Dental Benefits of Dairy Consumption

Nutritional counseling provided by dental hygienists typically focuses on caries prevention and reduction. This includes reducing sources of carbohydrates in the diet. Besides eliminating dietary sources that contribute to caries formation, nutritional counseling can include discussion of nutrients for enamel health and remineralization of weakened enamel. The dental benefits of dairy consumption are widely known. Numerous studies have associated consumption of milk and dairy products with decreased caries rates for almost 30 years.¹ Even prominent organizations such as the World Health Organization (WHO) acknowledge that as dairy intake increases, the incidence of dental caries decreases.²

A summary of evidence related to the relationship between milk products and dental health analyzed results from 11 observational studies dating from 2001 to 2015.³ This inclusive summary concurs with the WHO claim that dental caries incidence decreased as dairy intake increased.³ One reason for this outcome is that those who drink milk have lower levels of Streptococci mutans compared with those who do not.¹ Prior research on dairy products focused on caries formation, but little research has been performed on whether consuming dairy products remineralizes enamel. A search of the Cochrane Library revealed only one small in vivo trial to support dairy products and enamel remineralization.⁴ Without research to validate dairy products’ impact on the remineralization of enamel, indirect connections between dairy products and enamel changes need to be explored.

Dairy products include bovine milk and products made from it, such as cheese and yogurt.⁵ Calcium-fortified soymilk is considered a dairy product because of its calcium content.⁵ Most Americans meet their calcium intake through consumption of dairy products.⁶ Other sources of calcium include sardines, salmon with bones, soybeans, soy yogurt, soy tofu, tempeh, collard greens, turnip greens, kale, bok choy, and calcium-fortified products, such as juices, cereals, breads, rice milk, almond milk, or soymilk.⁷ Not all dairy products contain an adequate amount of calcium, such as butter, cream, and cream cheese.⁵

CASEIN PHOSPHOPEPTIDE-AMORPHOUS CALCIUM PHOSPHATE

While widespread awareness of the benefits of calcium from dairy products exists, less may be known about the other components found in dairy products. Milk and products made with milk also contain potassium, vitamin D, protein, casein, lactoferrin, lysozyme, and antibodies proven to be beneficial to oral health.^1,6 Calcium, casein, and phosphate are components of milk that are incorporated into dental enamel.⁸ These elements are directly linked to the anticariogenic properties of milk products.⁸ Anticariogenic activity occurs through direct contact with milk or dairy products, as calcium, casein, and phosphate are incorporated into saliva. Higher concentrations of calcium are found in saliva and biofilm after consumption of cheese.¹ Casein is a protein that recruits calcium phosphate to demineralized enamel surfaces.¹ Casein from milk is rapidly absorbed into the surface of enamel and provides resistance to acid attacks.⁸ Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is a natural derivative of milk.⁸ This acronym might sound familiar because it is currently added to dental products. As discussed next, CPP-ACP is a key component in remineralization of enamel.

CPP is the digested form of casein after it binds to phosphorus.¹ CPP influences the demineralization and remineralization process by preventing calcium and phosphate from being soluble.⁹ CPP stabilizes amorphous calcium phosphate (ACP), which in turn allows ACP to be concentrated in biofilm and to slowly diffuse free calcium into the tooth to promote remineralization and decrease demineralization.^1,8,9 ACP buffers the free calcium and phosphate ions, which maintain the saturation of these elements to decrease demineralization and enhance remineralization.^1,8 CPP-ACP is superior to other forms of calcium in its ability to remineralize enamel.¹⁰ CPP-ACP solutions are efficient at remineralizing enamel because they buffer the acid generated during demineralization through generation of calcium hydrogen phosphate.⁸

Although milk naturally contains CPP, improved remineralization of enamel occurs when milk is fortified with CPP-ACP.¹¹ The ability of CPP-ACP to remineralize enamel when added to milk demonstrates a dose-dependent response.¹² This means the more an individual consumes milk fortified with CPP-ACP, the more potential for remineralization of enamel. If an individual doesn’t want to consume milk fortified with CPP-ACP, one alternative is applying CPP-ACP to the teeth through chewing gum, dentifrice, lozenges, mouthrinses, or sprays.⁸ A small study evaluating the effects of four chewing gums revealed that chewing gum fortified with CPP-ACP resulted in significantly higher enamel remineralization than other chewing gum.¹³ Several other small scale studies have supported similar results, including an enhanced effect when CPP-ACP is combined with xylitol or fluoride. Casein combined with xylitol yields greater enamel remineralization than products combining xylitol with fluoride.⁹ Likewise, CPP-ACP combined in paste with fluoride showed improved enamel remineralization than use of CPP-ACP paste alone.^14,15 Shen et al¹⁶ reported that dentifrice containing calcium and fluoride remineralized subsurface enamel lesions better than dentifrice containing fluoride alone, once again proving that calcium can remineralize enamel. Lastly, CPP-ACP can be added to sugar-containing foods. Fortifying confectionary foods, such as candies, with CPP-ACP, allows for its oral delivery during an acid challenge.⁸ This is the optimal time to have CPP-ACP present in the mouth to prevent demineralization.

