduced daytime sleepiness in two trials (WMD -1.77 [95%CI: -2.91 to -0.62]). Oral appliances were less effective than continuous positive pressure in reducing apnoea-hypopnoea index (WMD 13 [95% CI: 7.63, 18.36], parallel studies - two trials; WMD 6.75 [4.93, 8.57] cross-over studies - six trials). However, no significant difference was observed on symptom scores (3 trials). Nasal continuous positive pressure was more effective at improving minimum arterial oxygen saturation during sleep compared with oral appliance. In two small crossover studies, participants preferred oral appliance therapy to continuous positive airways pressure.

Reviewer's conclusions: There is some limited evidence suggesting that oral appliance improves subjective sleepiness and sleep disordered breathing compared with a control. Nasal continuous positive airways pressure appears to be more effective in improving sleep disordered breathing than oral appliance. Until there is more definitive evidence on the effectiveness of oral appliances, it would appear to be appropriate to restrict oral appliance therapy to patients with sleep apnoea who are unwilling or unable to comply with continuous positive airways pressure therapy.