Micro-CT evaluation of the marginal fit of different In-Ceram alumina copings.

The aim of the study was to evaluate the marginal fit of different In-Ceram alumina ceramic cores manufactured by four different techniques. Four groups of four In-Ceram alumina core specimens (Vita), each 0.6 mm in thickness, were fabricated from a master die using four different techniques: Group SL, the slip-cast technique (In-Ceram system); Group CL, the copy-milling technique (Celay system); Group CR, a CAD/CAM system (Cerec inLab system) and Group WO, the electro-deposition dipping technique (Wol-Ceram). After the core specimens were fitted on the master die, they were scanned with the use of a microtomography device (1072 micro-CT, Sky- Scan). Datasets were processed by software (TView v1.1, SkyScan) and 10 vertical sections from each core were generated. On these microtomographic cross-sections the marginal gap (MG) and the absolute marginal discrepancy (MD) were measured in microscale (microm). The slip-cast and the electro-deposition dipping techniques presented the best results of MG with 22 microm and 35 microm, respectively (alpha<5%). The CAD/CAM system presented an MG of 55 microm. In addition, the slip-cast and the electro-deposition dipping techniques presented the best results of MD with 50 microm and 60 microm, respectively (alpha<5%). The slip-cast technique and the Wol-Ceram system presented the best marginal fit, followed by Cerec inLab, which presented clinically acceptable results. Microtomography analysis seemed to be a reliable method of evaluating the marginal fit of dental restorations.