Researches On The Attrition Resistance Of The Gold-paste Layer And The Layer Application Effects On The Cementation For PFM

[Objective]Doing contrastive research on the shade and the attrition resistance of the layer blending nanometer zirconia particals and micron dimension zirconia particals into the gold-paste with different proportion,and find a suitable one for clinical use. To evaluate the effect on cementation for porcelain fused metal crown(PFM) when the layer is to be used.[ Materials and Methods]1,The zirconia power were interfused to ethanol,and the zirconia particals were observed by Transmission Electron Microscope(TEM) after they had been vibrated by ultrasound for 20 minutes.Prepare the gold-paste being mixed 0．5 to 3 percent of nanometer zirconia particals and 3 percent of micron dimension zirconia particals separately,then brushed and fused them to Ni-Cr alloy.Observe the surface of the gold-paste layer with naked eyes and Electron Probe Microanalyzer.Test the attrition resistance of the layer with an attrition jet test apparatus after polishing.The values of the attrition resistance were analysed by ANOVA.2,The crowns were divided into experimental group and control groups randomly.Brushed and fused the gold-paste to the edge of PFM was as experimental group,and control groups were as gilded group and sand-blasting group,and zinc phosphate cement,glassionomer cement and DMG composite resin were applied to cement them on tooth abutments respectively.Recorded the maximum dislocated forces and the value of the separation forces with different cements were analysed by ANOVA. [Results]1,Observed the shade of the gold-paste including 3% micron dimension zirconia particals ,the pure gold-paste and the gold-paste including0．5%,1%,2% and 3% nanometer zirconia particals the layers with naked eyes,the shade became deeper.The hole rates of the layers were analysed took turns by Electron Probe Microanalyzer were5．5%,11．5%,15．3%,26．5%,31．1%,39．2%.After blending 1-3% nanometer zirconia and 3% micron dimension zirconia particals into the gold-paste, the attrition resistance rose obviously.The optimum choice is to mix 3% micron dimension zirconia particals.2,The separation forces of experimental group had no statistical, difference from sand-blasting group,and had obvious difference from gilded group.[Conclusion]1,Though the attrition resistance of the layer can be improved after blending some proportion nanometer zirconia particals into the gold-paste,the shade of the layer become deeper and deeper with the proportion of nanometer zirconia particals become higher, and the shade are not suitable for clinical use. After blending 3% micron dimension zirconia particals into the gold-paste, the attrition resistance of the layer rose the most obviously,and the shade is suitable for clinical use.2,The cementation will not be effected whatever cement is applied to cement PFM which brushed and fused the gold-paste to the edge of it .But gilding on the tissue surface of PFM maybe reduce the cement.