This double-blinded, placebo-controlled clinical trial aimed to evaluate the clinical and microbiological effects of lozenges containing L. reuteri Prodentis as an adjuvant treatment to initial periodontal therapy used twice a day for 3 weeks and to assess whether L. reuteri can colonise the periodontal pockets of chronic periodontitis patients.

A total of 40 patients were selected and randomly divided into 2 groups. Each patient had at least 2 teeth with one approximal site each with a probing depth (PD) of 5-7 mm and gingival index (GI) of ≥2 in each quadrant. Group 1 received scaling and root planing (SRP) plus lozenges containing L. reuteri Prodentis (10^8 CFU), and Group 2 received SRP plus placebo.

The plaque index (PI), GI, bleeding on probing (BoP), PD, and relative attachment level were measured. Microbiological sampling was performed at baseline and on days 21, 90, 180 and 360 and were analysed by culturing.

After treatment, the measured PI, GI, BoP, and PD as well as the total viable cell counts and the proportions of obligate anaerobes were significantly (p<0.05) lower in Group 1 compared with Group 2 at all time points. Similar observations were made for the total viable cell counts and the proportions of obligate anaerobes with the exception of day 360. In Group I, significantly fewer patients required surgery on ≥3 sites.

Conclusion
The results of this study demonstrated that the adjunctive usage of L. reuteri Prodentis lozenges improved the clinical and microbiological outcomes compared with the placebo-controlled group. L. reuteri Prodentis lozenges may be a useful adjuvant agent to slow recolonisation and improve clinical outcomes of chronic periodontitis.