Breastfeeding and Tooth Decay

Sometimes parents may notice their toddler’s tiny new teeth look marked with brown spots or have cavities. There are several possible causes of early cavities including eating a high sugar diet. Some dentists caution that breastfeeding is a cause of dental decay and a mother may feel pressure to stop breastfeeding.  Could breastfeeding be a cause of early tooth decay?

This article

This article looks at whether breastfeeding causes tooth decay, what research has found, what other causes of early tooth decay are possible and includes official recommendations for dental teams.

#1 Does breastfeeding cause early tooth decay?

It is biologically normal to breastfeed long after little milk teeth arrive and for as long as mother and baby want. Studies of prehistoric skulls did not find decay in breastfed children 1 suggesting early tooth decay could be caused by something else in the modern child’s diet. Breastfeeding protects both a baby’s health and his oral development2 and it would make little evolutionary sense for breastfeeding to harm a baby’s teeth. Dentist Brian Palmer explains:

  • If breast milk caused decay – evolution would have selected against it.
  • It would be evolutionary suicide for breast milk to cause decay.

Could the natural sugars in breast milk cause tooth decay?

The sugar present in breast milk is lactose. Breast milk lactose is not thought to have the same effect on teeth as pure sugar because of all the protective antibacterial properties, enzymes and high pH levels in breast milk.3 For example:

  • Streptococcus mutans (a bacteria causing cavities, see #5 below) is killed by lactoferrin—a glycoprotein in breast milk that carries iron and has a bactericidal action.
  • Milk has been shown to remineralise artificially demineralised enamel in laboratory studies, in other words creating a type of tooth repair process depositing calcium and phosphorus in the enamel.45
It is biologically normal to breastfeed long after little milk teeth arrive

#2 What does research say about breastfeeding and tooth decay?

Research has shown:

Breastfeeding protects teeth

In 2015 Tham et al 6 reviewed the literature and concluded that breastfeeding may protect against dental caries.

No link between breastfeeding and tooth decay

A large randomised trial by Kramer et al in 2007 followed 13,889 mother baby breastfeeding pairs but did not establish a link between breastfeeding past the baby stage with tooth decay at age six years:

Our results, based on the largest randomized trial ever conducted in the area of human lactation, provide no evidence of beneficial or harmful effects of prolonged and exclusive breastfeeding on dental caries at early school age.

There are other risk factors for tooth decay

A study in the United States in 2007 by Hiroko Lida et al, 20077 did not find a link between breastfeeding or its duration with early childhood caries on primary teeth. It did however highlight other risk factors for early tooth decay (see #5 below).

Laboratory tests show no tooth decay unless sugar present

A study by Erickson and Mazhari found that breast milk doesn’t cause teeth to decay in laboratory tests, unless another carbohydrate source is present e.g. sugary food.8 Lavigne et al also found that decay is associated with sugar in the diet and/or bacteria levels but there is no evidence of an association of early childhood caries (ECC) with breast milk in isolation9 and Devenish et al found a sugary diet and disadvantaged socioeconomic status (poverty) were associated with ECC10.

Bottles or sippy cups are commonly associated with causing early tooth decay

#3 Dentists and breastfeeding

Some dentists say that breastfeeding; especially breastfeeding during the night is a cause of dental decay. The mechanics of breastfeeding at night are no different to breastfeeding during the day and it is biologically normal for babies and toddlers to breastfeed frequently day and night. Possible reasons for dentists to blame breastfeeding include:

Confusion with baby bottle tooth decay or “bottle mouth syndrome”

Confusion about the difference between bottle feeding and breastfeeding may have led to assumptions that breastfeeding breast milk involves the same risk to teeth as bottle-feeding formula. The risks are not the same however. Bottles or sippy cups are commonly associated with causing early tooth decay.1112 Reasons include:

  • Bottles usually contain infant formula or sometimes other drinks such as juice or soft drinks which contain high levels of sugar without the protective factors present in breast milk (see #6 below).
  • The mechanics of bottle feeding are different to breastfeeding giving greater potential for the contents of the bottle to wash over little teeth. Lavigne explains:

It is also important to understand that the mechanics of breastfeeding versus bottle feeding are very different. When babies breastfeed, the nipple is drawn far back in the mouth and the milk is released into the throat more directly, whereas in bottle feeding the milk pools around the teeth. The use of a bottle is associated with reduced salivary flow, which would cause the fermentable carbohydrate to pool around the teeth and promote the development of ECC [early childhood caries]

Unfamiliarity with natural breastfeeding

Dr Jack Newman, Canadian paediatrician and breastfeeding expert, theorises that dentists are not familiar with breastfeeding:

What dentists don’t see is that the vast majority of children who are nursed during the night do not get cavities. Since those who do end up at the dentist’s office, the doctor often concludes that this is a common problem for children nursing past the first year of life. It isn’t. Even if the child is brought to the dentist for a routine check, the dentist will not usually ask about night nursing unless the child has cavities. Most dentists probably have no idea that some or even many of their cavity-free 18-month old patients are still breastfeeding at night.

