When dental constructions and devices are looked at as structures, it can be said that all of the constructions are composed not only of multiphase materials, but of combinations of different kinds of multiphase materials. Crowns and especially fixed dental prosthesis are affected by high stresses from occlusal loads, and cosmetically the most suitable materials are typically weak to withstand heavy occlusal loads. Therefore, dating back to early dentistry, framework for fixed dental prostheses was made of stronger materials like metal and veneered with acrylics, resin composites, or dental porcelain of tooth shade and color. In the time of nonmetallic materials, the alternative materials are zirconia veneered with porcelain, or monolithical zirconia and FRC veneered with particulate filler resin composite. A good example of a restoration that is affected by heavy loads is FRC fixed dental prostheses, which has the load-bearing framework made of continuous unidirectional FRC with a veneer of particulate filler resin composite. A distinction should be made between FRC fixed dental prostheses of this kind and those made for provisional use. When the fixed dental prosthesis is adhesively luted to teeth, there is a material combination of FRC—veneering composite—luting cement composite—tooth. It is obvious that the function of such a complex structure is largely dependent upon the quality of adhesive interfaces between the materials. Adhesive interfaces transfer stress from the occlusal loads to be carried by the durable FRC framework and finally by the abutment teeth.