Does dentin pretreatment with chitosan improve the bond strength of restorative material? A systematic review and meta-analysis of in vitro studies

Objective: This systematic review and meta-analysis evaluated the effect of dentin pretreatment with chitosan on resin-dentin immediate or long-term bond strength (BS). Materials and methods: In vitro studies assessing the effect of chitosan on BS published in English were included. The literature search was conducted including databases: MEDLINE via PubMed, Web of Science, SciELO, EMBASE, and Scopus, up to October 2022. After searching and removing duplicate articles, 1272 studies remained, of which 27 were read in full, and 11 were included. Manuscripts that reported the effect of using chitosan (0.1-2.5 %) before the application of the adhesive system on the BS were included. Subgroup analyses were performed by comparing the adhesive approaches (etch-and-rinse or self-etching) or treatment times (immediate and long-term). Data were analyzed, and the standard mean difference (SMD), with a 95 % confidence interval, was calculated. Results: In the immediate analysis, there was an increase in BS with chitosan followed by self-etching adhesives (SMD = -0.75; -1.27 to -0.24; I2 = 35 %). There was no difference in BS with chitosan and etch-and-rinse (SMD = -0.06; -0.45 to 0.34; I2 = 45 %). In the long-term, chitosan had a positive effect on BS for the etchand-rinse rinse technique (SMD = -1.24, -1.88 to -0.60, I2 = 50 %) compared to the control without chitosan there was no difference in intervention for the self-etching adhesives (SMD = -0.11; -0.62 to 0.41; I2 = 20 %). Conclusion: The prior application of chitosan can improve the immediate BS of self-etching adhesives and the long-term BS of etch-and-rinse adhesives.