The Effect Of Recasting On The Bonding Strength Of Cobalt-Chromium Ceramic Alloy

Objective The purpose of this study was to investigate the effect of recasting on bonding properties, including the bonding strength of porcelain fused to alloy,the structure of oxide layer, thermal expansion coefficients of Cobalt-Chromium alloy.Methods The Co-Cr cemamic alloys were recasted for1-7times in the vacuum pressure environment:(1)Veneer porcelain to alloys, then get the test specimens with porcelains of each generation. According to the standard of ISO9693, test the bonding strength in the three-point test of the test specimens.(2) Veneer porcelain to alloys, scan the oxide layer of the test specimens under the SEM.(3)According to ISO9693,test the thermal expansion coefficients with the thermal expansion coefficient testing apparatus.Results(1)According to the three-point test, it presented no statistical difference in the bonding strength of1-4generations (P>0.05);but it presented significance statistical difference in the bonding strength of5-7generations (P<0.05),the bonding strength presented a trend fall of each generation. (2)Under the SEM, the alloys and porcelains were in good interinfiltration and insertion without fissure of1-4generations;but the combination of metal-ceramic interface was gradually loosening and there were some fissures of5-7generations.(3)It presented no statistical difference in the thermal expansion coefficients of1-5generations(P>0.05);but it presented significance statistical difference in the thermal expansion coefficients of6-7generations (P<0.05),the thermal expansion coefficients presented a trend rise of each generation.Conclusion(1).In the vacuum pressure environment, it presented no statistical difference in the bonding strength, the alloys and porcelains were in good combination of1-4generations.(2)In the vacuum pressure environment, the bonding strength presented a trend fall, the combination of metal-ceramic interface was gradually loosening and there were some fissures of5-7generations.(3) In the vacuum pressure environment, it presented no statistical difference in the thermal expansion coefficients of1-5generations;but the thermal expansion coefficients presented a trend rise of6-7generations.