The Science Behind The Oral Health Probiotic from Bristle

In this article, we review the clinical studies & scientific research that support the 6 probiotic strains included in Bristle’s Oral Health Probiotic.

The Story Behind Creating an Oral Health Probiotic

At Bristle, we are committed to a science-backed approach to caring for our bodies and helping individuals optimize their oral & overall health.

One easy and effective way to improve your oral microbiome and health is by taking a probiotic specifically formulated for the mouth. In short, an oral health probiotic helps increase the levels of good bacteria in the mouth while reducing harmful bacteria that cause gum disease, cavities, and bad breath.

After an exhaustive review of all the scientific data and research to date, we found a number of oral probiotic species that were clinically shown to improve the oral microbiome (the ratio of good and bad bacteria in the mouth).

In looking at all the available oral health probiotics on the market, there were none with the combination of these clinically-effective strains and so in early 2023, we decided to create and launch our own probiotic.

Overview of Bristle’s Oral Health Probiotic

Bristle’s oral probiotic mint is formulated to rebalance the oral microbiome and promote better oral health. It includes 6 clinically & scientifically studied probiotic strains proven to combat the bacteria that drive gum inflammation, tooth decay, and bad breath.

The 6 probiotic strains are: Streptococcus salivarius M18, Streptococcus salivarius K12, Lactobacillus reuteri, Lactobacillus salivarius, Lactobacillus plantarum, and Bifidobacterium lactis.

  • Streptococcus salivarius M18clinically shown to reduce gum inflammation and bad breath
  • Streptococcus salivarius K12 supports gum & throat health; reduces bad breath
  • Lactobacillus reuteri improves immunity & kills bacteria that cause bad breath and gum inflammation
  • Lactobacillus salivarius – fights bacteria like S. mutans that cause tooth decay & reduces the bacteria that cause bad breath
  • Lactobacillus plantarum – inhibits the growth of species like P. gingivalis that cause gum inflammation
  • Bifidobacterium lactis – improves gum health & fights species that cause gum inflammation and bad breath

The probiotic includes xylitol instead of sugar which helps fight cavities-causing bacteria and lower risk for tooth decay. It’s made with all-natural and clean ingredients to make it dairy free, gluten free, and nut free. No GMOs, artificial colors, flavors, preservatives or sweeteners.

The recommended use is:

  • 1x/day for general oral health maintenance
  • 2x/day for combatting active oral health issues like gum disease, cavities, and bad breath

Below is a review of the clinical studies and scientific research for each of the 6 probiotic strains.

Streptococcus salivarius K12 and M18

Streptococcus salivarius is a commensal bacterium that is a normal part of the oral microbiome and has a beneficial role in promoting oral health and preventing pathogenic bacteria from colonizing the oral cavity. Research suggests that certain strains of S. salivarius, particularly K12 and M18, may be particularly effective at treating halitosis by decreasing volatile sulfur compounds (VSCs), and reducing bacterial species that coat the tongue and gum inflammation.

In one clinical trial, a 3-day regimen of chlorhexidine (CHX) mouth rinsing, followed by 4 week use of lozenges containing S. salivarius K12 reduced VSCs even after pausing probiotic administration. This trial was the first of its kind to demonstrate that the oral microbiome can be eradicated and recolonized with seed strains to improve oral health. Another similar study corroborated these findings, demonstrating that in patients with braces and halitosis, a 1 month administration of S. salivarius lozenges twice daily reduced VSC levels, even 3 months after halting probiotic usage.

One of the ways in which S. salivarius may promote oral health is through competing with pathogenic species of bacteria for space and resources in the oral cavity. This can help to prevent the growth and colonization of harmful bacteria that contribute to gum inflammation and periodontal disease. In addition, S. salivarius produces bacteriocins, which are antimicrobial peptides that inhibit the growth of other bacterial species including those associated with gum disease and halitosis.

Additionally, in vitro studies have shown that S. salivarius interacts directly with the gingival epithelium, secretes a small molecule that can reduce inflammation, and supports immune homeostasis.


  • A preliminary study of the effect of probiotic Streptococcus salivarius K12 on oral malodour parameters (Journal of Applied Microbiology)

  • Oral probiotics reduce halitosis in patients wearing orthodontic braces: a randomized, triple-blind, placebo-controlled trial (Journal of Breath Research)

  • A concerted probiotic activity to inhibit periodontitis-associated bacteria (PLOS One)

  • The commensal Streptococcus salivarius K12 downregulates the innate immune responses of human epithelial cells and promotes host-microbe homeostasis (Infection and Immunity)

  • Streptococcus salivarius inhibits immune activation by periodontal disease pathogens (BMC Oral Health)

  • Anti-inflammatory properties of Streptococcus salivarius, a commensal bacterium of the oral cavity and digestive tract (Applied and Environmental Microbiology)

  • Antimicrobial activity of Streptococcus salivarius K12 on bacteria involved in oral malodour (Archives of Oral Biology)

  • The rationale and potential for the reduction of oral malodour using Streptococcus salivarius probiotics (Oral Diseases)

Lactobacillus reuteri

Studies have suggested that Lactobacillus reuteri can help to maintain a healthy balance of bacteria in the mouth by inhibiting the growth of harmful bacteria that can contribute to oral health problems such as tooth decay, gum disease, and bad breath. L. reuteri is a probiotic bacteria that produces reuterin, a bacteriocin (an antibiotic made by bacteria) that can kill the anaerobic bacteria that cause gum inflammation.

