Bond strength of acrylic resin to cobalt-chromium alloy treated with the Silicoater MD and Kevloc systems.

BACKGROUND An optimum bond strength at the resin-metal interface of a prosthesis is essential to the success of that prosthesis. Silicoater MD and Kevloc are two systems used to increase bond strength at the resin-metal interface. This study investigated the effect that surface pretreatment and chemical shelf life had on the bond strength of silicoated samples and compared the shear bond strength of the two systems. METHODS Test samples consisted of autocure denture resin attached to cylinders of chrome cobalt that had been treated either with the Silicoater MD or the Kevloc bonding system. The shear strength of the resin-metal interface was tested using a universal testing machine. The following variables were tested: various silicoating pretreatments; shelf-life period of the silanating chemicals; the method of silicoating. The shear strength of repairs using the Kevloc system were also tested. RESULTS Surface pretreatment using aluminium oxide and sandblasting significantly enhanced the shear bond strength. The shelf life of the chemicals used in the silicoating process did not affect the bond strength over a six-week testing period. Samples treated with the Kevloc system showed significantly higher bond-strength values (17.3 +/- 1.7 MPa) and less variability than samples treated with the Silicoater MD system (11 +/- 3.6 MPa). In addition, all the samples repaired with the Kevloc system had bond strengths comparable to the original Kevloc-treated samples. CONCLUSION The Kevloc system has the potential to provide a more optimal resin-metal bonding system, a stronger and more consistent bond and a simpler laboratory technique.