Bond versus Rebond Strengths of a Base-Metal Alloy to Enamel

For resin-bonded bridgework rebonding is generally recommended in the case of bond failures; however there is little information in the literature comparing initial bond and rebond strengths. OBJECTIVES: The aim of this study was to compare the effects of various surface treatments on the shear bond and rebond strengths of a cobalt-chrome base metal alloy to enamel using two different adhesive luting cements. METHODS: The bonding surfaces of metal samples were either sandblasted with 110 micron aluminium oxide, tribochemically coated (Rocatec, 3M-Espe) or treated with Alloy Primer (Kuraray). Metal samples were bonded to human molar buccal enamel surfaces using Panavia F 2.0 (Kuraray) or Rely X ARC (3M-Espe) luting cements (n=12). Bonded specimens were thermocycled 1000 times in 5-55ºC. Samples were tested in shear mode using a universal testing machine (Lloyd LRX). Debonded samples were rebonded after appropriate metal conditioning and re-etching the enamel surface. Rebond strengths were then measured. RESULTS: The mean bond strengths (MPa) and standart deviations are presented in Table below. The shear rebond strengths were found to be greater than bond strengths except sandblasted samples. Multi-way ANOVA revealed that surface treatments appeared to have no significant effect on bond and rebond strengths however Panavia F showed significantly higher bond and rebond strengths than that of Rely X ARC (p<0.05). CONCLUSION: Within the limitations of this study it was concluded that rebonding may be a viable approach however choice of cement is important.