Carbonate apatite artificial bone.

Bone apatite is not hydroxyapatite (HAp), it is carbonate apatite (CO ₃ Ap), which contains 6-9 mass% carbonate in an apatitic structure. The CO ₃ Ap block cannot be fabricated by sintering because of its thermal decomposition at the sintering temperature. Chemically pure (100%) CO ₃ Ap artificial bone was recently fabricated through a dissolution-precipitation reaction in an aqueous solution using a precursor, such as a calcium carbonate block. In this paper, methods of fabricating CO ₃ Ap artificial bone are reviewed along with their clinical and animal results. CO ₃ Ap artificial bone is resorbed by osteoclasts and upregulates the differentiation of osteoblasts. As a result, CO ₃ Ap demonstrates much higher osteoconductivity than HAp and is replaced by new bone via bone remodeling. Granular-type CO ₃ Ap artificial bone was approved for clinical use in Japan in 2017. Honeycomb-type CO ₃ Ap artificial bone is fabricated using an extruder and a CaCO ₃ honeycomb block as a precursor. Honeycomb CO ₃ Ap artificial bone allows vertical bone augmentation. A CO ₃ Ap-coated titanium plate has also been fabricated using a CaCO ₃ -coated titanium plate as a precursor. The adhesive strength is as high as 76.8 MPa, with excellent tissue response and high osteoconductivity.
Competing Interests: No potential conflict of interest was reported by the author(s).
(© 2021 The Author(s). Published by National Institute for Materials Science in partnership with Taylor & Francis Group.)