Validity and Reliability of the Turkish Version of the Temporomandibular Joint Ankylosis Quality of Life Questionnaire (TMJAQoL-TR) in Patients with Severe Temporomandibular Disorders

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study aimed to translate, culturally adapt, and evaluate the Turkish version of the TMJAQoL (TMJAQoL-TR) in patients with severe temporomandibular disorders, including a predefined ankylosis subgroup. The manuscript is well-written and interesting for the journal readers. I have these minor comments.

Keywords: Please ensure that these keywords are MeSH terms. This situation allows a better classification of this manuscript.

Introduction: Adequate for the study purposes.

Methods: In general, the methods are appropriate. I have a few concerns:

• Please mention the study design clearly
• Please review the accomplishment of the STROBE guidelines for observational studies.
• It could be useful to have a flowchart or an illustrative figure to show the study steps or phases.

Results: Adequate for the study purposes.

Discussion: Adequate for the study purposes.

Following these recommendations, the manuscript could be accepted for publications

Congratulations to the authors of the study and this manuscript. Best wishes with the publication!

Author Response

We would like to express our sincere gratitude to the Reviewer for the careful evaluation of our manuscript and for the constructive and insightful comments. We believe that these valuable suggestions have significantly improved the scientific rigor, clarity, and overall quality of our work.

Comment 1: Keywords: Please ensure that these keywords are MeSH terms. This situation allows a better classification of this manuscript.

Response 1: We agree and have revised the keyword list to use MeSH headings. The keywords have been updated to: "Quality of Life; Temporomandibular Joint Disorders; Ankylosis; Psychometrics; Surveys and Questionnaires" (Abstract, Keywords).

Comment 2: Methods: Please mention the study design clearly.

Response 2: Thank you for this suggestion. We have explicitly stated the study design at the beginning of the Methods section, describing the work as a methodological, observational study of translation/cross-cultural adaptation with a cross-sectional assessment and a one-week test-retest component (Section 2, first paragraph).

Comment 3: Please review the accomplishment of the STROBE guidelines for observational studies.

Response 3: We appreciate this recommendation. This study was a methodological psychometric validation study designed to evaluate the translation, cross-cultural adaptation, and measurement properties of the TMJAQoL-TR through a cross-sectional assessment with a one-week test–retest reliability component. So, the study was conducted and reported in accordance with COSMIN guidelines for studies evaluating measurement properties of patient-reported outcome measures. We added this information in the text and as Supplementary file.

Comment 4: It could be useful to have a flowchart or an illustrative figure to show the study steps or phases.

Response 4: We agree. We have added an illustrative flow diagram summarizing the main phases of the study (translation/cultural adaptation, recruitment, baseline assessment, and test-retest subset) as Supplementary Figure S1, and referenced it in the Methods section (Section 2).

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

I want to thank the authors for their efforts in preparing this good study.

Minor notes:

Methods:

• The methods are written clearly and concisely. However, please add VAS to the assessment tools.

Results:

• For Table 1, please add percentages for the comorbidity details to make the table consistent.
• In Figure 1 (AMOS), I’m confused about q9. I thought it was related to Factor 2 because the line crosses F2, but it’s related to Factor 1.

Author Response

We would like to express our sincere gratitude to the Reviewer for the careful evaluation of our manuscript and for the constructive and insightful comments. We believe that these valuable suggestions have significantly improved the scientific rigor, clarity, and overall quality of our work.

Comment 1: Methods: “The methods are written clearly and concisely. However, please add VAS to the assessment tools.”

Response 1: We thank the Reviewer for this important suggestion. The Visual Analog Scale (VAS) has now been explicitly added to the “Assessment Tools” subsection of the Methods section. “Pain intensity was additionally assessed using a 10-cm Visual Analog Scale (VAS), where 0 indicated ‘no pain’ and 10 indicated ‘worst imaginable pain’. The VAS was used to evaluate concurrent validity by examining its correlation with TMJAQoL-TR total scores.”

Comment 2: Results: “For Table 1, please add percentages for the comorbidity details to make the table consistent.”

