Several pre-cementation procedures have been advocated to enhance adhesion between zirconia and resin-based cement. There is, however, limited documentation on how these pre-treatments affect the strength of zirconia crowns as most tests are performed on discs or bars.
The aim was to assess the effect of pre-cementation procedures on fracture mode, fracture strength and cement retention on zirconia.

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.

The main problem with ceramics as biomaterials is that they are brittle. One focus of research and development has been on improving the materials’ fracture strength and thereby increasing the clinical success rates for dental, all-ceramic restorations. The most advanced dental ceramics should, according to in vitro testing, be able to withstand human mastication forces.