Is there an association between sleep bruxism and obstructive sleep apnea syndrome? A systematic review.

To elucidate current knowledge on the potential association and causality between sleep bruxism (SB) and obstructive sleep apnea (OSA) using full-night polysomnography. Search strategies were developed for PubMed, Web of Science, Cochrane, LILACS, MEDLINE, and BBO-ODO and conducted until May 2019. The methodological quality was evaluated using the Qu-ATEBS tool. Two hundred seventy articles were identified and after independent screening of abstracts by two authors, 17 articles underwent full-text reading. Ten articles were excluded for not meeting the inclusion criteria and 7 were included in qualitative synthesis. Four studies support the association between SB and OSA: (a) a subtype of OSA patients may have SB as a protective response to respiratory events, (b) most episodes of bruxism occur shortly after the end of apnea/hypopnea (AH) events, (c) bruxism episodes occur secondary to arousals arising from AH events, and (d) there is a correlation between the frequency of SB and AH events, and three studies did not support: (e) AH episodes are related to non-specific SB oromotor activities, (f) SB episodes are not directly associated with the end of AH events, and (g) patients with OSA did not experience more SB events than control group. There is no scientific evidence to support a conclusive relationship between SB and OSA. Further, well-designed and randomized studies with control groups are needed to investigate whether possible mechanisms common to SB and OSA exist and whether OSA treatment could improve SB negative oral health outcomes in patients with SB and comorbidity of OSA.