Translation and validation of a Chinese version of the Mandibular Function Impairment Questionnaire

To adapt the English version of the Mandibular Function Impairment Questionnaire (MFIQ) for Chinese-speaking patients with temporomandibular disorder (TMD) and to evaluate its validity and reliability. In total, 352 patients diagnosed with TMD according to the research diagnostic criteria for TMD (RDC/TMD) Axis I were included in this study. The psychometric evaluation included reliability, which was evaluated by internal consistency (Cronbach's alpha coefficient), and test-retest reliability and validity, which were tested by content and construct validity. Because the content validity of item 11 (kissing) was low (0·12), this item was excluded in subsequent analyses. For exploratory factor analysis, three factors were extracted, accounting for 63·6% of the variance. All items had factor loadings above 0·4. Two models were tested by confirmatory factor analysis, and the two-factor model was adopted (χ(2) /df = 2·279, root mean square error of approximation (RMSEA) = 0·086, comparative fit index (CFI) = 0·910). Internal reliability (coefficient alpha values of 0·925 and 0·720 for each factor) and test-retest reliability (ICCfactor1 = 0·895, 95% CIfactor1 = 0·869-0·918, ICCfactor2 = 0·720, 95% CIfactor2 = 0·645-0·783) of the Chinese MFIQ were excellent. A reliable and valid Chinese version of the MFIQ was constructed for the evaluation of Chinese patients with TMD after some modification of the English version of the MFIQ.