Association between dental caries experience measured by dmft and oral health-related quality of life among preschool children: a cross-sectional study

Abstract Objective To examine the association between dental caries experience, measured using the decayed, missing, and filled deciduous teeth index (dmft), and parent-reported oral health-related quality of life (OHRQoL) among preschool children in Changde, northwestern Hunan, China. Methods This cross-sectional study included 517 children aged 3–5 years and their parents recruited from five kindergartens in Changde, between January and June 2025. Dental caries experience was assessed through standardized clinical examinations, and parent-reported OHRQoL was evaluated using the Early Childhood Oral Health Impact Scale (ECOHIS). Associations with the ECOHIS total score, Child Impact Section (CIS), and Family Impact Section (FIS) were examined using three exposure specifications: continuous dmft in the full sample, binary caries experience (dmft > 0 versus dmft = 0), and continuous dmft among children with dmft > 0. The primary outcome was the ECOHIS total score. Fully adjusted linear regression models used HC3 heteroscedasticity-consistent standard errors. Ordinal logistic and Poisson regression models were used in sensitivity analyses. Results Overall, 220 children (42.55%) had caries experience. The mean dmft and ECOHIS total scores were 1.87 (SD 3.08) and 16.56 (SD 5.62), respectively. Children with dmft > 0 had higher unadjusted ECOHIS and FIS scores than children with dmft = 0. In the fully adjusted models, each additional affected tooth was associated with a 0.41-point higher ECOHIS score in the full sample (95% CI: 0.22–0.61; P < 0.001). Children with dmft > 0 had a 1.09-point higher ECOHIS score than those with dmft = 0 (95% CI: 0.07–2.11; P = 0.036). Among children with dmft > 0, each additional affected tooth was associated with a 0.53-point higher ECOHIS score (95% CI: 0.26–0.81; P < 0.001). In the binary analysis, the association was evident for FIS but not CIS. Sensitivity analyses produced directionally consistent findings for the ECOHIS total score. Conclusion Greater dental caries experience was associated with poorer parent-reported OHRQoL in this sample, particularly for family-related impacts. Because of the cross-sectional design and convenience sampling, causal, temporal, and population-level interpretations are not warranted. Longitudinal studies are needed to clarify the clinical relevance and temporal direction of these associations.