Shear bond strengths of pressed andlayered veneering ceramics to highnoble alloy and zirconia cores
Motoaki Ishibe, DDS,a Ariel J. Raigrodski, DMD, MS,bBrian D. Flinn, PhD,c Kwok-Hung Chung, DDS, MS, PhD,dCharles Spiekerman, PhD,e and Robert R. Winter, DDSf
University of Washington, Seattle, Wash
Statement of problem. Heat-pressed ceramics to metal alloys and zirconia have been available for some time. However, information regarding their shear bond strengths is limited.
Purpose. The purpose of this study was to evaluate the shear bond strengths of heat-pressed and layered ceramics
with regard to their corresponding high-noble alloy and zirconia cores.
Material and methods. Forty cylinders (approx. 5 mm in diameter) of high-noble alloy (Olympia) were cast and divided into 4 groups (n=10). Metal cylinders were veneered with ceramics to produce shear test specimens: Group PMIwith IPS InLine POM; Group LMI with IPS InLine; Group PMC with Pulse press-to-metal; and Group LMC with Authentic Pulse Metal ceramic. Forty cylinders (approx. 5 mm in diameter) of zirconia (Lava) were obtained and dividedinto 4 groups (n=10). These cylinders were veneered with ceramics to produce shear test specimens: Group PZI with IPSe.max ZirPress; Group LZI with IPS e.max. Ceram; Group PZV with VITA PM9; and Group LZV with VITA VM9. The veneering ceramics, 3 mm in thickness, were either pressed or layered to their corresponding cylinders. Thermal cycling wasperformed at 5°C and 55°C for 20,000 cycles with a 20 second dwell time. Shear bond strength testing was conductedin a universal testing machine, and the failure strengths were recorded. Fracture surfaces were characterized visually, under a stereomicroscope, and with a scanning electron microscope (SEM). Data were analyzed using rank-based KruskalWallis and Mann-Whitney tests with Bonferroni correction to adjust for multiple comparisons (α=.05).
Results. For metal ceramic specimens, the mean (SD) shear bond strengths ranged from 37.8 (20.6) MPa to 66.4
(22.1) MPa. There were significant differences between Groups PMI and PMC and between Groups LMI and PMC, inwhich Groups PMI and LMI had significantly higher strength values than Group PMC (P=.041). For zirconia ceramic
specimens, the mean (SD) shear bond strengths ranged from 30.03 (9.49) MPa to 47.2 (13.0) MPa, with Group LZV
having a significantly higher shear bond strength value than Group LZI (P=.012). Half of the Group PZV specimens
failed during thermal cycling, and Group PZV was, therefore, excluded from statistical analysis. For all shear bondstrength testing specimens, cohesive failures in the veneering ceramics were observed.
Conclusions. For shear bond strength of veneering ceramics to high-noble alloy, there was no significant difference
between pressing and layering with the same manufacturer. For shear bond strength of veneering ceramics to zirconia,
there was no significant difference between the pressed and layered groups. (J Prosthet Dent 2011;105:29-37)

Clinical Implications

The results of this in vitro study suggest that, for shear bondstrength, clinicians and dental laboratory technicians should consider the use of pressed ceramics to high noble alloy and zirconia as
an alternative to traditional layering procedures.
Graduate student, Graduate Prosthodontics, Department of Restorative Dentistry, School of Dentistry.
Professor and Director, Graduate Prosthodontics, Department of Restorative Dentistry, School of Dentistry.
cResearch Associate Professor, Materials Science and Engineering.
dProfessor, Department of Restorative Dentistry, School of Dentistry.
e
Research Associate Professor, Department of Dental Public Health Sciences.
fAffiliate Professor, Graduate Prosthodontics, Department of Restorative Dentistry, School of Dentistry.
abIshibe et al