Abstract

The article presents the Polish version of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), the process of document translation and cultural adaptation.

Keywords: DC/TMD, temporomandibular disorders, TMD, diagnostic criteria

Temporomandibular disorders (TMDs) constitute a heterogeneous group of conditions characterized by the presence of signs and symptoms associated with the masticatory system, such as pain in the masticatory muscles and/or the temporomandibular joints (TMJs), limited jaw movements, and TMJ sounds (i.e., clicking and/or crepitus) during function.¹ Temporomandibular disorders pose a significant public health problem, affecting approx. 5–12% of the population, based on the United States estimates,² and likely have the same prevalence in Poland. Our understanding of the etiology, diagnosis and treatment of TMDs continues to improve. An essential part of the methodology facilitating this development is the use of standardized classification systems for ascertaining the case status, and for further investigating the disorders in terms of mechanisms and taxonomic improvement.

The first evidence-based diagnostic method for TMDs emerged in 1992 as the Research Diagnostic Criteria for TMDs (RDC/TMD).³ The RDC/TMD came from the openly acknowledged need for a diagnostic system that could not only reliably distinguish cases from controls for epidemiologic and clinical research purposes, but also differentially define and diagnose the common sub­types, such as pain-related TMDs and mechanical disturbances within TMJs. The RDC/TMD consisted of 2 axes: Axis I for a physical diagnosis; and Axis II for assessing the behavioral and functional status of the patient. The RDC/TMD utilize epidemiologic data to determine at a population level the threshold distinguishing a disorder from ordinary symptoms, such as a transient pain process or TMJ clicking that exhibits no symptoms or functional consequences. In the subsequent 2 decades, the RDC/TMD evoked a significant response to these foundational principles from the international scientific community – the research built on testable evidence in the context of an iterative process, providing a basis for reliable and valid revisions that were to come next.⁴

The RDC/TMD instrument utilizes both self-reported and clinical examination data. While the instrument was developed in English, it served as a source for more than 20 approved translations over the 10 years following its development, which included Polish among the languages. The RDC/TMD were replaced by the Diagnostic Criteria for TMDs (DC/TMD), which represent the current reference standard for a reliable and valid diagnosis of the prevalent TMDs for both clinical and research use.⁵ While the DC/TMD are not, as of yet, a mandatory protocol in any national patient care guidelines of which we are aware, it is the de facto standard for the clinical examination and diagnosis of the prevalent non-odontogenic disorders affecting the masticatory system.^{6, 7}

A key feature of both the RDC and DC approaches to TMD assessment is their dual-axis structure. Axis I, which concerns the physical domain, includes guidelines for oral history taking, as well as the clinical assessment of the joints and jaw muscles, and it leads to an algorithm-based dia­gnosis of the prevalent TMDs. Axis II, which concerns the psychosocial and behavioral dimensions, comprises instruments for the evaluation of pain intensity, pain-related disability, the functional limitation of the masticatory system, oral overuse behaviors, depression, anxiety, and the extent of multi-determined physical symptoms throughout the body. The content of the DC/TMD is presented in Table 1.

Both the English and the Polish version of the DC/TMD are available on the INfORM (International Network for Orofacial Pain and Related Disorders Methodology) website: https://ubwp.buffalo.edu/rdc-tmdinternational/tmd-assessmentdiagnosis/dc-tmd. The examination procedures are available as a detailed document with explanations and illustrations,⁸ and the examination process is fully presented in a video.⁹ The Polish translation package includes Axis I and Axis II instruments and diagnostic algorithms (as listed in Table 1), complete specifications for a clinical examination, and a scoring manual for self-reporting instruments.

