Microtensile bond strength on dentin using new adhesive systems with selfetching primers

To evaluate the bond strength of five simplified adhesive systems using microtensile test. The occlusal enamel was removed from 25 extracted sound human molars to expose a flat dentin surface. A standard smear layer was created. The teeth were randomly assigned to five groups. 3 new self-etching primer adhesives were used: Tyrian SPE + One Step Plus [TY] (BISCO, Inc.), Optibond Solo Plus selfetching [SO] (Kerr Corporation), and Clearfil SE Bond Plus [SP] (Kuraray Medical Inc.). Two adhesives were used as control group, a self-etching adhesive, Clearfil SE Bond [SE] (Kuraray Medical Inc.) and a one-bottle adhesive that uses phosphoric acid for dentin conditioning: Excite [EX] (Ivoclar/Vivadent). After adhesive application, a composite resin block was built using Tetric Ceram (Ivoclar-Vivadent). After 24 hour storage, the bonded specimens were sectioned to obtain an array of bonded sticks with a cross-sectional area of 0.8 mm2 . Each stick was tested in microtensile mode in a Universal Testing Machine at 0.5mm/min. The mean values of microtensile bond strength in MPa were: [TY] 27.5; [SO] 55.8; [SP] 45.6; [SE] 41.5; [EX] 46.7. With exception of Tyrian SPE + One Step Plus, all self-etching primers adhesives obtained bond strength values similar to those obtained by Excite