Influence of acidic pH on antimicrobial activity of different calcium silicate based-endodontic sealers

Objective To investigate the antibacterial activity of calcium silicate-based sealers (CSBSs) against Enterococcus faecalis biofilm in a neutral or acidic condition. Materials and methods Dentin cylinders (4 mm length) were prepared and infected with 3-week-old E. faecalis. The samples were filled with BioRoot RCS (BR), EndoSequence BC (ES), and NeoMTA Plus (NMTA) and incubated in either neutral or acidic conditions for 7 days (n=10/group). Sterile or infected samples alone were used as the positive and negative control. The root canal sealers were removed after 7 days, and the remaining bacteria on dentinal walls were determined by colony-forming units (CFUs/ml), and three samples from each group were visualized under a confocal laser scanning microscope (CLSM). The pH was also measured (n=3/group) after 4 h and 7 days of incubation at 37 degrees C in both conditions. Results In the neutral condition, all sealers significantly decreased the log-CFU values (p<0.05), while in the acidic condition, the log-CFU reduction was less for ES and NMTA, but a higher reduction was observed in BR (p<0.05). The antibacterial activity of CSBSs was similar in neutral conditions (p>0.05), and BR showed a greater antibacterial effect than ES and NMTA in the acidic condition (p<0.05). The pH of BR, ES, and NMTA ranged from 8.2 to 8.8 in the neutral condition in the presence of dentin after 7 days. However, acidic conditions reduced the pH values to 7.8 for BR, 6.0 for ES, and 5.8 for NMTA. Conclusions All CSBSs showed similar antibacterial activity in neutral conditions, while acidic pH had a reducing antibacterial effect on CSBSs.

Automated summary

All calcium silicate-based sealers showed similar antibacterial activity in neutral conditions, but BioRoot RCS demonstrated greater effectiveness in acidic conditions compared to EndoSequence BC and NeoMTA Plus. The pH values of the sealers ranged from 8.2 to 8.8 in neutral conditions, but decreased significantly in acidic conditions, with BioRoot RCS maintaining the highest pH. Acidic pH had a reducing effect on the antibacterial activity of the calcium silicate-based sealers.