Background
Breastfeeding has been utilized for centuries to supply infants with the nutrition they need to develop and thrive. With the option of feeding formula to infants instead of breast milk, questions have arisen about which nutrient source is better for infants. Both methods show positive effects on development, but one option offers more long-term advantages.
Breastfeeding has been proven to benefit an infant’s immune system as well as growth and weight gain.1 Biomarkers are influenced by the ingestion of breast milk and can stop the formation of certain T-cell disorders, such as celiac disease, insulin resistance, and obesity.1 These benefits are fleeting as there is no difference in infants’ immune systems after six months of life based on the source of nutrition.1 This result occurs because additional sources of nutrition are introduced at that time.1 Neurological effects are longer lasting when comparing the two sources of nutrition. A study on cognitive development found higher intelligence in breastfed children from seven weeks to seven years compared to those who were formula fed.1
While both breast milk and infant formula appear to provide adequate nutrition, could one be superior to the other in relation to the dentition? The source of infant nutrition is directly related to caries risk and enamel defects. This report aims to determine which source of infant nutrition results in a lower caries risk and formation of fewer enamel defects.
Dental caries and enamel defects
Dental professionals are familiar with dental caries because it has become a community health issue that affects 60% to 90% of children.2 Enamel defects are also commonly observed in early childhood.3 Enamel defects include delineated opacities, widespread opacities, and hypoplasia in enamel.3 The presence of enamel defects may increase the caries risk.3 A 2013 study found that low socioeconomic status was a contributing factor for enamel defects and early childhood caries in 72.9% of children.4 In this study, the mothers with low socioeconomic status had less education on the benefits of breastfeeding, which could relate to the higher incidence of enamel defects in infants of lower socioeconomic backgrounds.5 Infants of mothers from higher socioeconomic status had lower caries risk, which is thought to be linked to higher success rates with breastfeeding.5
When assessing the caries risk separately from enamel defects, breastfeeding has been effective in preventing dental caries more so than formula in the first six months of life.6 While these results look promising for promoting breastfeeding, the first tooth usually does not erupt until this time. Once teeth begin to erupt, more foods are incorporated into the diet, making it more difficult to judge the exact effects of breast milk on the teeth.6 As infants develop past six months of age, the dental caries risk increases due to socioeconomic and biological factors.6 Biological factors can include water fluoridation, on- demand feedings, and education regarding breastfeeding.7
On a larger scale, a 2015 systematic review evaluated seven studies on the prevalence of caries in relation to infant formula or breast milk. In each of the seven studies, breast milk was found to be more successful at preventing caries.2 One explanation for the lower caries risk relates to the extensive microbiome and chemical factors found in breast milk that can influence the immune response.1 Both factors may be vital in initial protection from caries.1 Higher levels of carbohydrates are found in infant formula compared to breast milk.1 Carbohydrates have been notoriously associated with caries formation for decades.
While it appears that breast milk is less cariogenic than infant formula, other factors influence the caries risk. Frequent feedings increase the dental caries risk, but more so when exposed to frequent feedings with infant formula.2 A 2015 systematic review found that comfort feeding may be the largest issue with breast milk and dental caries.2 If the infant falls asleep while feeding, the breast milk accumulates in the mouth against the dentition. This prolonged exposure dramatically increases an infant’s dental caries risk.2 Mothers who utilize breastfeeding to soothe infants to sleep must be made aware that this can be problematic to the dentition.
While the etiology of dental caries is multifactorial, enamel defects are frequently caused by medical conditions during infancy.3 Several medical conditions are related to the etiology of enamel defects, even down to the moment of birth. Having a birth weight of 5 lb., 8 oz. or less is associated with higher levels of enamel defects due to the underdeveloped ability to produce calcium.3,4 A systematic review on the incidence of enamel defects and preterm birth was inconclusive regarding whether breast milk or infant formula was more capable of increasing weight and reducing enamel defects.8
Infectious and congenital diseases in children may contribute to the formation of enamel defects.9 These include respiratory infection, chicken pox, congenital rubella, or otitis media.9 These illnesses may cause fever, decreased oxygen levels, and lead to hypocalcemia in the child or the mother.9 These diseases may not directly affect ameloblasts, but impact nutrition and growth.9 If ameloblasts do not obtain the nutrients they need to secrete enamel, enamel defects may occur.9 The presence of severe diseases between birth and age 3 have been associated with the formation of enamel defects.10 These include pneumonia, severe asthma, spina bifida, congenital heart disease, hepatitis B, thalassemia, and meningitis.10 Children who experience serious illness in the first month of life have a 10% higher incidence of enamel defects compared to those who do not become ill.9 The duration of illness had more of an impact than the specific type of illness.9 There is no connection between the nutritional source received and occurrence of severe diseases.
