Novel fabrication method for zirconia restorations: Bonding strength ofmachinable ceramic to zirconia with resin cements

Abstract

A novel method was developed to fabricate all-ceramic restorations which comprised CAD/CAM-fabricated machinable ceramicbonded to CAD/CAM-fabricated zirconia framework using resin cement. The feasibility of this fabrication method was assessed inthis study by investigating the bonding strength of a machinable ceramic to zirconia. A machinable ceramic was bonded to a zirconiaplate using three kinds of resin cements: ResiCem (RE), Panavia (PA), and Multilink (ML). Conventional porcelain-fused-to-zirconiaspecimens were also prepared to serve as control. Shear bond strength test (SBT) and Schwickerath crack initiation test (SCT) werecarried out. SBT revealed that PA (40.42 MPa) yielded a significantly higher bonding strength than RE (28.01 MPa) and ML (18.89MPa). 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 meetingthe ISO 9693 standard for metal-ceramic restorations. These results affirmed the feasibility of the novel fabrication method, in thata CAD/CAM-fabricated machinable ceramic is bonded to a CAD/CAM-fabricated zirconia framework using a resin cement.