A clinical evaluation of cobalt-chromium metal-ceramic fixed partial dentures an crowns: A three- to seven-year retrospective study

Statement of problem. In severely compromised dentition, loading of long-span and cantilever metal-ceramic fixed partial dentures (FPDs) could result in framework deformation and porcelain fractures. The use of cobalt-chromium (Co-Cr) alloys may be advantageous, but there is little information on the longevity of, and complications with, prostheses made with these alloys. Purpose. The aim of this retrospective study was to report the survival and complication rates of Co-Cr metal-ceramic FPDs and crowns followed over a 3- to 7-year period. Material and methods. The study included 42 patients with a total of 51 FPDs and 12 single crowns assigned to 1 of 3 groups. The 3 groups comprised patients with abutment teeth with a questionable prognosis (n=10), advanced chronic periodontitis (n=19), or abutment teeth with a positive prognosis (n=13). The FPDs had a mean of 9.7 units (range of 3-14). Of the FPDs, 32 were provided with a cantilever on 1 side (n=24) or both sides (n=8). The mean observation time was 51 months (range of 28-82). All patients were examined by 2 independent prosthodontists using the California Dental Association (CDA) assessment system for evaluation. One-way ANOVA with Fisher's LSD post hoc test and the Mann-Whitney U test were used for statistical analyses (alpha=.05). Results. Seventeen (34%) of the FPDs had biological and/or technical complications. Six (12%) FPDs were completely or partially removed during the observation period, 1 framework fractured, and 9 (17.6%) FPDs had ceramic fractures. Fifteen of the 21 fractured FPD units were related to FPDs that were placed in 3 patients with bruxing habits. The CDA rating for marginal integrity was "excellent" for more than 98% of the abutments. No patients reported adverse reactions to the material. Conclusions. Metal-ceramic FPDs made of cobalt-chromium alloy performed acceptably in the questionable prognosis and advanced chronic periodontitis groups.