A placebo-controlled, parallel study with the objective to investigate the effects of an orally administered probiotic on the oral microbiota. The study was conducted in 40 gingivitis subjects during 8 weeks. Treatment consisted on the administration of a daily tablet, either containing Lactobacillus reuteri or placebo. Unstimulated saliva and subgingival samples were collected and analysed by culture and PCR. Clinical and microbiological outcome variables were compared between and within groups.
There were no significant changes between and within the groups in the clinical variables. In saliva, total anaerobic counts after 4 weeks (p = 0.021) and counts of Prevotella intermedia after 8 weeks (p = 0.030), showed reductions in the test group. In subgingival samples, significant reductions in the changes baseline to 4 weeks were observed for P. gingivalis counts (p = 0.008). With PCR, Lactobacillus reuteri ATCC-PTA-5289 was more frequently detected than Lactobacillus reuteri DSM-17938.
The effect of Lactobacillus reuteri administered in tablets resulted in a reduction in the number of selected periodontal pathogens in the subgingival microbiota, without an associated clinical impact.