ADDRESSING DENTINAL HYPERSENSITIVITY

While components in dairy products are related to preventing enamel demineralization and remineralizing enamel, additional uses of milk were recently discovered. Two studies explored the use of milk as a post-treatment rinse to decrease dentinal hypersensitivity after scaling and root planing. Sabir and Alam¹⁷ assessed dentinal hypersensitivity on 31 individuals following nonsurgical periodontal debridement. Those assigned to the intervention group were instructed to rinse with room temperature milk five times a day for 5 minutes each time for 15 days. The control group did the same regimen, but with water. Follow-up assessments were performed at 4 days, 10 days, and 15 days after therapy. A four-point verbal rating scale was used to record the amount of discomfort experienced after drinking water at room temperature and cold water. The numerical values of the scale included 1 as no hypersensitivity, 2 as mild hypersensitivity, 3 as moderate hypersensitivity, and 4 as severe hypersensitivity. In the intervention group, 11% experienced mild hypersensitivity after 15 days, while all individuals in the control group still had mild to moderate hypersensitivity. The remineralizing capabilities of CPP allowed for the retreat of dentinal hypersensitivity in these individuals.¹⁷

A second study by Madhurkar et al¹⁸ used the same protocol but substituted a desensitizing mouthrinse containing sodium fluoride and potassium nitrate for water in the control group. This was the first study that used a comparative intervention instead of simply comparing milk’s potential to water. The same four-point verbal rating scale was used to measure sensitivity 4 days, 7 days, and 10 days after nonsurgical periodontal debridement. After 10 days, 48% of the intervention group had mild hypersensitivity, while 52% were pain free. The control group had slightly less favorable results, with 60% experiencing mild hypersensitivity and 40% remaining pain free.¹⁸ The results of this study illustrate the use of milk as a desensitizing agent.

MILK FLUORIDATION

While research on milk fluoridation dates back to 1959, there has been a resurgence in research related to milk fluoridation.² A 2014 publication summarized in situ results from a small study aimed at determining if adding fluoride to milk remineralized enamel more than milk alone.¹⁹ The control group drank 200 ml of nonfluoridated milk and saw the least amount of change in the enamel.¹⁹ The best results were found in the group that drank 100 ml of milk fortified with 3 mg of fluoride. The publication concluded that the dose and concentration of fluoride in milk impacts its cariostatic properties.¹⁹

DAIRY SOURCES

As the consumption of dairy products is proven to positively impact the oral cavity, oral health professionals should share this evidence with patients. The United States Department of Agriculture recommends 2 cups to 3 cups of dairy per day depending on age.⁵ Those younger than 9 should consume 2 cups to 2 ½ cups per day, while individuals age 9 or older should consume 3 cups of dairy per day. One cup of dairy is equivalent to 1 cup of milk, 1 cup of yogurt, 1 cup of calcium-fortified soymilk, 1 ½ ounces of natural cheese (1⁄3 cup), 2 ounces of processed cheese (American), 1 cup of pudding made with milk, or 1½ cups of ice cream.⁵

While water may be considered the best choice of beverage due to its positive impact on the oral pH, milk consumption should still be considered a healthy choice. Milk consumption slightly lowers the oral pH, but the increase in calcium and phosphate ions in biofilm offsets the drop in pH and prevents enamel demineralization.⁸ More recently, a study determined that not all dairy sources are equal in relation to caries reduction. Yogurt consumption at a frequency of four or more times per week was linked to the lowest prevalence of dental caries compared with consumption of cheese or milk.²⁰ The sugar content in dairy products should also be considered when making recommendations of dairy products to individuals who have moderate to high caries risk.

CONCLUSION

Components found in dairy products appear to improve enamel health and decrease dentinal hypersensitivity. Dietary dairy recommendations can be incorporated into patient education and caries prevention plans. Individuals who have white spot lesions may benefit from counseling pertaining to dairy intake and use of CPP-ACP products to remineralize enamel. Yogurt appears to have the most promise of all dairy products in the prevention of caries formation. If available, purchase milk fortified with CPP-ACP or fluoride for additional benefits. It may be easiest to incorporate CPP-ACP by replacing a current product with one containing CPP-ACP, such as chewing gum, dentifrice, or a mouthrinse. And lastly, consider recommending that patients rinse with room temperature milk for several days following nonsurgical periodontal therapy to reduce dentinal hypersensitivity, especially when other desensitization methods are not possible.

REFERENCES

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From Dimensions of Dental Hygiene. October 2019;17(9):20,22—23.