Morphology of third molars has been described as unpredictable. However restorative, prosthodontic, and orthodontic considerations often requires endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. OBJECTIVES: The purpose of this study was to investigate and characterize the anatomy of maxillary and mandibular third molars. METHODS: A total of 106 human extracted third molars (56 maxillary, 50 mandibular) were included in this in vitro study. With the aid of a carborundum disc in a straight headpiece, each specimen was prepared according to the standard techniques. The anatomy of the root canal system was then recorded. The following observations were made: number of roots, number of canals per root, root-canal configuration, frequency of root canal configuration, number of lateral canals, the average length of the root-canals. RESULTS: Most of the maxillary third molars (83.9%) had three roots, 8,9% had one root, 5.4% had two roots, and 1.8% had four roots. 56% of mandibular molars had one root, and 44% had two roots. 75% of the maxillary third molars had 3 canals, 10.7% had 4 canals, 7.1% had one canal, and 7.1% had two canals. 90% of the mandibular molars had 3 canals, and 4% had 1 canal. The frequency of deviation of the maxillary root-canals was 76.8%, and of the mandibular root-canals was 84%. 12% of the maxillary and two percent of the mandibular third molars contained lateral canals. The average length of the maxillary third molars was approximately 17.98, and of the mandibular third molars was approximately 18.9 mm. CONCLUSION: Third molars show great anatomic variability. Maxillary third molars may have one to four roots, while mandibular may have one or two roots. Maxillary third molars may have up to 4 root canals, while mandibular have up to 3 canals.
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