Methods: Injectable ceramic restorations were made according to lost wax process, each ingot being heated at 900°C and pressed into a mold for 15 to 25 min. After pressing, the crystallization process was accomplished automatically during the cooling down process of the casting ring to room temperature. 115 injectable ceramic restorations were placed on 34 patients, from a period of December 7th, 2001 up to February 4th, 2005 at Aichi-Gakuin University dental hospital. These restorations were investigated at the time of dental treatment by dentists. Statistical method of survival analysis according to the Kaplan-Meier was applied to investigate the effects of fractures. Not only observed fractures but also those demonstrating cracking or chipping were considered to be fractured.
Results: Observed fractures were 17 out of the 115 (14.8%) of the restorations. The longest survival time until now has been 75 months. The Kaplan-Meier survival probability calculated for these restorations were 0.97 anterior teeth region and 0.82 posterior teeth region after a time interval of 24 months, and giving a survival probability of 0.97 anterior teeth region and 0.81 posterior teeth region after a time interval of 60 months. There were significant differences (P=.022, log-rank test) in the survival between the two region.
Conclusion: It was thus concluded that injectable ceramic restorations are suitable for clinical use, although not totally without problem, especially attention is necessary for use in the molar region for long-term use.