Comparison of marginal adaptation of Cercon and metal ceramic crowns before and after applying porcelains

Nowadays many developed all ceramic laboratory systems are introduced to dentistry and Marginal adaptation is an important factor in longtime clinical success. The purpose of this study was to compare the marginal adaptation of the Cercon all-ceramic crowns with metal -ceramic crowns. The In vitro marginal discrepancy of Cercon crowns and a control group of metal-ceramic restorations were evaluated and compared by measuring the gap dimension between the crowns and prepared tooth. The crowns were made for 1 extracted maxillary central incisor prepared with chamfer margin. Ten crowns per system were fabricated. Crown measurements were recorded with a stereomicroscope, at 4 points on prepared tooth. The criterion of 120 micron was used as the maximum clinically acceptable marginal gap. Mean gap dimensions and standard deviation were calculated for marginal opening. The data were analyzed with Kruskal-Wallis test & Mann-Whitney test. Mean gap and standard deviations at the marginal opening for the incisor crowns were 8.7 μm (±5.5) before applying porcelain an 8.9μm (±5) for control, 30.5μm (±28.5) & 31.3μm (±24.1) for Cercon group before and after applying porcelain, compared with the control group, the Cercon group had significantly bigger marginal discrepancies (p<0.05). Within the limitation of this study, the marginal gaps were all within the clinically acceptable standard but the Cercon group had significantly bigger marginal discrepancies. The marginal gap of the control group and the Cercon crowns were not affected by porcelain firing cycles.