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.