The aim of this book is to discuss the proposed mechanisms by which oral splints exert their effects and to assess the quality of the evidence supporting the efficacy of oral splints in the treatment of temporomandibular joint disorders. The clinicians face the daunting task of determining whether or not the occlusal factors are related to each patient's temporomandibular joint disorder symptoms and then decide as to what should be the optimum contact relationship for the patient. The answers to these key questions are extremely important in the development of a case-specific, evidence based treatment plan.