Treatment of composite surfaces for indirect bonding

Composite can be cured extraorally to fabricate indirect or direct/indirect restorations. These restorations are bonded to the tooth with a dual-cure resin cement. This study evaluated various methods for treating the surface of an indirect glass-filled composite to improve its bond to enamel. The methods tested were air abrasion (sandblasting), hydrofluoric (HF) acid etching, silanation, and combinations of these techniques. Shear bond strengths were measured for thermocycled and non-thermocycled specimens. Air abrasion, followed by silanation, provided the strongest and most consistent bonds. Etching with 9.6% HF gel decreased the bond strengths obtained by air abrasion. HF alone produced the weakest bonds, with most failures occurring adhesively between the indirect composite and the resin cement.