The effect of nanometric surface texture on bone contact to titanium implants in rabbit tibia Ljupcho Prodanov a,1 , Edwin Lamers a, 1 , Maciej Domanski b , Regina Luttge b , John A. Jansen a, * , X. Frank Walboomers a a Radboud University Nijmegen Medical Centre, Department of Biomaterials, P.O. Box 9101, 6500HB Nijmegen, The Netherlands b Mesoscale Chemical Systems, MESAþ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands article info Article history: Received 14 November 2012 Accepted 4 January 2013 Keywords: Animal experiment Cortical bone Titanium Surface roughness Nano-grooves abstract Designing biomaterial surfaces to control the reaction of the surrounding tissue is still considered to be a primary issue, which needs to be addressed systematically. Although numerous in vitro studies have described different nano-metrically textured substrates capable to influence bone cellular response, in vivo studies validating this phenomenon have not been reported. In this study, nano-grooved silicon stamps were produced by laser interference lithography (LIL) and reactive ion etching (RIE) and were subsequently transferred onto the surface of 5 mm diameter Titanium (Ti) discs by nanoimprint lith- ography (NIL). Patterns with pitches of 1000 nm (500 nm ridge and groove, 150 nm depth), 300 nm (150 nm ridge and groove, 120 nm depth; as well as a 1:3 ratio of 75 nm ridge and 225 nm groove, 120 nm depth) and 150 nm (75 nm ridge and groove, 30 nm depth) were created. These samples were implanted in a rabbit tibia cortical bone. Histological evaluation and histomorphometric measurements were performed, comparing each sample to conventional grit-blasted/acid-etched (GAE) titanium con- trols. Results showed a significantly higher bone-to-implant contact at 4 weeks for the 300 nm (1:3) specimens, compared to GAE (p ¼ 0.006). At 8 weeks, there was overall more bone contact compared to 4 weeks. However, no significant differences between the nano-textured samples and the GAE occurred. Further studies will need to address biomechanical testing and the use of trabecular bone models. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Due to the aging of the population the need of orthopedic and oral bone-anchored implants increases almost exponentially every year [1]. However, the number of revision surgeries also grows [2]. In the last few decades much effort has been placed on optimizing implant lifespan, through methods involving improvement of eg. surface wettability [3], bulk composition [4], and surface top- ography [5,6]. From in vitro and pre-clinical animal studies it is generally accepted that introducing random macro- or micro- roughness on a biomaterial surface positively affects implant integration in the human body [7,8]. Frequently, the combination of grit-blasting and acid-etching (GAE) is used, in which grit-blasting is responsible for creating macro-roughness, while acid-etching is mainly responsible for micro-and nanoroughness [9,10]. Although the mechanism behind the osteophilicity of roughened surfaces is not fully elucidated, an important factor is the initial response towards the implant [11]. Certainly, roughened surfaces give rise to different protein accumulation and subsequent bone cell attachment. Although surface roughness is reported to enhance the bone-to- implant contact, it can be hypothesized that the currently created roughness patterns are not optimal from a biological point-of-view. For example, in terms of protein accumulation, collagen is one of the key-proteins in all living tissues. The collagen molecules reside in a very organized fashion in the bone extracellular matrix (ECM), forming parallel arrays of fibrils with nanometric dimensions and providing structural cues for cell anchorage. Such organization guides cells towards geometrically and structurally functional dif- ferentiated tissues [12,13]. Thus, it could be postulated that mim- icking a similar nanostructure, by applying organized grooves on the surface of biomaterials (Fig. 1), might provide a more “natural surface” and may lead to an improved ECM (re)organization, min- eral deposition on the implant surface and promotion of tissue integration. Already, many in vitro studies have been performed to * Corresponding author. Department of Biomaterials, Radboud University Nijmegen Medical Centre 309 PB, P.O. Box 91, 6500HB Nijmegen, The Netherlands. Tel.: þ31 243614920; fax: þ31 243614657. E-mail address: j.jansen@dent.umcn.nl (J.A. Jansen). 1 These authors contributed equally to this work. Contents lists available at SciVerse ScienceDirect Biomaterials journal homepage: www.elsevier.com/locate/biomaterials 0142-9612/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biomaterials.2013.01.027 Biomaterials 34 (2013) 2920e2927