Subjects. Sample size estimations are based upon a recent review of randomized clinical trials, in which acrylic appliances were evaluated (see Appendix 2 in (Huynh et al., 2007)). The mean +/- 1 standard deviation (SD) number of bruxism episodes per hour with a Michigan bite splint was 3.97 + 0.58, and for a palatal splint, the mean +/- 1 SD was 4.45 + 0.63. Using these means and the higher SD (0.63), along with an alpha = 0.05 and beta = 0.8, a study would be sufficiently powered with sample sizes of 29 per group. Based on other Michigan studies, wherein recruitment, exclusion and attrition rates are known, it is estimated that an initial screening sample size of 120 will be necessary to end up with 29 per group.