Shofu Vintage® MP can easily and safely be applied to all PFM alloys within a CTE range of 13.6 to 15.2 x 10-6K-1 and can be effectively used in a simple two-layer dentin-enamel technique (Fig. A illustrates its use on palladium alloy, while Fig.
Shofu Vintage® MP can easily and safely be applied to all PFM alloys within a CTE range of 13.6 to 15.2 x 10-6K-1 and can be effectively used in a simple two-layer dentin-enamel technique (Fig. A illustrates its use on palladium alloy, while Fig. B shows the metal bond porcelain used on Captek).
Despite today’s high cost of gold alloys and the ever-increasing options in all-ceramic CAD/CAM technology, it is now a good time for ceramists to re-think porcelain-fused-to-metal technology.
Many labs are either considering or already using frames made from less-expensive palladium-based, non-precious, or titanium alloys, developed either through CAD/CAM technology or through conventional casting techniques.
Base metal alloys
Cr-Co alloys (more commonly referred to as base metals or non-precious alloys) can be a very practical core material for restorations on implants and prepared teeth. Selecting a base metal alloy is not strictly economical; it’s also a good choice because of its ability to be as thin as 0.1 mm in the anterior region. The metal at this extreme dimension will not flex and undermine the strength of the veneering porcelain. A frame thickness of only 0.1 mm saves valuable space within a restoration that will later be used for the opaquer and the veneering porcelains.
Vintage MP from Shofu Dental Corp. has a paste opaque material that will create a final opaque layer of only 0.1 mm and that completely masks the metal substructure. Using an instrument for opaque application ensures a smooth and even thickness. The exceptionally fine initial 0.05 mm Base Opaque layer with its warm orange-colored hue increases the bonding strength. When applied over a 0.1 mm Cr-Co frame, the total final core thickness before layering dentin is then only 0.2 mm. An added benefit to a metal coping is the instant and complete masking of either a discolored prepared tooth, composite buildup or a metal post and core (Fig. C).
Cr-Co alloys deliver esthetics
Vintage MP mimics the natural diffused light reflection of dentin and enamel even in areas of limited tooth reduction. It is possible to work within a total prep reduction thickness of 1.0 mm to 1.2 mm.
Many non-precious alloys that are available with a Vickers hardness below 300 contain nickel, a biocompatibility concern for some dentists and their patients. There are newer Cr-Co alloys below 300 Vickers hardness and without nickel. These alloys are easily cast and finished to the desired thickness. Example: Argen’s Argeloy N.P. Special.
Furthermore, the oxidation of Cr-Co alloys does not pose esthetic problems with maintaining the value (brightness) of the shade. Oxidation, which is necessary for creating a chemical bond between the alloy and the opaque layer, does not continue past the degassing cycle and continuously darken the frame with each successive firing up to the final glaze and correction firing programs (Fig. D). Also, the complete masking layer of Vintage MP opaque material is stable and doesn’t change in value or chroma throughout the subsequent firing cycles (Fig. E). The shade is easily maintained and matched to the shade tab without any loss of value (brightness), even with a bleached shade (Fig. F).
Margin kit, powders offer benefits
Another added benefit within the Vintage MP system is the margin kit’s properties. The standard margin powders allow for optimal esthetics and fluorescence even in severely limited space near the margin-without any shadowing effect, even with its bleached shade margin powder, W0M. The Shofu Vintage MP kit also offers two masking margin powders, MLM (light) and MDM (dark) as well as several margin effect colors. Labial porcelain margins in the anterior region are a necessity with all PFM alloys to avoid the metal “black line” at the margin. Facial, as well as full-circumference 360º porcelain margins are easily attainable because of the superior handling properties of the margin powders (Fig. G).
CPM Fine is a dedicated low-fusing correction powder (750ºC - 770ºC) for making minor corrections to porcelain margins after the porcelain is stained and glazed. It is found in the counterpart kits for Vintage Halo® PFM, alumina and zirconia (Fig. H). Two other correction powders that also fuse at the same temperature, Add-On B (body) and Add-On T (translucent), are available. Add-On B is used in the dentin areas and Add-On T for incisal areas. The exceptionally low firing temperatures of these materials are important because the restoration can be repeatedly fired with them after glazing without any change in contour or shade whatsoever (Fig. I).
Body firings are between 900ºC - 920ºC and self-glazing with Vintage Art® Stains at 880ºC - 900ºC. Vintage MP is a versatile porcelain system that can also be used in the fabrication of porcelain inlays as well as veneers and jacket crowns (on platinum foil or refractory die material).
About the author
Joe Weisz, BS, CDT, has been a CDT since 1982 and has a B.S. degree in Dental Laboratory Technology from the University of Texas Health Science Center at San Antonio. For 7 years he was Co-Director and an instructor at the UCLA Master Dental Ceramist Program, a full-time 2-year institute for technicians, directed by Dr. Ed McLaren. He also taught Dental Technology at Los Angeles City College. Drawn from his years as an educator, he established Esthetic Contour, which offers contouring courses to dental professionals, including ceramists and dentists who seek to upgrade their skill levels in creating natural looking 6-unit sets of anterior restorations.