Response 2: We appreciate this suggestion to improve clarity and consistency. Table 1 is divided into two. Percentages (%) have now been added to the comorbidity variables in Table 2 and presented as: n (%)

Comment 3: In Figure 1 (AMOS), I’m confused about q9. I thought it was related to Factor 2 because the line crosses F2, but it’s related to Factor 1.

Response 3: We thank the Reviewer for pointing out this graphical ambiguity. The AMOS path diagram (Figure 1) has been revised to improve clarity and prevent misinterpretation.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I read your manuscript with great interest. The topic you address is relevant and of clear social significance. However, I believe that the manuscript could be improved through several revisions and clarifications in order to achieve greater scientific precision and stronger reader engagement.

The introduction provides a comprehensive overview of the problem. It includes references to health organizations and other authors and clearly distinguishes between the medical condition and the accompanying psychosocial states of the patients.

Materials and Methods

I recommend explicitly stating that a prospective study was conducted. This would clarify that the authors were involved in patient admission, diagnosis, and follow-up within the studied group.

This section should be entitled Materials and Methods. When describing it, a clear distinction should be made between the materials (i.e., the studied patients and the criteria for their selection) and the methods applied in patient selection and examination. In the materials subsection, it should be stated that the study included 120 participants, specifying the percentage of male and female patients, as the two sexes differ in their subjective self-assessment. I further recommend including demographic characteristics of the studied cohort when describing the sample. These characteristics are presented in Table 1; however, demographic characteristics are not outcomes of the study.

Results
Table 1 is entitled “Demographic Characteristics,” yet it also includes general medical conditions of the patients. I believe this table should be divided into two separate tables: one to be included in the Materials section and the other in the Results section.

The description of the Sawhney method for classifying TMJ ankylosis into four types should be included in the Methods section. The Results section should present the outcomes of its application, as shown in Table 2.

The results presented in the tables are also described in the text, which facilitates their comprehension.

Discussion
The Discussion section interprets the obtained results and highlights their significance. The limitations of the study are appropriately identified, providing a rationale for further research on the topic. I consider the discussion to be sufficient.

Author Response

We would like to express our sincere gratitude to the Reviewer for the careful evaluation of our manuscript and for the constructive and insightful comments. We believe that these valuable suggestions have significantly improved the scientific rigor, clarity, and overall quality of our work.

Comment 1: I recommend explicitly stating that a prospective study was conducted.

Response 1: We thank the Reviewer. The study design has now been clearly stated at the beginning of the Materials and Methods section. “This prospective cross-sectional study included a total of 120 patients who consecutively presented to the Ondokuz Mayıs University Physical Medicine and Rehabilitation outpatient clinic between March 2023 and March 2025.”

Comment 2: This section should be entitled Materials and Methods.

Response 2: We agree with the Reviewer’s suggestion regarding structural clarity. The section title has been revised from “Methods” to “Materials and Methods.”

Comment 3: Clear distinction between Materials and Methods.

Response 3: We appreciate this recommendation. The section has now been reorganized into two subsections: - Materials – Methods

Comment 4: Demographic characteristics are not outcomes

Response 4: We agree that demographic characteristics should not be presented as study outcomes. Demographic data were moved to the Materials subsection. Table 1 has been revised accordingly.

Comment 5: Table 1 includes general medical conditions – divide into two tables.

Response 5: We thank the Reviewer for this structural suggestion. Table 1 has been divided into:

Table 1: Demographic Characteristics of the Study Population

Table 2: General Medical Conditions of the Participants

The numbering of subsequent tables has been updated accordingly.

Comment 6: Sawhney classification should be described in Methods.

Response 6: We agree with the Reviewer. A detailed description of the Sawhney classification system has been added to the Methods section.

Comment 7: Discussion is sufficient

Response 7: We sincerely thank the Reviewer for the positive evaluation of the Discussion section.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review the paper titled “Validity and Reliability of the Turkish Version of the Temporomandibular Joint Ankylosis Quality of Life Questionnaire (TMJAQoL-TR) in Patients with Severe Temporomandibular Disorders.” This paper aims to translate and culturally adapt the TMJAQoL-TR, a QOL measure specifically designed for TMJ ankylosis, and to verify its reliability and validity. This objective is clearly defined and has significant clinical importance. This disease is particularly rare, making disease-specific QOL measurement highly significant. On the other hand, improvements are needed regarding the selection of subjects and the interpretation of statistical validity. Improving the following items will enhance the robustness of your paper.

