d e n t a l m a t e r i a l s 2 7 ( 2 0 1 1 ) e205–e212 av ailab l e at www.sciencedirect.com jo u rn al hom epa ge : www.intl.elsevierhealth.com/journals/dema Zirconia–hydroxyapatite composite material with micro porous structure Takuya Junior Matsumoto a , Sang-Hyun An a , Takuya Ishimoto b , Takayoshi Nakano b , Takuya Matsumoto a,∗ , Satoshi Imazato a a Department of Biomaterials Science, Osaka University, 1-8 Yamada-oka, Suita 565-0871, Japan b Division of Materials and Manufacturing Science, Osaka University, Suita 565-0871, Japan a r t i c l e i n f o Article history: Received 10 November 2010 Received in revised form 17 May 2011 Accepted 13 July 2011 Keywords: Zirconia Hydroxyapatite Composite material Bone tissue reconstruction a b s t r a c t Objectives. Titanium plates and apatite blocks are commonly used for restoring large osseous defects in dental and orthopedic surgery. However, several cases of allergies against tita- nium have been recently reported. Also, sintered apatite block does not possess sufficient mechanical strength. In this study, we attempted to fabricate a composite material that has mechanical properties similar to biocortical bone and high bioaffinity by compounding hydroxyapatite (HAp) with the base material zirconia (ZrO 2 ), which possesses high mechan- ical properties and low toxicity toward living organisms. Methods. After mixing the raw material powders at several different ZrO 2 /HAp mixing ratios, the material was compressed in a metal mold (8 mm in diameter) at 5 MPa. Subsequently, it was sintered for 5 h at 1500 ◦ C to obtain the ZrO 2 /HAp composite. The mechanical prop- erty and biocompatibility of materials were investigated. Furthermore, osteoconductivity of materials was investigated by animal studies. Results. A composite material with a minute porous structure was successfully created using ZrO 2 /HAp powders, having different particle sizes, as the starting material. The material also showed high protein adsorption and a favorable cellular affinity. When the mixing ratio was ZrO 2 /HAp = 70/30, the strength was equal to cortical bone. Furthermore, in vivo experiments confirmed its high osteoconductivity. Significance. The composite material had strength similar to biocortical bones with high cell and tissue affinities by compounding ZrO 2 and HAp. The ZrO 2 /HAp composite material having micro porous structure would be a promising bone restorative material. © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. 1. Introduction Bone tissue is an important locomotive tissue that supports the living body. Furthermore, it possesses diverse functions such as protection of important organs like brain, heart, and lungs [1,2]. Bone tissue is greatly involved in the retention ∗ Corresponding author. Tel.: +81 6 6879 2919. E-mail address: tmatsu@dent.osaka-u.ac.jp (T. Matsumoto). of teeth, mastication, and face structure particularly in the maxillofacial region, and is an important tissue in terms of QOL. There are various causes of osseous defects and reduc- tion in bone volume, such as absorption of the alveolar bone due to a loss of teeth or periodontal diseases as well as tumors and injuries [3,4]. In general, the bone defect size is an important factor when deciding the treatment direction. For 0109-5641/$ – see front matter © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2011.07.009