Date of Award

Spring 2018

Document Type


Degree Name

Master of Science (MS) in Dental Hygiene


Dental Hygiene


Purpose: The primary aim of this study was to evaluate the efficacy of brushing with the probiotic Lactobacillus reuteri on plaque accumulation and gingival inflammation. This study included 34 healthy adult subjects, ages 18-65, exhibiting gingivitis. Participants were asked to participate in a randomized, double-blind, placebo controlled study testing whether brushing with L. reuteri probiotic drops added to toothpaste reduced the clinical parameters of gingivitis more than brushing with a placebo drop added to toothpaste.

Methods: Biological measurements of plaque accumulation were recorded using disclosing solution and an O’Leary Plaque Score (PS), and gingival inflammation was recorded using a modified Löe-Silness Gingival Index (GI). Each participant was randomly divided into one of two groups: group A or group B followed by baseline data collection of clinical parameters. Participants were assigned their study drops to add to their study toothpaste.

Results: Analysis included both descriptive and inferential statistics. Inferential statistics employed Wilcoxon Signed Rank tests, due to the small sample size and inability to assume normal distribution of the study population. Statistical significance level was set at p < 0.05. Variables included median differences between the probiotic and placebo groups’ baseline and final data for both PS and GI. Comparisons were also made by age and gender, and to evaluate the difference between final PS for placebo versus probiotic and final GI for placebo versus probiotic. Statistically significant differences were noticed between baseline and final data for GI of the placebo group as a whole (p = 0.001), and females of the placebo group (p = 0.004). No statistical difference was noted in PS between baseline and final data for either group. Conclusion: Although results of this clinical study were unexpected, further research regarding the use of probiotics as a natural, healthy alternative therapy to antibiotics for the treatment and management of oral diseases should continue to be evaluated. Several research studies reviewed in the process of completing this thesis have shown probiotics have great possibilities in the oral cavity. Most researchers agree the type, application method, and quantity of probiotic needed to be effective at treating and managing oral diseases has yet to be determined.