en Endodontics Endodontics Original article Original article <div style="text-align: justify;"><span style="font-size:13pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif"><span style="color:#2e74b5">Background and Aim</span></span></span></b><b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif"><span style="color:#2e74b5">:</span></span></span></b> <span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif">Effective cleaning and shaping of the root canal system is an essential part of a successful root canal treatment and is considered as one of the basic features of rotary instruments. The present study aimed to compare the efficacy of two types of nickel-titanium rotary files namely BioRaCe and Mtwo, in reduction of <i>Enterococcus faecalis (E. faecalis)</i> count in the root canal system. </span></span></span></span><br> <span style="font-size:13pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif"><span style="color:#2e74b5">Materials and Methods: </span></span></span></b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif">In this in vitro study, 50 extracted human single-rooted teeth were assigned to two groups plus a positive and a negative control group (20 samples in each group). First, the root canals were sterilized and were then inoculated with <i>E. faecalis</i> (ATCC: 11700). Subsequently, all the root canals were instrumented with BioRaCe and Mtwo nickel-titanium rotary instruments. Then, samples were collected from inside the root canals and cultured in a special medium to evaluate the remaining colonies. The Chi-square goodness of fit test was used to assess the difference in bacterial colony count after root canal preparation with the two rotary systems (alpha=0.05).&nbsp; </span></span></span></span><br> <span style="font-size:13pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif"><span style="color:#2e74b5">Results: </span></span></span></b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif">Complete bacterial growth was observed in both the BioRaCe and Mtwo groups. There was no statistically significant difference between the two groups regarding bacterial elimination from the root canal system (P>0.05).</span></span></span></span><br> <span style="font-size:13pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><b><span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif"><span style="color:#2e74b5">Conclusion:</span></span></span></b> <span style="font-size:9.0pt"><span style="font-family:&quot;Verdana&quot;,sans-serif">Under the limitations of the current study, the two rotary systems exhibited no superiority over each other in terms of their ability to eliminate microorganisms from the root canal system. </span></span></span></span><br> &nbsp;</div> Enterococcus Faecalis, Root Canal Therapy, Root Canal Preparation 28 34 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-910-2&slc_lang=en&sid=1 Hadi Mokhtari mokhtari.z.h@gmail.com 100319475328460011821 0000000199225952 Yes Department of Endodontics, Dental Faculty, Tabriz University of Medical Sciences, Tabriz, Iran. Negin Ghasemi neginghasemi64@gmail.com 100319475328460011822 100319475328460011822 No Department of Endodontics, Dental Faculty, Tabriz University of Medical Sciences, Tabriz, Iran. Negin Firouzi neginfirouzi@gmail.com 100319475328460011823 0000000196257625 No Department of Endodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. Mohammad Hossein Soroush Barhaghi mhsoroushb@gmail.com 100319475328460011824 000000030524738X No Department of Microbiology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran Davood Sokhandani davoodsokhandani@gmail.com 100319475328460011825 100319475328460011825 No Department of Endodontics, Dental Faculty, Tabriz University of Medical Sciences, Tabriz, Iran.