A Combined Acid-etching And Silica-coating Pretreatment Method For Titanium

Objectives: For durable and stable adhesion with resin-composites an ideal titanium-based restoration surface is rough with large surface area, silica-coated and silanized. The aim of this study was to assess the effect of combined surface treatments on titanium, and evaluate the effects on the surface roughness and topography.
Methods: Commercially-pure grade-2 titanium specimens (10mmx10mmx1mm); 1 for each analysis (n=63{21+21+21}) were first polished, etched with HNO₃(69%) and a blend(1:1) of HCl(35%).H₃PO₄(85%) at 80°C for 1h. Half of the etched specimens were silica-coated (Rocatec Plus,3M ESPE,110µm silica-coated alumina powder) at a distance of 10mm perpendicular to the Ti-surface for 15s and silanized by experimental silane primer system (1.0vol% 3-acryloxypropyltrimethoxysilane + 0.30vol% 1,2-bis-(triethoxysilyl)ethane, Monobond Plus (Ivoclar-Vivadent) and Z-Prime Plus (Bisco). SEM/EDX and surface roughness (R_a) analysis were carried out. Polished titanium was the control.
Results: EDX results indicated the highest atomic concentration of [Si]= 16.85% - 17.11%, [Al]= 7.65% - 8.02% before and after silanization in the samples treated with HCl.H₃PO₄ and silica-coating. Same trend was observed in R_a analysis, R_a= 1.18-1.22. There was a difference in the Si and Al concentrations when compared to the control [Si]= 2.12, [Al]= 0 with R_a= 0.24. The lowest concentration of [Si]= 0.90% - 1.05%, [Al]= 0.90% - 1.10% were observed with not much difference before and after silanization in specimens etched with HCl.H₃PO₄ without silica-coating. The lowest R_a= 0.24 - 0.28 was observed in specimens treated with HNO₃ before and after silanization without silica-coating. Same trend was observed in SEM analysis: specimens treated with HCl.H₃PO₄ + silica-coating showed the highest roughness before and after silanization.
Conclusions: A combined acid-etching and silica-coating using HCl.H₃PO₄ + silica-coating has a stronger effect on titanium surface roughness when compared to other surface pretreatments. Silanization did not affect the surface roughness. This might create durable adhesion between titanium and resin-composite cements for cementation.