A longitudinal study on the impact of breastfeeding with or without formula milk on dental caries

Concerns exist about prolonged breastfeeding increasing dental caries risk, but evidence is mixed. This 2-year cohort study followed 486 toddlers, to examine the association between breastfeeding duration and caries at age 3. Caregivers reported feeding practices and potential confounders every 6 months. "Full breastfeeding" was defined as feeding breastmilk without formula milk regardless of other foods/liquids, whereas "any breastfeeding" was feeding breastmilk with/without formula milk. A calibrated dentist performed dental examinations. We used multivariable log-binomial and negative binomial regressions to estimate relative risks (RRs) and 95% confidence intervals (CIs) for caries prevalence and severity, adjusted for confounders. At 3-year-old, 60.3% of children exhibited caries (mean decayed-and-filled-teeth, dft: 3.3). Notably, full breastfeeding for 6-17 months reduced caries prevalence (RR = 0.84, 95%CI 0.73-0.98 for 6-11 months; RR = 0.78, 95%CI 0.63-0.96 for 12-17 months). Conversely, any breastfeeding ≥ 18 months significantly increased caries risk (RR = 1.45, 95%CI 1.31-1.60). Full breastfeeding ≥ 6 months or any breastfeeding 6-17 months was associated with lower dft scores in children. Our findings suggest a complex relationship between breastfeeding duration and caries. Full breastfeeding for moderate durations (6-17 months) offers protective benefits, while any breastfeeding ≥ 18 months increases risk in this population.