Associations of early childhood caries and child intelligence quotient: evidence from the Shanghai Birth Cohort.

Introduction and aims: Growing evidence indicates that early childhood oral health, particularly dental caries, may be associated with children's cognitive development; however, findings remain inconsistent, especially in preschool-aged populations. This study aimed to examine the associations between early childhood caries and intelligence quotient (IQ) in four-year-old children. Method: This study used a cross-sectional design based on data from 1,099 four-year-old children in the Shanghai Birth Cohort. Oral health measurements included the decayed, missing, filled teeth (dmft) index, and caries status. Child IQ was assessed using the fourth edition of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-IV). Multivariable linear regression models were used to estimate the associations between oral health indicators and child IQ. Restricted cubic spline models were used to assess non-linear relationships. Results: Higher dmft index scores were significantly associated with lower full scale intelligence quotient (FSIQ) scores ( Conclusion: Dental caries, particularly as measured by the dmft index, was associated with lower IQ scores in preschool children. These findings should be interpreted as population-level associations rather than deterministic outcomes for individual children. Longitudinal studies are needed to confirm these findings and clarify the mechanisms linking early oral health and neurocognitive development.