Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Sleepiness
Systematic review	130 people 4 RCTs in this analysis	Daytime sleepiness with active oral appliance with control oral appliance Absolute results not reported	Reduction in Epworth Sleepiness Scale (ESS) score (see table 3 ): WMD –2.09 95% CI –3.8 to –0.37	Effect size not calculated	oral appliance
Systematic review	182 people 2 RCTs in this analysis	Daytime sleepiness with active oral appliance with control oral appliance Absolute results not reported	Reduction in ESS score: WMD –1.81 95% CI –2.72 to –0.90. Difference between groups was not significant using a random-effects model (–2.95, 95% CI –6.69 to +0.79)	Effect size not calculated	oral appliance
RCT Crossover design 3-armed trial	24 people; mean AHI 26.7 (see table 2 ) and ESS score 11.9	Daytime sleepiness (ESS) score 1 week 9.0 with first oral appliance that produced mandibular advancement 9.0 with second oral appliance that produced mandibular advancement 13.0 with no treatment	P <0.01 for each oral appliance v no oral appliance	Effect size not calculated	oral appliance
RCT Crossover design	28 people; mean AHI 27	Daytime sleepiness (ESS) score 3.9 with active oral appliance 10.1 with control oral appliance that did not advance the mandible	P <0.01	Effect size not calculated	active oral appliance
RCT Crossover design	85 people with mild to severe OSAHS (mean AHI 26.9)	Daytime sleepiness (ESS) score 4 weeks 7.1 with active oral appliance 9.1 with inactive oral appliance	P <0.01	Effect size not calculated	active oral appliance
Intermediate outcomes
Systematic review	156 people 5 RCTs in this analysis	Reduction in AHI (see table 2 ) with active oral appliance with control oral appliance Absolute results not reported	WMD –10.78 95% CI –15.53 to –6.03	Effect size not calculated	oral appliance
Systematic review	155 people 4 RCTs in this analysis	Reduction in AHI with active oral appliance with control oral appliance Absolute results not reported	WMD –15.15 95% CI –19.40 to –10.89	Effect size not calculated	oral appliance
RCT Crossover design 3-armed trial	24 people; mean AHI 26.7 and ESS score 11.9	AHI score 1 week 8.7 with first oral appliance that produced mandibular advancement 7.9 with second oral appliance that produced mandibular advancement 22.6 with no treatment	P <0.05 for appliance v no appliance	Effect size not calculated	oral appliance
RCT Crossover design	28 people; mean AHI 27	AHI score 14 with active oral appliance 30 with control oral appliance that did not advance the mandible	P <0.001	Effect size not calculated	active oral appliance
RCT Crossover design	85 people with mild to severe OSAHS (mean AHI 26.9)	Mean AHI 12.2 with active oral appliance 25.4 with inactive oral appliance	P <0.01	Effect size not calculated	active oral appliance
RCT Crossover design	85 people with mild to severe OSAHS (mean AHI 26.9)	Mean number of arousals per hour 25.0 with active oral appliance 33.1 with inactive oral appliance	P <0.01	Effect size not calculated	active oral appliance
Quality of life
RCT Crossover design	85 people with mild to severe OSAHS (mean AHI 26.9)	Quality of life 17.9 with active oral appliance 15.7 with inactive oral appliance	P <0.05	Effect size not calculated	active oral appliance
RCT Crossover design	85 people with mild to severe OSAHS (mean AHI 26.9)	Quality of life 8.8 with active oral appliance 6.9 with inactive oral appliance	P <0.05	Effect size not calculated	active oral appliance
RCT Crossover design	85 people with mild to severe OSAHS (mean AHI 26.9)	Quality of life 2.11 with active oral appliance 2.7 with inactive oral appliance	P <0.05	Effect size not calculated	active oral appliance