Bond strength of self-etching adhesives to dental hard tissues

Since most cavity preparations show not only areas of exposed enamel and superficial dentin but also of deep dentinal areas, it would be desirable to use a dental adhesive which can obtain equally good bond strength to these hard tissues. The objective of this study was to measure the bond strength of self-etching adhesives to enamel and superficial and deep dentin. Human molars were ground to expose a surface of enamel or superficial (2.0-2.5 mm distance to pulp) or deep dentin (0.5-1.0 mm), embedded in acrylic resin and assigned to three groups (total n=90). The adhesives tested were: Clearfil SE Bond (SE), Prompt L-Pop (LP), and Etch&Prime 3.0 (EP). After application of the adhesives, an inverted, truncated cone of composite (Pertac II, ESPE) was cured. After storage, specimens were debonded in tension at a cross-head speed of 0.5 mm/min. The median tensile bond strength values to enamel were SE 29.1 MPa, LP 22.4 MPa, and EP 21.5 MPa. The median bond strengths for superficial dentin were SE 27.3 MPa, LP 8.4 MPa, and EP 3.2 MPa. The median bond strengths for deep dentin were SE 20.2 MPa, LP 5.7 MPa, and EP 1.3 MPa. The adhesives tested bonded effectively to enamel, but only SE achieved promising bond strengths to superficial and deep dentin.