ScientificDocumentationTARGISVECTRISResearchand.ppt

TARGIS/VECTRIS Materials with very different physical properties are used in the conventional crown and bridge technique. The thermal and elastic properties are the most important ones to observe. Metal alloys are most often used for frameworks. These materials, however, cannot always be used, since they are biologically incompatible and they compromise the aesthetics of the restorations. In addition, metal veneered restorations are complex systems with a number of interfaces between a variety of materials. These areas are the potentially weak points of the restoration and are often the cause of clinical failure. Tension in materials Materials expand when heated. When their are left to cool, they take on their original dimensions. The degree of this behaviour differs from one material to the other. It is represented by the particular coefficient of thermal expansion (CTE). The CTEs of conventional crown and bridge materials are listed in the table. The difference between the CTEs of metals and resins is considerably greater than that between metals and ceramics. Metal-ceramics are exposed to high temperatures during the production procedure. Lightcuring veneering composites, however, are only exposed to then-nocycles when they come in contact with foods with different temperatures. Despite the use of special adhesive systems that produce a bond between metals and resins, chipping off of the material is often observed. Materials demonstrate different degrees of deformation when subjected to load. Their particular trend to deformation is determined with the modulus of elasticity. Metals also clearly differ from popular veneering materials in this respect. As a result, tension is produced in the interface areas when load is applied. This tension can cause the bond to fail.In contrast to metal, the CTE and modulus of elasticity of the new Vectris framework material is coordinated with the new Targis complete veneer material. Furthermore, the pro