Abstract
Pitting corrosion is an electro-chemical corrosion frequently observed in metal and alloy, and the pits produced by this corrosion have a fairly good undercut. B. Dunn and M.H. Reisbick applied this corrosion to enable the ceramic to attach to Vitallium. The purpose of this study was to determine the retentive force of the pits for retaining thermo-setting acrylic resin veneers. The metal casting casted by 92% Ni-6% Cr alloy was placed in a 4% NaCl solution and biased positively with respect to a stainless steel electrode. A direct current was passed and by modifying the level and the treatment time, varying degree of pitting corrosion were achieved. After etching, current thermo-setting acrylic resin was veneered. Then all the specimens were subjected to thermal cycling at 4°C and 60° C for two hours. All the specimens were then measured the amount of force required to separate the facing resin from the metal casting. The strongest retention, 100 kg/cm2, were obtained at the following combination of the current density and the treatment time ; 625 mA-6 min, 500 mA-8 min, 375 mA-10 min, 250 mA-18 min. The pits appeared to be effective for retaining thermo-setting acrylic resin veneers.
