Evaluation of Root Canal Morphology of Mandibular Premolars Using Cone Beam Computed Tomography in Northern Cities in Iran During 2018

Mandibular premolars are considered the most difficult of all teeth for endodontic treatment due to variation in the shape and the number of canals. For this reason, endodontic treatments showed the most failure rates. In this study, the number and morphology of canals of the mandibular premolar are investigated in northern cities in Iran. This cross-sectional study investigated the archived cone beam computed tomography images of patients who referred for diagnostic purposes to private centers of maxillofacial radiology. In total, 280 mandibular first premolars from 111 males and 169 females and 248 mandibular second premolars from 95 males and 154 females were investigated in this study. Data were analyzed in SPSS software (Version 2016) through descriptive statistics using frequency distribution and Chi-square test. Level of significant considered 0.05. Mandibular first premolars in males and females had one or two roots. One root premolars were the most prevalent of mandibular premolars (95.7%). Similarly, mandibular second premolars had one or two or three roots and one root premolars were the more prevalent of mandibular second premolars (97.6%). In terms of the number of canals, the majority of premolars had a single canal and were of type I. Among mandibular first premolars, types III, IV, and VII were not seen and Vertucci type VIII was the rarest.  Out of mandibular second premolars types IV, VI, and VII were not observed, and Vertucci types II and IIIV were the rarest. According to the results, mandibular first and second premolars in females and males are more single rooted and have a single canal. Regarding the Vertucci classification, the most prevalent type was type I.