In this study, the stress distribution in a maxillary central incisor subjected to an endodontic treatment was determined by using a three-dimensional finite-element method. The tooth had a variable root canal cross-sectional area, and the canal was assumed to be filled with vertical condensation. The Clinical practice was simulated by considering the obturation in successive stages. The main aim of the study was to investigate the possibility of fracture due to the obturation process. It was found that, within the limits of the study, the likelihood of a root fracture in such a process is a remote possibility. © 1995 The American Association of Endodontists.