Effect of thione primers on bonding of noble metal alloys with an adhesiveresin

Objectives: The purpose of the current study was to evaluate the effects of two metal conditioners on the bond durability of an adhesive resin joined to noble metal alloys by comparing pre- and post-thermocycling bond strengt hs. Methods: Two different sizes of disk specimens (10 and 8 mm in diameter by 2.5 mm thickness) were prepared from silver-indium (Ag-In-Zn, Salivan), sil ver-palladium-copper-gold (Ag-Pd-Cu, Castwell M.C.12), metal-ceramic gold ( Au-Pt-Pd, Degudent-Universal), metal-ceramic palladium (Pd-Ga-Co, PTM 88), type IV gold (type TV, Casting Gold) alloys, and pure silver (pure Ag). The specimens were air-abraded with 50-mu m grain sized alumina, conditioned e ither with a thiouracil primer (Metaltite) or with a thione-phosphate prime r (Alloy Primer), then bonded with an adhesive resin (Super-Bond Opaque). S hear bond strengths were determined both before and after repeated thermocy cling (4 degrees C and 60 degrees C, 1 min each, 100,000 cycles). The resul ts were compared by analysis of variance and post-hoc multiple comparison i ntervals. Results: The average post-thermocycling bond strengths in MPa (n = 8) gener ated with the thiouracil primed and thione-phosphate primed groups, respect ively, were: 3.4 and 5.8 for the Ag-In-Zn alloy, 40.4 and 37.7 for the Ag-P d-Cu alloy, 26.4 and 33.5 for the Au-Pt-Pd alloy, 27.4 and 36.6 for the Pd- Ga-Co alloy, 40.2 and 40.3 for the type IV alloy, and 37.3 and 32.4 for the pure Ag. The Ag-In-Zn alloy exhibited significantly lower bond strength th an the other alloys, whereas the Ag-Pd-Cu and type IV alloys exhibited the greatest magnitude of bond strength for both primers (p < 0.05). Conclusions: It can be concluded that the combined use of either of the two thione primers and the adhesive resin is effective for bonding the metal/a lloys examined, with the exception of the Ag-In-Zn alloy. (C) 2000 Elsevier Science Ltd. All rights reserved.