Psychometric Evaluation of the Vietnamese Version of the Child-OIDP Index Among Schoolchildren Aged 12–15 Years

Background: Oral health–related quality of life (OHRQoL) has become an essential dimension for evaluating the functional, psychosocial, and social consequences of oral conditions in children and adolescents. This study aimed to translate, culturally adapt, and psychometrically evaluate the Vietnamese version of the Child-Oral Impacts on Daily Performances (Child-OIDP) index. Methods: A cross-sectional study was conducted among 505 schoolchildren aged 12–15 years in Ho Chi Minh City. The translation and cultural adaptation followed international guidelines. Clinical oral examinations were performed using WHO criteria. Psychometric testing included internal consistency, test–retest reliability, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), concurrent validity, and discriminant validity. A subsample of 135 adolescents completed the instrument twice for reliability assessment. Results: Overall, 65.1% of participants reported at least one oral impact. Eating, smiling, and cleaning teeth were the most frequently affected daily performances. The Vietnamese Child-OIDP demonstrated good internal consistency (Cronbach’s alpha = 0.82) and excellent test–retest reliability (ICC = 0.89). EFA supported a three-factor structure representing functional, psychosocial, and social domains, explaining 62.83% of the variance. CFA showed satisfactory model fit (RMSEA = 0.092; CFI = 0.906; GFI = 0.958). Child-OIDP scores were significantly associated with self-rated oral health, satisfaction with appearance, and perceived treatment need (all p < 0.001), and were higher among children with dental caries and malocclusion. Conclusions: The Vietnamese Child-OIDP is a reliable and valid instrument for assessing OHRQoL in adolescents. Its application in surveys, school-based programs, and clinical evaluations may support more comprehensive oral health assessments and guide evidence-based planning in Vietnam.