[Compressive strength of metal-ceramic occlusal veneers]

Ceramometallic specimens, circular in section, of varying thickness and manufactured by means of different procedures, have been tested to destruction of the ceramic layer under a once-through continuously increasing force at defined points. Identical specimens were used to determine the number of load cycles under increasing continuous stress of 430 N until the ceramic layer failed. The fatigue strength increased with the thickness of the metallic layer and was further increased by a high inherent strength of the ceramic layer. In restorations with only a thin metallic layer (foil crowns) and/or low strength values of the metal (electroplated ceramic crowns) an overall thickness of the layers of more than 1.5 mm is recommended in the occlusal area to avoid premature failure.