The source of nutrition during the first months of life impacts the prevalence of enamel defects. Substances found in infant nutritional sources may influence the development of enamel defects. Breast milk may contain dioxin, which is an environmental pollutant created as a by-product of industrial processes.10,11 Dioxins can cause developmental problems and are linked to the formation of enamel defects.10,11 The rapidly developing systems in newborns are sensitive to dioxin exposure.11 Dioxin from maternal dietary sources can be incorporated into breast milk.10 Most exposure to dioxins comes from consuming meat, dairy products, fish, and shellfish.11 Occupational exposure, such as working in the pulp and paper industry, in incineration plants, and at hazardous waste sites, may increase systemic levels of dioxin.11 The length of time an infant is exposed to dioxin is not relevant to formation of enamel defects, but the confirmation of exposure is helpful in determining an association.10 Since dioxin is stored in fat and has a seven-year half-life, girls and young women should be encouraged to trim fat from meat and consume low-fat dairy products to decrease exposure to dioxin compounds.11 This practice can reduce dioxin exposure of a developing fetus and reduce dioxin presence in breast milk later in life.11 Infant formula may also contain dioxin.12 The levels of dioxin in infant formula vary, but are generally lower than the level found in breast milk.12
And the winner is…
When all factors are taken into consideration, it appears that breast milk is associated with a lower caries risk compared to infant formula. Other factors determining the caries risk include socioeconomic and biologic factors, frequency of feeding, and comfort feeding. There is not enough evidence available to determine which nutrition source is more effective at reducing formation of enamel defects. Infant formula contains less dioxin than breast milk, which is one reason why enamel defects develop. It is unclear if this alone will impact the development of healthy enamel. In a dental practice, education about both options of infant nutrition should be provided. While not all mothers can breastfeed, they can be encouraged to provide breast milk to their infants through expression and use of bottles. Proper feeding techniques should be taught to mothers to assist with decreasing the chance of forming dental caries. Mothers should also be encouraged to receive vaccines and to seek them for their children to avoid preventable infections such as chicken pox and rubella, which are linked to the formation of enamel defects.
Dental professionals can share this information with others who directly impact a mother’s decision on which method of nutrition is best for infants. Nurses are with postpartum mothers through their hospital stay and are the perfect advocates for breastfeeding.1 Lactation consultants assist in breastfeeding techniques and education regarding all things related to breastfeeding.1 Dental hygienists could educate nurses and lactation consultants about the dental benefits of breastfeeding. Breastfeeding should be strongly encouraged to mothers of low-birth-weight babies.1 Additional topics may include the negative effects of comfort feeding, use of a bottle at night, and the need to wipe out the mouth after feedings. Dental hygienists are ideal educators to connect infant nutrition and its effects on the oral cavity. Sharing this content with patients and other health-care professionals can improve outcomes for developing dentition.
References
1. Campbell K, Fritz S. A systematic review: effects of breastfeeding on early and late childhood. Honors Research Project. 2016;236. http://ideaexchange.uakron.edu/honors_research_projects/236.
2. Tham R, Bowatte G, Dharmage S, et al. Breastfeeding and the risk of dental caries: a systematic review and meta-analysis. Acta Paediatr. 2015;104(467):62-84. doi:10.1111/apa.13118.
3. Masumo R, Bårdsen A, Astrøm AN. Developmental defects of enamel in primary teeth and association with early life course events: study of 6-36 month old children in Manyara, Tanzania. BMC Oral Health. 2013;13:21. doi:10.1186/1472-6831-13-21.
4. Nelson S, Albert JM, Geng C. Increased enamel hypoplasia and very low birthweight infants. J Dent Res. 2013;92(9):788-794. doi:10.1177/0022034513497751.
5. Küçükog˘lu S, Çelebiog˘lu A. Effect of natural-feeding education on successful exclusive breast-feeding and breast-feeding self-efficacy of low-birth-weight infants. Iran J Pediatr. 2014;24(1):49-56.
6. Kato T, Yorifuji T, Yamakawa M, et al. Association of breast feeding with early childhood dental caries: Japanese population-based study. BMJ Open. 2015:5(3):e006982. doi:10.1136/bmjopen-2014-006982.
7. Avila WM, Pordeus IA, Paiva SM, Martins CC. Breast and bottle feeding as risk factors for dental caries: a systematic review and meta-analysis. PloS One. 2015;10(11):e0142922. doi:10.1371/journal.pone.0142922.
8. Jacobsen PE, Haubek D, Henriksen TB, Østergaard JR, Poulsen S. Developmental enamel defects in children born preterm: a systematic review. Eur J Oral Sci. 2013;122(1):7-14. doi:10.1111/eos.12094.
9. Memarpour M, Golkari A, Ahmadian R. Association of characteristics of delivery and medical conditions during the first month of life with developmental defects of enamel. BMC Oral Health. 2014;14:122. doi:10.1186/1472-6831-14-122.
10. Wong HM, Peng SM, Wen YF, King NM, McGrath CP. Risk factors of developmental defects of enamel—a prospective cohort study. PloS One. 2014;9(10):e109351. doi:10.1371/journal.pone.0109351.
11. Dioxins and their effects on human health. World Health Organization website. https://www.who.int/news-room/fact-sheets/detail/dioxins-and-their-effects-on-human-health. Published October 4, 2016. Accessed April 26, 2019.
12. Pandelova M, Piccinelli R, Kasham S, Henkelmann B, Leclercq C, Schramm K. Assessment of dietary exposure to PCDD/F and dioxin-like PCB in infant formulae available on the EU market. Chemosphere. 2010;81(8):1018-1021. doi:10.1016/j.chemosphere.2010.09.014.
