EVALUATION OF THE MARGINAL ACCURACY, STRENGTH AND MICROSTRUCTURE OF SOME METAL-FREE RESTORATIONS USING THREE DIFFERENT TECHNIQUES

Abstract

One of the prime goals of restorative dentistry is to substitute the lost or discolored parts of teeth with a material that matches the natural tooth structure in esthetic, physical and mechanical properties.

Although the metal ceramic system allows maximum strength and color stability, the light transmission properties are completely different from those of natural teeth because of the metal substructure. This requires great effort from the dentist and the laboratory technician to mask the color of the metal substructure with the porcelain veneering material. Base metal alloys, which are commonly used in clinical practice may exhibit corrosion or elicit allergic reaction to some patients, also certain constituents of some base metal alloys may even cause a variety of acute and chronic health hazards to laboratory personnel < 17>.

Ceramic materials have become popular for dental restorations because of their biocompatibility and improved esthetics compared with metal ceramic restorations. Nevertheless, the use of all ceramic restorations has been limited by their relatively low resistance to fracture. With the introduction of glass infiltrated alumina core restorations (In-Ceram), considerable improvement in the mechanical properties has been obtained