Thirty chronic periodontitis patients were included in the double blind, randomized, placebo-controlled clinical trial that lasted for 42 days. On day 0 the teeth in one half of the mouth were treated with SRP whereas the teeth in the other half were left untreated. From day 21 to day 42 the patients were supplemented with either L. reuteri Prodentis lozenges (1X10^8 CFU DSM 17938 and 1×10^8 CFU ATCC PTA 5289) or placebo lozenges twice daily.

The result showed that a combination of L. reuteri Prodentis and SRP was significantly better than all other modalities in reducing gingivitis and plaque. Moreover, L. reuteri Prodentis, either alone or following SRP, significantly reduced the pathogens Aggregibacter actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia by up to 90 % as compared to the treatments that did not include L. reuteri Prodentis. The combination of L. reuteri Prodentis and SRP was also significantly better than SRP alone in reducing both PPD (p<0.001) and CAL (p<0.001).

Conclusion
This trial confirms the plaque inhibition, anti-inflammatory, and antimicrobial effects of L. reuteri Prodentis. L. reuteri Prodentis probiotic can be recommended during non-surgical therapy and the maintenance phase of periodontal treatment. Considering the beneficial effects of probiotics, this therapy could serve as a useful adjunct or alternative to periodontal treatment when SRP might be contraindicated.