Marginal discrepancy of ceramic crowns with redesigned implant components

A previous study indicated a mean marginal discrepancy of 169 microns (SD = 23) for cemented CeraOne ceramic crowns. Since then, the components have been redesigned by the manufacturer. This study assessed the marginal discrepancy of the new components by use of a video camera and stereomicroscope connected to a computer. Fifteen samples each of (a) ceramic caps (control), (b) ceramic caps fired once in a porcelain oven (c) ceramic crowns, and (d) cemented (zinc phosphate) ceramic crowns were examined. The results indicated that the mean marginal discrepancies were: caps 20.4 microns (SD = 10.8), fired caps 18.3 microns (SD = 9.3), crowns 28.1 microns (SD = 9.7), and cemented crowns 65.9 microns (SD = 15.8). Statistical analysis (ANOVA) revealed significant differences between these mean marginal discrepancies (p < 0.0001). A Scheffe F-test revealed no statistically significant difference between the means for caps, fired caps, and crowns, whereas cemented crowns had significantly greater mean marginal discrepancies compared with all uncemented retainers (p < 0.0001). The mean marginal discrepancy of the redesigned CeraOne ceramic system (cemented crowns) was reduced by more than 100 microns compared with the original design.