Abstract<br />Since the introduction of single-step adhesives to the market, there are still few publications, that analyse the shear bond strength of single-step adhesives to enamel.<br /><br />Material and Methods<br />The products Adhese Universal, Futurabond M+ and OptiBond XTR were investigated with special focus on differences of shear bond strength values comparing the self-etch technique with the total-etch technique. 240 bovine teeth were tested, divided in groups of 80 for each product, half of them were preconditioned with phosphoric acid. Furthermore, the enamel was prepared, to obtain a plain 5mm diameter surface. The products were applied, following the instructions of the manufacturers. Afterwards a composite specimen of CeramXUniversal with a diameter of 4 mm was applied, at a right angle. Test specimens were stored for 24 hours in water at 37C. Before the tests, the specimens were stabilized in plaster. The bond strength between the composite specimen and the enamel was determined by the universal test machine (Zwick) with a cross head speed of 0,8mm/min. Bonding strength values and the fracture behavior were analysed.<br /><br />Results<br />The total-etch application of Adhese Universal and Futurabond M+ showed significant higher bond strengths compared to OptiBond XTR. Results for the selfetch technique exhibited significant lower bond strengths using Futurabond M+, compared to Adhese Universal and Optibond XTR.<br />Significant higher bond strengths were found for Adhese Universal and Futurabond M+ when using the total-etch application compared to the self-etch technique. Only for OptiBond XTR a similar bonding strength was found regardless of application technique. Cohesive failures were mainly investigated when using the total-etch technique.<br /><br />Conclusion<br />The significant higher bond strength on enamel using total-etch technique of the one-step-systems Adhese Universal and Futurabond M+ may indicate the superiority of the phosphoric acid preconditioning compared to the intrinsic preconditioning of the adhesive system. The primer of OptiBond XTR, the only two-bottle-system, could precondition the enamel similar to the phosphoric acid.