[The quality appraisal of copy-milled complete-ceramic crown structures (Celay/In-Ceram)].

In the present in vitro-study, the fitting accuracy on In-Ceram crown structures, produced by copy milling under the Celay system, is examined. A total of 32 specimen was produced for four different stump forms (idealized incisor and premolar, each with a shoulder preparation or a 120 degree chamfer preparation) with indirect techniques. The data for the marginal gap ranged between 6 and 274 microns. The shoulder preparation lead to significantly better fitting qualities than the 120 degree chamfer preparation. Median gaps were found at 44 microns (premolar) and 32 microns (incisor). Examinations under the scanning electron microscope showed a homogeneous structure of the sinter with a small variation of grain size and a compact particle packing. As far as the clinical application of In-Ceram crown structures, produced by copy milling, is concerned, a shoulder preparation with a rounded inner edge is recommended.