Antimicrobial activity, viability, and physicochemical properties of an MTA-type cement with different concentrations of bismuth trioxide

In medicine, bismuth is used as an antimicrobial agent. In dentistry, it is used primarily to increase radiopacity in some endodontic materials. The objective is to evaluate the antimicrobial activity, cell viability, pH, solubility, film thickness, and setting time of a mineral trioxide aggregated (MTA)-types of cement with different concentrations of bismuth trioxide. Three experimental MTA-types of cement with a bismuth trioxide (Bi₂O₃) concentration of 15 wt%, 20 wt%, and 25 wt% were used. The antimicrobial activity test was conducted on Streptococcus mutans and Porphyromonas gingivalis strains. Cell viability was measured by the quantitative colorimetric assay using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide) assay on a mouse fibroblast cell line (L929). Solubility, film thickness, and setting time were performed according to ISO 6876. The lowest Bi₂O₃ concentrations showed the best antimicrobial activity and cell viability. pH, solubility, setting time, and film thickness did not show statistically significant differences between the different Bi₂O₃ concentrations tested.