L. rhamnosus and the oral microbiota Original paper

In this randomized controlled trial in adolescents, use of a probiotic lozenge containing L. rhamnosus was associated with increased oral bacterial diversity and a reduction in the cavity-causing species Streptococcus mutans.

The effect of lozenges containing Lacticaseibacillus rhamnosus SD11 (aka L. rhamnosus) on the oral microbiota, with changes in the pathogenic Streptococcus mutans and nonpathogenic Lactobacilli strains as the primary and secondary outcomes, respectively.

121 adolescent participants (average age of 13; 65 girls and 56 boys) who had fewer than 3 teeth with cavities, of whom 102 were included in the final analyses.

This 8-week randomized controlled trial began with a 4-week intervention period of daily lozenge use. The probiotic group received lozenges containing L. rhamnosus, and the control group received similar lozenges without L. rhamnosus. A follow-up assessment was conducted after another 4 weeks.

Oral examinations were conducted at baseline and 8 weeks, and saliva samples were collected for genetic analysis of oral microbiota at baseline, 4 weeks, and 8 weeks. Oral microbiota diversity was assessed using the ACE, Chaol, Observed OUT, and Shannon indices.

Probiotic lozenge use increased (improved) levels of Lactobacilli bacteria and reduced (improved) levels of cavity-causing Streptococcus mutans at 4 and 8 weeks, compared to the control.

Microbiota diversity was increased in the probiotic group at 4 weeks compared to baseline on all 4 indices.

The authors of this study highlighted increases in the beneficial Firmicutes phylum with probiotic use and decreases in the potentially pathogenic Bacteroidetes and Proteobacteria phyla. They concluded that L. rhamnosus use could provide a balance shift towards a beneficial microbiota, which might promote good oral health in children.