Are dairy products containing probiotics beneficial for oral health? A systematic review and meta-analysis.

Objectives: To evaluate the effect of probiotic containing in dairy products on oral and salivary parameters.
Material and Methods: Electronic searches were performed based on the PICO criteria. Randomized controlled trials in adults/children (P) in which dairy products containing probiotics (I) were compared to controls (C) for establishment of oral health (O) were included. Risk of bias and data extraction were performed. The meta-analysis evaluated the influence of probiotics on Streptococcus mutans (SM), Lactobacillus spp. (LB), and yeast counts, plaque index, and salivary pH. Random or fixed effect models were used, and heterogeneity was tested.
Results: Thirty-two studies were included in the qualitative synthesis, and 24 in the meta-analysis. For dichotomous results, individuals who consumed probiotics exhibited decreased scores in SM concentrations (RD 0.15 [0.02, 0.28] p = 0.03, I ²  = 70%), but no change was observed for LB (RD 0.10 [- 0.03, 0.23] p = 0.13, I ²  = 94%), or yeast levels (RD 0.05 [- 0.02, 0.12] p = 0.7, I ²  = 48%). For continuous analysis, both probiotic and control groups presented similar results for SM and LB (MD - 0.55 [- 1.16, 0.07] p = 0.08, I ²  = 62%, and RD 0.10 [- 0.03, 0.23] p = 0.13, I ²  = 94%, respectively). The consumption of probiotics increased salivary pH (MD 0.20 [0.04, 0.35] p = 0.01, I ²  = 46%) and plaque index (MD 0.38 [0.11, 0.65] p = 0.005, I ²  = 0%). The probiotic milk reduced SM (MD - 0.59 [- 0.96, - 0.22] p = 0.002, I ²  = 0%), and the probiotic yogurt decreased LB counts (RD 0.35 [0.19, 0.51] p < 0.0001, I ²  = 0%).
Conclusions: In general, dairy probiotics were effective in reducing SM, increasing salivary pH, and promoting a higher plaque index. Liquid matrices, such as milk and yogurt, seem to be more effective in reducing SM and LB levels.
Clinical Relevance: Consumption of dairy products containing probiotics could be a supporting method in caries prevention.