Surface Characteristics of Electrochemically Oxidized Implants and Acid-Etched Implants: Surface Chemistry, Morphology, Pore Configurations, Oxide Thickness, Crystal Structure, and Roughness

Purpose: This study was undertaken to investigate surface properties of surface-modified titanium implants in terms of surface chemistry, morphology, pore characteristics, oxide thickness, crystal structure, and roughness. Materials and Methods: An oxidized, custom-made Mg implant, an oxidized commercially available implant (TiUnite), and a dual acid-etched surface (Osseotite) were investigated. Surface characteristics were evaluated with various surface analytic techniques. Results: Surface chemistry showed similar fingerprints of titanium oxide and carbon contaminant in common for all implants but also revealed essential differences of the elements such as about 9 at% Mg for the Mg implant, about 11 at% P for the TiUnite implant and about 12 at% Na for the Osseotite implant. Surface morphology of the Mg and TiUnite implants demonstrated a duplex oxide structure, ie, an inner barrier layer without pores and an outer porous layer with numerous pores, whereas the Osseotite implant revealed a crystallographically etched appearance with pits. The diameter and depth of pores/pits was = 2 µm and = 1.5 µm in the Mg implant, = 4 µm and = 10 µm in the TiUnite implant, and = 2 µm and = 1 µm in the Osseotite implant, respectively. Oxide layer revealed homogeneous thickness, about 3.4 µm of all threads in the Mg implants. On the contrary, TiUnite showed heterogeneous oxide thickness, about 1 to 11 µm, which gradually increased with thread numbers. Crystal structure showed a mixture of anatase and rutile phase for the Mg implants. With respect to roughness, Sa showed 0.69 µm in the Mg implant, 1.35 µm in the TiUnite implant, and 0.72 µm in the Osseotite implant. Conclusions: Well-defined surface characterization may provide a scientific basis for a better understanding of the effects of the implant surface on the biological response. The surface-engineered implants resulted in various surface characteristics, as a result of different manufacturing techniques. Keywords: acid-etched surface, characterization of surface properties, oxidized Mg-incorporated surface, titanium implant