Influence of substructure design and spacer settings on the in vitro performance of molar zirconia crowns.

Objectives: The aim of this study was to evaluate the in vitro behaviour of all-ceramic zirconia molar crowns in regard to different core designs and marginal fit.

Methods: Identically shaped methacrylate molars were prepared according to the ceramic restoration directives resulting in a 1-mm deep circular shoulder preparation. They were embedded in polymethylmethacrylate resin after covering their roots with a polyether layer to simulate periodontal mobility.