Association between salivary s-IgA concentration and dental caries: an updated meta-analysis

Objective: To determine the levels of s-IgA in saliva of caries patients and healthy controls, and to evaluate whether there is a correlation between it and caries by meta-analysis. Methods: The PubMed, MEDLINE, EMBASE, Web of Science, Cochrane Library, Scopus, Chinese National Knowledge Infrastructure, Wanfang Data, Chongqing VIP database for Chinese Technical Periodicals, and China BioMedical Literature Services System databases were searched initially in April 2020 and repeated in August 2020. Two independent evaluators screened the literature and extracted the data according to the inclusion and exclusion criteria. R 4.0.2 software was used for meta-analysis. I(2) test was commonly reflected the heterogeneity. Subgroup analysis and meta-regression analysis explore the sources of heterogeneity. Sensitivity analysis, funnel diagram, Begg’s rank correlation, and Egger’s linear regression were used to determine the possibility of publication bias. Results: The study was reviewed according to the project guidelines for optimal reporting (PRISMA) based on meta-analysis. A total of 30 case–control studies were included, with a total sample size of 1545 patients, including 918 caries patients and 627 healthy controls. Salivary s-IgA levels in caries patients were significantly lower than those in healthy controls (SMD = −0.49, 95%CI: [−0.94; −0.03], P=0.03). In addition, the results of subgroup analysis showed that the significant decrease of salivary s-IgA level was correlated with children patients, mixed dentition and Asian people (children: SMD = −0.45, 95%CI: [−0.89; −0.01], P=0.04; mixed dentition: SMD = −0.61, 95%CI: [−1.24; 0.03], P=0.06; Asian: SMD = −0.62, 95%CI: [−1.17; −0.08], P=0.02). The funnel diagram included in the study was symmetrically distributed, and the sensitivity analysis confirmed the robustness of the results. Conclusion: Salivary s-IgA levels in caries patients were significantly lower than in healthy controls. It has also been demonstrated that salivary s-IgA may be used as an alternative measure to identify subjects at risk of caries susceptibility, suggesting that salivary s-IgA may be a protective factor for dental caries.