Relationship between bruxism and temporomandibular disorders: a systematic review of literature from 1998 to 2008

Objectives: The present paper aims to systematically review the literature on the temporomandibular disorders (TMD)-bruxism relationship published from 1998 to 2008. Study design: A systematic search in the National Library of Medicine's PubMed database was performed to identify all studies on humans assessing the relationship between TMD symptoms and bruxism diagnosed with any different approach. The selected articles were assessed independently by the 2 authors according to a structured reading of articles format (PICO). Results: A total of 46 articles were included for discussion in the review and grouped into questionnaire/self-report (n = 21), clinical assessment (n = 7), experimental (n = 7), tooth wear (n = 5), polysomnographic (n = 4), or electromyographic (n = 2) studies. In several studies, the level of evidence was negatively influenced by a low level of specificity for the assessment of the bruxism-TMD relationship, because of the low prevalence of severe TMD patients in the studied samples and because of the use of self-report diagnosis of bruxism with some potential diagnostic bias. Conclusions: Investigations based on self-report or clinical bruxism diagnosis showed a positive association with TMD pain, but they are characterized by some potential bias and confounders at the diagnostic level (eg, pain as a criterion for bruxism diagnosis). Studies based on more quantitative and specific methods to diagnose bruxism showed much lower association with TMD symptoms. Anterior tooth wear was not found to be a major risk factor for TMD. Experimental sustained jaw clenching may provoke acute muscle tenderness, but it is not analogous to myogenous TMD pain, so such studies may not help clarify the clinical relationship between bruxism and TMD