الفهرس 
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Abstract
Aim: This study was designed to compare the effect of bioactive cement versus MDP-containing
resin cement on the shear bond strength of zirconia to human dentin; and detect the mode of failure
by Scanning Electron Microscope (SEM) analysis.
Methodology: Twenty free-caries molar teeth were randomly equally distributed into 2 groups, 10
teeth each; group (A) and group (B) to receive zirconia discs (Zolid fx Zirconia ML). The surfaces
of all zirconia discs of both groups were air-abraded with 50-µm alumina particles with 2.5 bar, 10
mm distance and 20 seconds. All of the zirconia discs of both groups were cemented after air borne
particle abrasion over their dentin surface of tooth structure from buccal side; then, each specimen
was seated under a uniform vertical load. (5-kg seating force). Samples were stored in a distalled
water for 24 hours; then, subjected to 5,000 cycles between 5°C and 55°C temperature with 60
seconds dwell time at each temperature in distilled water to simulate 6 months clinical intraoral
service. Bond strength was evaluated through the Macroshear test performed via a universal testing
machine (UTM), by compressive static load was applied at the dentin-cement interface, by a 0.5
mm mono-bevel chisel shaped metallic load applicator attached to the upper movable compartment
of the testing machine, at a crosshead speed of 0.5 mm/min. until failure occurred. The mean and
standard deviation of shear bond strength for each group was calculated, and statistically compared
using independent t-test. EDX analysis was used to identify element composition, also, AFM was
used to measure surface roughness of air abraded zirconia disc.
Results: Calibra bio cement group (CB) has demonstrated statistically insignificant higher bond
strength (19.06 MPa ± 2.76) than TheraCem group (TH) (17.85 MPa ± 3.57). SEM showed that
Mixed‖ failure mode was the predominant in both groups.
Conclusions: Calibra bio cement demonstrated clinically accepted higher bond strength, to dentin
surface of tooth structure, than that of TheraCem cement, after simulation of 6 clinical service
months by thermal aging.
Keywords: bioactive cement,MDP-containing resin cement,shear bond strength,zirconia dentin.