 

・The abstract is too long and should be more concise. Conversely, the sentence beginning with “A weak but significant” should explain its clinical significance in greater detail.

・The original TMJAQoL is a scale exclusively for ankylosis, but in this study, ankylosis cases were few, and most included severe TMD. The authors should note that there is a high likelihood of significant bias in structural validity.

・The explanation regarding the ankylosis subgroup is lengthy and difficult for readers to understand. Furthermore, the sample size for this subgroup should be clearly specified.

・To perform both EFA and CFA, approximately 200 cases is generally desirable, while 120 cases is borderline.

・The basis for “10 participants per item” is outdated and is no longer recommended (especially for CFA). EFA alone is sufficient; if conducting CFA, the sample size limitations should be clearly stated and caution should be advised.

・The test-retest ICC of 0.995 indicates near-perfect agreement, which is unnatural for a clinical study. The response procedure and conditions during retesting (same facility, same researcher, same room, etc.) should be clarified.

・The explanation of the two-factor model for structural validity is insufficient. Although the two-factor model is based on EFA results, it is necessary to present the factor loading table and discuss validity by comparing it with the original structure.

・The methodology must be described in greater detail as a validation study, including specifics of the translation process, handling of missing values, and whether normality was verified.

Author Response

We would like to express our sincere gratitude to the Reviewer for the careful evaluation of our manuscript and for the constructive and insightful comments. We believe that these valuable suggestions have significantly improved the scientific rigor, clarity, and overall quality of our work.

Comment 1: The abstract is too long and should be more concise. Conversely, the sentence beginning with ‘A weak but significant’ should explain its clinical significance in greater detail

Response 1: We thank the Reviewer. The abstract has been shortened for clarity and conciseness. The sentence regarding the weak but significant correlation has been revised to better clarify its clinical relevance. “A weak but significant negative correlation with the SF-36 physical role subscale suggests that TMJ-related quality-of-life impairment is associated with role limitations in daily activities, although the magnitude of this association was modest.”

Comment 2: The original TMJAQoL is a scale exclusively for ankylosis, but in this study, ankylosis cases were few, and most included severe TMD. The authors should note that there is a high likelihood of significant bias in structural validity.

Response 2: We appreciate this important methodological observation. Among the total sample, 26 participants (21.7%) were diagnosed with TMJ ankylosis, and this information has now been clearly specified in the Materials section. We acknowledge that the predominance of severe TMD cases may influence structural validity. Accordingly, this limitation has been explicitly addressed in the Discussion, and the factor structure findings are now interpreted with caution, particularly regarding applicability to ankylosis-dominant populations.

Comment 3: The explanation regarding the ankylosis subgroup is lengthy and difficult for readers to understand. Furthermore, the sample size for this subgroup should be clearly specified.

Response 3: The description of the ankylosis subgroup has been simplified, and the exact number and percentage of ankylosis cases have now been clearly specified in the Materials section.

Comment 4: To perform both EFA and CFA, approximately 200 cases is generally desirable, while 120 cases is borderline.

Response 4: We appreciate this methodological concern. We acknowledge that larger samples are generally recommended when conducting both EFA and CFA. Accordingly, the CFA findings have been reframed as preliminary, and a clear statement regarding the sample size limitation has been added to the Limitations section. Future studies with larger samples are recommended to further confirm the stability of the factor structure.

“The total sample size, while adequate for preliminary validation, may be considered borderline for confirmatory factor analysis. Therefore, the structural findings should be interpreted as preliminary and require replication in larger, diagnostically homogeneous cohorts.” Added to limitations section.

Comment 5: The basis for “10 participants per item” is outdated and is no longer recommended (especially for CFA). EFA alone is sufficient; if conducting CFA, the sample size limitations should be clearly stated and caution should be advised.

