Bond strength of composite to alloy treated with bonding systems.

PURPOSE: The in-vitro bond strengths of a composite bonded to a nickel-chromium-beryllium alloy treated by eight bonding systems were measured after three storage conditions.

MATERIALS AND

METHODS

Nickel-chromium-beryllium alloy samples were treated by eight commercial bonding systems including adhesive composite cements, all-purpose bonding agents, and silica-coating systems. A composite was bonded to the alloy samples. Sample groups were stored in water for 24 hours at 23 degrees C, or thermocycled, or stored for 6 months at 23 degrees C and then debonded in tension.

RESULTS

Bond strengths after 24 hours storage were: adhesive composite cements, 14.2 to 22.1 MPa; all-purpose bonding agents, 11.4 to 14.6 MPa; and silica-coating systems, 18.6 to 20.2 MPa. Bond strengths after thermocycling were: adhesive composite cements, 12.6 to 20.6 MPa; all-purpose bonding agents, 9.9 to 17.7 MPa; and silica-coating systems, 11.1 to 19.2 MPa. Bond strengths after 6 months were: adhesive composite cements, 12.0 to 13.1 MPa; all-purpose bonding agents, 8.7 to 14.1 MPa; and silica-coating systems, 14.8 to 18.4 MPa.

CONCLUSIONS

Only two bonding systems showed decreased bond strength after thermocycling, as compared with 24 hours' storage; whereas four bond systems showed decreased bond strength after 6 months' storage. Bond strengths measured after thermocycling were not predictive of those measured after 6 months' storage.