Across 3 studies, 1 reported beneficial effects (large effect size) on reduced probing depth, while 2 found neutral effects. The evidence is preliminary and mixed, with the lone beneficial study using 1×10⁹ CFU/day for 56 days in periodontitis or gingivitis patients, while two longer (180-day) studies in diabetic periodontitis patients showed no significant benefit over placebo. Median study duration was 180 days.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. The only beneficial study had a shorter duration (56 days) than the null studies (180 days), and the null studies focused on diabetic patients, which may represent a different population response.
PD improved by 35.8% (4.92 ± 1.13 vs 3.12 ± 0.37 mm, p 0.05)
At 6 months, both groups showed statistically significant reductions in the primary outcome (mean probing depth), with reductions of 0.9 mm in the probiotic group and 0.8 mm in the placebo group, with no significant differences between them.
At #PD ≥ 7 mm, SI + Probi had a more frequent number of sites (p = 0.03) compared to SI + Placebo only at baseline.