We conducted a meta-analysis and systematic review to investigate the efficacy of chitosan-containing chewing gums, and to test their inhibitory effects on Streptococcus mutans. The systematic search was performed in three databases (Cochrane Library, EMBASE, and PubMed) and included English-language randomized–controlled trials to compare the efficacy of chitosan in reducing the number of S. mutans. To assess the certainty of evidence, the GRADE tool was used. Mean differences were calculated with a 95% confidence interval for one outcome: bacterial counts in CFU/mL. The protocol of the study was registered on PROSPERO, registration number CRD42022365006. Articles were downloaded (n = 6758) from EMBASE (n = 2255), PubMed (n = 1516), and Cochrane (n = 2987). After the selection process, a total of four articles were included in the qualitative synthesis and three in the quantitative synthesis. Our results show that chitosan reduced the number of bacteria. The difference in mean quantity was −4.68 × 10⁵. The interval of the random-effects model was [−2.15 × 10⁶; 1.21 × 10⁶] and the prediction interval was [1.03 × 10⁷; 9.40 × 10⁶]. The I2 value was 98% (p = 0.35), which indicates a high degree of heterogeneity. Chitosan has some antibacterial effects when used as a component of chewing gum, but further studies are needed. It can be a promising antimicrobial agent for prevention.

Background and Objectives: This study compared the antimicrobial effects of chitosan and sodium hypochlorite against Enterococcus faecalis (E. faecalis) at different irrigation solution concentrations. E. faecalis is a persistent pathogen frequently surviving root canal treatment, while sodium hypochlorite remains the current gold-standard irrigation material. Materials and Methods: A systematic review and meta-analysis of in vitro studies was conducted using Cochrane Library, EMBASE, and PubMed. Evidence certainty was assessed with GRADE. Two outcomes were analyzed: colony-forming units (CFU/mL) and the inhibition rate (IR). Two reviewers independently screened studies and extracted data. Results: Of 889 identified records, 10 studies met the inclusion criteria. For CFU/mL, the overall effect was −0.28 (95% CI: −1.54 to 0.97). For IR, chitosan concentrations < 1% showed an effect of –7.35 (95% CI: −27.27 to 12.56), while concentrations ≥ 1% showed an effect of −0.90 (95% CI: −19.24 to 17.45). Conclusions: Chitosan demonstrated antimicrobial activity comparable to sodium hypochlorite in vitro, with concentrations above 1% showing enhanced antibacterial effects. However, methodological heterogeneity limits direct comparison, and clinical equivalence cannot be concluded.