The purpose of this study is to compare the antibacterial effect of Listerine® on two microorganisms (P. gingivalis and E. faecalis) with various root canal irrigants (NaOCl, CHX, EDTA) and to identify possibility of using Listerine® as a root canal irrigant. Porphyromonas gingivalis ATCC 3327 and Enterococcus faecalis ATCC 29212 were used in this experiment. For the test irrigants, 0.5%, 1%, 2.5%, 5.25% NaOCl, 0.1%, 0.2%, 1%, 2% CHX, 0.5M EDTA (18.6% EDTA) and Listerine® were prepared. Distiled water was used as control. Two methods-1) Comparison of turbidity in broth and 2) Agar diffusion test-were used to determine the extent of antibacterial effect of Listerine® and to compare it with that of NaOCl, CHX, and EDTA. All solutions tested were effective against two bacterial strains compared with control (p<0.001). Any concentration of NaOCl, CHX, and EDTA showed similarly high effectiveness against all bacterial strains. In all experiment, Listerine® showed significantly low antibacterial effect compared with the other root canal irrigants (p<0.05).

In conclusion, the results reflect remarkably low antibacterial effect of Listerine® as compared with root canal irrigants in general so it is not suitable for the root canal irrigant.

This study was carried out in order to determine in vitro biocompatibility of white mineral trioxide aggregate (MTA), and to compare it with that of the commonly used materials, i. e. calcium hydroxide liner (Dycal), glass ionomer cement (GIC), and Portland cement which has a similar composition of MTA. To assess the biocompatibility of each material, cytotoxicity was examined using MG-63 cells. The degree of cytotoxicity was evaluated by scanning electron microscopy (SEM) and a colorimetric method, based on reduction of the tetrazolium salt 2,3 bis {2methoxy 4nitro 5[(sulfenylamino) carbonyl] 2H tetrazolium hydroxide} (XTT) assay.

The results of SEM revealed the cells in contact with GIC, MTA, and Portland cement at 1 and 3 days were apparently healthy. In contrast, cells in the presence of Dycal appeared rounded and detached. In XTT assay, the cellular activities of the cells incubated with all the test materials except Dycal were similar, which corresponded with the SEM observation. The present study supports the view that MTA is a very biocompatible root perforation repair material. It also suggests that cellular response of Portland cement and GIC are very similar to that of MTA.