Materials Design of Ceramic-based Layer Structures for Crowns

TLDR

Radial cracking is the main failure mode of all‑ceramic crowns. The study tests whether the critical load for radial cracking scales with the square of ceramic layer thickness. Using spherical indenters on flat laminates of dental ceramics bonded to polycarbonate bases, the authors recorded damage initiation in situ and measured critical loads. Zirconia exhibited the highest resistance to radial cracking, followed by alumina and porcelain, enabling simple a priori predictions and ranking of ceramic materials for clinical performance.

Abstract

Radial cracking has been identified as the primary mode of failure in all-ceramic crowns. This study investigates the hypothesis that critical loads for radial cracking in crown-like layers vary explicitly as the square of ceramic layer thickness. Experimental data from tests with spherical indenters on model flat laminates of selected dental ceramics bonded to clear polycarbonate bases (simulating crown/dentin structures) are presented. Damage initiation events are video-recorded in situ during applied loading, and critical loads are measured. The results demonstrate an increase in the resistance to radial cracking for zirconia relative to alumina and for alumina relative to porcelain. The study provides simple a priori predictions of failure in prospective ceramic/substrate bilayers and ranks ceramic materials for best clinical performance.