Table 2: Quality of studies in review of oral appliances.

Study	Study design	Randomization method	Blinding	Intent-to-treat	Adequate sample size
MAS versus Placebo Devices
Petri et al. 2008 (8)	3-armed, parallel group design	Computer generated	Yes§	No	Yes
Blanco et al. 2005 (9)	Parallel group design	Unclear	No	No	Unclear
Barnes et al. 2004 (10)*	Randomized crossover study (3 arm)	Random draw	No	No	Yes
Gotsopoulos et al. 2004 † (11-13)	Randomized crossover study	Unclear	Yes	Yes	Unclear
Johnston et al. 2002 (14)	Randomized crossover study	Unclear	No	No	Yes
Mehta et al. 2001 (15)	Randomized crossover study	Unclear	No§	No	Unclear
MAS versus CPAP
Hoekema et al. 2008 † (16-19)	Parallel group design, Non-inferiority	Block randomization	No	Yes	Yes
Lam et al. 2007 (20)	Parallel group design	Unclear	No	Yes	Yes
Barnes et al. 2004 (10)*	Randomized crossover study (3 arm)	Random draw	No	No	Yes
Engleman et al. 2002 (21)	Randomized crossover study	Balanced blocks of 4 stratified by OSA severity	No	No	Yes
Randerath et al. 2002 (22)	Randomized crossover study	Unclear	No	N/A	Unclear
Tan et al. 2002 (23)	Randomized crossover study	Unclear	No	Yes	Unclear
Ferguson et al. 1997 (24)	Randomized crossover study	Unclear	No	No	Unclear
Ferguson et al. 1996 (25)	Randomized crossover study	Unclear	No	No	Unclear
MAS versus Surgery
Walker-Engstrom et al. 2002 † (26-30)	Parallel group design	Closed envelope system	No	Inconsistent	Yes
Tongue Repositioning Devices
Deane et al. 2009 (in press) (31)	Randomized crossover study	Unclear	No	No	Yes‡
Dort et al. 2008 (32)	Randomized crossover study	Block randomization	Unclear	No	Unclear

^*Barnes et al was a 3-arm trial that compared MAS, CPAP and placebo tablet.

^†These trials were reported in multiple publications.

^‡The study was powered to detect difference between baseline and endpoints, not between group differences.

^§Contacted authors