The castable ceramic restorations have advantages on clinical applications. However the clinical strength of the restorations for long-term have yet to be fully investigated.
The purpose of this study was 1) to evaluate the clinical strength of the castable ceramic crown (OCC), 2) to estimate the cause of failure, and then to improve the clinical technique.
In this study, 65 single crowns (including 4 onlays to molar) were placed in 25 patients and observed for a 5-year follow-up.
The results were as follows:
1. Nineteen of 65 restorations fractured, chiped and hair-cracked.
2. The incidence of failure for molars, premolars, and anteriors was 39%(7/18), 25%(5/20), and 26%(7/27), respectively.
3. The mean period of these failure cases was 27.9 (±S. D. 9.7) months.
4. Kaplan-Meier's estimation revealed that the estimated mean time of success was 47 months andsuccessful probability of 3 years later was about 65%, and 5 years later was 45%.
The successful life time of OCC might be shorter than other restorations.
