Sleep bruxism and related risk factors in adults: A systematic literature review

Objective: The aim of this article was to systematically review the literature to assess the relationship between risk factors and sleep bruxism (SB) in adults (age >= 18 years). Design: A systematic search of the following databases was carried out: PubMed, Embase, Scopus, Cochrane Oral Health Group's Trial Register and Cochrane Register of Controlled Trials, Web of Science, LILACs and SciELO. Nine out of the 4583 initially identified articles were selected. This review was conducted according to the guidelines from the Cochrane Handbook for Systematic Reviews of Interventions, with reporting in agreement to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Results: Among the nine analyzed articles, associations between SB and gastro-esophageal reflux disease (GERD) (OR = 6.6, CI = 1.4-30.9) was found in one randomized clinical trial (RCT). Four cross-sectional studies suggested history of SB during childhood (OR = 8.1 CI = 5.4-12-2), age (OR = 3.1, CI = 2.3-4.1) and chronic migraine (OR = 3.8, C.I = 1.8-7.8) as determinant factors for the development of SB. In one case-control study, patients with genetic polymorphisms were more likely to present SB (OR = 4.3, CI = 1.6-11.3). Smoking (OR = 2.8, CI = 2.2-3.5) and alcohol intake (OR = 1.9, CI = 1.2-2.8) showed moderate association in two case-control studies. Conclusions: History of SB during childhood, gastro-esophageal reflux disease and genetic polymorphisms seem to be important risk factors associated to SB in adults. Dry mouth on awakening seems to be a protective factor. Association does not infer with causality. Even if the evidence emerged from the considered studies was clinically relevant, further studies are requested to better understand the biological mechanisms behind the described associations.