Methods: The study was designed as a randomized clinical study and approved by the local Ethics Committee. A total of 37 patients received one 3-unit bridge between 2001 and 2003. The all-porcelain bridges (study group) were fabricated using an experimental lithium disilicate glass ceramic. According to information provided by the manufacturer, this ceramic is identical to the lithium disilicate glass ceramic in the new IPS e.max system (Ivoclar Vivadent, Schaan, FL). The bridges in the control group were porcelain-fused-to-metal bridges (high-gold-alloy D.SIGN 96, IPS D.SIGN porcelain, Ivoclar Vivadent, Schaan, FL). All bridges were fitted using glass ionomer cement with follow-up examinations over a period up to six years.
Results: Mean observation time was 1090 days; maximum observation time was 2470 days. In the study group after 527 days Kaplan-Meier survival probability was 63% and then remained constant. In the control group Kaplan-Meier survival probability was 97% after 112 days and then remained constant. The log-rank test established statistically significant differences (p=0.028).
Conclusion: Within the limits of this study the poor success rates in the study group compared to the control indicate that lithium disilicate glass ceramic bridges have a high risk of failure at least when cemented conventionally. However, other studies reported comparable data on longevity with adhesive luting. Hence clinical indication of for lithium disilicate ceramic bridges must be judged critically.
Ivoclar Vivadent (Schaan, FL) provided financial support for this study.