Streptococcus salivarius is a commensal oral probiotic bacterium, and its use to support gum (periodontal) health is primarily grounded in scientific research rather than tradition. Several clinical and in vitro studies suggest that specific strains, such as S. salivarius K12 and M18, may help maintain oral health by competing with pathogenic bacteria implicated in gum disease and by modulating inflammatory responses in the oral cavity. For example, Burton et al. (2013) demonstrated that supplementation with S. salivarius M18 reduced markers of oral inflammation and improved oral health outcomes in adults.

The mechanisms proposed include the production of bacteriocins (antimicrobial peptides) that inhibit growth of periodontal pathogens such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, as well as enzymatic activities that may reduce dental plaque formation. Some randomized controlled trials have shown modest improvements in gingival indices and reductions in plaque and bleeding scores with S. salivarius supplementation. However, evidence is still emerging, and not all studies report significant clinical benefits; further, long-term data are limited.

In summary, there is moderate scientific support (rated 3/5) for the use of Streptococcus salivarius in supporting gum health, with efficacy likely depending on strain specificity and individual oral microbiome factors.