Bonding characteristics of a phosphonated anaerobic adhesive to amalgam

The shear bond strength of a phosphonated anaerobic resin dental adhesive (Panavia-Ex) to amalgam was determined and clinically important parameters affecting the bond strength: amalgam type, surface finish and corrosion, were investigated. It is possible to bond to high copper set amalgam using this adhesive with a clinically useful shear bond strength. Three copper-enriched, single composition alloys were studied. One was a spherical alloy and two were lathe cut. The bond strength to one of the lathe-cut alloys was significantly lower than to the other two alloys. A significantly higher bond strength to aged lathe-cut amalgam than to fresh amalgam was found. However, Weibull analysis indicated that these latter changes were less consistent and indicated patchy, localized changes in the amalgam surface. The bond strength to the spherical alloy was significantly reduced by polishing with a finishing bur or Prophy-Jet. Therefore when bonding to a large amalgam restoration with such a phosphonated anaerobic adhesive, no polishing of the amalgam should be undertaken.