Survival and Chipping of Metal-ceramic and All-ceramic Fixed Dental Prostheses

Objectives: The aim of this retrospective analysis of data from a prospective long-term study was to determine survival and survival without chipping of metal-ceramic and all-ceramic fixed dental prostheses (FDP) after 5 years in function and to isolate risk factors for failure or ceramic fractures.
Methods: From originally 455 patients with 619 FDP, follow-up data of 295 patients (41.5% male, mean age 59 years) with 417 FDP were evaluated. Survival and chipping-free survival estimates were calculated according to the Kaplan-Meier method and Cox-Regression analysis adjusted for patients with multiple restorations was used to determine risk factors for FDP failure or chipping (all α=0.05).
Results: The mean observation period of the restorations was 6.8 years (max: 16.6). Frameworks were made from high noble alloy (n=197, 47.2%) or cobalt-chromium alloy (CoCr) (n=121, 29%), zirconia (n=82, 19.7%), or lithium disilicate ceramic (n=17, 4.1%). A total of 233 (56%) FDP were located in the maxilla and 184 (44%) in the mandible including 57 FDPs (14%) in anterior quadrants, 331 FDPs (79%) in posterior quadrants, and 29 FDPs (7%) overarching the canine. Five-year survival probabilities were 94.7% for high noble alloy, 93.7% for CoCr, 92.9% for zirconia, and 79.4% for lithium disilicate based FDPs, with no statistically significant difference between the framework materials (log-rank test, p=0.338). Five-year chipping-free survival probabilities were 94.1% for high noble alloy, 96.1% for CoCr, 82.6% for zirconia, and 76.9% for lithium disilicate based FDP, with statistically significant differences between the groups (log-rank test, p=0.015). Cox regression analysis identified framework material as a significant risk factor for chipping. Compared to high noble alloy, zirconia showed a 2.6 times higher chipping risk.
Conclusions: Apart from lithium disilicate, all frame materials demonstrated high 5-year survival rates. Due to the high chipping incidence, the indication of full-coverage veneers (especially on zirconia frameworks) should be critically evaluated.