The English source version of the DC/TMD was formally translated into Polish – the target language – following the guidelines described in several documents.^{10, 11, 12} They embrace guidelines for establishing the cultural equivalency of instruments, which describe how to create a valid translation of an instrument designed to collect research-quality data,¹⁰ guidelines on the translation and adaptation of the DC-TMD protocol, which highlight specific translation challenges with regard to the DC/TMD,¹¹ and guidelines on the translation and review process (step by step, with explanatory notes), which further illustrate the procedures involved in the rigorous translation.¹² The development of a valid translation consists of 10 stages, with each stage resulting in written documentation via the translation log:

1. forward translation by 2 independent translators whose first language is Polish;

2. independent resolution of discrepancies between the 2 forward translations and their synthesis;

3. backward translation by 1 independent translator whose first language is English;

4. independent review of the backward translation vs. the source document by a medical translation professional;

5. revision and iterative development related to discre­pancies that require repeating the forward and backward translations of the indicated parts, followed by an independent review;

6. after approval from an independent reviewer, consoli­dation of all translation and review activity into a single instrument appropriate for an internal review;

7. assembly of an expert committee comprised of 4 individuals and review of the translation quality by each committee member;

8. construction of a pre-final instrument;

9. independent review of the translation process and documentation; and

10. posting the translation on the INfORM website so that others can begin to contribute to Phase II: Translation Validation and Documentation.¹⁰

Specific details further highlight the rigorous process required for creating a medical instrument appropriate for both patient care and research. For the Polish trans­lation, there were 2 forward translators whose first language is Polish – one was informed or aware of the health concepts intrinsic to the DC/TMD, and the other was uninformed or naive of those concepts. This ideal allocation of the knowledge regarding the instrument ensures that the final translation adheres to both technical accuracy and the common-sense usage of Polish. Each forward translator produced an independent translation from the source language into the target language. The team leader reviewed both forward translations and resolved any differences in the translation style to facilitate the synthesis of the 2 translation versions. The backward translation of the synthesized forward translation was done by 1 independent translator whose first language is English and whose second language is Polish. The backward translator was totally blinded to the original source. The source and the backward translation were submitted for simultaneous evaluation by an independent reviewer, a medical translation professional who works across multiple areas of medicine and whose first language is English – the language of the source instrument. This particular reviewer was also highly experienced with the content and purpose of the source instrument. The reviewer identified the potential translation problems with regard to the backward translation, adding comments on the nature of the dis­crepancies. This review was sent back to the team leader. During revision and iterative development, the team leader coordinated the repeated forward and backward translations of the problematic areas until the independent reviewer approved the backward translation as the evidence of an acceptable forward translation.

The team leader then created a consolidated version of the approved forward-translation parts for each instrument, and the necessary comments were added for each item. An expert committee for cultural equivalency review was created; the committee consisted of 4 members, not involved in any of the prior steps: 3 of them were clinicians, and one was a language expert. Each committee member independently reviewed the forward translation against the source and the backward translation for the suitability of content within the context of the Polish culture. Recommendations were made with respect to 4 areas: semantic, idiomatic, experiential, and conceptual equivalence. The expert committee members suggested, as needed, further changes to the translation to ensure cultural appropriateness. Collectively, the review of an expert committee leads to cultural validity. The re­commendations were submitted to the team leader, who incorporated the concerns and suggestions into the final forward translation.

On the home stretch, the team leader created the final draft of the instrument and compiled the translation logs. The final instrument draft serves for initial administration and the subsequent empirical testing. All documentation was sent to the Chair of Committee on Translation at INfORM, who reviewed the materials and determined whether the documentation for the translation process was acceptable. After the INfORM review was completed and the translation was approved, the Polish DC/TMD were posted on the INfORM website (https://buffalo.app.box.com/s/4ujx1lvndnxtw4suzvk2ymu9xhe8a5oz).

Although the accumulation of evidence over the years has been a strong argument against invasive and irreversible therapeutic TMD procedures, the biopsychosocial model of TMDs is still not fully accepted by all clinicians in Poland. It is partly due to the lack of knowledge on how to effectively implement the model.¹³ Hence, this article aimed to introduce the operationalized tools for both a reliable and valid clinical examination leading to the diagnosis and psychosocial assessment of patients with TMDs. The DC/TMD provide the structure for the “bio” with Axis I diagnoses for physical disorders, and the structure for the “psycho” and “social” with Axis II tools for the assessment of the psychosocial profile. This approach is recommended for use in all patients with a potential TMD diagnosis.