en ارتودنسی Orthodontic پژوهشي Research <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times="">Abstract</span></span></b><span style="font-size:10.0pt"><span aparajita="" style="font-family:"><span style="letter-spacing:-.1pt"></span></span></span></span></span><br> <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Background and Objective:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> The antibacterial properties of nanoparticles have been recently considered in the treatment of root canals.&nbsp; Therefore, this study aimed to compare the antibacterial effect of green-synthesized nanoparticles of silica, calcium hydroxide and tannic acid as intracanal medicaments against <i>Enterococcus faecalis</i> bacteria.</span></span></span></span><br> <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Methods:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> 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 nano-silica 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&ndash;Wallis test and Mann&ndash;Whitney test. The level of statistical significance was set at <i>P</i><0.05.</span></span></span></span><br> <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Results:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> 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 <i>Enterococcus</i> 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.</span></span></span></span><br> <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Conclusion:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> 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.</span></span><span style="font-size:12.0pt"><span style="font-family:"Times New Roman",serif"></span></span></span></span><br> <span style="font-size:11pt"><span style="tab-stops:9.0pt"><span style="font-family:Calibri,sans-serif"><span style="font-size:4.0pt"><span style="font-family:"Times New Roman",serif"></span></span></span></span></span><br> <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Key words:</span></span></b> <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Silicon dioxide, Nanoparticles, Tannic acid, Calcium hydroxide, <i>Enterococcus faecalis</i>&nbsp; </span></span><span style="font-size:10.0pt"><span style="font-family:"Times New Roman",serif"></span></span></span></span> <div> <div> <div class="msocomtxt" id="_com_3" language="JavaScript" on=""><illegal tag=""></illegal></div> </div> </div> Silicon dioxide, Nanoparticles, Tannic acid, Calcium hydroxide, Enterococcus faecalis 0 0 http://jsurgery.bums.ac.ir/browse.php?a_code=A-10-510-1&slc_lang=en&sid=1 Amirhosein Hoseini seyyedamirhoseinhoseine@gmail.com 100319475328460012444 100319475328460012444 No Department of General Dentistry, Birjand university Mehdi Shakibaie shakibaie_m@yahoo.com 100319475328460012445 100319475328460012445 No Department of Medical Nanotechnology, School of Medicine, Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran Shima Bijari shima.bijari223@gmail.com 100319475328460012446 100319475328460012446 Yes Department of Endodontics, Faculty of Dentistry and Dental Research Center, Birjand University of Medical Sciences, Birjand, Iran maryam mortazavi maryam_mortazavi85@yahoo.com 100319475328460012447 100319475328460012447 No Department of Endodontics, Faculty of Dentistry and Dental Research Center, Birjand University of Medical Sciences, Birjand, Iran