Background: Sleep bruxism (SB) and obstructive sleep apnea (OSA) are closely associated. Scores of occlusal splints are prescribed around the world for the management of bruxism and the symptoms associated with it. This prompted Gagnon et al1 to conduct a pilot study in 2004 investigating the effects of an occlusal splint adjusted in centric occlusion on different OSA variables. The investigators observed some differences in OSA variables, but none were statistically significant. Furthermore, the study had a low level of evidence. Aim: The objective of this review, conducted as part of a Master's thesis, was to systematically evaluate the national and international literature on this subject and derive conclusions for dental practice. Methods: Systematic searches of the Cochrane, PubMed, LIVIVO (formerly MEDPILOT), and TRIP medical databases and of various publishing company databases and national and international sleep medicine association journal databases were conducted and supplemented by manual searches of the cited references to identify potentially suitable studies. The identified studies were analyzed for design, methodological quality, and level of evidence (Oxford Centre for Evidence-Based Medicine criteria), and were evaluated and discussed. Results: Currently, there is insufficient evidence to support the hypothesis that the use of a monomaxillary occlusal splint provokes the aggravation of clinical symptoms and the escalation of diagnostically relevant parameters in OSA patients. In addition to design weaknesses and methodological differences, another main limitation of the three thematically relevant and hitherto published studies is that the number of cases studied was too small to draw any statistically reliable conclusions. Conclusions: In view of the close association between SB and OSA and the trends identified in the available studies, it still seems wise to review the medical history before prescribing an occlusal splint to determine whether the patient has OSA. A positive history of snoring, pauses in breathing during sleep, daytime tiredness, micro-sleep, sleep laboratory testing or the use of a positive airway pressure (PAP) device for respiratory ventilation should prompt the dentist to refer the patient to a sleep laboratory for polysomnography (PSG) to test for OSA. If the diagnosis is confirmed by a sleep medicine specialist, it is recommended that a portable device is used to monitor sleep-related parameters with the occlusal splint in place. Keywords: apnea/hypopnea index (AHI), history, occlusal splint therapy, sleep bruxism (SB), obstructive sleep apnea (OSA)