Objective The aim of this study was to evaluate the effect of different finish line designs on the fatigue, fracture resistance, and failure type of veneered zirconia restorations. Methods A computer aided design and computer aided manufacturing（CAD/CAM） system was used to prepare zirconia frameworks for a maxillary central incisor. Three finish line designs were evaluated: A complete narrowchamfer, a narrowchamfer with a lingual ledge, and a complete ledge. The prepared frameworks were veneered using a press-on ceramic and were cemented on the corresponding prepared teeth using a resin cement. The cemented specimens were thermocycled, subjected to dynamic fatigue, and finally loaded till fracture. One-way ANOVA was used to analyze the data and the fractured specimens were examined under a stereo microscope to assess fracture type. Results There was no significant difference among the fracture resistance of three kinds of finish line designs（P>0.05）. The form of specimen failureis cracking and fracture of the veneer ceramic. Meanwhile, the framework remained entirely intact. Conclusion Within the limitations of this study, the finish line design did not influence the fatigue or the fracture resistance of veneered zirconia crowns. Selection any of the finish line designs should be based on the clinical condition of the restored tooth.
