Tensile bond strengths of resin cements to bovine dentin using resin coating

To evaluate the effect of a resin coating technique on dentin tensile bond strengths of dual-cured resin cements.

10 bovine dentin specimens were tested for tensile bond strengths of each of the following four materials: Panavia F, Link Max, Bistite II, Rely-X. Bovine dentin ground with 600-grit SiC was bonded with a resin cement according to the manufacturers' instructions or the resin coating technique, which was used in combination with one coat of a dentin adhesive; Clearfil SE Bond, Unifil Bond, One-Up Bond F or Single Bond, with one coat of a low viscosity micro-filled resin, Protect Liner-F. Each dentin adhesive and the low viscosity micro-filled resin were cured for 10 seconds and 20 seconds respectively. After 1 day storage in water, the specimens were subjected to the tensile bond test at a crosshead speed of 2 mm/minute. The data were analyzed by two-way ANOVA and Fisher's PLSD test (P < 0.05). The mode of failure after the tensile bond test was classified by visual inspection. The resin cement - dentin interfaces were examined by SEM.

The tensile bond strengths (MPa +/- SD) of four resin cements to dentin with/without resin coating were: Panavia F (22.9 +/- 3.1; 10.2 +/- 2.5), Link Max (16.1 +/- 4.4; 9.6 +/- 3.2), Bistite II (14.8 +/- 3.2; 14.3 +/- 3.9), and Rely-X (15.7 +/- 4.7; 13.5 +/- 4.5), respectively. The resin coating significantly improved the bond strengths of resin cements to dentin in Panavia F and Link Max, while there were no significant differences of mean bond strengths between Bistite II or Rely-X with and without resin coating (P> 0.05). Regarding the fracture modes, complete and partial adhesive failures were observed in the cases without resin coating. For the resin coating groups, the fracture modes were much more complicated, although, adhesive failures rarely occurred. Hybrid layer formation was observed for all materials used.