[Efficacy of 4 adhesive systems for amalgam. In vitro study]

The aim of this research is to study the shear bond strength of 4 adhesive systems of the last generation: All-Bond 2 (AB2), Clearfil Liner Bond 2 (CL), Scotchbond MP plus (SBMP) and High Q Bond plus (HQB). According to the manufacturing company these products are suitable for amalgam adhesion to dentin.

Forty extracted human third molars have been ground to expose a flat dentin surface. The teeth were randomly assigned to 4 groups, and every group was treated with one of the adhesive system according to the manufacturer's instructions. Samples were then secured in a split Teflon mould, having a 6 mm diameter opening and a spherical amalgam was triturated and condensed onto the treated dentin surfaces. The amalgam cylinders have been exposed to a tensile bond test using a Universal Testing Machine (Instron 4500). ANOVA test has been used to the statistic study among groups.

The study of the tensile mean range, showed that dentin shear bond strength values (MPa) for the adhesive systems tested were: 8.13 +/- 1.48 for AB2, 7.06 +/- 1.41 for SBMP, 4.2 +/- 1.06 for HQB, 3.04 +/- 0.68 for CL. The statistic test revealed significant differences among the 4 groups (p < 0.05).

The bond strength mean values of amalgam adhesives are lower than the ones for composite resins, nevertheless dentin-enamel adhesive systems specific for amalgam have to be taken into consideration particularly in case of conservative restorations that need chemical retention as a support, when the mechanical one is not enough.