Root canal morphology of human maxillary and mandibular third molars

The anatomy of third molars has been described as unpredictable. However re storative, prosthetic, and orthodontic considerations often require endodon tic treatment of third molars in order for them to be retained as functiona l components of the dental arch. The purpose of this study was to investiga te and characterize the anatomy of maxillary and mandibular third molars. O ne hundred fifty maxillary and 150 mandibular extracted third molars were v acuum-injected with dye, decalcified, and made transparent. The anatomy of the root canal system was then recorded. Seventeen percent of mandibular mo lars had one root (40% of which contained two canals), 77% had two roots, 5 % had three roots, and 1% had four roots. Teeth with two roots exhibited hi ghly variable canal morphology, containing from one to six canals, includin g 2.2% that were "C-shaped" Fifteen percent of maxillary molars had one roo t, 32% had two roots, 45% had three roots, and 7% had four roots. Teeth wit h one root demonstrated the most unusual morphology, with the number of can als varying from one to six. An in vivo study of the canal morphology of tr eated third molars is suggested to provide the practitioner with an underst anding of the clinical implications of third molar root anatomy.