When speaking with patients, there are certain questions that come up particularly often. It’s important to be able to answer these professionally and thoroughly. Today’s focus: Three common questions about milk, breast milk, and milk alternatives.

1. Can the lactose in milk cause tooth decay?

A recent scoping review (a systematic review that maps the literature) examined the noncariogenic and, in some cases, protective effects of milk and dairy products on the oral health of children and adolescents. The results clearly show that regular consumption of unsweetened milk and dairy products such as cheese and plain yogurt does not lead to tooth decay but actively contributes to the protection of tooth structure. Although milk naturally contains lactose (milk sugar), which can be metabolized by oral bacteria, lactose has a far lower cariogenic potential than sucrose. Sucrose causes a more significant drop in the pH level of dental plaque and also facilitates the formation of sticky extracellular polysaccharides.

The following factors in dairy products contribute to the prevention of tooth decay in children and adolescents:

• Mineral content: Calcium and phosphate promote the remineralization of tooth enamel. 
• Protective proteins: Proteins such as casein (especially casein phosphopeptides) form a protective film on the tooth surface and inhibit the adhesion of decay-causing bacteria. 
• Saliva stimulation: The consumption of cheese, in particular, stimulates saliva flow, which neutralizes acids and has a cleansing effect. 

Practical Conclusion: It is important to note when advising patients that these positive effects apply exclusively to unprocessed products. As soon as free sugar is added to dairy products (eg, in cocoa drinks, sweetened fruit yogurt, or milk-based beverages), the protective effect is completely lost, and the risk for caries increases significantly.

2. Does breastfeeding promote the development of early childhood caries?

A recent systematic review investigated whether — and under what conditions — breastfeeding increases the risk for early childhood caries (ECC). The available data paint a nuanced picture: Breastfeeding in the first months of life not only offers general health benefits but even has a protective effect against ECC during the first year of life. Even when children are still breastfed between the ages of 12 and 24 months, no significant influence on the development of ECC can be demonstrated.

However, this changes significantly after the age of 24 months. If children are still breastfed after their second birthday, the risk for ECC increases significantly. Possible reasons for this include:

• Children aged 2 years or older have additional access to sugary foods and beverages as part of their complementary feeding 
• There is evidence that the content of protective minerals in breast milk decreases over time 

The authors also discuss two additional points. There is evidence that nighttime breastfeeding or frequent nighttime feedings is a risk factor for ECC as the protective effect of saliva is almost entirely lost during sleep. Furthermore, the development of dental caries is multifactorial, and in addition to diet, oral hygiene, fluoridation measures, and genetic factors play a role. For ethical reasons, randomized, double-blind studies on this topic are not possible. The findings of the review are therefore based on prospective cohort studies.

Conclusion for clinical practice: For counseling in clinical practice, the following can be summarized: Mothers should be explicitly encouraged to breastfeed during the first year of life. Starting with the eruption of the first primary teeth — but no later than the 12th month of life — frequent prolonged suckling and nighttime breastfeeding should be gradually reduced in parallel with the establishment of age-appropriate oral hygiene. If mothers are still breastfeeding after the 24th month of life, they should be made aware of the resulting risk for dental caries.

3. Are milk alternatives harmless to teeth?

A recent in vitro study by the University of Bern, Bern, Switzerland, investigated the effects of cow’s milk and three unsweetened plant-based alternatives (oat, almond, and soy milk) on selected oral microorganisms and biofilms. The results show that plant-based milk alternatives cannot be generally classified as either better or worse than cow’s milk. The effects on bacteria associated with dental caries and periodontitis depend on the specific plant source and yielded varying results in the laboratory.

• Effects on caries development: In the test model, cow’s milk and soy milk reduced both the amount of biofilm formed and its metabolic activity. Almond milk, on the other hand, reduced the number of colony-forming units of caries-causing bacteria. 
• Effects on periodontal pathogens: Cow’s milk and oat milk demonstrated a protective effect here by reducing both the bacterial count and the metabolic activity of the periodontal biofilm. In addition, almond milk blocked the activity of gingipains — virulence factors through which Porphyromonas gingivalis contributes to the development of periodontitis. 
• Promotion of initial bacteria: Cow’s milk, as well as almond and soy drinks, led to slight growth of Streptococcus gordonii, which can result in inhibition of Streptococcus mutans and an increase in the pH value within the biofilm. 

Practical Implications: For patient counseling, it can be concluded that natural, unsweetened plant-based beverages generally have a low caries potential due to their low content of fermentable carbohydrates. However, because clinical relevance depends heavily on the specific product, careful oral hygiene remains the decisive factor regardless of consumption habits. The authors of the study emphasized as a limiting factor that only a few bacteria and specific biofilms could be considered in the laboratory and that further research is necessary.