Ning Xu, DDS,a Chiharu Shin, DDS, PhD,a Yuji Fukui, DDS, PhD,b Satoshi Omori, DDS, PhD,a Shiho Otake, DDS, PhD,a Reina Nemoto, DDS, PhD,a Wataru Komada, DDS, PhD,a Naosuke Kumagae, DDS, PhD,a Keiichi Yoshida, DDS, PhD,a and Hiroyuki Miura, DDS, PhDa
aFixed Prosthodontics, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, bInternational Exchange Center, Tokyo Medical and Dental University, Tokyo, Japan
Purpose: The purpose of the present study was to determine the effect of prolonged holding time in firing schedule to the bonding strength of zirconia core to the veneered porcelain.
Materials and Methods: Twenty cubes of zirconia (Y-TZP, Cercon Base 47) were prepared and veneering ceramics (Vintage ZR) were layered. The bond strengths of zirconia core and layered porcelain with different holding time in firing schedule were evaluated by shearing test.
Results: The shear bond strengths of zirconia core and veneered porcelain with different holding time showed a statistically significant difference, 38.8±5.6 MPa (holding time; 1 minute) and 44.0±4.2 MPa (holding time; 21 minutes).
Conclusion: Prolonged holding time in firing schedule will improve the bond strength of zirconia core and veneered porcelain which reduce chipping failure of zirconia-based all ceramic restorations.
(Asian Pac J Dent 2013; 13: 19-25.)
Key Words: chipping, firing schedule, shear bond strength, thermocouple, zirconia ceramics