Effect of gold coating on interfacial reaction between dental porcelain and titanium

Cross-sectional microstructure observation of the titanium firing porcelain inserted ion-coated gold layer was performed by SEM-EDS that can analyze light elements from boron. Two gold-coated samples applied to mirror finished titanium surface were prepared; one was applied only degassing treatment, and the other was applied firing after degassing treatment. Effect of gold coating on interfacial layer formation was investigated and discussed by the comparison with titanium /porcelain interface without gold coating. From SEM-EDS observation of the specimen, approximately 2.5 mu m thickness titanium oxide layer appeared across the gold film in the degassed sample. In the titanium firing porcelain after degassing treatment, two obvious reaction layers appeared across the gold coating. One included mainly titanium and oxygen, and another included titanium, oxygen, gold and aluminum. A firing process and gold layer affected thickness of the reaction layers. Titanium/porcelain without gold coating had two reaction layers at the interface, however, many cracks and crevices appeared in the layer and between the layers. Thickness of the reaction layers decreased by gold coating, and cracks and crevices in the layer disappeared. The results suggested that titanium diffusion became lower due to gold coating, and titanium-gold reaction changed layer's microstructure. Subsequently it was suggested gold coating on titanium contributes to improvement of adhesion between titanium and porcelain due to these mechanism.