Focus Article: Evaluation of the Research Diagnostic Criteria for Temporomandibular Disorders for the Recognition of an Anterior Disc Displacement with Reduction

The aim of this Focus Article is to review critically the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) for the recognition of an anterior disc displacement with reduction (ADDR) in the temporomandibular joint (TMJ). This evaluation is based upon the experience gained through the careful analysis of mandibular movement recordings of hundreds of patients and controls with or without an ADDR. Clinically, it is a challenge to discriminate between the two most prevalent internal derangements of the TMJ: ADDR and symptomatic hypermobility. It is due to the very nature of these derangements that they both show clicking on opening and closing (reciprocal clicking), making reciprocal clicking not a distinguishing feature between these disorders. However, there is a difference in timing of their opening and closing clicks. Unfortunately, it is not feasible to use this difference in timing clinically to distinguish between the two internal derangements, because it is the amount of mouth opening at the time of the clicking which is clinically noted, not the condylar translation. Two other criteria proposed by the RDC/TMD for the recognition of an ADDR are the 5-mm difference in mouth opening at the time of the opening and closing clicks, and the detection of joint sounds on protrusion or laterotrusion in case of non-reciprocal clicking. These, however, run the risk of false-positive or negative results and therefore have no great diagnostic value. Instead, it is recommended that the elimination of clicking on protrusive opening and closing be examined in order to distinguish ADDRs from symptomatic hypermobility. Keywords: anterior disc displacement, clinical examination, mandibular movement recordings, RDC/TMD, temporomandibular joint