Antibacterial activity of two MTA-based sealers root canal sealers

Aim This laboratory study evaluated the pH and antibacterial activity of Endo CPM Sealer and MTA Fillapex by two different methods, using White MTA and Endofill as references for comparison. Methodology Antibacterial activity was evaluated against Enterococcus faecalis (ATCC 29212). The agar diffusion test (ADT) was performed to evaluate the effect before setting. The materials were placed in four equidistant wells made in ten agar plates. After incubation at 37oC for 48 h, the inhibition zones were measured using a digital paquimeter. The direct contact test (DCT) was performed to assess the antibacterial effect after setting. Suspensions of crushed materials were prepared and mixed with E. faecalis. After different periods of time (1, 6, 15 and 60 min), the survival of bacteria was assessed by using 10-fold serial dilution and cultivated on agar plates in triplicate. Colony-forming units (CFU)/mL were calculated after incubation. pH values were also measured in triplicate. Comparison between sealers in the ADT and DCT were performed by the Kruskal-Wallis test. Results In the ADT, inhibition zones were found with MTA Fillapex and Endofill. They were similar to each other and greater than the other sealers (P<0.05). None of the tested sealers demonstrated antibacterial activity in the DCT, thus all sealers had similar bacterial counts compared to the negative control group (P>0.05). White MTA and Endo CPM Sealer suspensions had pH values greater than 11, while MTA Fillapex and Endofill had lower values. Conclusions MTA Fillapex and Endofill had an antibacterial effect against E. faecalis before setting, but none of the sealers maintained antibacterial activity after setting, despite the high pH of the MTA-based materials.