Dye penetration at a cobalt-chromium alloy--composite resin interface

This study examined microleakage along the interface of resin systems bonded to cobalt-chromium alloy; a microfine resin with adhesive properties based upon methacrylic acid, and a hybrid resin containing an adhesive phosphate monomer. Specimens were thermocycled between 4 degrees, 37 degrees and 60 degrees C over 1000-10,000 cycles and placed in 0.1% neutral red dye for 7 days. Each was cut diagonally and the interfaces photographed using an optical microscope. Dye penetration was expressed as a percentage of the total length of each edge. The hybrid resin showed significantly less microleakage than the microfine resin.