Validation of the "obturator functioning scale" for Chinese-speaking patients with obturator prostheses after cancer-related maxillectomy

The Obturator Functioning Scale (OFS) is a scale without formal measures of validity in any language. This study aimed to translate and adapt the OFS from English to Chinese and check its reliability and validity in Chinese-speaking patients with obturator prostheses after cancer-related maxillectomy. The 15-item Chinese preversion of the OFS was completed by 133 patients in three tertiary stomatological hospitals. Of these, 41 completed it again one week after the first measurement. The patients also completed the Chinese version of the University of Washington quality of life scale (UW-QOL, Version 4). Item 12 ("upper lip feels numb") was deleted to achieve a better statistical fit. The 14-item Chinese version of the OFS (OFS-Ch) demonstrated high internal consistency (Cronbach's alpha = 0.908). The test-retest reliability coefficients for most items exceeded 0.90, indicating substantial reproducibility. Confirmatory factor analysis found that the scale consisted of three correlated factors: 1) eating (four items), 2) speech (five items), and 3) other problems (five items). This explained 70.2 % of the total variance using exploratory factor analysis. The scale was significantly convergent and discriminant and could validly discriminate between patients with Brown I and IId maxillary defects. Our results showed that the OFS-Ch scale is a valid tool for evaluating oral dysfunction and satisfaction with appearance for patients with the obturator prosthesis and identifying those at risk of poor obturator function in clinical settings.