comparing the antibacterial effect of green-synthesized nano-silica with calcium hydroxide and tannic acid in canals infected by enterococcus faecalis

Introduction: the antibacterial properties of nanoparticles have been recently considered in the treatment of root canals. therefore, this study aimed to compare the antibacterial effect of green-synthesized nanoparticles of silica, calcium hydroxide and tannic acid as intracanal medicaments against enterococcus faecalis bacteria.methods: in this in-vitro study, 58 single-rooted teeth were first treated, silica nanoparticles (sinps) were synthesized by the green method, and then minimum inhibitory concentration (mic) and minimum bacterial concentration of tannic acid, calcium hydroxide, and green nanosilica were measured using the microbroth dilution method. then, the minimum bactericidal concentration was measured in extracted teeth prepared for each material, and this concentration obtained for each material was placed in three groups of teeth (green nano-silica, tannic acid, and calcium hydroxide) to count the number of colonies. brunauer-emmett-teller, dynamic light scattering, and transmission electron microscopy analyses were also performed for the nanoparticles. data were analyzed using spss software (version 20) and the kruskal– wallis test and mann–whitney test. the level of statistical significance was set at p<0.05.results: the results of the microbroth dilution test for green-synthesized nano-silica, tannic acid, and calcium hydroxide showed mic values of 0.2, 0.8, and 1.56 mg/ml, respectively. green-synthesized silica had the highest antibacterial activity against enterococcus among different materials. the results obtained from the evaluation of minimum bactericidal concentration in teeth and colony counting also showed a greater effect of green-synthesized nano-silica compared to other materials.conclusion: using sinps can effectively clean root canals of bacteria; however, further in vivo studies and assessments of long-term safety and efficacy are necessary before clinical application.