Study On The Effect Of Gold-Porcelain Blended Layer On Bond Strength Of Porcelain Fused To Ni-Cr Alloy

Objective: The key of the success of porcelain-fused-to-metal restoration(PFM) is to obtain better bond strength between metal and porcelain. In this study, gold intermediate layer of Blendgold Neu(Neu) or mixture of Gold and WO(Gold+WO) was painted on the preoxidized face of Ni-Cr alloy ,and baked in different temperatures. Related to common method of making PFM, the bond strengths obtained using different layers or baked in different temperatures were compared. This study could provide certain experimental basis for using inexpensive and good PFM, and help chose good condition. Methods: Based on different layers and heated conditions, 54 Pull-Rod samples were made and divided into nine groups. In every group, five specimens were used to test bond strength by shear bond test, and one specimen was used to observe interfacial bond state and diffusion of interfacial elements by electron probe. In addition, the samples' destructive forms during the test were observed by eyes. The values of bond strength were analyzed by ANOVA. Results: The samples' destructive form during the shear bond test basically is that the porcelain layer and gold intermediate layer completely dropped from the preoxidized face of Ni-Cr alloy. The experimenter does not observe single porcelain destruction, and a few samples' destructive alloy face still remain a little gold intermediate layer. By statistical analysis, the bond strength between the following groups is not different obviously: group 1 and group4, group 1 and groups, group 1 and group6, group 1 and group7, group4 and group5, group6 and group7, group8 and group9, group4 and group6, groupS and group7; however, the bond strength between the following groupsis different evidently: group 1 and groupS, group 1 and group9, group4 and groupS, groupS and group9, group6 and groupS, group? and group9. Second Electron Image(SEI) shows the gold intermediate layer and alloy bond closely and the gold intermediate layer intrudes into alloy like anchors. The gold intermediate layer and porcelain layer diffuse mutually. The distance and quantity of the main elements of gold intermediate layer diffusing to alloy are less than those of diffusing to porcelain layer, and the diffusion among elements becomes abundantly along with ascending heated temperature. Conclusion: Compared with common method of making PFM, the bond strength obtained in the two following conditions raises obviously. One is coating a layer of WO and Neu on the preoxidized face of Ni-Cr alloy from inner to outer, and baked in 950 and 820 respectively; the other is coating a layer of gold intermediate layer(Neu or Gold+WO) on the preoxidized face of Ni-Cr alloy, baked in 960then coating a layer of WO, baked in 950. In the same baked temperature, the bond strengths obtained using Neu or Gold+WO do not appear obvious difference. The same gold intermediate layer, heated in 820,890and 960,the bond strengths obtained in 820 and 890 are not different obviously, but the bond strength obtained in 960 is higher than that obtained in 820 and 890.The bond between the porcelain layer and gold intermediate layer is better than that between the gold intermediate layer and alloy. The diffusion among elements become abundantly and the bond strength improves well along with ascending baked temperature.