Clinical scenario

A new mum attends her general dental practitioner for a routine checkup. Mum is very concerned because she has heard that if she continues to breastfeed her baby beyond 6 months of age, as she has been advised by her public health nurse, the baby will develop tooth decay. She asks the dentist if this is true. The dentist admits that he is not sure what the correct answer to this is, but advises that he will find out and let her know. To find the answer he decides to undertake a bibliographic search.

Clinical question

The PICO (population–intervention–comparison–outcome) question developed was: does continuation of breastfeeding (intervention) increase the risk of early childhood caries (ECC; outcome) in infants of over 6 months of age (population), compared with other methods of infant feeding (comparison)?

Search strategy

The databases Medline (1996–2008), Embase (1996–2008) and CINAHL (1982–2008) were searched using OVID, along with all evidence-based medicine journals within OVID, PubMed and Trip Database (www.tripdatabase.com). The OVID search (see Table 1) used the following search terms: “breastfeeding” or “infant feeding” and “dental caries” or “oral health”. Studies were limited to human subjects and English language and review articles (where possible). The OVID search identified 30 studies of which four were considered relevant. The PubMed and Trip database searches used similar search terms with only the PubMed search identifying an additional study. Details of the papers are summarised in Table 2.

Table 1 Search strategy
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Table 2 Summary or relevant papers
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Discussion

There have been reports in the literature that prolonged and on-demand breastfeeding is a potential risk factor for the development of ECC.5 Reliance on this evidence has, in some cases, led to dental professionals issuing advice regarding cessation of breastfeeding at 6 months. This bibliographic search identified five relevant articles on this topic, all of which failed to find an association between breastfeeding and development of ECC. Both review articles, however, highlight the poor quality of studies available on this topic.1,2 In particular, studies lack clarity and consistency in the definitions of breastfeeding patterns, ie, whether it is exclusive, on-demand, or at night. Inconsistency in the definitions of ECC also creates problems in comparability of studies. The review by Valaitis et al.1 which undertook systematic quality assessments of articles and would therefore be considered the more robust of the two reviews, concludes that, “the available evidence does not support a consistent and strong association between breastfeeding and development of ECC”. The review does not include any randomised controlled trials (RCT), but it could be argued that a RCT is neither appropriate or ethical in this area. The RCT reported by Vitolo et al.3 and Kramer and colleagues5 are in fact secondary analyses of RCT of the promotion of healthy infant feeding interventions. This, together with other methodological issues highlighted in Table 2, suggests that the results and conclusions of these studies should be interpreted with caution.

The study undertaken by Iida et al.5 does appear to take us a step further forward in answering the question of duration of breastfeeding and increased risk of ECC. Although this study's initial analysis suggested that children breastfed for >1 year in total were more likely to experience ECC than children who were breastfed for <1 year, the subsequent analysis (which controlled for confounding factors such as poverty, ethnicity and maternal smoking) demonstrated that there was no evidence that breastfeeding or its duration was associated with increased ECC. Unfortunately, the study was not able to explore the implications of other potential confounding factors such as oral hygiene practices and exposure to fluoride, but it does highlight that there are several other —and possibly more important — factors affecting development of ECC besides breastfeeding.

Breastfeeding has been found to have many health benefits for both the child, including protection against gastrointestinal infection, otitis media and necrotising enterocolitis,7 and mother, including delayed return of fertility and postpregnancy weight loss.8 Current UK guidance recommends exclusive breastfeeding for the first 6 months of an infant's life and that breastfeeding should continue beyond this, along with appropriate types and amounts of solid foods. No upper age limit for cessation of breastfeeding is given (www.dh.gov.uk/en/Healthcare/Maternity/Maternalandinfantnutrition/index.htm)

The World Health Organization also advises exclusive breastfeeding for the first 6 months of life and recommends that it continue in addition to other suitable sources of nutrition for up to 2 years or beyond (www.who.int/features/qa/57/en/index.html) although it is of note that the health benefits of continuation of breastfeeding for periods greater than 6 months in industrialised countries remain unclear.9

The incidence of breastfeeding has increased in all regions of the UK in recent years,10 but there has been change in the duration of women breastfeeding, with declines in duration seen in Scotland.10 The prevalence of infants being breastfed at 6 months of age in the UK was still only 25% in 2005,10 but with national and international policies emphasising breastfeeding, it is likely that this figure will increase. It may, therefore, be appropriate for further high-quality research to be undertaken to explore the relationship between prolonged breastfeeding and ECC.

Clinical bottom line

Given the proven health benefits of breastfeeding and the lack of consistent evidence linking breastfeeding to the development of ECC, dental professionals should support current recommendations for breastfeeding. Emphasis should be placed on promoting good oral hygiene practice from the time of eruption of the first tooth and advice to reduce the frequency and consumption of sugar-containing foods and drinks.