Dentin Bond Strength of Self-Adhesive Luting Materials

Purpose: To determine the shear bond strength of five newer-generation self-etching resin cements to dentin.

Methods:  Flat bonding sites were prepared on 120 extracted human molar teeth with 600-grit silicon carbide paper, exposing dentin.  The systems tested were: Clearfil Esthetic Cement (Kuraray); RelyX Unicem (3M/Espe); Breeze (Pentron); Maxcem (Kerr); and G-Cem (Fuji).  RelyX ARC (3M/Espe) a conventional resin cement, was used as a control.  Each system was used to place 10 ceramic rods and 10 gold rods to dentin, according to manufacturers' instructions.  Specimens were debonded after water storage for 24 hours at 37 degrees Centigrade.  Specimens were loaded to failure in an Instron Model 1123 testing machine with a crosshead speed of 1.0 mm/minute.  A one-way ANOVA and post-hoc Tukey's test were used for pair-wise comparison independently for the ceramic and gold groups

Results:  Mean shear bond strengths (MPa) for ceramic rods at 24 hours were:

	Ceramic		Gold
Clearfil Esthetic Cement	19.7 ± 9.2 a	Clearfil Esthetic Cement	16.5 ± 3.3 a
Breeze	15.8 ± 5.6 a,b	G-Cem	14.9 ± 4.6 a,b
Rely X Unicem	14.7 ± 8.8 a,b	RelyX ARC	13.1 ± 6.1 a,b
G-Cem	13.9 ± 8.1 a,b	Rely-X Unicem	10.8 ± 4.4 b
RelyX ARC	12.5 ± 4.4 b	Breeze	8.0 ± 4.6 b,c
Maxcem	7.2 ± 9.4 b	Maxcem	4.2 ± 3.4 c

Groups with a similar letter were statistically similar (p >0.05). Clearfil cement generated the highest values to dentin for both gold and ceramic. Maxcem generated significantly lower bond strength values (p<0.05).

Conclusion:  There are significant differences in the in vitro shear bond strength among the self-etching resin cement systems tested.