ENHANCEMENT OF RESIN BONDING TO HEAT-CURED COMPOSITE RESIN

The purpose of this study was to evaluate the effectiveness of various surface treatments used to enhance the bond strength of resin cements to two different laboratory-processed composite resins. Seventy speci mens of a microfilled composite resin (Concept) and 70 specimens of a micro-hybrid composite resin (Herculite XRV) were fabricated in metal wells and subjected to heat (250 degrees F) and pressure (85 psi) curi ng. An additional 70 specimens of each material were fabricated in the shape of disks and also subjected to the same heat/pressure curing. A ll composite resins were subjected to one of seven treatment regimens. The like-treated specimens were then bonded together using dual-curin g resin cement and a uniform seating force(106 gm). After 7 days, bond ed specimens were thermocycled 1000 times at 5 and 55 degrees C, and d ebond shear strengths were determined on a Universal Testing Machine. The use of microabrasion (50 mu m aluminum oxide at 60 psi) and cerami c layer deposition (30 mu m aluminum oxide with a ceramic additive at 75 psi) consistently improved the shear bond strength of the resin cem ents to both composite resins. The other treatment combinations provid ed varying effects. In conclusion, microabrasion or ceramic layer depo sition are preferred methods to entrance the bond of resin cements to composite resins.