Breastfeeding and Tooth Decay

Sometimes a parent will notice their toddler’s tiny new teeth are marked or have cavities. Parents naturally worry about what could have caused these and how to prevent further damage. There are several possible causes of early cavities but some dentists blame breastfeeding; especially breastfeeding during the night. Some dentists may advise a mother to wean or night wean so that she feels pressured to stop breastfeeding.

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 2 and his oral development 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) 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 4.

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

Research has not found a link between breastfeeding and early tooth decay. Research has shown:

Breastfeeding protects teeth

In 2015 Tham et al 5 reviewed the literature and concluded that breastfeeding may protect against dental caries.

No link found 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, 20076 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 7.

#3 Why do dentists blame breastfeeding?

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 8 9. 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. Joylyn Fowler explains:

The mechanics of breastfeeding make it unlikely for human milk to stay in the baby’s mouth for long. During breastfeeding, the nipple is drawn deep within the baby’s mouth, and milk is literally squirted into the back of his mouth. The suckling process includes a swallow and the nursing child must swallow before he can go on to the next step. In contrast, baby bottles can drip milk, juice, or formula into the baby’s mouth even if he is not actively sucking. If the baby does not swallow, the liquid can pool in the front of the mouth around the teeth. The artificial nipple is very short, so the liquid in the bottle is likely to pass over teeth before being swallowed.

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.

Historic studies

The Australian Breastfeeding Association refers to poor quality historical studies that may explain why dentists blame breastfeeding as a cause of early childhood cavities;

The belief that breastfeeding to sleep causes dental caries is based on only three articles by Bram and Maloney, Gardner, Norwood and Eisenson and Kotlow that were done in the late 1970s and early 1980s. The authors presented case reports of just nine babies in total, two of whom also received bottles.

#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 10 11. Peres et al12 13 found that breastfeeding can reduce the risk of teeth being misaligned (malocclusions).


#5 What causes tooth decay?

If infant tooth decay is a relatively recent problem, yet breast milk has always been the same recipe since historical times, 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 medicines 1415 16.
  • Presence of Streptococcus mutans (a bacteria) in the mouth. Infection by Strep mutans from adults’ kisses and sharing spoons, using dummies or pacifiers can 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 decay17.
  • Not cleaning teeth properly. Decay of the top front teeth could occasionally be associated with a tight membrane (labial frenulum) connecting the upper lip to the gum. This might happen if the membrane traps solid food or makes it difficult to clean where the teeth meet the gums beneath the top lip.
  • 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 18.
  • 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 19.
  • Poverty, Mexican American ethnic status, and maternal smoking during pregnancy 20.
  • 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 21.

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 22. A study by Pamela Erickson, DDS, Ph.D. et al 23 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].


It is normal and natural to breastfeed and to still be breastfeeding by the time a baby has little teeth. The idea that breastfeeding is the cause for tooth decay makes no sense biologically, and is not borne out by research. Breastfeeding is too important to abandon without good evidence. 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.

cleaning teeth