Enhanced bond strengths of compomers using two dentin bonding systems.

To measure bond strengths of three commercial compomers using recent dentin bonding systems, and to observe the micromorphology of the cross-sectional interface of the bonded specimens.One hundred and ten bovine teeth stored frozen were used. The dentin surfaces were ground flat with #600-grit silicon carbide paper, and divided into three groups for bonding: original bonding system group (Xeno Bond/Xeno, Prime&Bond 2.1/Dyract AP, and F2000 Primer/Adhesive/F2000 compomer), Clearfil Liner Bond 2V group (LB 2V/Xeno, LB2V/Dyract AP, LB2V/F2000 compomer, LB2V/AP-X), and Single Bond group (SB/Xeno, SB/Dyract AP, F2000 compomer, SB/Z100). After the bonding procedures had been performed, the bonded assemblies were stored in water for 24 hours at 37 degrees C. Then, tensile bond strengths were measured using a universal testing machine at a crosshead speed of 2 mm/minute. All data were statistically analyzed using one-way ANOVA and Fisher's PLSD at 95% of confidence. Specimens for SEM observations were bonded in the same manner as for the tensile bond test, cut in half, and embedded in epoxy resin. These were then polished to high gloss, gold sputter-coated, and observed with the SEM.Compomers bonded to dentin with recent dentin bonding systems showed significantly higher bond strengths than those with the original bonding systems (P< 0.05). Tensile bond strength of Clearfil Liner Bond 2V was also significantly higher than that of Single Bond (P< 0.05). SEM observations showed good interaction between the compomers, adhesive systems, and dentin with any restorative material used. For Xeno Bond/Xeno, Prime & Bond 2.1/Dyract AP, and Primer/Adhesive/F2000 compomer, the thicknesses of the hybrid layer were approximately 0.8-1.1 microm, 0.3-0.5 microm, and 0.7-1.5 microm respectively. On the other hand, the hybrid layer produced by LB2V was approximately 0.5 to 1.0 microm, whereas for SB was approximately 3.1 to 4.1 microm thick. The thickness of the hybrid layers created in each bonded sample depended on the adhesive material used.