Probiotics and Dental health

The most common dental health issues are caused by bacteria.

Dental caries, or tooth decay, is the destruction of the outer surface of the enamel of a tooth, by the metabolic activities of bacteria, generating acid end products that dissolve (demineralize) the tooth surface. The bacteria form a sticky film, termed plaque, which allows them to strongly adhere to the tooth surface, thereby keeping their destructive acids in contact with the tooth.

Gingivitis, or inflammation of the gingiva (gums), is caused by bacterial plaques, in which toxins are generated that irritate the gum tissue. Characteristics of gingivitis include reddened, tender, and swollen gums, which may pull away or recede from the teeth,

Periodontitis or inflammation of the periodontal membrane is a more advanced stage of gingivitis. The periodontal membrane secures the tooth within the jaw. Inflammation of the periodontal membrane can lead to tooth loosening and eventual tooth loss.

Halitosis, or bad breath, is caused by anaerobic bacteria that decompose proteins to amino acids. Further degradation of the sulfur-containing amino acids, cysteine and methionine, generates foul-smelling sulfur-containing volatiles. The sites for these processes may be on the back of the tongue and in regions between neighboring teeth.

The concept of probiotics is to “fight fire, with fire,” that is, to introduce competing healthy bacteria to combat the more destructive bacteria. Regarding the oral cavity and maintaining dental health, species of Bifidobacterium and Lactobacillus are most commonly used as probiotics. These bacteria are classified as producers of lactic acid, a rather weak acid. Adherence of these bacteria to a tooth surface would not lead to demineralization of the enamel. A commonality among the above-noted four dental diseases is that each is caused by bacterial metabolic activities that generate acid or toxins. Also, strong adhesion, such as within a biofilm of the cariogenic bacteria to a tooth surface, is a factor favoring the dental health risk. The approach of probiotics is to ingest bacteria in an adequate quantity,  so they out compete the cariogenic bacteria to prevent their proliferation within the biofilm. The cariogenic bacteria are usually species of Streptocccus mutans and the probiotics are usually those within dairy products and yogart, such as species of Lactobacillus. In one study of 694 children aged 1 to 6 years, those children consuming milk products with Lactobacillus had few dental caries and lower levels of S. mutans in their saliva than controls.

The bacteria responsible for gingivitis and periodontitis differ from those causing dental caries. Studies showed that ingestion of species of Lactobacillus inhibited growth of bacteria causing periodontitis and that chewing gum with Lactobacillus protected against gingivitis. Gargling with a solution of the bacterium Weissella cibaria (formerly, classified as a Lactobacillus) inhibited the bacterial production of sulfur-containing volatiles responsible for halitosis.

The literature on the dental health benefits of probiotics is not, as yet, sufficient enough to make an unequivocal statement of its benefits. However, although many studies are still in the early stage, the data show that the ingestion of probiotics has a positive impact on dental caries, gingivitis, periodontitis, and halitosis. Further studies are mandatory before the full benefits of probiotics can be ascertained.