Aims: The aim of this study was to analyze whether gender, reported bruxism, and variations in dental occlusion predicted incidence and persistence of temporomandibular disorders (TMD) during a 2 year period.
Methods: The study population comprised 280 dental students at Umeå University, Sweden. The study design was that of a case-control study within a 2-year prospective cohort. The investigation comprised a questionnaire and a clinical examination at enrolment, and at 12 and 24 months. Cases (incidence) and controls (no incidence) were identified among those without signs and symptoms of TMD at start. Cases with persistent TMD were those with such signs and symptoms at all three examinations. Clinical registrations of baseline variables were used as independent variables. Odds ratio estimates and 95% confidence intervals of the relative risks of being a case or control in relation to baseline registrations were calculated using logistic regression analyses.
Results: The analyses revealed that reported bruxism and crossbite, respectively, increased the risk of incidence and duration of temporomandibular joint (TMJ) signs or symptoms. Female gender was related to an increased risk to develop and maintain myofascial pain. Signs of mandibular instability increased the risk of long-standing signs and/or symptoms of TMD.
Conclusion: This 2-year prospective observational study indicated that reported bruxism and variations in dental occlusion were linked to incidence and persistence of TMJ signs and symptoms to a higher extent than to myofascial pain.