Document Type: Original Article


1 Dept. of Endodontics, Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran

2 Dentist, Iran


Statement of Problem: The human teeth have a lot of anatomical variations, and treatment of each tooth is under the influence of its configuration. Therefore, recognizing canal configuration is necessary for proper endodontic therapy, and lack of knowledge about it leads to failure in therapy.Purpose: Since one of the most effective factors in canal configuration is race, we planned an in vitro investigation in canal configuration of the mandibular first and second molars.Materials and Method: This descriptive-analytic study was conducted on 160 extracted mandibular first and second molars, collected from a number of clinics and private offices in Isfahan. Access cavities were made and canal systems were stained with India ink. The teeth were decalcified with 10% nitric acid, dehydrated and cleared with methyl salicylate. Then, they were studied to determine the number of roots and type of canal configuration in each root using Weine classification. Mandibular first molars were additionally cut in cross-sections in three points of the root and then canal configurations of the teeth were evaluated. For statistical analysis, Chi-square test was used.Results: In this study, using the clearing method, out of 80 mandibular first molars, 98.75% had two roots and 1.25% had three roots. The mesial roots had type II and III (50.63%, 31.65%) configuration. The distal root had I and II (84.82%, 10.12%) configuration. Out of 80 mandibular second molars, 90% had two roots, and 10% had single root, 6.25% of which had C-shaped root. In the two- rooted molars, the mesial roots had type I and II (31.95%, 42.22%) and distal roots had type I and II (88.88%, 6.95%) configuration. Out of 80 mandibular first molars in the sectional method, the mesial roots had type II and III (51.90%, 46.83%) configuration. The distal roots had type I and II (56.49%, 31.65%) configuration. The difference between clearing and sectional methods was statistically significant ( p < 0.05).Conclusion: In other countries, many researches have been done using different methods about internal anatomy of teeth; their results are different form those of this study. It appears that these differences are due to genetic or race factors and the methods used. Additionally, the results of different studies indicate that more attention should be paid to new studies on canal configuration of these teeth.Key words: Root canal, Configuration, Mandible, Molar