ADHESIVE COMPOSITE RESINS FOR ARTIFICIAL TEETH - A LABORATORY INVESTIGATION OF BOND STRENGTH TO A COBALT-CHROMIUM ALLOY

Adhesive resin systems are reported to improve the bond strength betwe en resins and cast cobalt-chromium alloy. This investigation compares the behaviour of three resin systems. Cylinders and beams of cobalt-ch romium, with 0.6-mm-diameter retention beads regularly cast onto the b onding surfaces, were air-abraded and ultrasonically cleaned. Resin ve neers 4 mm deep on the cylinders and 2 mm on the bars were polymerized by heat and pressure or by light. Specimens were water-stored for 7 o r 90 days, including thermocycling between 4, 37 and 60 degrees C, bef ore testing in a Universal Testing Machine to examine the shear bond s trength or the effect of the bonded resin spine on the flexural streng th of the beams using a three-point bend test. Specimens were examined with an optical microscope to attempt to determine the nature of the failures that occurred. The investigation showed that, overall, the he at- and pressure-cured urethane dimethacrylate resin with an adhesive based upon methacrylic acid performed significantly less well than a c onventional acrylic resin, or a hybrid composite resin with an adhesiv e monomer. (C) 1997 Elsevier Science Limited.