Parent‒Child Concordance in Toothbrushing Behaviours and Its Association with Early Childhood Caries: A Dyadic Cross-Sectional Study

Background To quantify parent‒child concordance in toothbrushing behaviours and to determine whether dyadic toothbrushing phenotypes are associated with early childhood caries (ECC) among preschool children. Methods This analytical cross-sectional study included 486 parents‒child dyads recruited consecutively during routine dental visits to a university dental clinic in Selangor, Malaysia. Parallel parent and child toothbrushing behaviours, parental modelling, supervision, dietary practices, and the Malay Parenting and Child Tooth Brushing Assessment (M-PACTA) were recorded. Children underwent calibrated caries examinations via the dmft index. Item-level concordance was assessed with Cohen’s kappa, and dyads were classified as favourable concordant (FF), parent-favourable/child-unfavourable (FU), parent-unfavourable/child-favourable (UF), or unfavourable concordant (UU). Multivariable logistic and negative binomial regression models were used to examine ECC and dmft, respectively. Results ECC was present in 278/486 children (57.2%), and the mean dmft was 3.16 (SD 3.48). The phenotype distribution was 174 FFs (35.8%), 112 FUs (23.0%), 76 UFs (15.6%), and 124 UUs (25.5%). Kappa was 0.49 for twice-daily brushing, 0.44 for bedtime brushing, and 0.31 for brushing duration. The prevalence of ECC increased from 39.1% in FF dyads to 83.1% in UU dyads ( p < 0.001). Relative to FF, the adjusted odds of ECC were greater in FU (aOR 1.82, 95% CI 1.09–3.04) and UU dyads (aOR 4.72, 95% CI 2.79–7.98); UF was imprecise (aOR 1.69, 95% CI 0.96–2.98). The UU dyads also had higher dmft counts (adjusted IRR 2.31, 95% CI 1.77–3.02). Conclusion Unfavourable parent‒child brushing concordance was strongly associated with both ECC incidence and caries burden. Family-centred prevention may benefit from assessing parental self-care, modelling, supervision, and child brushing together.