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Abstract
PURPOSE. The aim of this study was to evaluate the influence of different cement
thicknesses of two adhesive cements on resin-zirconia shear bond strength..
MATERIALS AND METHODS. Thirty zirconia discs were prepared from ICE
zirconia block.Thirty freshly extracted molars were transversely sectioned at the deep
dentin level and bonded to air-abraded zirconium oxide ceramic disks. The specimens
were divided into two groups according to cement type: Rely X UniCem or Rely X
ARC, and further subdivided into three subgroups according to cement thickness:50
μm,100 μm or 150 μm. All cemented specimens were stored in distilled water for 2
weeks. Then thermocycled between 5oC and 55oC for 1000 cycles with a dwell time
of 30 seconds and a transfer time of 2 seconds. All the samples were subjected to a
shear test to evaluate their bond strengths. Two-way Analysis of Variance (ANOVA)
was used in testing significance for the effect of cement type, cement thickness and
their interactions on mean shear bond strength.
RESULTS. All failures occurred at the resin-zirconia interface (adhesive failure).
RelyX ARC with 100 μm thickness recorded the statistically significantly highest
mean shear bond strength. This was followed by RelyX ARC with 50 μm thickness.
There was no statistically significant difference between RelyX ARC with 150 μm
thickness, RelyX Unicem with 50 μm thickness, RelyX Unicem with 100 μm
thickness and RelyX Unicem with 150 μm thickness; all scored the statistically
significantly lowest mean shear bond strength values
CONCLUSION. Effect of cement type on the shear bond strength more effective
than cement thickness.