Biomaterials 29 (2008) 944–953 Osteoconduction and osteoinduction of low-temperature 3D printed bioceramic implants Pamela Habibovic a,b,Ã,1 , Uwe Gbureck c,1 , Charles J. Doillon d,e , David C. Bassett a , Clemens A. van Blitterswijk b , Jake E. Barralet a a Faculty of Dentistry, McGill University, Strathcona Anatomy and Dentistry Building, 3640 University Street, Montre´al, Que´bec, Canada H3A 2B2 b Department of Tissue Regeneration, Institute for Biomedical Technology, University of Twente, Zuidhorst Building, Drienerlolaan 5, 7522 NB Enschede, The Netherlands c Abteilung fu ¨ r Funktionswerkstoffe, ZMK-Klinik, Pleicherwall 2, 97070 Wu ¨ rzburg, Germany d Department of Surgery, Universite´Laval, Que´bec, Canada G1V 4G2 e Oncology and Molecular Endocrinology Research Centre, CHUL Research Centre, CHUQ, 2705 Boulevard Laurier, Que´bec City, Que´bec, Canada G1V 4G2 Received 24 July 2007; accepted 17 October 2007 Available online 4 December 2007 Abstract Rapid prototyping is a valuable implant production tool that enables the investigation of individual geometric parameters, such as shape, porosity, pore size and permeability, on the biological performance of synthetic bone graft substitutes. In the present study, we have employed low-temperature direct 3D printing to produce brushite and monetite implants with different geometries. Blocks predominantly consisting of brushite with channels either open or closed to the exterior were implanted on the decorticated lumbar transverse processes of goats for 12 weeks. In addition, similar blocks with closed channel geometry, consisting of either brushite or monetite were implanted intramuscularly. The design of the channels allowed investigation of the effect of macropore geometry (open and closed pores) and osteoinduction on bone formation orthotopically. Intramuscular implantation resulted in bone formation within the channels of both monetite and brushite, indicating osteoinductivity of these resorbable materials. Inside the blocks mounted on the transverse processes, initial channel shape did not seem to significantly influence the final amount of formed bone and osteoinduction was suggested to contribute to bone formation. r 2007 Elsevier Ltd. All rights reserved. Keywords: Calcium phosphate cement; Three dimensional printing; Osteoconduction; Osteoinduction; In vivo test 1. Introduction In the search for a synthetic biomaterial that is able to successfully replace autografting, the ‘‘gold-standard’’ in orthopaedic and cranio-facial surgery, a range of materials have been developed in the past four decades. Motives influencing the design of synthetic bone graft substi- tutes are often based upon mimicking one or more properties of natural bone, since this is the intended tissue to be repaired or augmented. Various types of calcium- phosphate biomaterials, which resemble either the compo- sition of bone mineral or its precursors have been developed, such as hydroxyapatite-, a- and b-tricalcium phosphate, octacalcium phosphate and dicalcium phos- phate in the form of ceramics, cements and thin coatings [1]. Many relatively insoluble calcium-phosphate materials are osteoconductive, and in some cases, even able to induce new bone formation in extraskeletal sites, i.e. are osteoin- ductive [2–5]. In the case of large or dense bone graft substitutes, biodegradation is important for allowing simultaneous replacement of the material with new bone. This process ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2007.10.023 Ã Corresponding author. Department of Tissue Regeneration, Institute for Biomedical Technology, University of Twente, Zuidhorst Building, Drienerlolaan 5, 7522 NB Enschede, The Netherlands. Tel.: +31 53 489 3400; fax: +31 53 489 2150. E-mail address: p.habibovic@tnw.utwente.nl (P. Habibovic). 1 Equal contributions.