Improving the flexural strength of a gold alloy metal-ceramic

Objective: To compare the bond strength of a gold alloy and a feldspathic ceramic (VM 13 Vita, Vita Zahnfabrick) (AuC) in the presence or absence of coupling agent wash opaque (Vita Zahnfabrick) (WO). Methods: Gold alloy bars were treated with tungsten tip and Al3O2 blasting and opaque (Opaque Vita VM13, Vita Zahnfabrick) and coverage (VM13 Vita, Vita Zahnfabrick) ceramics were applied. The variables analyzed were the presence of bonding agent (WO) and thermal cycling and (3000 cycles; 5-55ºC; immersion period: 30 seg) mechanical loading (20000 cycles, 10 N, 37ºC) (TMC), as follows: G1- AuC + WO; G2- AuC without treatment; G3- AuC + WO + TMC; G4- AuC + TMC. The use of WO in G1 and G3 was performed after the blasting. Three-points bending test (1,5 mm/min, 10 kg) was employed. Results: Statistically significant differences were found between G1 and G3 (p <0.001) and between G2 and G4 (p <0.001), indicating that the presence of WO had significantly increased the values of bond strength of the system. However, the thermo-mechanical cycling had significantly reduced the values of bond strength between metal and ceramics. Stereomicroscope analysis revealed that the failure mode was predominantly adhesive on G3 and G4, and exclusively mixed for G1 and G2. Conclusion: It can be concluded that the application of WO had significantly improved the bond strength values between ceramic and gold alloy, and its use is indicated on the preparation of gold alloy metal ceramics.