On the importance of crystallographic texture in the biocompatibility of titanium based substrate Majid Hoseini, 1 Philippe Bocher, 1 Arash Shahryari, 2 Fereshteh Azari, 3 Jerzy A. Szpunar, 4 Hojatollah Vali 3,5 1  Ecole de Technologie Sup erieure, Montr eal, Quebec, Canada 2 R&D Department, TSO 3 Inc., 2505 Dalton Ave., Quebec, Canada 3 Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada 4 Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada 5 Facility of Electron Microscopy Research, McGill University, Montreal, Quebec, Canada Received 6 September 2013; revised 22 October 2013; accepted 31 October 2013 Published online 20 November 2013 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.a.35028 Abstract: The role of grain size and crystallographic orienta- tion on the biocompatibility of commercially pure titanium was investigated. Samples, with significant differences in crystallographic texture and average grain size (from 0.4 to 40 mm) were produced by equal channel angular pressing (ECAP) and post deformation annealing. X-ray diffraction and electron back scattered diffraction (EBSD) were used to evalu- ate differences in texture and microstructural characteristics. The titanium oxide film present on the surface of the samples was analyzed to determine the oxidation state of titanium and the chemical bonds between oxygen and titanium using X-ray photoelectron spectroscopy (XPS). Biocompatibility experiments were conducted using MC3T3 preosteoblast cells. Cell attachment was found to be texture-sensitive, where the number of attached cells was higher on the sam- ples with higher number of (0002) planes exposed to the sur- face, regardless of the grain size. A relationship was also found between the titanium oxide species formed on the sur- face and the crystallographic texture underneath. The surface texture consisting of more densely packed basal planes pro- mote the formation of Ti-OH on the surface, which in turn, enhances the cell-substrate interactions. These surface char- acteristics are deemed responsible for the observed differ- ence in cell attachment behaviour of surfaces with different textures. Finally, it is inferred that texture, rather than the grain size, plays the major role in controlling the surface bio- compatibility of biomedical devices fabricated from pure metallic titanium. V C 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3631–3638, 2014. Key Words: commercially pure titanium, ECAP, biocompati- bility, crystallographic texture, grain size How to cite this article: Hoseini M, Bocher P, Shahryari A, Azari F, Szpunar JA, Vali H. 2014. On the importance of crystallo- graphic texture in the biocompatibility of titanium based substrate. J Biomed Mater Res Part A 2014:102A:3631–3638. INTRODUCTION Metallic materials, such as titanium and its alloys, are widely used for the fabrication of medical implants. 1 In the past decade, nanograined and ultra-fine grained (UFG) tita- nium produced by one of the severe plastic deformation (SPD) techniques have attracted a great deal of attention. 1–4 In these studies, it has been claimed that the submicron grained structures fabricated by SPD not only result in improved mechanical properties but also offer a higher level of biocompatibility 1,5–8 and the corrosion properties 9 of commercially available pure titanium (CP-Ti). Ultra-fine grained titanium samples have been mainly produced by two SPD techniques: (i) equal channel angular pressing (ECAP) and (ii) high pressure torsion (HPT). 4 In both proc- esses, a remarkable grain refinement is achieved as a result of applying large plastic shear deformation without chang- ing the sample dimensions. While HPT has been, so far, more efficient in refining the grain size of small disc shaped samples (0.3 mm thickness), ECAP has been capable of pro- ducing UFG structures in large bulk samples. 4 It has been shown that grain sizes, as small as 0.3 mm, could be obtained in CP-Ti by applying 8 consecutive passes of ECAP. 2,3 The effect of grain size refinement by SPD techniques on biocompatibility of titanium have been studied by many researchers. 1,5–8 Faghihi et al. 6,7 reported a significant improvement in the attachment and growth rate of preos- teoblast cells on the surface of UFG pure titanium fabricated by HPT. The potential application of ECAP-processed pure titanium as medical implants has been proposed by Valiev et al., 1 who has shown that the fibroblast cell adhesion to the surface of ECAP-processed titanium is stronger and more frequent as compared with the untreated titanium substrate. An accelerated preosteoblast cell proliferation on the surface of ECAP-processed titanium has also been reported by Estrin et al. 5 An improved absorption of Correspondence to: M. Hoseini; e-mail: hoseini.ma@gmail.com V C 2013 WILEY PERIODICALS, INC. 3631