Bond strength of composite to dentin using conventional, one-step, and self-etching adhesive systems

Objectives: This in vitro study compared the dentin bonding performance of eight adhesive systems using a microtensile bond strength test. Methods: Thirty bovine teeth were ground to 600-grit to obtain flat root-dentin surfaces. Two conventional adhesive systems (Scotchbond Multipurpose Plus, OptiBond FL), four one-step adhesive systems (Scotchbond 1, Asba S.A.C., Prime and Bond NT, Excite) and two self-etching adhesive materials (Clearfil Liner Bond 2 V and Prompt L-Pop) were evaluated. Each bonding system was applied according to manufacturerʹs instructions and followed by composite (Z100) application. Immediately after bonding, the teeth were prepared for microtensile testing. Bond strength to dentin was measured using a Vitrodyne V-1000 universal tester. There were 14 replicates for each material. Fractured specimens were further observed by SEM. Results: Scotchbond Multipurpose Plus exhibited significantly (p<0.05) higher bond strength values (30.3±9.4 MPa) than all other materials. The bond strengths of the other materials were (from highest to lowest): Opitbond FL (22.4±4.3 MPa); Scotchbond 1(18.9±3.2); Clearfil Liner Bond 2 V (18.9±3.0); Prime and Bond NT (18.3±6.9); Asba S.A.C. (14.4±2.9); Excite (13.8±3.7); and Prompt L-Pop (9.1±3.3). Statistical comparisons frequently overlapped, but Optibond was significantly (p<0.05) greater than Asba, Excite, and Prompt L-Pop; whereas, Scotchbond 1 was only significantly (p<0.05) greater than Prompt L-Pop. Asba, Excite and Prompt L-Pop were not significantly different. The fracture modes were mostly adhesive. Conclusions: The conventional adhesive systems produced higher bond strengths to root dentin than most one-step adhesives and one self-etching adhesive; with the exception of one material in each respective system.