Root and canal morphology of teeth has a significant role in endodontic treatment success. Third molars have strategic roles after losing first and second molars. Objectives: This study investigated the morphology of permanent third molar using radiography in Dentistry University of Hamadan during 2011. Materials and Methods: In this experimental study, 352 extracted molars (179 maxillary and 173 mandibular molars) were collected. After preparing access cavity and file placement in canals, to

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... vestigate the number of roots, canals and canal type periapical radiographies were taken from two directions (mesiodistal and buccolingual). The results were analyzed using SPSS version 16.0 software and descriptive statistics. Results: According to the study on 173 mandibular third molars, 92.4%, 4.6%, and 2.89% had two, one, and three roots, respectively. Majority of them had two or three canals and most of mesial root canals were type 2; but in 179 maxillary third molars, findings showed that 67.6%, 15%, 11.7%, and 5.6% of teeth had three, one, two, and four roots, respectively, majority of which had three canals (68.7%). Canals of 100% of distobuccal and palatal roots and 91% of mesiobuccal roots were type 1. Conclusions: However, root and canal anatomies of third molar teeth are unknown, but studies focusing on third molar teeth have shown their possibility of treatment.