The All-ceramic Restoration Zirconia And Zirconia Base Stations For Experimental Study

Objective:The main aim of the research is to study the fitness of the interface between the CAD/CAM zirconia crowns and zirconia abutments as well as its guiding significance for implant restoration.Methods:20 zirconia abutments and 20 titanium abutments were divided into two groups. In zirconia crowns-zirconia abutments group,20 zirconia crowns were made upon the zirconia abutments by CAD/CAM. While in Co-Cr alloy based PFM crowns-titanium abutments group,20 Co-Cr alloy based PFM crowns were made upon the titanium abutments by finished plastic cap casting. The finished crowns were inserted onto the abutments respectively, and observe whether the crowns insert onto the abutments smoothly. Evaluate the marginal adaption by the Modified USPHS criterion.Then the microgap models of the interface between crowns and abutments were made using silicone rubber impression. Afterwards, repair and cut these models. Observe and collect microgap pictures by SEM, and test microgap by Digora Optime.Results:1 The insertion rate:The insertion rate of the two groups was both 100%.2. Marginal adaption assessment:In zirconia crowns-zirconia abutments group, marginal adaption of grade A is 18 cases/90%, grade B is 2 cases/10%,Grade C and Grade D are 0;In Co-Cr alloy based PFM crowns-titanium abutments group, marginal adaption of grade A is 16 cases/80%,grade B is 4 cases/20%,Grade C and Grade D are 0. No statistically significant difference between the two groups are observed (P>0.05).3. Measuring result of the adaption3.1 The microgap in the axial surface:The microgap in the axial surface of zirconia crowns-zirconia abutments group is 28.4±0.58μm,while the microgap in the axial surface of Co-Cr alloy based PFM crowns-titanium abutments group is 35.2±0.23μm. The microgap in the axial surface of zirconia crowns-zirconia abutments group is less than Co-Cr alloy based PFM crowns-titanium abutments group. A statistically significant difference between the two groups are observed (P<0.05).3.2 The microgap in the transversal surface:The microgap in the transversal surface of zirconia crowns-zirconia abutments group is 35.5±0.35μm,while the microgap in the axial surface of Co-Cr alloy based PFM crowns-titanium abutments group is 35.7±0.46μm. No statistically significant difference between the two groups are observed (P>0.05).3.3 The microgap in cervix:The microgap in the cervix of zirconia crowns -zirconia abutments group is 23.5±0.35μm,while the microgap in the cervix of Co-Cr alloy based PFM crowns group-titanium abutments is 45.5±0.43μm. The microgap in the cervix of zirconia crowns-zirconia abutments group is less than Co-Cr alloy based PFM crowns-titanium abutments group. A statistically significant difference between the two groups are observed (P<0.05).Conclusion:1. The interface between zirconia crowns and zirconia abutments shows a good fitness and provides a reliable scientific basis for the clinical application.2. The marginal adaption of the zirconia crowns made by CAD/CAM is batter than the PFM made by finished plastic cap casting...