en Dentistry Dentistry پژوهشي Research <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Introduction</b>: Endodontic treatment errors (EEs) can lead to complications and require additional follow-up care. This study aimed to investigate the prevalence of root canal treatment errors among dental students, identifying error types based on radiographic criteria, tooth type, location, and technical errors.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Materials & Methods</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: </span></span></b>A cross-sectional study analyzed data from 201 patients who underwent root canal treatment at Ilam University of Medical Sciences between 2021 and 2022. Inclusion criteria were confirmed root disease diagnosis, adherence to standard treatment protocol, availability of radiographs, and complete patient files. The protocol included rubber dam isolation, radiographic length determination, manual file canal preparation, irrigation, obturation with the lateral compression method, and temporary restoration. Two endodontists evaluated filling length, density, convergence, and technical errors such as floor perforation, broken instruments, transportation, ledge formation, and access cavity gouging.<span lang="FA" dir="RTL" style="font-family:"Times New Roman",serif"></span></span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Results</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: &nbsp;</span></span></b>The study included 89 male (44.3%) and 112 female (55.7%) dental students with a mean age of 25.36 years. Among the 201 patients (28.9% male, 71.1% female; mean age 35.24 years), 71.6% had fillings of appropriate length, 12.14% short, and 15.9% long. Appropriate density was observed in 67.6%, and convergence in 86.1%. Technical errors included ledge formation (8.5%), floor perforation (1%), access cavity gouging (1.5%), and broken instruments (0.5%). A significant relationship was found between density and tooth type (p < 0.002) and convergence and tooth type (p < 0.009).</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Conclusion</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: &nbsp;</span></span></b>Proper filling, convergence, and density were more frequent in anterior teeth. Maxillary teeth had higher rates of proper filling compared to mandibular teeth. The overall rate of treatment errors was low, likely due to professor supervision.</span></span> Frailty, Geriatric, Anxiety, Syndrome, Hospital 59 67 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-851-1&slc_lang=en&sid=1 Masoumeh Ahmadi ahmadi-m@medilam.ac.ir 10031947532846006578 10031947532846006578 Yes Department of Endodontics, School of Dentistry, Ilam University of Medical sciences, Ilam, Iran Hossein Seidkhani seidkhani-h@medilam.ac.ir 10031947532846006579 10031947532846006579 No Department of Biostatistics, School of Health, Ilam University of Medical sciences, Ilam, Iran Naser Shikhi shikhi-n@medilam.ac.ir 10031947532846006580 10031947532846006580 No Department of Endodontics, School of Dentistry, Ilam University of Medical sciences, Ilam, Iran