Marit Øilo, Ketil Kvam, Nils R. Gjerdet
Context
- 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.
Purpose of the Study
To compare three all-ceramic systems using a clinically relevant test method that is able to simulate clinical failure modes.
Key Findings
- Ten incisor crowns of three types of all-ceramic systems were exposed to soft loading until fracture. The initiation and propagation of cracks in these crowns were compared with those of a reference group of crowns that failed during clinical use.
- All crowns fractured in a manner similar to fracture of the clinical reference crowns.
- The zirconia crowns fractured at statistically significantly higher loads than alumina and glass-ceramic crowns. Fracture initiation was in the core material, cervically in the approximal areas.
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