Summary: There is a need to expand the current temporomandibular disorders' (TMDs) classification to include less common but clinically important disorders. The immediate aim was to develop a consensus‐based classification system and associated diagnostic criteria that have clinical and research utility for less common TMDs. The long‐term aim was to establish a foundation, vis‐à‐vis this classification system, that will stimulate data collection, validity testing and further criteria refinement. A working group [members of the International RDC/TMD Consortium Network of the International Association for Dental Research (IADR), members of the Orofacial Pain Special Interest Group (SIG) of the International Association for the Study of Pain (IASP), and members from other professional societies] reviewed disorders for inclusion based on clinical significance, the availability of plausible diagnostic criteria and the ability to operationalise and study the criteria. The disorders were derived from the literature when possible and based on expert opinion as necessary. The expanded TMDs taxonomy was presented for feedback at international meetings. Of 56 disorders considered, 37 were included in the expanded taxonomy and were placed into the following four categories: temporomandibular joint disorders, masticatory muscle disorders, headache disorders and disorders affecting associated structures. Those excluded were extremely uncommon, lacking operationalised diagnostic criteria, not clearly related to TMDs, or not sufficiently distinct from disorders already included within the taxonomy. The expanded TMDs taxonomy offers an integrated approach to clinical diagnosis and provides a framework for further research to operationalise and test the proposed taxonomy and diagnostic criteria.

This review explores the principles and process associated with the diagnosis of temporomandibular disorders (TMDs). TMD diagnosis has evolved substantially over the past 25 y. Previously, diagnosis focused solely on aberrations in oral structures, largely without empirical evidence. The Research Diagnostic Criteria for TMD (RDC/TMD) were developed on core principles of 1) a dual-axis system reflecting the biopsychosocial model, 2) a clear operationalization for reliability, and 3) the allowance of multiple diagnoses. These principles were retained in the subsequent validation research of the RDC/TMD, and the current diagnostic system—the Diagnostic Criteria for TMD (DC/TMD)—has improved on those principles as well as on diagnostic validity and protocols for assessing the psychosocial domain. Further investigations into etiology and its potential contribution to taxonomy revision are described, particularly within the context of complex disease. The review concludes with an outline of major research areas already underway that will support future revisions of the DC/TMD.

Four studies are presented testing the validity and reliability of pressure pain thresholds (PPTs) and of examination parameters believed to be important in the clinical assessment of sites commonly used for such measures in patient samples. Forty-five patients with a myogenous temporomandibular disorder were examined clinically prior to PPT measures. Criteria for history and examination included functional aspects of the pain, tissue quality of the pain site, and the type of pain elicited from palpation. Control sites within the same muscle and in the contralateral muscle were also examined. PPTs were measured as an index of tenderness using a strain gauge algometer at these sites. The data from the 5 male subjects were excluded from subsequent analyses due to the higher PPT in the males and to their unequal distribution among the various factorial conditions. The first study demonstrated strong validity in PPT measures between patients (using pain sites replicating the patients' pain) and matched controls (n = 11). The PPT was not significantly different between the primary pain site (referred pain and non-referred pain collapsed) and the no-pain control site in the same muscle (n = 16). The PPT was significantly lower at the pain site compared to the no-pain control site in the contralateral muscle (n = 13). The second study indicated adequate reliability in patient samples of the PPT measures. In the third study, the PPT was significantly lower at sites producing referred pain on palpation compared to sites producing localized pain on palpation. The PPT findings from the control sites were inconsistent on this factor. The fourth study presented preliminary evidence that palpable bands and nodular areas in muscle were most commonly associated with muscle regions that produce pain; such muscle findings were not specific, however, for regions that produce pain. Further, the intraexaminer reliability in reassessing these pain sites qualitatively was only fair. Referred pain had a poor association with the pain pattern and physical findings, which may suggest a need to reevaluate part of the theory regarding referred muscle pain. The reliability of PPT measures was better overall than the reliability of the signs and site-specific symptoms, suggesting that pressure pain thresholds may be an important tool in clinical studies of pain. PPT measures demonstrate a high within-subject variability in pain patient subjects as well as non-pain subjects.(ABSTRACT TRUNCATED AT 400 WORDS)