Across 3 studies, all reported beneficial effects of Lactobacillus reuteri on reducing Bleeding on Probing (BOP), with effect sizes ranging from small to large. The most-studied population includes patients with periodontitis, with one study using a dose of 2 lozenges per day. Effects were typically observed at 6+ months in longer trials, but one short-term observational study also noted improvements within 2 weeks.

• Effective dose range: 2 lozenges/day (one study), twice daily for 14 days (one study); limited data prevents clear dose convergence
• Studied populations: Patients with generalized periodontitis stage III and IV, grade C; patients with chronic periodontitis; adolescents with betel quid chewing habits

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). One study is observational with no sample size reported and a pilot study with 20 participants limits generalizability. Effect sizes vary substantially (small to large), so the magnitude of benefit remains uncertain.