Investigation of the Number of Root Canals in Mandibular Molars and Premolars Teeth in Ilam in 2020

types of be at least one the some roots have multiple canal of different length. The goal of this study was investigation of the number of root canals in mandibular molars and premolars teeth in Ilam in 2020. Material & Methods: This study was descriptive-analytic study that performed on 60 mandibular premolars and molars (first premolars 15, second premolars 15, first molars 15, second molars 15) randomly with considering of the sex of patients. Data were analyzed by SPSS22. (Ethic Findings: In the first and second premolars, the highest frequency of single canal as 86.7% and 93.3%, respectively. In the first and second molars, the highest frequencies related to the three channels were 53.3% and 86.7%, respectively. The prevalence of 4-channel molars was higher in women and 3-channel in men. This difference was not statistically significant. Between two radiologists and endodontists to determine the number of root canals in the first and second premolars and the first and second molars, a good agreement was reported with kappa agreement coefficient of 0.92 and (P = 0.000). Conclusion: study, the and second mandibular premolars single root and one and the first and second mandibular molars had often two roots and three channels.