en Endodontics Endodontics Review article Review article <pre style="text-align: justify;"> <span style="font-family:Times New Roman;"><span style="font-size:14px;"><span style="line-height:95%"><b><span style="line-height:95%"><span style="color:#2e74b5">Background and Aim:</span></span></b> <span style="line-height:95%">This study reviewed the prevalence of C-shaped root canal morphology in different provinces of Iran.</span></span> <span style="line-height:95%"><b><span style="line-height:95%"><span style="color:#2e74b5">Materials and Methods: </span></span></b><span style="line-height:95%">This systematic review was conducted according to the PRISMA guidelines. Embase, Medline, PubMed, Scopus, Web of Knowledge, Google Scholar, Cochrane Library, Ovid, SID, CIVILICA, Magiran, IranMedex, and ISC electronic databases were searched for articles published from 2000 to 2021. The searched keywords included &ldquo;C-shaped root canal system&rdquo; and &ldquo;prevalence&rdquo;, &ldquo;molar teeth&rdquo;, &ldquo;premolar teeth&rdquo;, and &ldquo;Iranian population&rdquo;. Full-text assessment of the articles and critical appraisal were performed using the CONSORT and STROBE checklists. Gender, tooth type (first/second molar, first/second premolar), upper/lower jaw, and type of C-shaped classification were extracted from the eligible articles, pooled, and analyzed using forest plots with proportions and odds ratio with 95% confidence interval (CI). Meta-regression was performed to evaluate possible sources of heterogeneity. </span>&nbsp;&nbsp;</span> <span style="line-height:95%"><b><span style="line-height:95%"><span style="color:#2e74b5">Results: </span></span></b><span style="line-height:95%">The prevalence of C-shaped canals was 0.06% (95% CI: 0.04-0.08). The prevalence of C-shaped canals was 0.08% (95% CI: 0.05-0.11) based on cone-beam computed tomography (CBCT) scans. The pooled prevalence of C-shaped root canal system was higher in Mazandaran (Sari and Babol) and East Azarbaijan (Tabriz) (0.10%) than other provinces. There was no significant difference between the pooled prevalence of C-shaped root canal system in males (0.26%) and females (0.36%). The pooled prevalence of C-shaped morphology was 0.03% in first molars and 0.12% in second molars.<span style="font-family:"Verdana",sans-serif"></span></span></span> <span style="line-height:95%"><b><span style="line-height:95%"><span style="color:#2e74b5">Conclusion:</span></span></b> <span style="line-height:95%">The prevalence of C-shaped morphology is high in the Iranian population. Tooth type has a significant effect on the prevalence of C-shaped canals. </span>&nbsp;</span></span> &nbsp;</span></pre> Tooth root, Prevalence, Molar, Bicuspid, Iranian people 132 143 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-391-7&slc_lang=en&sid=1 Azam Haddadi haddadi-azam@yahoo.com 100319475328460012326 100319475328460012326 No Department of Endodontics, Dental Research Center, Dental School, Mazandaran University of Medical Sciences, Sari, Iran. Narjes Hoshyari narjeshoshyari@rocketmail.com 100319475328460012327 100319475328460012327 Yes Department of Endodontics, Dental Research Center, Dental School, Mazandaran University of Medical Sciences, Sari, Iran. Hadis Abbaspour abbaspour.hadis@yahoo.com 100319475328460012328 100319475328460012328 No Department of Endodontics, Dental Research Center, Dental School, Mazandaran University of Medical Sciences, Sari, Iran. Abolfazl Hossein Nataj hosseinnataj.a@gmail.com 100319475328460012329 100319475328460012329 No Department of Biostatics and Epidemiology, School of Health, Mazandaran University of Medical Sciences, Sari, Iran. Ahmad Keshvari ahmad.keshvari81@gmail.com 100319475328460012330 100319475328460012330 No Dentist, Sari, Iran