RESUMEN
AIM: The aim of the present study was to compare the antibacterial properties of PLGA polymer containing ZnO, Ag and ZnO/Ag nanoparticles with those of 2.5% NaOCl in root canals contaminated with Enterococcus faecalis. METHODS: A total of 100 maxillary central incisors were selected. After the crowns were removed to achieve 12-mm-length roots, the root canals were prepared with RaCe rotary system. The samples were sterilized; then 200 µL of E. faecalis suspension (ATCC 29212) was placed in each root canal. The samples were divided into 5 groups based on the antibacterial agent used. Group 1 served as the control group. In group 2 the polymer suspension containing ZnO nanoparticles, in group 3 the polymer solution containing ZnO/Ag nanoparticles, in group 4 the polymer solution containing Ag nanoparticles and in group 5, 2.5% NaOCl were used. After 24 hours, a solution was prepared using dentin chips from each root canal and placed on agar plates, followed by colony-forming units (CFU) count determination. Means ± standard deviations were calculated and Kruskal-Wallis test was used to evaluate the antibacterial properties of different irrigation agents. Mann-Whitney U test was used for two-by-two comparisons of the groups, with the level of significance being set at 0.05. RESULTS: The maximum and minimum CFU counts were observed in the control and NaOCl groups, respectively. In the polymer groups, the maximum and minimum CFU counts were observed in the Ag and ZnO/Ag groups, respectively. There were significant differences in CFU counts between the study groups after application of irrigation solutions (P<0.05). Two-by-two comparisons of the groups using Mann-Whitney U test showed significant differences between all the study groups (P<0.05), except for groups ZnO and Ag (P=0.7). CONCLUSION: Sodium hypochlorite solution was more effective than copolymer containing nanoparticles and of all the tested nanoparticles; ZnO/Ag nanoparticles exhibited the highest antibacterial activity.