Surface treatment of gold alloys for adhesion

A lthough several efforts have been made to develop adhesives and bonding methods for dental gold alloys, the results failed to provide adequate attachment to counteract the severe conditions in the oral cavity.le3 Poor water resistance of the adhesives or lack of effective surface pretreatment of the gold alloys were the main reasons for failure. Previous studies found that adhesives containing 4methacryloxyethyl trimellitate anhydride (CMETA), a synthesized adhlesion-promoting monomer, provided strong adhesion 1.0 nonprecious alloys.4,5 In addition, the bonding durability of the 4-META resin with these alloys was much improved by oxidation of the metal surface. To apply these findings to gold alloys, various trials using experimental thermosetting type 4-META resins were conducted. This research resulted in two kinds of surface oxidation, singleand double-heating.6 Because the clinical use of a thermosetting resin is less frequent than that of a self-curing resin, the effectiveness of both surface treatments with a self-curing type 4-META resin was investigated.‘,* Favorable bonding strength of greater than 200 kg/cm2 was obtained after 20,000 thermocycles in both treatment methods. In addition, the single-heating method was studied for application to fixed partial dentures and other adhesionretained restorat:ions.