Assessment of the Effect of Probiotic Yoghurt and Different Probiotic Strains on Salivary Streptococcus Mutans in Children : An in Vivo and an in Vitro Study

Introduction: Streptococcus mutans (S. mutans) is the major pathogen involved in caries development which is the most common childhood infection.  Lactobacilli and Bifidobacteria are commonly used as probiotics and are added to fermented food such as yoghurt, and have been linked to reducing caries risk in children. Objectives: to investigate the effect of probiotic-containing yogurt on salivary levels of S. mutans, gingival inflammation and plaque accumulation in children and to evaluate the possible inhibitory effect of two probiotic bacterial strains (Lactobacillus rhamnosus and Bifidobacterium animalis) against S. mutans invitro. Methodology: This study was performed with 30 children; who were given yohgurt containing probiotic (group 1) or control yoghurt (group 2) daily for a period of 6 weeks; Sreptococcal mutans count, gingival index (GI) and plaque index (PI) were assessed throughout the 6 weeks of intervention and 2 weeks post-intervention. Lactobacillus rhamnosus and Bifidobacterium animalis were tested against S. mutans invitro. Results: There was a statistically significant decrease (p<0.001) in S. mutans count and GI in the intervention group as compared to the control group. The PI showed a statistically significant decrease in both groups 2 weeks after the intervention. Lactobacillus rhamnosus had an inhibitory effect whereas B. animalis had no inhibitory effect on the tested S. mutans strains invitro. Conclusion: The use of probiotic yoghurt decreases the salivary S. mutans count and improves oral dental health in children. Further research should assess the long term effect of plain and probiotic yoghurt on oral health conditions. The addition of alternate probiotic strains to yoghurt such as Lactobacillus rhamnosus should also be considered