2003 年 70 巻 2 号 p. 114-123
Tetragonal zirconia polycrystals stabilized with 3 mol-% yttria (TZP) exhibit good mechanical properties, favorable esthetic appearance and translucency. Despite this, zirconia has not been widely used for all-ceramic restorations due to the difficulty of shaping it. A new process called the cercon smart ceramics® system overcomes this limitation by milling ceramic blanks in a porous, presintered and yet easily machinable state which are afterwards sintered to full density. The sintering shrinkage is compensated for by enlarging the shape prior to machining. Not only the fracture resistance but also the marginal fitness are important for all-ceramic restorations to produce satisfactory results.
In this comparative in vitro study, the marginal fitness of TZP all-ceramic crowns and fixed partial dentures (FPDs) were examined.
The marginal discrepancies of the FPDs (29.3μm) were not significantly different from those of the crowns (31.3μm) .
The results of this work suggest that
1) The marginal fitness of all-ceramic restorations fabricated by the Cercon® system was satisfactory for clinical use.
2) The dimensional stability of the Cercon® substructure was maintained during firing of the porcelain and successive glazing.