Impact of convergence angle of tooth preparation on the fracture resistance of incisor monolithic zirconia crowns

The results indicated that the convergence angle had a significant effect on the fracture resistance of monolithic zirconia crowns. Instead of preparing parallel axial walls (0°) in central incisors, creating a tapered preparation design with different levels (8°, 16°, or 22°) increased the fracture resistance. Specifically, 16° was related to the greatest fracture resistance. However, the absence of thermocycling and fatigue testing limits the simulation of long-term clinical performance.