Abstract
The effect of air abrasion particle size on the shear bond strengths of a silicoated metal surface was evaluated. Eighty square metal specimens were prepared by casting Rexillium III into 1 cm × 1 cm × 1 mm units. One side of the metal specimens was ground flat to a 600 grit. Forty of the specimens were air abraded with 50‐micron and 40 with 250‐micron aluminum oxide. All specimens were then silicoated. Microfil Pontic was applied to the silicoated surface in a cylindrically shaped matrix (3.66 mm in diameter). All specimens were stored in distilled water at 37°C for 24 hours. One group was tested at 24 hours (20 of the 50‐micron and 20 of the 250‐micron), while the second group (20 of the 50‐micron and 20 of the 250‐micron) was thermocycled (2,500 cycles at 6°C‐60°C). The specimens were stressed to fracture in an Instron testing machine with a crosshead speed of 5 mm/min. At 24 hours, the 250‐micron air abraded surface had a higher mean bond strength (21.79 MPa ± 5.02) than the 50‐micron group (18.92 MPa ± 4.48). After thermocycling, the mean bond strengths were practically identical: the 250‐micron group was 17.04 ± 4.49 and the 50‐micron group was 17.05 MPa±4.43. When this data was subjected to a t‐test, no statistical difference (p ± 0.05) was found between the 50‐micron and 250‐micron air abraded groups either at 24 hours or after thermocycling. However, there was a significant decrease (p < 0.05) in bond strength of the 250‐micron group after thermocycling when compared to the 24‐hour group.