New physico-chemical approaches on titanium surfaces: characterization and topography

Abstract

Objectives: Rough, silica-coated + silanized titanium surfaces promote durable resin adhesion for dental prostheses. This study evaluates and characterizes the effect of combining physico-chemical surface treatments of titanium and their effect on surface chemistry and topography. Methods: Cp-2 titanium coupons (10mmx10mmx1mm, n=6) were acid-etched with HNO3 (69%) and HCl(35%).H3PO4(85%), in ratio 1:1, at 80°C for 1h, followed by with/without silica-coating (Rocatec Plus, 3M ESPE, 110µm alumina-coated silica powder) at a distance of 10mm perpendicular to the Ti-surface for 15s. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and surface roughness (SR) analysis were carried out. Control group was polished-titanium. Results: The results from EDX and XPS revealed the presence of [Si] =EDX: 24.5%, XPS: 27% and, [Al] =EDX: 7.4% and XPS: 9% in higher percentages on Ti specimens etched with HCl.H3PO4+silica-coating. The values were significantly higher than those obtained after etching with one acid+silica-coating: [Si] =EDX: 15%, XPS: 18%, and [Al] =EDX: 7.4%, XPS: 4% or with silica-coating only [Si] =EDX: 14.5%, XPS: 15% and, [Al] =EDX: 7.8%, XPS: 7%. A very negligible amount of [Si] was found in the control, polished-Ti+acid-etching with one acid and polished-Ti+acid-etching with two acids. No traces of [Al] were found in these specimens. The numerical values obtained from surface-roughness profilometry show greater surface-roughness in the specimens treated with etching (HCl.H3PO4)+silica-coating (Ra=1.22) than those acid-etched with one acid+silica-coating (Ra=0.82), those with only silica-coating (Ra=0.80), only one acid (Ra=0.24) or with acid-etching without silica-coating (Ra=1.03). The surface roughness of the control group was Ra=0.24. SEM and AFM analyses showed greater surface roughness in specimens which were acid-etched (HCl.H3PO4)+silica-coated than any other modification. Conclusions: The combination of surface modification methods, HCl.H3PO4+silica-coating, strongly effects Ti-surface topography and chemistry. Such treated surface might be beneficial for durable resin bonding to titanium crown and bridges.