What conservative interventions improve bite function in those with temporomandibular disorders? A systematic review using self-reported and physical measures

Background: Bite is an important function of the human stomatognathic system. Despite this, it is commonly impaired in temporomandibular disorder (TMD) populations. The aim of this review is to evaluate the effectiveness of conservative interventions on self-reported and physical measures of bite function in individuals with TMD. Methods: This review was performed in compliance with PRISMA guidelines. An electronic search was performed on databases including PubMed, CINAHL, Embase, and Cochrane Central. Inclusion criteria were journal articles evaluating the effect of any non-pharmacological conservative interventions on bite function in participants diagnosed with TMD. Risk of bias for individual studies was assessed using the Cochrane risk-of-bias v2 tool, and the NIH NHLBI pre-post tool. Data was synthesised based on outcome measures of bite function, and the quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. Results: Eleven studies were eligible for this review. Interventions included splinting, photobiomodulation, needling, exercise, manual therapy, and patient education, which were evaluated using mastication-related pain, self-reported chewing difficulty, and bite force/endurance outcome measures. Findings suggested manual therapy, needling, oral splinting, exercise, and PBM interventions may improve bite function in TMD, although confidence in cumulative evidence ranged from moderate to very low. There was no evidence that patient education improved bite function. Conclusion: Conservative interventions may be helpful to address bite-related impairments associated with TMD, although further research is needed to improve the quality of evidence and direct clinical guidelines.