Antibacterial activity, cytotoxicity, and microshear bond strength of an experimental adhesive system containing...

The aim of this study was to investigate the antimicrobial effect, cytotoxicity, and the microshear bond strength (µSBS) of several experimental adhesives containing different concentrations of chitosan-silver oxide (CH-Ag₂O) particles. Eight experimental etch-and-rinse adhesives were prepared using four different concentrations of CH-Ag₂O particles (0.125, 0.25, 0.5, and 1% w/v) combined with two CH-Ag₂O compositions (20 mg and 60 mg Ag₂O). An experimental adhesive with no additives served as the negative control, while the conventional etch-and-rinse adhesive (Adper Single Bond 2) served as the positive control. Antimicrobial activity was assessed against Streptococcus mutans, Streptococcus salivarius, and Streptococcus oralis using the broth microdilution method. The cytotoxicity assay was done on human gingival fibroblast cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The study groups exhibiting the greatest antibacterial activity and the lowest cytotoxicity were subjected to the (µSBS) evaluation. The data were analyzed using descriptive statistics, one-way ANOVA, Tukey HSD, and Chi-square tests. The antibacterial properties of the adhesives containing CH-Ag₂O 60 were two times greater than those containing CH-Ag2O 20. The lowest MIC and MBC were observed when 1% of CH-Ag₂O particles was used. The highest cytotoxicity presented in the same dilution of MTT assessment for each concentration of CH-Ag₂O (p < 0.001), with no significant differences detected among concentrations (p > 0.05) or measuring times (p > 0.05). The lowest bond strength was observed in the adhesive containing 1% CH-Ag₂O 60. The adhesive containing 1% CH-Ag₂O 20 showed comparable µSBS with two control groups. The experimental etch-and-rinse adhesive containing 1% CH-Ag₂O 20 demonstrated favorable antibacterial properties without negatively affecting gingival fibroblasts or dentin adhesion.