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Does breastfeeding overnight cause tooth decay?

One of the primary reasons sleep training is recommended to parents is to break the ‘habit’ of breastfeeding to sleep. Between the suggestion that feeding to sleep is a crutch, and the idea that it can lead to dental problems, parents are both shamed and fear mongered into stopping something that may be working both for them and for their baby. Add to this the fact that there is information circulating online about whether or not feeding to sleep can cause dental issues, and you have a recipe for disaster if you’re a parent whose child routinely nurses to sleep.

Firstly, I’ll say that this post is not meant to replace advice from any qualified medical professional, so if you have questions about your own child’s oral health, it would be best to consult with a dental professional.

Having said that, there is a great deal of evidence to suggest that breastmilk does not lead to tooth decay.

Generally speaking, much of the evidence on feeding to sleep finds that the challenges lie in milk staying in the mouth and not being swallowed, which is more common with formula/bottle fed babies than it is with breastfed babies. Breastmilk flow slows and stops when a baby stops actively eating, thereby limiting the possibility of milk pooling in the mouth. Bottles, by comparison, do not stop their flow when a baby stops sucking, and so milk/formula is more likely to pool in the mouth.

Challenges are also common when supplemental foods are introduced, especially if the teeth and/or gums are not cleaned regularly. Sugars in foods, coupled with bacteria in the mouth, can create oral health concerns (ie tooth decay). However, breastmilk on its own has been shown to have antibacterial properties that can actually protect teeth.

In a 1999 study done by Pamela Erickson, teeth were submerged in various liquids to see what effect the fluids would have on tooth decay. Breastmilk was found to be almost identical to water 1. Further, a study in the British Dental Journal in 2008 that found that, in the absence of any underlying dental issues, such as soft enamel or genetic defects, breastmilk helped to keep bacteria in the mouth at bay 2.

The advice of feeding to sleep being ‘bad’ was likely borne in a time where bottle and/or formula feeding was the primary method for feeding babies. The concerns about breastfeeding and tooth decay comes from two small studies from the 1970s, when all 9 children who exhibited cavities had been breastfed for over 1 year 3 4. However, CDC data from 2018 shows that 83.9% of babies have breastfeeding initiated 5. In Canada, it’s even higher, with 91% of breastfeeding parents initiating breastfeeding 6.

Despite the older data showing some parallel between feeding to sleep and dental health concerns, newer data shows more positive results. Most recent research has demonstrated that the longer a child is breastfed, the lower the incidence of bite issues 7. Additionally, breastfed children showed fewer decayed baby teeth, compared to formula fed babies 8.

So, if you’ve ever been told that your baby’s association of feeding to sleep is problematic for their dental health, rest assured that breastfeeding to sleep, as well as throughout the night, does not cause tooth decay.

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Studies referenced:

  1. Investigation of the role of human breast milk in caries development: Pamela R. Erickson, DDS, PhD Elham Mazhari, 1999 (
  2. Cartwright, A. Breast is best. Br Dent J 204, 351–352 (2008).
  3. Gardner D E, Norwood J R, Eisenson J E . At will breastfeeding and dental caries: four case reports. ASDC J Dent Child 1977; 44: 186–191.
  4. Kotlow L A . Breastfeeding: a cause of dental caries in children. ASDC J Dent Child 1977; 44: 192–193.
  7. Labbok M H, Hendershot G E . Does breastfeeding protect against malocclusion? An analysis of the 1981 child health supplement of the National Health Interview Survey. Am J Prev Med 1987; 3: 227–232.
  8. Buhl M et al. Epidemiologic findings concerning the incidence of caries in the deciduous dentition of infants. Dtsch Zahnarztl Z 1986; 41: 1038–1042.

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