Bonding of amalgam and a gallium alloy to bovine dentin

The shear bond strengths of an amalgam (Permite C) and a gallium alloy (Galloy) to dentin, mediated by four dentin adhesives (Super-Bond D-Liner, Super-Bond D-Liner II, Paama 2, and Panavia 21), were investigated. Flat labial dentin surfaces were prepared from bovine lower incisor teeth. A 3 mm-in-diameter area of dentin was bonded according to each manufacturer's directions before placement of Permite C or Galloy. The bonds were stressed in shear at a crosshead speed of 1 mm/min. The mean shear bond strengths were analyzed using one-way ANOVA and Student's t-test, and fracture modes were assessed under X20 magnification and analyzed using Kruskal-Wallis and Mann-Whitney U tests. Scanning electron micrographs were taken of the bond interface of separate samples. The results showed no significant difference among the bond strengths of Super-Bond D-Liner (2.79 MPa, 2.69 MPa), Super-Bond D-Liner II (3.41 MPa, 2.65 MPa), and Paama 2 (0.70 MPa, 0.50 MPa) bonded to Permite C and Galloy (respective values in parentheses); however, Panavia gave a significantly better bond with Permite C (0.42 MPa) than with Galloy (0 MPa). Super-Bond D-Liner and Super-Bond D-Liner II gave stronger bonds than Paama 2 and Panavia with both Permite C and Galloy. For each dentin adhesive, there was no difference in fracture mode between Permite C and Galloy. It was concluded that, since all bond strengths were very low, none of the dentin adhesives tested would enhance the clinical retention of Permite C or Galloy. However, although the use of Paama 2 with Galloy was originally recommended by the manufacturer for dentin sealing purposes, no adhesion was claimed.