A scanning electron microscopic evaluation of root surfaces and the gutta-percha interface following root-end resection in vitro

Aim The aim of this study was to evaluate the effects that various commonly used instruments have on root surface morphology, the obturating material, and the interface between the obturation and the soot canal walls followin g root-end resection in vitro. Methodology Sixty human single-rooted teeth with fully formed apices were c ollected and decoronated. The root canals were instrumented, and then obtur ated with thermoplasticized gutta-percha using AH-26 as the sealer. The roo ts were randomly divided into 12 different groups, and apical root-end rese ctions were performed using eight different instrument configurations, and two different directions in which the bur moved across the root face in rel ation to its direction of rotation. Epoxy resin replicas of the resected ro ot ends were examined using scanning electron microscopy. Results Each instrument produced a characteristic surface finish on the res ected root end that mirrored its cutting profile. Irrespective of the desig n of the bur used, smearing and shredding of the gutta-percha across the ro ot face occurred only when the handpiece was moved across the root face in reverse direction in relation ion to the direction of rotation of the bur. Conclusions To ensure minimal disruption and distortion of the root filling and to prevent shredding of the gutta-percha interface, care should be tak en to ensure that the final pass of the bur across the root canal is in the correct direction in relation to its direction of rotation.