Effects Of Base Crown And Post - Core Background On The Color Of Zirconia All - Ceramic Restorations

Purpose:The purpose of the study is to investigate the influence of different colors of ceramic bases and types of post-core systems on the color of zirconia-based all-ceramic restorations by in vitro experiments. The Crystaleye spectrophotometer is used to analyze the color parameters of zirconia specimens with different colors of ceramic base and under the context of different types of post-core materials. The aim of the study is to explore the law of the effects on the color of the zirconia-based all-ceramic restorations with the same layer by different background color and finally provide a theoretical and laboratorial basis to help dentists and technicians present better aesthetic effect of the zircona-based all-ceramic restorations.Methods:PART I:10standard specimens with10mm side length and0.5mm thickness were fabricated by four different colored zirconia base r:pure、light、medium and intense. All the specimens were divided into four group as A、B、C、D according to the color of the materials. The porcelain layers were in the same thickness as1.0mm. Firstly the color parameters of all the40specimens were measured by Crystaleye spectrophotometer. Each specimen was tested three times and the average number was recorded. ΔE between each of the two group were calculated.Then the Vita Classical shade guide was used to evaluate the color of the specimens and ΔE between the tab and the specimens were assessed. Results were analyzed by SPSS12.0software.PART Ⅱ:10standard specimens with10mm side length and0.5mm thickness were fabricated by four different colored zirconia base r:pure、light、medium and intense. All the specimens were divided into four group as A、B、C、D according to the color of the materials. The porcelain layers were in the same thickness as1.0mm. A resn、an Au-Pt alloy and a Co-Cr alloy background specimens were fabricated in the same size with the zirconia specimens. The color parameters of zirconia specimens placed on the three different background specimens were measured by Crystaleye spectrophotometer. Each specimen was tested three times and the average number was recorded. AE between Co-Cr/Au-Pt and resin background were calculated. Results were analyzed by SPSS12.0software. Results:Part Ⅰ:There were statistical difference among the value of L*a*b*in the each two groups. AE between each two groups were greater than1.5.The result of all the groups by using the Vita Classical shade guide were the same as B3.The smallest△E was between the B3tab and the specimens of group C while the largest AE was between the B3tab and the specimens of group A.Part Ⅱ:The resin group was used as standard. There were statistical difference among the value of L*a*b*between the Co-Cr group and the resin group,the same result between the Au-Pt group and the resin group.△E between the Co-Cr/Au-Pt group and the resin group is smaller than1.5.△E between Co-Cr/Au-Pt and resin background of group B specimens were the largest while the group D specimens were the smallest,Conclusion:l.The color of zirconia base had a certain influence on the color of entire zirconia all-ceramic restorations with the0.5mm thickness of the base porcelain,1.0mm thickness of the same colored layer ceramic by changing the color parameters.2.The color difference of specimens made by each different colored base can be perceptible by human eyes which means it should be cautious to choose the right zirconia base. It is recommended that the technicians should follow the related shade guide for zirconia base selection so that perfect color of the zirconia-based all-ceramic restorations can be presented.3. The WIELAND ZENO(?) TRANSLUCENT Zirconia materials are less influenced by the different color of the post-core systems and covering the background color is therefore not necessary. Among the four types of colored zirconia base, the covering effect of the intense color is much better than the light color.