prevalence of extra roots in permanent mandibular first molars in iranian population: a cbct analysis

introduction: having knowledge about the anatomy of root canal system is essential for success of endodontic treatment. the present study used cone-beam computed tomography (cbct), to evaluate the prevalence of third root in mandibular first molars in a selected iranian population. methods and materials: a total of 386 cbct images from subjects referred to oral and maxillofacial radiology department of dental faculty of tabriz university of medical sciences from 2011 to 2013 were selected and evaluated for this study and the cases with well-developed permanent mandibular first molars were included. the 3d images were reconstructed in axial cross sections and evaluated by two endodontists for the presence of the third extra lingual (radix entomolaris) or buccal (radix paramolaris) root. the chi-squared test was used to evaluate the relationship between gender and bilateral incidence of extra roots in mandibular first molars. results: the distribution of three-rooted mandibular first molars with an additional root was 3%, (3.53% in female and 2.50% in male patients). there was no significant relationship between gender and bilateral occurrence of three-rooted mandibular first molars. conclusion: the occurrence of three-rooted mandibular first molars in iranian population is not uncommon which should be taken into consideration by the dental practitioners during root canal treatment of these teeth.