Wavelength-dependent roughness: A quantitative approach to characterizing the topography of rough titanium surfaces

Topographies of grit-blasted, etched, grit-blasted and etched, and microfab ricated and etched surfaces of commercially pure titanium have been investi gated. Such surface topographies vary across the scale range of interest fo r dental implants, extending from nanometers to millimeters. The complete c haracterization of topography requires the use of complementary methods. Th is study compared the topographic characterization methods of non-contact l aser profilometry, interference microscopy, stereo-scanning electron micros copy (stereo-SEM), and atomic force microscopy. Non-contact laser profilome try was shown to be a useful method to characterize topographic features in the micron to millimeter range, whereas interference microscopy and stereo -SEM can be employed down to the submicron range. Stereo-SEM is particularl y useful for quantifying topographies with complex, strongly corrugated ("s harp"), and high-aspect-ratio features and was shown to be complementary to non-contact laser profilometry and interference microscopy. Because of tip -related envelope problems, atomic force microscopy was not found to be sui table for the type of surfaces investigated in this study. Independent of t he method used, the commonly used "integral" amplitude roughness parameters , such as R-a, R-q, or R-t, were often of limited value in the description of actual implant surfaces. The application of the wavelength-dependent rou ghness approach was shown to be an effective method for the description of surface topographies in the complete range of characteristic roughness and is also a useful means of examining the effects of surface treatment proces ses.