Response 5: We thank the Reviewer for this important methodological clarification. We acknowledge that the sample size may be considered borderline for CFA. The confirmatory findings are now described as preliminary, and a clear limitation statement has been added advising cautious interpretation and recommending replication in larger samples.

Comment 6: The test-retest ICC of 0.995 indicates near-perfect agreement, which is unnatural for a clinical study. The response procedure and conditions during retesting (same facility, same researcher, same room, etc.) should be clarified.

Response 6: We thank the Reviewer for this important observation. Additional details regarding the retest procedure have been added to the Methods section. The retest was conducted after a one-week interval in a clinically stable subsample, with no interim treatment initiated. The second administration was performed under standardized outpatient conditions using identical instructions. As the TMJAQoL-TR is a self-reported instrument, examiner-related variability was minimized. The short retest interval and clinical stability may explain the very high ICC values.

Comment 7: The explanation of the two-factor model for structural validity is insufficient. Although the two-factor model is based on EFA results, it is necessary to present the factor loading table and discuss validity by comparing it with the original structure.

Response 7: We thank the Reviewer for this important suggestion. A detailed factor loading table has now been added (Table 10). All standardized loadings exceeded the recommended 0.50 threshold (range: 0.53–0.85), supporting adequate item–factor relationships. Communality values ranged between 0.28 and 0.72, indicating that each item contributed meaningfully to the latent construct. No problematic cross-loadings were observed, demonstrating a clear two-factor structure.

Additionally, construct reliability and convergent validity indices were calculated and added (Table 11). Composite Reliability was 0.90 for Factor 1 and 0.77 for Factor 2, while Average Variance Extracted (AVE) was 0.56 and 0.40, respectively, confirming acceptable internal coherence of the constructs.

Compared with the original TMJAQoL structure, the Turkish version preserved the conceptual separation between functional limitation and symptom-related impact domains, although item distribution reflects the broader severe-TMD population included in this validation. This has now been clarified in the Discussion.

Comment 8: The methodology must be described in greater detail as a validation study, including specifics of the translation process, handling of missing values, and whether normality was verified.

Response 8: We thank the reviewer for this important methodological comment. In response, the Methods section has been revised and expanded to clarify the validation framework of the study. Specifically:

The translation and cross-cultural adaptation procedure has been further detailed in accordance with Beaton et al.’s guidelines, including the qualifications of translators, independence of forward translations, synthesis procedure, back-translation process, and pilot testing phase. We added “Both forward translators were native Turkish speakers fluent in English; one had clinical expertise in temporomandibular disorders, and the other had methodological experience in health measurement instruments. The translators worked independently to minimize bias. The synthesis process focused on semantic, idiomatic, experiential, and conceptual equivalence rather than literal translation. During the expert committee review, discrepancies were resolved through consensus, ensuring conceptual fidelity to the original construct measured by the TMJAQoL.”

A new paragraph describing data completeness and handling of missing values has been added. We clarified that questionnaires were checked at the time of administration, no missing item-level data were observed in the final dataset, and therefore no imputation procedure was required. “All questionnaires were reviewed for completeness at the time of administration. No item-level missing data were detected in the final dataset for TMJAQoL-TR, OHIP-14, or SF-36. Therefore, no data imputation procedure was required. In cases where minor omissions occurred during initial completion, participants were asked to review and complete the missing responses immediately. Consequently, analyses were conducted using complete-case data.”

The statistical analysis section has been expanded to explicitly state how normality was assessed (Kolmogorov–Smirnov test and examination of skewness–kurtosis values), and how distribution results guided the selection of parametric or non-parametric analyses.

” Distributional assumptions were examined using the Kolmogorov–Smirnov test and inspection of skewness and kurtosis values. Variables with p > 0.05 and skewness–kurtosis values between –1 and +1 were considered normally distributed. Based on distribution results, parametric or non-parametric statistical tests were selected accordingly. Since several scale scores demonstrated non-normal distribution, correlation analyses were performed using Spearman’s rank correlation coefficient”

Author Response File: Author Response.pdf

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

Congratulations. All modifications confirmed.