A 30 µm-thick masking tape (Mending Tape Kokuyo Co., Ltd., Osaka, Japan) with a 5 mm diameter opening was placed on the airborne-particle abraded surface to restrict the porcelain firing areas, and a thin layer of either of the metal conditioners was applied. Procedures for fabrication of bonding specimens are presented in Fig. Then the bonding surface was airborne-particle abraded using 110 µm alumina particles (Korox110, Bego, Bremen Germany) at 0.4 MPa pressure for 10 seconds with a 5 mm nozzle-to-alloy distance, followed by drying with filtered air.
![arloy nonprecious high fusing metal arloy nonprecious high fusing metal](https://c1.neweggimages.com/ProductImageCompressAll1280/AM5V_1_201910221482201263.jpg)
The bonding surfaces of the adherend were polished with a 240, 400, and 600-grit silicon carbide paper (Carbimet Paper Discs Buehler, Lake Bluff, IL, USA) under ample water coolant. The null hypothesis of the study was that the metal conditioners were not effective for the improvement of the bonding of porcelain to a Co-Cr alloy.ĭisk-shaped specimens (2.5 × 10.0 mm) were cast with Co-Cr alloy according to the manufacturer's instruction, and used as adherend materials. The purpose of this study was to evaluate the efficacy of a novel metal conditioner for a Co-Cr alloy, and to compare its efficacy to that of traditional metal conditioner available for non-precious metal alloy. This conditioner improves the bonding of porcelain to non-precious metal ceramic alloy by controlling the formation of oxidized layer and by increasing the wettability of alloy surface.
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A metal conditioner for non-noble metal ceramic alloy has been developed recently. Therefore, studies on the efficacy of metal conditioners for Co-Cr alloys are desired. 11, 22 However, the reports on the effectiveness of metal conditioners to Co-Cr alloys are very limited, 22 and the effectiveness of metal conditioner to Co-Cr alloys is yet unknown. These metal conditioners are employed with the intension of improving the aesthetics of the porcelain by masking dark oxide color of non-noble metal frameworks and also increasing the bonding of porcelain to noble metal alloys, 10, 28 cpTi, Ti alloys, 10, 11 and Ni-Cr alloys. Among these endeavors, applications of metal conditioners 19, 28 have also been attempted. 13, 22 In order to resolve this problem, there have been attempts to modify alloy components 23, 24 and metal surface treatment, including degasification, 25 firing temperature of opaque layer 26 and employment of air-borne particle abrasion, 14, 27 have been made.
![arloy nonprecious high fusing metal arloy nonprecious high fusing metal](https://jensendental.com/wp-content/uploads/2015/08/lf2.png)
19, 20, 21 However, non-precious metal alloys are readily oxidized and thick oxidized layer is formed on the alloy surface during porcelain firing, 13, 22 and excessively oxidized layer leads to the complications in bonding between alloy and porcelain by yielding the facture through the thick oxidized layer. 13, 14, 15, 16, 17, 18Īppropriate oxidation of metal surface is required for the stable bonding between metal alloy and porcelain. 10, 11, 12 When Co-Cr alloys is compared to Ni-Cr, the use of more biocompatible Co-Cr alloys is suggested due to the hazardous effect of Ni-Cr alloys. 8, 9 Furthermore, cpTi and Ti alloys show some difficulty in porcelain fusing. Although cpTi and Ti alloys possess excellent biocompatibility, corrosion resistance, and mechanical properties, they require special casting machines and investment materials due to their high melting temperature. The non-precious metal ceramic alloys, including nickel-chromium (Ni-Cr), cobalt-chromium (Co-Cr) alloys, commercially pure titanium (cpTi), and Ti alloys are the alternatives to noble metal ceramic alloys.
![arloy nonprecious high fusing metal arloy nonprecious high fusing metal](https://www.kuwatapandent.com/img/7941-PFM-Fixed-Thumb.png)
5, 6, 7 However, because of the soaring price of noble metal alloys in the last decade, the non-precious metal alloys have been attracting considerable attention in clinical practices. The advantages of noble metal ceramic alloys include excellent biocompatibility, sufficient mechanical properties and excellent bonding capacity with the veneered porcelain. 3, 4 Noble metal ceramic alloys have been frequently used for the fabrications of metal ceramic restorations. Metal ceramic crowns and fixed dental prosthesis have been widely used in clinical practices because of their good mechanical properties and acceptable aesthetics, 1, 2 regardless of the development of all ceramic crowns.