Characteristics of the surface oxides on turned and electrochemically oxidized pure titanium implants up to dielectric breakdown: the oxide thickness, micropore configurations, surface roughness, crystal structure and chemical composition

Titanium implants have been used widely and successfully for various types of bone-anchored reconstructions. It is believed that properties of oxide f ilms covering titanium implant surfaces are of crucial importance for a suc cessful osseointegration, in particular at compromized bone sites. The aim of the present study is to investigate the surface properties of anodic oxi des formed on commercially pure (c.p.) titanium screw implants as well as t o study 'native' oxides on turned c.p. titanium implants. Anodic oxides wer e prepared by galvanostatic mode in CH3COOH up to the high forming voltage of dielectric breakdown and spark formation. The oxide thicknesses, measure d with Auger electron spectroscopy (AES), were in the range of about 200 - 1000 nm. Barrier and porous structures dominated the surface morphology of the anodic film. Quantitative morphometric analyses of the micropore struct ures were performed using an image analysis system on scanning electron mic roscopy (SEM) negatives. The pore sizes were less than or equal to 8 mum in diameter and had 1.27-2.1 mum(2) opening area. The porosity was in the ran ge of 12.7-24.4%. The surface roughness was in the range of 0.96-1.03 mum ( S-a), measured with TopScan 3D((R)). The crystal structures of the titanium oxide were amorphous, anatase, and a mixtures of anatase and rutile type, as analyzed with thin-film X-ray diffractometry (TF-XRD) and Raman spectros copy. The chemical compositions consisted mainly of TiO2, characterized wit h X-ray photoelectron spectroscopy (XPS). The native (thermal) oxide on tur ned implants was 17.4 run (+/-6.2) thick and amorphous. Its chemical compos ition was TiO2. The surface roughness had an average height deviation of 0. 83 mum (S-a). The present results are needed to elucidate the influence of the oxide properties on the biological reaction. The results of animal stud ies using the presently characterized surface oxides on titanium implants w ill be published separately. (C) 2001 Elsevier Science Ltd. All rights rese rved.