The Comparative Research of the Marginal Adaptation of Cercon Zirconia Ceramic Produced by Two Methods

Objective In order to provide the theoretical basis for clinical application,this research studied the marginal adaptation of cercon zirconia ceramic produced by two methods through copying clearances in crown margin edge with silicon rubber,using cobalt chromium metal ceramic crown as the control group.Methods A caries-free extracted for orthodontic mandibular premolars was selected with the routine tooth preparation,and the dual impression method was used to copy 24 die stone models of the same size.Die models were randomly divided into three groups(cobalt chromium metal ceramometal crown,zirconium dioxide all-ceramic crown producted with CerconCAD/CAM system,zirconium dioxide all-ceramic crown producted with Cercon ClassⅡlaser scanning system),to produce 8 all-ceramic crown restoration.The method of copying clearances in crown margin edge with silicon rubber was used to measure the absolute edge cleareance.Then the crown was cut into 4 parts along the buccal lingual and the midpoint of mesiodistal edge.Digital images of the absolute edge cleareance were collected under stereo microscope and measured.The data results were analyzed with SPSS13.0.Result The average of the three kinds of absolute edge clearance is between 48.68 and 98.69 μm.Compared with controls,zirconium dioxide all-ceramic crown producted with CerconCAD/CAM system,zirconium dioxide all-ceramic crown producted with Cercon ClassⅡlaser scanning system presented significant differences.Conclusion(1)Under this experimental conditions,the clearances of zirconium dioxide all-ceramic crown producted with CerconCAD/CAM system and Cercon ClassⅡlaser scanning system are smaller,compared with those of cobalt chromium metal ceramic crown.(2)Compared with the clearances of zirconium dioxide all-ceramic crown producted with Cercon ClassⅡlaser scanning system,the ones of those producted with Cercon CAD/CAM system are smaller.(3)The clearances of crowns in these three experimental groups are all bellow 100 μm,which is acceptable in clinical use.