Journal of Craniomandibular Function, 04/2018

The recently published Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I, which is recommended for use in clinical and research settings, has provided an update of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The authors of the DC/TMD based their publication on the results of a Validation Project (2001 to 2008), and consecutive workgroup sessions held between 2008 and 2013. The DC/TMD represents a major change in both content and procedures; nonetheless, earlier concerns and new insights have only partly been followed up when drafting the new recommendations. Moreover, the emphasis on immediate implementation in clinical and research settings is not in line with the provided external evidence on which the DC/TMD is based. This Focus Article describes these concerns with regard to several aspects of the DC/TMD: the additional classification categories; the high dependency on pressure-pain results from use of the recommended palpation technique; the TMD pain-screening instrument; the test population characteristics; the utility of additional subgroups; the use of a reference standard; the dichotomy between pain and dysfunction; and the DC/TMD algorithms. Thus, although the DC/TMD represents an improvement over the RDC/TMD, its immediate implementation in research and clinical care does not yet appear to be adequately substantiated. Keywords: classification, diagnosis, facial pain, reference standards, temporomandibular disorders

There are two main purposes for the development of diagnostic criteria: research and clinical management. The original Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)1 provided an initial structure to assist in confirming that research studies were being carried out in similar, standardized diagnostic groups, and although these diagnostic categories were only broadly defined, they did provide some consistency for studying similar diagnostic populations. However, the original RDC/TMD did not provide any assistance in management. The newer Diagnostic Criteria for TMD (DC/TMD)2 attempted to refine research and clinical criteria for the study of TMD; however, because TMD symptoms are common findings in many head and neck complaints, rigid, all-inclusive criteria are difficult to establish. Drs. Steenks, Türp, and de Wijer3 should be commended for their efforts in their Focus Article, since they have more specifically addressed some of the shortcomings of the more recent DC/TMD. This Focus Article has critically evaluated the DC/TMD, commenting on the advantages and disadvantages of these suggested guidelines. Steenks et al state both their support and concerns regarding these new criteria. I comment below on some of their statements.

First of all, we would like to thank our esteemed colleagues Drs. Steenks, Türp, and de Wijer for their thoughtful Focus Article1 related to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)2. In a way it is almost déjà vu, as already in 20093 Drs. Steenks and de Wijer aired their concerns about the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)4, which in essence would have been one of the many factors leading to the publication of the DC/TMD5. Steenks et al now raise a number of new critical comments that no doubt will be valuable to consider in the next revision of the DC/TMD.

We thank the authors of the critical commentaries for their efforts and appreciation of our recommendations to improve the DC/TMD1. Drs. Schiffman and Ohrbach have mentioned the Standards for Reporting Diagnostic Accuracy (STARD) requirement to justify the use of computed tomography (CT) and magnetic resonance imaging (MRI) as a reference standard in the Validation Project. Yet the inclusion of a reference standard that does not show an association with the temporomandibular conditions under study cannot be the basis for reporting diagnostic accuracy. Without doubt, CT and MRI play an important role in specific TMD conditions to confirm temporomandibular joint (TMJ) inflammation in rheumatic disease, malignancy, or growth disorders. In nonspecific temporomandibular conditions, however, the role of imaging is less pronounced. We are convinced that this point will continue to be discussed as long as a proper reference standard for nonspecific temporomandibular conditions is lacking. Without an appropriate reference standard, it is not possible to report the sensitivity and specificity of the (R)DC/TMD tests. The most one can achieve at this point in time is to report the reliability of test results within and among examiners. Moreover, the risk of circularity in the Validation Project raises doubt over the presented diagnostic validity, as other authors have already pointed out.

A real or virtual articulator is used for the analysis and reconstruction of the occlusion. The joint-related transfer from the clinical situation to the articulator is mostly performed with a facebow transfer. This is not based on a dynamically determined hinge axis but on nearby anatomical landmarks. The axis misalignment caused by this procedure unavoidably leads to an occlusion error in the case of a change in height in the articulator. When correcting the occlusion, the jaw relation is determined in the centric condylar position. This requires a bite-elevating centric relation record, and generally necessitates a change in height in the articulator when lowering the support pin to achieve contact. The error can be disregarded only if the deviation of the 'arbitrary axis' determined by the facebow transfer from the hinge axis of the patient happens to be very small. The repercussions of this problem have mostly been underestimated because no simple procedure has been available to date to calculate the occlusal and condylar deviation. For the first time, with the aid of the didactic Dyna-Sim-Axis software, the cause and effect of this complex problem can be explained in a way that can be grasped more easily and intuitively. Keywords: hinge axis, centric hinge axis, axis error, arbitrary axis, mounting the model, jaw relation, centric bite record, centric relation, centric relation record, facebow, locked jaw

In digital axiography, relative movements of the mandible are recorded with a paraocclusal mounted writing bow and a facebow attached to the head. The attachment of the writing bow is either carried out by individualized preparation of the paraocclusal tray in the dental laboratory (indirect method) or by intraoral attachment using a bite registration material (direct method). In the present study, a comparative analysis of the impact of the paraocclusal mounting method on the reliability of measurements was conducted. Bennett angle (BA) and condylar path angle (horizontal condylar inclination [HCI]) were recorded in all subjects using the ARCUSdigma II system, with both direct and indirect mounting methods and three repeated measurements for each method. The reliability was determined by applying the Pearson correlation coefficient and by performing a Bland-Altman analysis. The results of the present study show that both of the attachment methods allow for the acquisition of reliable data. Nevertheless, in clinical practice, the direct method is easier to use because it provides similar measurement accuracy and reliability without the need for dental laboratory work. Keywords: instrumental functional analysis, axiography, Bennett-Winkel, horizontal condylar inclination, paraocclusal

In view of the relevance of the topics put forward, it is worth taking a closer look at two new publications by Teamwork Media.

Progressive tooth surface loss unrelated to caries or trauma has been an increasing focus of dentistry over the last several decades. New clinical diagnostic procedures had to be established to address this problem. Established procedures for the measurement and classification of tooth wear and its pathological relevance for the individual patient now exist in the form of a two-stage examination procedure comprising tooth wear screening followed by an in-depth tooth wear status assessment, if indicated. This was not taken into account in the 2012 update of the German Dental Fee Schedule (GOZ), whose list of functional diagnostic services remained largely unchanged compared to the previous version of 1988. The German Dentistry Act, on the other hand, requires dentists to practice dentistry in Germany according to the current state of science. Dentists would be unable to meet the requirements of the German Dentistry Act if limited solely to the services listed in the GOZ fee schedule. Therefore, legislators drafting the new GOZ fee schedule gave dentists the option to bill for independent services not included in the fee schedule commensurate with the fees charged for analogous services of similar type, cost, complexity, and time requirement. Based on the example of tooth wear screening and tooth wear status assessment, this article describes the legal and scientific background as well as the consequences of implementing the GOZ 2012 fee schedule in daily clinical practice. Keywords: temporomandibular dysfunction (TMD), tooth wear, tooth wear screening, tooth wear status assessment, fee schedule, GOZ, analogous billing