Scanning electron microscopic evaluation of different endodontic procedures on dentin morphology of human teeth.

Four manual endodontic instruments, an ultrasonic and an endosonic system were studied with a view to evaluating the morphology of the smear layer and the amount of debris and pulpal residues in the apical third of human extracted straight teeth from 55- to 75-yr-old patients. The manual instruments were K files, Ergoflex files used with the step-back technique, Canal Master with its own technique, and Flex-R with the Roane technique. The ultrasonic system was Suprasson Piezo and the endosonic was Excalibur. Human extracted teeth with straight canals were used and examined under a scanning electron microscope. All manual instrumentations showed a homogeneous compact smear layer and no pulp residues. No statistical differences were observed among the four manual techniques. Ultrasonic technique showed the complete removal of the smear layer, leaving small amounts of pulp debris at the apical third, while the Excalibur showed an almost complete elimination of the smear layer, leaving a homogeneous layer of pulpal residues along the canal.