الفهرس 
Sandblasting techniqueOnly 14 pages are availabe for public view
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Abstract
This study was designed to evaluate the effect of different surface treatments of base metal alloys Ni-Cr on shear bond strength with two different types of resin based cements, resin modified glass ionomer and dual cure self adhesive resin cement.
Discs of Ni-Cr metal alloy were casted using a split copper mold with dimensions 5.5 mm. in diameter and 3.5 mm. in height.
A total of 120 discs were divided into two groups each was subdivided into six subgroups each containing ten discs as follows: first subgroup (control) without any surface treatment except metal surface oxidation that was done to all discs samples, then single surface treatment groups, metal chemical acid etching surface treatment using (Met-etch gel), sandblasting groups using 125 micrometer alumina oxide particles size, and combined surface treatments groups which chemical acid etching with application of metal primer (Alloy primer), sandblasting with metal primer, and finally sandblasting, chemical etching and Alloy primer application.
After surface treatment the samples were ultrasonically cleaned, for groups were alloy primer was applied ultrasonic cleaning was made only before application.
The surface topography were evaluated qualitatively by scanning electron microscope and the data was recorded photographically.
Results revealed that the metal acid etching showed large deep pores but smaller in width and less in distribution compared to topographic retentive features of sandblasted groups which showed irregular wide retentive features which are distributed allover the surface of samples. while metal alloy primer showed homogenous film of resin metal primer covering the entire surface and fill the microretentive features produced by different types of surface roughness. Some areas show honey comb appearance after combining sandblasting or chemical etching with alloy primer.
Then the samples were cemented using a specially designed assembling device all cements were manipulated according to the manufacturer’s instructions. the mixed cement was applied on the bonding surfaces of both paired samples and a load of 2.5 kg was applied. After removal of the load the excess cement were removed manually and ultrasonically. The cemented samples were stored in distilled water at room temperature for 72 hours, then shear bond strength was tested using Instron testing machine using a specially constructed testing device ,the shear bond strength was calculated by dividing the force at which the bond failure occurred by the bonding area, the results were recorded, tabulated and statistically analyzed.
Scanning electron microscope evaluation was made for the debonded samples.
The results showed that the alloy surface treated with sandblasting irrespective to the type of cement used either resin modified glass ionomer or adhesive resin cement showed the highest shear bond strength, the untreated control groups gave the least shear bond strength irrespective to the type of cement.
The highest shear bond strength values were always obtained with adhesive resin cement followed by resin modified glass ionomer cement irrespective to the type of surface treatment applied to the alloy surface. SEM of debonded samples confirmed the results of shear bond testing with highest cement remnant in adhesive resin cement and least with resin modified glass ionomer whatever the type of surface treatment considering the type of surface treatment the greatest cement remnant was always seen in sandblasting surface treatment and in combined surface treatment was in sandblasting, acid etching and metal alloy primer application groups.