The Study of Marginal Adaptation of All-Ceramic Crown

[Abstract]Purpose:The purpose of this study was to compare the marginal fit of three commonly used all-ceramic systems.by bicolor methyl silicone rubber,and a control group of metal ceramic systems. Materials and methods: One extracted maxillary premolar without caries is prepared for crown fabrication. After the preparation, a high polish is done using a polishing bur. A negative impression is made by double impression, and 40 dies is made by super-hard plaster. The dies are divided into 4groups randomly, Ten crowns are made for each system (porcelain fused to metal, Kavo Everest, IPS e.max, In-Ceram alumina). The measurement of the gaps is done according to the way described by Toshiyuki et al. the digital images of margins between the restoration and the shoulder are collected using anatomical microscope and measured the absolute marginal discrepancy, vertical marginal discrepancy and horizontal marginal discrepancy using an AutoCAD2006 software. All the data is processed statistical analysis. Results: The result shows that the mean values for horizontal marginal discrepancy between 41.1um and 44.9um, and for vertical marginal discrepancy between 51.4um and 71.7um ,for absolute marginal discrepancy between 66.2um and 85.1um. Compared with the control group, the horizontal marginal discrepancy,vertical marginal discrepancy and absolute marginal discrepancy of Kavo Everest and IPS e.max system have significant differences (P<0.01);for the In-Ceram the horizontal marginal discrepancy have significant differences(P<0.01).Compared with In-Ceram alumina, Kavo Everst and IPS e max have significant differences (P<0.05). There's no difference between In-ceram alumina and the control group (P>0.05), Kavo Everest and IPS Empress (P>0.05). Conclusion: The horizontal marginal discrepancies,vertical marginal discrepancies and absolute marginal discrepancies of three all-ceramic systems were within the clinically acceptable standard of 120um.However, the IPS e.max system, Kavo Everest System showed a better marginal fit compared with the metal ceramic(control) restoration and In-Ceram alumina system.