A novel method was developed to fabricate all-ceramic restorations which comprised CAD/CAM-fabricated machinable ceramic bonded to CAD/CAM-fabricated zirconia framework using resin cement. The feasibility of this fabrication method was assessed in this study by investigating the bonding strength of a machinable ceramic to zirconia. A machinable ceramic was bonded to a zirconia plate using three kinds of resin cements: ResiCem (RE), Panavia (PA), and Multilink (ML). Conventional porcelain-fused-to-zirconia specimens were also prepared to serve as control. Shear bond strength test (SBT) and Schwickerath crack initiation test (SCT) were carried out. SBT revealed that PA (40.42 MPa) yielded a significantly higher bonding strength than RE (28.01 MPa) and ML (18.89 MPa). SCT revealed that the bonding strengths of test groups using resin cement were significantly higher than those of Control. Notably, the bonding strengths of RE and ML were above 25 MPa even after 10,000 times of thermal cycling -adequately meeting the ISO 9693 standard for metal-ceramic restorations. These results affirmed the feasibility of the novel fabrication method, in that a CAD/CAM-fabricated machinable ceramic is bonded to a CAD/CAM-fabricated zirconia framework using a resin cement.

The aim of this study was to examine the compatibility of Ce-TZP/Al 2 O 3 nanocomposite (CTA) frameworks and veneering porcelains using the Schwickerath crack initiation test and clarify the effects on debonding/crack initiation strength (DIS) of both surface pretreatment (include heat treatment) of the frameworks, type of veneering porcelain varying the coefficient of thermal expansion (CTE), and surface roughness of the frameworks. The surfaces of Ce-TZP/Al 2 O 3 plates were mechanically treated and followed by post-heat treatment. The liner and body porcelains were built up and fired according to the manufacturer's instructions. Surface analyses of the fractured plates showed compatibility with liner porcelains. Since no statistically difference in the DIS was found amongst the different surface treatments, post-heat treatments don't be mandatory. Whereas, since differences in DIS were found when different porcelains with different CTE were used, we concluded the matching of CTE of the porcelain with that of Ce-TZP/Al 2 O 3 was important for successful all-ceramic restorations using Ce-TZP/Al 2 O 3 frameworks.