Quantitative assessment of surface roughness as measured by AFM: application to polished human dentin

Atomic force microscopy (AFM) has been used to investigate the surface morp hology of polished dentin. In the studies of chemical conditioning (acid et ching, bleaching), the morphology of polished dentin is of great importance and offers a controlled reference point for the correct and unambiguous as sessment of morphological effects induced by subsequent chemical treatments . The characterization of polished dentin is required so as to permit relia ble and normalized comparisons of various chemical modifications of dentin. AFM topographic data, over a fixed area of 1 mum x 1 mum, have been quantit atively analyzed and compared, using standard roughness descriptors such as the root mean square (RMS) of the surface height deviations. In addition, for a more general and complete description of surface roughness, Fourier t ransform analysis has been used to determine characteristic parameter value s that fully describe the surface roughness in both vertical and lateral di rections, independent of the feature size bandwidth considered. As a result , a confident spectral analysis interval has been assigned which ranges ove r the specific length scales of fibrous dentin structure. To understand how surface-polishing affect dentin roughness, and to evaluate its spatial ext ent of influence, AFM experiments were carried out on aluminum test surface s which were prepared and imaged under the same conditions as the dentin sa mples. (C) 2001 Elsevier Science B.V. All rights reserved.