the authors reviewed the factors involved in the etiology, diagnosis and treatment of temporomandibular joint disorders (tmd). although essential, specific criteria for inclusion and exclusion in tmd diagnosis have shown limited usefulness. currently, the research diagnostic criteria for temporomandibular disorders (rdc/tmd) offer the best evidence-based classification for the most common tmd subgroups. the rdc/tmd includes not only methods for physical diagnostic classification, comprised in axis i, but also methods to assess the intensity and severity of chronic pain and the levels of non-specific depressive and physical symptoms, in axis ii. although historically malocclusions have been identified as risk factors for the development of tmd-including those predominantly joint-related-in many cases the association established between these variables seems to have taken opposite directions. regarding internal tmj derangements, the results of studies on the induced shortening of the mandibular ramus, secondary to anterior articular disk displacement, indicate that repositioning the displaced disk in children or young adolescents may make more sense than previously imagined. the therapeutic use of dietary supplements, such as glucosamine sulfate, seems to be a safe alternative to the anti-inflammatory drugs commonly used to control pain associated with tmj osteoarthritis, although evidence of its effectiveness for most tmd patients has yet to be fully established.