Bond strength of fibre-reinforced composite to the metal surface

The aim of this study was to measure push-out bond strength of gold alloy and pure titanium bars to dimethacrylate polymer-glass fibre composite. Metal bars were either left untreated, or sandblasted with 110 microm grain size aluminium oxide, pyrolytically silica-coated (Silicoater, Heraeus Kulzer) and silanized, tribochemically silica-coated, silanized (Rocatec, 3M-ESPE) and heat treated (100 degrees C/10 min), or tribochemically silica-coated and left unsilanized. Light-polymerizable opaque was applied on the metal surface and unidirectional glass fibres with Bis-GMA-PMMA monomer-polymer gel matrix was placed in contact to the bars and polymerized. Push-out test was performed for dry specimens and for those thermocycled (12.000 x55-5 degrees C). For titanium and gold alloy silica-coatings with the silane treatments resulted in the highest bond strengths. Values for titanium were somewhat higher than those for gold alloy. Silica-coating without silane treatment gave lower bond strengths but higher than that obtained with aluminium oxide sandblasting. The control specimens showed the lowest bond strength values. anova showed differences between the groups (P < 0.0001) whereas no significant differences between dry and thermocycled specimens were found. The results suggest that pyrolytical silica-coating with silane application resulted in highest bond strengths of dimethacrylate based fibre-reinforced composite to pure titanium and gold alloy.