Development of chewing ability questionnaire for Thai temporomandibular disorder patients

Objective: To develop a Thai version of chewing ability questionnaire for local Temporomandibular Disorder (TMD) patients for use in clinical practice. Materials and methods: This study consisted of two parts. The first part was to develop a questionnaire. A list of local Thai foods, which can either elicit painful symptoms or cause no pain when chewing, was provided to a group of 30 TMD patients. Subsequently, 200 healthy subjects were selected to evaluated the toughness and hardness of those foods listed by TMD patients. The final questionnaire included seven selected foods and chewing tasks. The second part of the study tests the validity and reliability of the questionnaire. The final questionnaires were given to both a TMD group and a healthy control group. Both groups were required to answer the final version of the questionnaire. In order to test the criterion validity, scores of chewing ability from the questionnaire were compared with measurements of masticatory performance using a sieving technique. One week later, the same 72 people were re-tested using the same questionnaire. Results: The designed questionnaire was able to distinguish between healthy subjects from TMD patients. Scores of chewing ability of TMD patients correlated significantly with their level of pain (p<0.05). Criterion validity was in an average range (correlation coefficient = 0.594). The questionnaire indicated a strong test-retest reliability (correlation coefficient = 0.968). Conclusion: The newly developed Thai questionnaire was able to reliably and conveniently assess the chewing ability of Thai TMD patients in clinical practice.