There have been numerous studies examining the impact of L. reuteri on gum health and periodontal pathogens. One study showed that administration of L. reuteri alone for 42 days reduced gingival bleeding, plaque index, and the abundance of pathogens that are responsible for periodontal disease such as P. gingivalis. Another study showed a significant reduction in halitosis parameters and symptoms after taking a lozenge containing L. reuteri.

One study looked at 30 patients with severe periodontal disease, and showed that patients who took an oral probiotic lozenge with L. reuteri twice per day after a deep cleaning had significantly improved measures of gum disease, like gum attachment and pocket depth, compared to people on placebo. Additionally, patients on oral probiotic L. reuteri had lower levels of P. gingivalis compared to placebo. Another followup study with a similar cohort of patients with periodontal disease demonstrated that oral probiotic L. reuteri improved measures of gum disease, but also reduced levels of inflammatory markers such as MMP-8.

L. reuteri can also help protect against cavities by reducing levels of lactic acid in saliva and helping prevent the formation of dental plaque.

Lactobacillus reuteri most likely does not colonize the oral cavity, but exerts its activity transiently by producing bacteriocins. L. reuteri also modulates the immune system, and has activity in the gut where it reduces levels of pro-inflammatory cytokines such as TNF-a and IL-8.


  • Effect of the probiotic Lactobacilli reuteri (Prodentis) in the management of periodontal disease: a preliminary randomized clinical trial (Journal of Oral Microbiology)

  • Clinical effect of Lactobacillus on the treatment of severe periodontitis and halitosis: A double-blinded, placebo-controlled, randomized clinical trial (Journal of the American Dental Assocation)

  • Clinical and microbiological effects of Lactobacillus reuteri probiotics in the treatment of chronic periodontitis: a randomized placebo-controlled study (Journal of Clinical Periodontology)

  • Effectiveness of Probiotic Lozenges in Periodontal Management of Chronic Periodontitis Patients: Clinical and Immunological Study (European Journal of Dentistry)

  • Acid production in dental plaque after exposure to probiotic bacteria (BMC Oral Health)

  • Oral administration of Lactobacillus reuteri during the first year of life reduces caries prevalence in the primary dentition at 9 years of age (Caries Research)

  • Effect of chewing gums containing the probiotic bacterium Lactobacillus reuteri on oral malodour (Acta Odontologica Scandinavica)

Lactobacillus salivarius

Lactobacillus salivarius is a well studied probiotic species that improves oral health. Clinical trials have shown beneficial effects of L. salivarius on halitosisgum disease, and tooth decay. L. salivarius produces potent bacteriocins that can broadly kill pathogenic species that cause oral disease. Additionally, it can help to tune the immune system, potentially reducing chronic inflammation.

In one study, administration of L. salivarius by lozenge for two weeks led to a significant reduction in S. mutans levels. Another study showed that biofilms containing L. salivarius had much lower levels of S. mutans, demonstrating that L. salivarius may directly inhibit S. mutans.

In a 51 patient study of patients with periodontal disease, administration of oral L. salivarius reduced bleeding on probing, and pocket depth compared to placebo.


Lactobacillus plantarum

In several clinical trials, Lactobacillus plantarum has been shown to improve both the oral microbiome and clinical parameters of halitosis and gingivitis. L. plantarum can help reduce pathogens at the gum line such as Tannerella forsythia, which can cause both halitosis and gum inflammation. Lactobacillus plantarum produces compounds called plantaricins, which can kill other microorganisms, even Candida.


  • Clinical and microbiological effects of the adjunctive use of probiotics in the treatment of gingivitis: A randomized controlled clinical trial (Journal of Clinical Periodontology)

  • Genome Analysis of Lactobacillus plantarum Isolated From Some Indian Fermented Foods for Bacteriocin Production and Probiotic Marker Genes (Journal of Periodontology)

  • Daily Intake of Heat-killed Lactobacillus plantarum L-137 Decreases the Probing Depth in Patients Undergoing Supportive Periodontal Therapy (Oral Health and Preventive Dentistry)

Bifidobacterium lactis

Bifidobacterium lactis has been clinically studied for its beneficial effects on reducing inflammation, in both the gut and mouth. B. lactis as an oral probiotic can also reduce levels of gum inflammatory pathogens, such as T. forsythia and P. gingivalis. B. lactis also produces compounds that can prevent P. gingivalis from colonizing the gum line.


  • Effects of Bifidobacterium probiotic on the treatment of chronic periodontitis: A randomized clinical trial (Journal of Clinical Periodontology)

  • Bifidobacterium animalis subsp lactis HN019 presents antimicrobial potential against periodontopathogens and modulates the immunological response of oral mucosa in periodontitis patients (PLOS One)

  • The Influence of a Bifidobacterium animalis Probiotic on Gingival Health: A Randomized Controlled Clinical Trial (Journal of Periodontology)

The Oral Health Probiotic

6 clinically & scientifically studied probiotic strains proven to help maintain oral health & fight bacteria that cause bad breath & gum inflammation

3.5B CFU for high bacterial concentration & impactful delivery

Xylitol instead of sugar to fight cavities-causing bacteria & lower your risk for tooth decay

All-natural ingredients & flavors to keep it delicious

Are you currently experiencing oral symptoms? Examples include halitosis (bad breath), gingivitis and gum disease.

We recommend taking our probiotic twice daily for 1-3 months to combat the harmful bacteria driving your symptoms. Then you can switch to once daily!

🚗 Free Shipping | 👶 Ages 5+





No GMOs, No Herbicides or Pesticides, No Artificial Colors, Flavors, Preservatives or Sweeteners.