ABSTRACT
The human teeth have different anatomical variations and treatment of each tooth is under the influence of its configuration. The root canal anatomy, not only in various teeth, but also in one tooth might be different. The important point is to understand the canal anatomy that is essential for root canal therapy. In various studies, different results have been reported from different regions of the world, additionally a number of studies have shown different trends in shape and number of roots and canals among different races. Since there is a lack of information about canal configuration in the city of Isfahan, therefore this study was done to determine the frequency of canal configuration in maxillary first and second molars This study was descriptive, that was done on 160 extracted maxillary first and second molars, which were collected from clinics and private offices in the city of Isfahan. Pulp tissue was removed and canal system was stained with Indian ink, the teeth were decalcified with 10% nitric acid, dehydrated and cleared with methyl salicylate. Maxillary first molars were additionally cut in cross sections in three points of the root and canal configuration of teeth were evaluated. The examination of root canal systems of teeth was based on Weine classification. The majority of maxillary first and second molars had three separate roots. A variety of canal types were found in mesiobuccal [MB] roots of first and second molars. More than half of the MB roots of first molars [61%] had two canals, whereas MB roots of second molars mostly had type I canals [76.38%] in the clearing method. The palatal and distobuccal canals mainly had type I canal configuration. In the sectional method more than half the MB roots of first molars had two canals [78.47%]. In other countries many researches have been done using different methods about internal anatomy of teeth and the results are different from this study. It appears that the differences are caused by genetic factors and methods used. Also results of this study were different in types I and IV in MB roots in the two methods, this difference is probably due to better access and visibility to canal in the sectional method