Chairside computer-generated ceramic restorations: the Cerec third generation improvements

Cerec chairside computer-generated ceramic restorations have well passed a five-year clinical observation period with convincing clinical success. The new system COS 2.1 allows an essentially automatic design of inlays, the construction of 3/4 and 4/5 cusp protection onlays, and individually-shaped aesthetic laminate veneers. The new E-drive grinding increases the machining capacity by factor 3 to 4, reduces edge roughness by 50%, and doubles machining precision. Cementation gap width at the cervical margin is 37-48 microns in normal-depth preparations and 54-76 microns in deep cavities. It is the purpose of this article to review the third generation improvements of this method.