Bonding of autopolymerizing denture base resin to cast Type IV gold alloy

Purpose: To evaluate the shear bond strengths of an autopolymerizing denture base resin to cast Type 1 V gold alloy using four metal conditioners. Methods: Type IV gold alloy discs were cast. The disc surfaces were sandblasted with 50 mu m alumina particles and primed with four metal conditioners (Metaltite; Alloy Primer; Metal Primer II; and V-Primer). An autopolymerizing denture base resin was applied on an area of the discs defined by a hole punched in a piece of sticky tape and by a Teflon ring. All the specimens were immersed in 37 C distilled water for 24 hours. Half of the specimens were thermocycled up to 20,000 cycles in water between 4 C and 60 C with a dwell time of 1 minute at each temperature. The shear bond strengths were determined at a crosshead speed of 1.0 mm/minute. The data was analyzed using a 2-way ANOVA (P< 0.05). Results: The shear bond strengths of the autopolymerizing denture base resin to cast Type IV gold alloy specimens primed with the four metal conditioners (P< 0.05) were significantly enhanced. However, the bond strength was reduced for all themocycled groups (P< 0.01). Metaltite exhibited the greatest pre- and post-thermocycling bond strength (27.5 and 22.4 MPa) compared to the other groups (P< 0.05). (Am J Dent 2008;21:323-326).