Background: Mandibular premolars, because of high anatomic variations, are among the most difficult teeth for root canal treatment.The aim of this study is to compare and evaluate root canal morphology of mandibular first premolars between males and famales in an Iranian population applying CBCT imaging.

  Materials and Methods: In this analytical-cross sectional study, 230 CBCT imaging belonged to 115 males and 115 females were evaluated in this study. Images were assessed in the three spatial planes and the difference in the number of canals and roots were compared and reported statistically. Data were analyzed using SPSS 17 software and Chi-square test.The significance level was set as p<0.05.

  Results: In total, of 460 mandibular first premolars, 85.7% had one root, 14.3% had two roots, 63.9% had one canal and 36/1% had two canals. In comparison between two genders, in the males the prevalence of one root was 78.7%, two roots 21.3%, one canal 60% and two canals 40%. In the females, the prevalence of one root was recorded as 92.6%, two roots 7.4%, one canal 67.8% and two canals 32.2%.

Conclusion: According to the results of this study the number of roots in the mandibular first premolars in males was statistically more than in females.