Operative Dentistry, 2008, 33-6, 644-650 SUMMARYThe composite luting gap between ceramic and dental hard tissue can be termed an "Achilles heel." Therefore, one major goal of luting ceramics focuses on minimizing the inter-marginal gap area. This study evaluated the marginal accuracy of two all-ceramic systems. The null hypothesis was that there is no statistical difference between the marginal accuracy of the IPS Empress and Cerec 3D all-ceramic systems.On 16 casts, representing different clinical situations, the left first mandibular molar was prepared to receive large onlays (MOD and replacement of the distobuccal and distal cusps). For each cavity, one laboratory heat-pressed (IPS Empress) and one chairside CAD/CAM restoration (Cerec 3D) were manufactured. A newly developed milling unit was used for CAM processing. The restorations were placed in their respective cavities and die replicas were taken and examined under SEM for quantitative gap measurement. The gap width was measured at 11 defined landmarks by two different examiners.An overall gap width of 56 µm (± 31 µm) was measured for IPS Empress, compared to the significantly increased value of 70 µm (± 32 µm) forThe marginal fit of all-ceramic restorations has an important influence on the clinical performance and lifetime of adhesively luted restorations. In proximal boxes, an average marginal gap of less than 100 µm is claimed. These clinical requirements are fulfilled by both processing procedures.

No abstract