It is generally accepted that titanium is non-toxic material and shows excellent biocompatibility. The high success rate of endosteal titanium dental implants for oral reconstruction has been attributed to the formation of a direct bone-implant interface with no intervening soft tissues. This behavior is due to titanium limiting surface oxide layer. The thickness of the oxide layer and the composition of the layer depend greatly on conditions of manufacture. Consequently, the implant-bone interaction may differ according to the surface characteristics. To achieve improved osseointegration, there have been many efforts to modify the surface composition and topography of dental implants. The purpose of this study was to investigate the surface chemistry and crystal structure of a titanium oxide layer on commercially micro arc oxidized dental implants. The surface chemistry and oxide crystal structure of machined dental implants and two types of commercially oxidized titanium dental implants, Vulcano Actives and TiUnite, manufactured by Conexão Sistemas de Prótese (Brazil) and Nobel Biocare (Sweden), respectively, were analyzed. The implant surfaces were analyzed by scanning electron microscopy (SEM), XPS (X-ray photoelectron spectroscopy), X-ray diffraction and Raman spectroscopy. The outermost layer of the oxidized implants investigated contained anatase titanium oxide and incorporated Ca and P. The machined dental implant surface exhibited an amorphous structure. The machined dental implants without surface treatments and oxidized implant surfaces have different surface characteristics and oxide structures. As both implants showed osseointegration, it is suggested that their surfaces interact differently with cells and vital bone tissue.