Comparison of the antibacterial effect of gels containing nano ZnO and nano Ag/ZnO with Calcium Hydroxide paste as an intracanal medicaments on Enterococcus faecalis in infected root canals at various time intervals

Abstract

Intracanal medicaments are one of the supplementary methods to eliminate bacteria in root canal systems along with other methods such as cleaning, shaping and irrigation in root canal therapy procedures. Calcium hydroxide is the most common material used for this purpose. Despite the widespread use of this material, it has some disadvantages such as the lack of effect on Enterococcus faecalis. One of the methods to enhance the effectiveness of calcium hydroxide is to mix it with Chlorhexidine. However, due to limitations and disadvantages of available materials, several studies have been done to introduce a material with better properties, including the use of nanotechnology. Nanoparticles of zinc oxide and zinc oxide / silver are examples of these materials. The aim of this study was to compare the antibacterial effect of gels containing nano ZnO and nano Ag/ZnO with Calcium Hydroxide / Chlorhexidine mixture paste as an intracanal medicaments on Enterococcus faecalis in infected root canals at various time intervals. Methods and Materials: After preparation and culturing of Enterococcus faecalis bacteria in samples, the initial count of the number of bacteria was performed. Then, different materials as intra canal medicaments were used in period of 3, 7 and 14 days. After the specified time, intracanal medicament was removed and the final count of bacteria was performed. Antibacterial effect of materials used in the sample was counted by measuring the percentage reduction in the number of colonies (%RCC) determined in the first and second stages. Data obtained from the study were analyzed using descriptive statistics (Mean SD) and multi-factorial analysis of variance (by taking into account the effect of the time factor on the dependent variable) by statistical software SPSS 15. Normality of data distribution was assessed using the Kolmogorov-Smirnov test. In this study the P values less than 0.05 were considered statistically significant. Results: Antibacterial effect of calcium hydroxide / Chlorhexidine mixture was more than zinc oxide and zinc oxide / silver nanoparticles (P<0.001), however; there was no statistically significant differences between zinc oxide and zinc oxide / silver nanoparticles (P>0.05). In addition to differences among antibacterial effect of intra canal medicaments in various time intervals of 3, 7 and 14 days were not significant ( P=0.09). Conclusions: According to the findings of this in vitro study, the mixture of calcium hydroxide / Chlorhexidine as an intracanal medicament was more effective than zinc oxide and zinc oxide / silver nanoparticles gels at various time intervals