Very limited comparative information about bond strengths of dual-polymerizing self-adhesive resin-based cements to different substrates is currently available.  Objective: to assess and compare the shear-bond strength of self-adhesive cementsto a variety of restorative materials.

Methods: Enamel, Dentin, Lava Zirconia (3M ESPE), IPS Empress II (Ivoclar) and Gold alloy were used in this study.  Fifteen samples from each substrate were randomly assigned to four cement groups: Nexus II (Control):  (Kerr Corp), FujiCem (GC America), MaxCem: (Kerr Corp.) and Relyx Unicem (3M ESPE)

The bonding surfaces were prepared according to the manufacturers' instructions of the respective cement.  Cements were placed directly into the opening of a cylindrical polyethylene mold and allowed to chemically cure. Shearing force was applied at 1mm/min until failure.  Bond strengths were calculated in (MPa.).

Results: Mean (Standard Deviation) and results of ANOVA and Tukey's HSD tests at a=0.05 for each substrate are presented in Table.

Substrate Cement	Enamel	Dentin	Gold	LAVA	Empress
Nexus	18.61(4.06) A	8.47 (2.61) A	7.16 (2.08) A	8.99(4.47) A	12.14 (4.05) A
Fujicem	6.11(1.25) B	2.13  (2.02) C	3.91 (2.14) B	5.57 (0.91) B	4.53 (2.73) B
Maxcem	5.93(3.44) B	5.92 (2.43) B	8.26 (2.31) A	8.97 (1.94) A	13.30 (3.28) A
Unicem	4.09(1.06) B	5.07 (2.28) B	8.33 (2.10) A	9.10 (2.23) A	12.41 (2.86 ) A
p- Value	p< 0.001	p < 0.001	p < 0.001	p =.001	p < 0.001

            Conclusions:  Within the limitation of this study, The two auto-adhesive cements ( MaxCem and Relyx Unicem) were comparable for all substrates, comparable to Nexus II (Control) resin cement for the high noble Gold alloy, LAVA Zirconia and Empress II substrates, and had significantly higher shear bond strength to Dentin, high noble Gold alloy, LAVA Zirconia, Empress II than FujiCem but were comparable in the Enamel group.

Research supported by Kerr Corporation