Damage characterization of dental materials in ceramic-based crown-like layer structures

A materials perspective of layered dental material systems representing tooth and crown structures is presented. In this study, failure modes in model bilayers and tri-layers with relatively hard, brittle ceramic (veneer and veneer/core) outer-layers on soft, tough (dentin-like) under-layers are evaluated. Contact testing simulating dental function on model layer systems with selected monolith or double-layer ceramic plates bonded to transparent polycarbonate substrates is used as a means for investigating the evolution of clinically relevant fracture modes. Data for the critical contact loads to initiate different damage modes in the ceramic layers are presented. These data quantify resistance of any given dental material to lifetime-threatening damage, especially subsurface radial cracking (but also other, upper-surface modes), thereby providing a sound basis for materials selection and design. We demonstrate how such data may be used to rank dental ceramics for damage resistance. The role of controlling material properties in determining damage resistance, especially strength, will be discussed.