Possible Role of Microcrystallinity on Surface Properties of Titanium Surfaces for Biomedical Application

Dental implantology has grown tremendously, since the introduction of titanium. To enhance osseointegration, roughening techniques such as grit blasting, chemical etch, electrochemical anodization have been used with good results. An oxide layer mainly composed of TiO2 covers the surface of dental implants ensuring excellent corrosion resistance and chemical stability. Despite its biological role in achieving bone interlock, surprisingly, little is known about the structure of TiO2, which may be either amorphous or crystalline. Furthermore, at least two crystalline polymorph phases can be found at the bone-implant interface: anatase (tetragonal) and rutile (tetragonal). Therefore, besides the recognized importance of surface topography, energy, and charge, a more refined knowledge of surface chemistry is advisable when studying the bone-implant interface. Recently, sophisticated analysis techniques have been applied to dental implants such as Raman spectroscopy and X-ray diffraction to obtain structural-crystallographic characterization. This book chapter reviews the scientific literature with the scope of assessing what is known about the surface micro-/nanotopography and the crystallographic microstructure of titanium dental implants. Also, the correlation between these surface features and the biological outcomes in vitro and in vivo is a primary object of the manuscript. An electronic search was made in the databases of MEDLINE (through MeSH) and SCOPUS, extended to September 30th 2015, with no linguistic restrictions. Based on the results of the most recent studies, the surface of titanium dental implants may be constituted of anatase, rutile, and amorphous phases. Anatase seems more present in arc-oxidized implants, alone or with rutile, according to the oxidation conditions (voltage, electrolyte etc.). Rutile and amorphous phases are more frequently found in machined, double-etched, sandblasted, sandblasted acid-etched implants. Particular interest is raised by the possible presence of brookite, which was found on a commercially available sandblasted acid-etched implant. Taking into consideration the variations in the biological activity of these polymorphs, identification of the TiO2 phases found in the surface layers of implants should be regarded as fundamental not only by researchers but also by manufacturers.