2019 年 127 巻 9 号 p. 595-601
Bone is not composed of hydroxyapatite (HAp), but of carbonate apatite (CO3Ap). Although the decomposition of CO3Ap begins at around 400°C, and thus, the fabrication of CO3Ap blocks by sintering is difficult, CO3Ap blocks have recently been fabricated via a dissolution–precipitation reaction in Na2HPO4 solution using a CaCO3 block as a precursor. Compared to sintered HAp, which is not resorbed by osteoclasts, CO3Ap is resorbed by osteoclasts. Furthermore, CO3Ap upregulates the differentiation of osteoblasts. Therefore, CO3Ap can be used as a replacement for bones with regards to the so-called bone remodeling process. Clinical trials have confirmed the safety and usefulness of CO3Ap granules, including the replacement of CO3Ap granules to new bone. In Dec 2017, CO3Ap was approved as an artificial bone substitute by the Pharmaceuticals and Medical Devices Agency. CO3Ap granules can be used for all dental and maxillofacial surgeries, including the bone reconstruction aimed for dental implantation.
