Is sustained breastfeeding associated with early childhood caries?

Abstract

There is conflicting evidence of an association between breastfeeding and dental decay in very young children (early childhood caries (ECC)). While a recent systematic review and meta‐analysis reported that breastfeeding up to the age of 12 months reduced the risk of ECC, breastfeeding beyond 12 months was associated with a greater risk (Cui et al., 2017). The evidence however, is limited and inconsistent, with some studies finding an association only if breastfeeding continued beyond 18 or 24 months. Furthermore, a recent national study from Australia demonstrated that sustained breastfeeding (> 24 months) was not associated with ECC amongst children exposed to fluoridated water (Ha et al., 2019), indicating that the use of fluoridated water early in life moderated the relationship. The purpose of this presentation is to 1) critique the evidence related to breastfeeding practices and ECC; and 2) report the findings of an investigation into the effects of breastfeeding duration and night‐time breastfeeding on ECC amongst a cohort of Australian toddlers.

The Study of Mothers’ and Infants’ Life Events affecting oral health (SMILE) is a population‐based birth cohort study conducted in Adelaide, Australia (Do et al., 2014). Data on breastfeeding practices were derived from questionnaires completed by mothers at recruitment, 3, 6, 12 and 24 months. The primary exposures were 1) duration of breastfeeding, defined as minimal (0 ‐ <1mo), breastfed for 1 ‐<6 months, breastfed for 6 ‐ < 12 months, and sustained (≥ 12months), and 2) the practice of night‐time breastfeeding at 12 months, defined as Yes or No. Standardised oral epidemiological examinations were conducted by trained and calibrated dental practitioners on children when they were 2‐3 years old (median 29.1, IQR 5.2 months). The primary outcome was ECC prevalence (presence of any decayed, missing or filled primary tooth surfaces), defined as Yes or No. Multivariable regression models generated adjusted prevalence ratios for the association between ECC and breastfeeding duration (n = 965); and between ECC and night time breastfeeding (n = 873). Confounders adjusted for in the models were free sugars intake, child age, maternal education and index of relative socioeconomic advantage and disadvantage.

We found no independent association between the prevalence of caries and sustained breastfeeding (PR = 1.42, 95% CI 0.85–2.38) or the practice of breastfeeding at night‐time at 12 months (PR 1.27, 95% CI 0.80–2.01). The only variables that were significantly associated with ECC were high free sugars intakes and greater socioeconomic disadvantage.

Adelaide is a city with a fluoridated mains water supply and hence the SMILE cohort were exposed to fluoridated water. More than 85% of participants reported tap water as their primary water source. We failed to find an association between either sustained breastfeeding or night‐time breastfeeding and ECC reported in other studies.

The results of our study support the findings of Ha et al, (2017), that any negative association between breastfeeding duration and ECC is likely to be moderated by exposure to fluoride. Future studies investigating the association between breastfeeding and ECC should, where possible, investigate the interaction between water fluoridation and breastfeeding duration.