Objective: The objective of this prospective, randomized, controlled clinical study was to evaluate the clinical performance of zircon-based cantilever fixed dental prostheses (FDPs). Materials and Methods: The investigation was realized by twenty-one cantilever FDPs supplying 21 patients. The FDPs were designed as three or four units replacing one premolar or one incisor. Patients with missing canines were not included. These 21 FPDs were randomly assigned to 11 zirconia cantilever FDPs (test group) and 10 conventional metal-ceramic cantilever FDPs (control group). The all-ceramic FDPs were manufactured using a Y-TZP framework (Lava; 3M Espe) and veneered with feldspatic ceramic (Lava Ceram; 3M Espe). The 10 metal-ceramic FDPs were manufactured by fusing a conventionel feldspathic ceramic to a noble metal alloy. Controls were scheduled after 2 weeks (baseline), 6 months, 1 year and after 2 years. Complications, plaque accumulation, signs of inflammation of the gingiva, aesthetic performance and patients satisfaction were documented. Statistical analysis was performed by use of the Log-rank-test, the Mann-Whitney U-test and the Chi-square test.
Results: During the two-years observation period, a total of four clinical relevant complications occured, including root canal treatment once in each group and two chippings in the test group. The Log-rank-test showed no significantly difference to the rate of complication (p=0.315). After 2 years in service all restorations showed similar plaque retention and bleeding indices of the marginal gingiva. Without significant differences between the groups. All patients rated the aesthetic performance of both types of FDPs very good without significant differences between the test- and the control-group (p≥0.173). No caries, discolourations, retention loss was observed.
Conclusion: Stability and aesthetic performance were acceptable for all-ceramic cantilever FDPs made of zirconia. A long observation period with a large number of all-ceramics FDPs is needed to make valid predictions about the longevity of these restorations.