Influence of dietary supplementation with Lactobacillus reuteri on the oral flora of healthy subjects.

Investigate the presence of Lactobacillus reuteri in saliva after supplementation with L. reuteri and the probiotic effect of L. reuteri on plaque index and supra- and subgingival microbiota.The study included 23 healthy individuals, randomised into test or control subjects. At baseline and after 12 weeks saliva samples, plaque index and supra- and subgingival plaque samples were obtained. The test subjects were given the study product (containing L. reuteri, ATCC 55730 and ATCC PTA 5289) and the control subjects placebo for 12 weeks. Microbiological analyses were done by checkerboard DNA-DNA hybridization technique and selective culturing for lactobacilli determination.A significant increase in total Lactobacillus counts in saliva occurred in both groups (p < 0.05) with a significant increase of L. reuteri (p = 0.008) in the test group.Termination of intervention resulted in a wash out of L. reuteri. The control group demonstrated a statistically significant increase in PII after 12 weeks (p = 0.023) whilst there was no significant change in the test group. A significant increase was found for most bacterial species in both groups in supra- and subgingival plaque with no significant difference for any of the species between the groups. The ratio between "bad/good" supragingival bacteria decreased for the test group but this decrease did not reach significance. The corresponding ratio for subgingival bacteria decreased significantly in both groups. Supplementation of L. reuteri resulted in presence of L. reuteri in saliva but L. reuteri was washed out after termination of intervention. No significant effect on supra- or subgingival microbiota was observed. The significant increase in PII in the control group with no significant change in the test group may, however, indicate a probiotic effect of L. reuteri in this study population.