Low temperature solidification of calcium carbonate through vaterite-calcite wet transformation

Mechanical improvement of calcium carbonate cements by in situ HEMA polymerization during hardening

The brittleness of calcium carbonate-based cements, which currently impedes their exploitation, can be overcome by a straightforward polymer-reinforcement strategy.

Preparation of Hydroxyapatite Ceramics by Hydrothermal Hot-Pressing Technique

The hydrothermal hot-pressing (HHP) technique was used to prepare hydroxyapatite (HAp) ceramics from a HAp powder with low crystallinity, and the effects of processing factors such as temperature, loading pressure and reaction time on densification were investigated. The crystallinity of HAp was increased by the HHP treatments. With the increase in reaction temperature, loading pressure and reaction time, the density and Vickers hardness of the compacts increased. The HAp compact with high relative density of 83% and high Vickers hardness of 2.9 GPa was successfully prepared by the HHP treatment at 200°C for 3 h under loading pressure of 60 MPa.

Preparation, physical–chemical characterisation and cytocompatibility of calcium carbonate cements

The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composition was obtained by mixing amorphous calcium carbonate and vaterite with an aqueous medium. The cement set and hardened within 2h at 37 degrees C in an atmosphere saturated with water and the final composition of the cement consisted mostly of aragonite. The hardened cement was microporous and showed poor mechanical properties. Cytotoxicity tests revealed excellent cytocompatibility of calcium carbonate cement compositions. Calcium carbonates with a higher solubility than the apatite formed for most of the marketed calcium phosphate cements might be of interest to increase biomedical cement resorption rates and to favour its replacement by bone tissue.

New Calcium Carbonate-Based Cements for Bone Reconstruction

The feasibility of calcium carbonate-based cements involving the re-crystallization of metastable calcium carbonate varieties has been demonstrated. Two cement compositions were obtained by mixing either calcium carbonate phases (cement A) or a calcium carbonate and a calcium phosphate phase (cement B) with an aqueous media. These cements set and hardened after 30 minutes and 90 minutes respectively. The final composition of cement A was calcite and aragonite whereas cement B lead to a carbonated apatite analogous to bone mineral. Despite poor mechanical properties the presence of a high carbonate content in the final phase might be of interest to increase the cement resorption rate and to favour its replacement by bone tissue. First assays of implantation performed on fresh anatomical pieces (fresh cadavers) at 37°C revealed important advantages of such cement compositions: easiness of use, rapid setting, good adhesion to bone, very good homogeneity and stability of the cement.