Methods:
This invitro experimental study was done on 20 specimens from human third molars(enamel). Specimens were randomly assigned into two groups,In group 1 Rely X Unicem cement was applied as manufacturer’s instruction( without any pre- treatment preparation), just after 15 seconds of mixing.In group 2 the enamel part was etched ,using phosphoric acid for 15 seconds, rinsed and dried, and Rely X ARC cement was applyed as manufacturer’s instruction. 0.7 X 1mm rods of Composite resine (Z100-3M, ESPE) was placed on the prepared surfaces and cured.All specimens were stored in distilled water for 24 hours in ancubator(37oC) . The micro-shear bond strength of the specimens was measured with universal testing machine(Bisco Inc USA) and the data were analyzed with student t- test.
Results: After storage for 24 hours ,Rely X ARC enamel specimens exhibited bond strength of 18.56±4.08 MPa and Rely X Unicem showed bond strength of 14.99±4.17 MPa.Data showed no statically significant differences.
Conclusions:
Within the limitation of this study the micro-shear bond strength of Relay X Unicem self adhesive cement is not significantly different from that of multi-step Rely X ARC cement.