The aim of this study was to use a clinically relevant test method to evaluate the effect of the curvature of the cervical crown margins on load at fracture

Despite the high fracture strength of modern dental core ceramics, fracture is a common cause of failure in clinical trials. Fracture origins are typically in the crown margin in the appoximal region where the margin curves upwards. The scientific evidence for optimal marginal design of preparation is limited. The aim was to use a clinically relevant test method to evaluate the effect on strength of the cervical margin’s curvature of ceramic crowns.

Comparison of fracture strength and fracture modes of different all-ceramic crown systems is not straightforward. Established methods for reliable testing of all-ceramic crowns are not currently available. Published in-vitro tests rarely simulate clinical failure modes and are therefore unsuited to distinguish between the materials. The in-vivo trials usually lack assessment of failure modes. Fractographic analyses show that clinical crowns usually fail from cracks initiating in the cervical margins, whereas in-vitro specimens fail from contact damage at the occlusal loading point. The aim of this study was to compare three all-ceramic systems using a clinically relevant test method that is able to simulate clinical failure modes.