title: Assessing the hierarchical structure of titanium implant surfaces.
abstract: The physical texture of implant surfaces are known to be one important factor in creating a stable bone-implant interface. Simple roughness parameters (for e.g., Sa or Sz) are not entirely adequate when characterizing surfaces possessing hierarchical structure (macro, micro, and nano scales). The aim of this study was to develop an analytical approach to quantify hierarchical surface structure of implant surfaces possessing nearly identical simple roughness. Titanium alloys with macro/micro texture (MM) and macro/micro/nano texture (MMN) were chosen as model surfaces to be evaluated. There was no statistical difference (p > 0.05) in either Sa (13.56 vs. 13.43 µm) or Sz (91.74 vs. 92.39 µm) for the MM and MMN surfaces, respectively. However, when advanced filtering algorithms were applied to these datasets, a statistical difference in roughness was found between MM (Sa = 0.54 µm) and MMN (Sa = 1.06 µm; p < 0.05). Additionally, a method was developed to specifically quantify the density of surface features appearing similar in geometry to natural osteoclastic pits. This analysis revealed a significantly greater numbers of these features (i.e., valleys) on the MMN surface as compared to the MM surface. Finally, atomic force microscopy showed a rougher nano-texture on the MMN surface compared with the MM surface (p < 0.05). The results support recent published studies that show a combination of appropriate micron and nano surface results in a more robust cellular response and increased osteoblast differentiation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1083-1090, 2016.
authors.affiliation: Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania, 16802.
authors.forename: Jesse L
authors.initials: JL
authors.lastname: Matteson
authors.affiliation: Spinode Consulting, St. Augustine, Florida, 32086.
authors.forename: David C
authors.initials: DC
authors.lastname: Greenspan
authors.affiliation: Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania, 16802.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Tighe
authors.affiliation: Zygo Corporation, Middlefield, Connecticut, 06455.
authors.forename: Nathan
authors.initials: N
authors.lastname: Gilfoy
authors.affiliation: Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania, 16802.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Stapleton
mesh_terms: D000497:Alloys / Q000737:chemistry*; D000818:Animals; D002454:Cell Differentiation; D006801:Humans; D020007:Implants, Experimental; D010006:Osteoblasts; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D014025:Titanium
keywords: interface; profilometry; roughness; surface analysis; titanium