A Meta-Analytical Correlation Between Salivary pH, Buffer Capacity, and Microbiome Composition in Caries-Free and Caries-Active Individuals

Background: Salivary composition, including pH, buffer capacity, and microbial profile, which are important in oral health and susceptibility to caries. This systematic review and meta-analysis aimed to provide an aggregate of available information on salivary pH, buffer capacity, and levels of S. mutans in caries-active and caries-free individuals. Methods: PubMed, Scopus, Web of Science, and Google Scholar (2010-2025) were searched according to PRISMA 2020. Studies included examined salivary pH, buffer capacity, and the level of Streptococcus mutans of human populations in correlation with dental caries. RoB 2 and NOS determined the risk of bias, and quality of evidence was assessed using the GRADE. Pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated by a random-effects meta-analysis based on the inverse-variance technique. Subgroup and sensitivity analyses were also conducted. Results: A total of 12 studies were incorporated, of which 09 studies were used for meta-analysis. There was no statistically significant difference in salivary pH in cohorts of experiments and controls (SMD = 1.68; I2 = 94%). Experimental cohorts had much better scores in salivary buffer capacity (SMD = 0.55; I2 = 82%). There were no significant changes in Streptococcus mutans (SMD = 1.79; I2 = 97%). Risk of bias was low to moderate, and the quality of the evidence was moderate, as per GRADE. Conclusion: Salivary buffer capacity seems to be a major protective variable related to caries in dentistry, whereas salivary pH and S. mutans alone do not seem to be reliable predictors of caries.