Apart from precision, the time factor plays a decisive role in the fabrication of all-ceramic dental restorations. Therefore, the aim of this study was to compare two all-ceramic systems with regard to the time required for the fabrication of partial crowns [MODB]. The null hypothesis tested was that the fabrication times of CAD/CAM generated partial crowns are shorter than the fabrication times of partial crowns manufactured in the laboratory.
Materials and Methods: In sixteen model pairs mounted in the articulator, which corresponded to different clinical situations, tooth 36 was prepared for an all-ceramic partial crown [MODB]. With the Cerec3D method [CHAIR], the fabrication of the restoration was simulated directly on the phantom patient. The IPS Empress system [LAB] was used for the indirect fabrication method via an impression of the phantom patient. Both methods were used for each preparation. The adhesive luting procedure was not simulated and, therefore, not measured.
Results: The mean processing times [hh:mm:ss] were 00:35:05 (SD ± 03:27 min) for the Cerec method and 04:17:54 (SD ± 26:01 min) for the Empress method. The mean time on the phantom patient for process-induced activities was 11:47 minutes (SD ± 02:08 min) for the Cerec method and 03:58 minutes (SD ± 02:50 min) for the Empress method.
Discussion: Time expenditure for fabrication is only one aspect in order to assess the suitability of a restoration system. Both methods enable the dentist to provide high quality all ceramic restorations. Although the Empress method showed a time advantage of 65% during the fitting phase and occlusal grinding-in on the phantom patient in comparison to the Cerec method, the time spent during the laboratory phase has to be considered as well.
Keywords: time expenditure, Cerec 3D, IPS Empress, partial crown, onlay, ceramic materials