Prevalence of bruxism in patients with different research diagnostic criteria for temporomandibular disorders (RDC/TMD) diagnoses.

The relationship between bruxism and temporomandibular disorders is complex and is not yet clearly understood. The purpose of this study was to investigate the prevalence of clinically diagnosed bruxism in 212 patients with different Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) diagnoses, as compared with that in 77 sex- and age-matched TMD-free subjects. A significant association between bruxism and temporomandibular disorders emerged (p < 0.05). The highest prevalence of bruxism was found in patients with the following diagnoses: combined myofascial pain and disk displacement (87.5%); combined myofascial pain, disk displacement, and other joint conditions (73.3%); and myofascial pain (68.9%). In general, it is suggested that bruxism has a stronger relationship with muscle disorders than with disk displacement and joint pathologies, and that such a relationship seems to be independent from the presence of other RDC/TMD diagnoses along with myofascial pain.