Antibacterial effects of five different root canal sealing materials

The aim of this in vitro study was to assess the antibacterial effects of gray and white mineral trioxide aggregate (GMTA and WMTA), calcium hydroxide (CH), Portland cement (PC) and a new endodontic cement (NEC) on various species of microorganisms, using agar diffusion test. A base layer of Petri plates was made using Muller-Hinton agar. Five cavities were made in agar and filled with fresh mixed materials after 24 h. Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and a mixture of these bacteria were seeded by pour plate. The plates were preincubated for 2 h at room temperature followed by incubation at 37 degrees C. The inhibition zone diameters were measured at 24, 48 and 72 h. The highest mean diameters of growth inhibition zones were observed around NEC and CH. According to one-way ANOVA, there was a significant difference among test groups (P < 0.001), while post-hoc test revealed no significant difference between the mean zone diameters of NEC and CH, and also between MTAs and PC. However, there was a significant difference between CH and NEC in comparison with MTAs and PC groups (P < 0.001). It appears that NEC may act as a potent antibacterial agent similar to CH.