Application of principles of evidence-based medicine to occlusal treatment for temporomandibular disorders: are there lessons to be learned?

Critical evaluation of treatment methods has become an important part of health care and will certainly have a major influence on decisions about acceptable treatment methods in the future. Evidence-based medicine (EBM) means the systematic, explicit, and judicious implementation of the best evidence in patient care. The most reliable sources of evidence are high-quality systematic reviews and randomized controlled trials (RCTs). A systematic EBM approach could be particularly useful in the treatment of temporomandibular disorders (TMD), where controversial and conflicting ideas about management are common. In this field, concerns about the lack of evidence are often expressed. This article aims to elucidate and discuss the application of EBM to the treatment of TMD, using the most controversial treatments (i.e., occlusal treatments) as an example. By applying the principles of EBM to TMD treatments, we wish to highlight some of the important issues that form the basis for high-quality care in this field. A systematic review of occlusal treatments (occlusal splints and occlusal adjustment) updated to January 2003 revealed 16 RCTs of occlusal splints and 4 of occlusal adjustment. The overall quality of the trials was fairly low. Recently, however, some high-quality RCTs of occlusal splints have been published. The most obvious methodologic shortcomings in published trials included problems in defining the patient population, inadequacies in performing randomization and blinding, problems in defining the therapies or appropriate control treatments, short follow-ups, and problems in monitoring patient compliance. Occlusal splint studies yielded equivocal results. Even in the most studied area, stabilization splints for myofascial face pain, the results do not justify definite conclusions about the efficacy of splint therapy. Their clinical effectiveness to relieve pain also seems modest when compared with pain treatment methods in general. None of the occlusal adjustment studies provided evidence supporting the use of this treatment method. The clinical implications of the findings and future perspectives are discussed.