#4 How does breastfeeding affect development of the mouth and teeth?

Compared to bottle feeding, breastfeeding promotes normal mouth, palate and airway shape, and optimal teeth alignment. These factors can help to reduce sudden infant death syndrome (SIDS), sleep apnea, the need for orthodontics and can promote other future health benefits.13 14 Peres et al1516 found that breastfeeding can reduce the risk of teeth being misaligned (malocclusions).

#5 What causes tooth decay?

Since infant tooth decay is a relatively recent problem in history, what else could be causing early cavities in breastfed children? Risk factors for tooth decay or early childhood caries in infants include:

  • How often a child eats sugary food, including juices, cereals, breads, dried fruit, sweetened medicines171819 20 and formula (see #6 below).
  • Presence of Streptococcus mutans (a bacteria) in the mouth. Infection by Strep mutans from sharing spoons and using dummies or pacifiers may give rise to levels of bacteria capable of causing disease when they are combined with a sugary diet. This combination of acid and bacteria can cause rapid demineralization or dissolving of enamel, leading to dental decay.2122
  • Not cleaning teeth properly.  For more information on cleaning teeth see Avoiding Tooth Decay in Toddlers.
  • Lack of saliva flow (dry mouth). Saliva is the first line of defence to wash away food and bacteria but saliva flow is reduced during sleep and with certain medical conditions and medications (Palmer, 2000).
  • Enamel defects eg enamel hypoplasia or physical injury to enamel. Enamel hypoplasia may be linked to a mother’s illness, stress or anaemia during pregnancy or with disease in the baby during their first year of life.23
  • Maternal vitamin D levels during pregnancy. One study indicated a possible association between early childhood caries and low vitamin D levels of the mother during pregnancy.24
  • Genetics (Palmer, 2000)
  • Stress to the mother or foetus during pregnancy. Dentist Dr Patrick (Harry) Torney found in his unpublished thesis Prolonged, On-Demand Breastfeeding and Dental Decay – An Investigation, 1992 that alongside defective enamel; maternal stress, illness or a reduced intake of dairy products during the mother’s pregnancy were associated with a high rate of tooth decay for the child. 25
  • Poverty, Mexican American ethnic status, and maternal smoking during pregnancy.26
  • Low birth-weight (including premature births), malnutrition, asthma, recurrent infections, chronic diseases and medication use alongside infection caused by Strep mutans, enamel hypoplasia, intake of sugars and social conditions.27

Another possible cause of marked teeth could be fluorosis (mottling of tooth enamel due to too much fluoride) see Avoiding Tooth Decay in Toddlers for further reading.

#6 What about formula milk and teeth?

In contrast to the protective effects of breast milk, milk based infant formula including formula that doesn’t have sucrose in it has been shown to cause tooth decay.28 A study by Pamela Erickson, DDS, Ph.D. et al 29 looked at the effects of formula on enamel and found most artificial baby milks reduced the pH (acidity) significantly, supported significant bacterial growth and dissolved enamel. Some caused decay in a matter of weeks.

Recommendations for dental teams

Public Health England says:

  • dental teams should continue to support and encourage mothers to breastfeed
  • not being breastfed is associated with an increased risk of infectious morbidity (for example gastroenteritis, respiratory infections, middle-ear infections)
  • breastfeeding up to 12 months of age is associated with a decreased risk of tooth decay

Breastfeeding is the physiological norm against which other behaviours are compared; therefore dental teams should promote breastfeeding and include in their advice the risks of not breastfeeding to general and oral health.

The American Dental Association says:

we call upon all dental team members to be advocates, promoters and supporters of breastfeeding. We also encourage dental professionals to inform care-givers of the importance of cleansing infants’ teeth as soon as they erupt by using a washcloth or soft toothbrush to reduce bacterial colonization and to help reduce children’s risk of developing ECC [early childhood caries].

cleaning teeth
Not cleaning teeth properly is a risk factor for tooth decay


It is biologically normal to breastfeed for many months or years after a baby’s milk teeth first arrive. The idea that breastfeeding causes tooth decay makes no sense biologically, and is not borne out by research. Breastfeeding is too important and has too many health benefits to pressure mothers to stop breastfeeding in case of an association with dental decay when good evidence is absent. There are many possible causes of tooth decay and it is important to keep teeth clean and try to minimise all the risk factors whether breastfeeding or not. For ideas to help protect your children’s teeth see the article  Avoiding Tooth Decay in Toddlers.