Aims: To assess the efficacy of occlusal stabilization splints in the management of sleep bruxism (SB) in a double-blind, parallel, controlled, randomized clinical trial. Methods: Twenty-one participants were randomly assigned to an occlusal splint group (n = 11; mean age = 34.2 ± 13.1 years) or a palatal splint (ie, an acrylic palatal coverage) group (n = 10; mean age = 34.9 ± 11.2 years). Two polysomnographic recordings that included bilateral masseter electromyographic activity were made: one prior to treatment, the other after a treatment period of 4 weeks. The number of bruxism episodes per hour of sleep (Epi/h), the number of bursts per hour (Bur/h), and the bruxism time index (ie, the percentage of total sleep time spent bruxing) were established as outcome variables at a 10% maximum voluntary contraction threshold level. A general linear model was used to test both the effects between splint groups and within the treatment phase as well as their interaction for each outcome variable. Results: Neither occlusal stabilization splints nor palatal splints had an influence on the SB outcome variables or on the sleep variables measured on a group level. In individual cases, variable outcomes were found: Some patients had an increase (33% to 48% of the cases), while others showed no change (33% to 48%) or a decrease (19% to 29%) in SB outcome variables. Conclusion: The absence of significant group effects of splints in the management of SB indicates that caution is required when splints are indicated, apart from their role in the protection against dental wear. The application of splints should therefore be considered at the individual patient level. Keywords: bruxism, occlusal stabilization splint, polysomnography, randomized clinical trial, sleep