Objectives: Recently, cantilevered all-ceramic RBFPDs were introduced as an conservative treatment approach. The purpose of this clinical study was to evaluate the clinical outcome of all-ceramic RBFPDs with a cantilevered single-retainer design and to compare it with that of a conventional two-retainer design. Methods: Overall, 37 anterior RBFPDs were made from the glass-infiltrated alumina ceramic In-Ceram, which was veneered with Vitadur-Alpha (both Vita, FRG). Sixteen RBFPDs with a conventional two-retainer design (group R2) were inserted in 14 patients, while 21 RBFPDs with a cantilevered single-retainer design (group R1) were inserted in 16 patients. The bonding surface of the retainers were sandblasted with 50 µm alumina particles at 2.5 bars pressure. Panavia or Panavia 21 (Kuraray, J) were used as luting agents. The mean observation time in group R2 was 75.8 months (min. 3, max. 146), and in group R1 it was 51.7 months (min. 25, max. 86). Results: No RBFPD debonded. In group R2 one RBFPD was lost because it fractured after 3 months at both connectors, and one RBFPD was removed alio loco accidentally. Also in group R2, four RBFPDs fractured within 15 months after insertion at one connector, but the pontic remained in situ as a cantilevered RBFPD for several years. In group R1 only one RBFPD fractured and was lost 48 months after insertion. The five-year survival rate according to Kaplan-Meier was 73.9% in group R2 and 92.3% in group R1. When unilateral fracture of a RBFPD was taken as criterion for failure, the five-year survival rate decreased to 67.3% in group R2. Considering fractures, the survival rates of the two groups were statistically significantly different (p=0.014, Gehan-Wilcoxon test). Conclusions: Conventional two-retainer design all-ceramic RBFPDs showed a high fracture rate within the first years of clinical service. However, cantilevered all-ceramic RBFPDs seem to be a promising alternative.

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