Fabrication of B-type carbonate apatite blocks by the phosphorization of free-molding gypsum-calcite composite

Abstract

B-type carbonate apatite (CO3Ap) block may be an ideal artificial bone substitute because it is closer in chemical composition to bone mineral. In the present study, the feasibility to fabricate CO3Ap blocks was investigated using compositional transformation, which was based on the dissolution-precipitation reaction of a gypsum-calcite composite with freemolding behavior. For the compositional change, or phosphorization, gypsum-calcite composites of varying CaCO3 contents were immersed in 1 mol/L (NH4)3PO4 aqueous solution at 100°C for 24 hours. No macroscopic changes were found after the treatment, whereas microscopic change was observed at SEM level. X-ray diffraction, Fourier transform infrared spectroscopy and CHN analysis indicated that the composites were B-type CO3Ap containing approximately 6 -7 wt％ of CO3, a value similar to that of biological bone apatite. Diametral tensile strength of the CO3Ap block was approximately 1-3 MPa. Based on the results obtained, it was therefore concluded that gypsum-calcite was a good candidate for the fabrication of CO3Ap blocks, coupled with the advantage that the composite can be molded to any shape by virtue of the setting property of gypsum.

Fabrication of carbonate apatite block based on internal dissolution-precipitation reaction of dicalcium phosphate and calcium carbonate

“…On the other hand, there was a lack of formability, because the shape of CO3Ap block was dependent on the precursor prepared by powder compacting device. In order to improve the formability, Zaman et al have reported that calcite block, which includes gypsum as bonding material, could be applied as precursor 13) . With this method, since the precursor block can be formed by gypsum setting and not by pressing, various shapes could be obtained using molds with various shapes for precursor setting.…”

Fabrication of carbonate apatite blocks from set gypsum based on dissolutionprecipitation reaction in phosphate-carbonate mixed solution

“…However, the solubility of calcite is lower when compared with that of gypsum. Therefore, some calcite remained unreacted when a mixture of gypsum and calcite was used as a precursor 8) . In contrast, pure set gypsum with the same composition was used as a precursor in this study.…”

“…It also should have low solubility in the solution to allow a balanced dissolution and precipitation process. To date, calcite (CaCO 3) , α-tricalcium phosphate, a mixture of gypsum and calcite were proposed as precursors [7][8][9][10] . Among the array of precursors, gypsum is unique because it has self-setting ability, which allows it to be molded and shaped to how we would like it to be at room temperature.…”

“…To fabricate CO 3Ap blocks using gypsum, a carbonate source must be added to the system. For example, set gypsum containing calcite was used as a precursor and then treated in phosphate salt solution 8) . Set gypsum containing calcite was simply prepared by adding calcite to gypsum slurry.…”

Evaluation of Powder Property of Calucium Phosphate

“…These calcium phosphate compounds are classified in this paper as that the materials of HAP are 'HAP series', those of -TCP, -TCP and TTCP are 'other calcium phosphate series'. HAP, -TCP, -TCP and TTCP made by our technology were utilized as reagents and raw materials for commercial products [4][5][6][7][8] .…”