Biomaterials 26 (2005) 3009–3019 Osteoconductive modifications of Ti-implants in a goat defect model: characterization of bone growth with SR mCT and histology Ricardo Bernhardt a,Ã , Juliette van den Dolder b , Sussane Bierbaum a , Rene Beutner a , Dieter Scharnweber a , John Jansen b , Felix Beckmann c , Hartmut Worch a a Max-Bergmann-Center of Biomaterials, Dresden, University of Technology, Budapester Str. 27, D-01062 Dresden, Germany b Department of Biomaterials, University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands c GKSS-Research Center, D-21502 Geesthacht, Germany Received 12 May 2004; accepted 26 August 2004 Available online 5 October 2004 Abstract In this work the osteoconductive potential of coatings for titanium implants using different extracellular matrix components was evaluated. Cylindrical implants with two defined cavities A and B were coated with collagen type I, type III, or RGD peptide, and placed in the femur of goats together with an uncoated reference state. Bone contact and volume were determined after 5 and 12 weeks implantation, using both histomorphometry and synchrotron radiation micro computed tomography (SR mCT) as the methods complement each other: SR mCT allows for a high precision of bone detection due to the large number of analysed slices per sample, while histology offers a better lateral resolution and the possibility of additionally determining bone contact. Both methods revealed similar tendencies in bone formation for the differently bio-functionalized implants, with the SR mCT data resulting in significant differences. After 5 and 12 weeks, all three coatings showed a significant increase in bone volume over the uncoated reference, with the highest results for the collagen coatings. The coating consisting of just the RGD-sequence to improve cell adhesion showed only a slight improvement compared with the reference material. For uncoated titanium, RGD, and especially collagen type I, the response in cavity A, situated in denser bone, was stronger than in cavity B. Collagen type III, on the other hand, appeared to be the more effective coating in areas of lesser bone density as represented by cavity B. These results indicate that matrix molecules (or combinations thereof) are capable of generating the appropriate signals for the specific microenvironment around implants and can thus accelerate the bone formation process and increase the stability of implants. r 2004 Elsevier Ltd. All rights reserved. Keywords: Titanium; Collagen type I; Collagen type III; RGD peptide; Osseointegration; Histomorphometry; Synchrotron radiation; Micro computed tomography 1. Introduction The integration of titanium implants into host bone is already comparatively good, based on periimplant bone formation and the occurrence of direct bone anchorage. However, due to the ageing of our population, there is an increasing group of patients with challenging general health and bone conditions where implants are more prone to failure. Therefore, there is need for simple methods that improve the periimplant bone formation and the short- and long-term implant stability in applications like dental implants and orthopaedic prostheses. As the interaction of cells with the implant surface determines periimplant bone regeneration to a large part, the preparation of biomaterials with advantageous ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$-see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2004.08.030 Ã Corresponding author. E-mail address: ric_bern@web.de (R. Bernhardt).