**6. Conclusions**

Brushite crystals consist of platy and needle-like crystals. It is found that the pH of the solution during the precipitation of brushite plays the main role in determining the shape of the crystals. Usually at a relatively low pH, around 5, platy crystals are formed, while at a higher pH, around ph = 6.5, needle-like crystals are precipitated. In this study, brushite crystals with a monoclinic structure were synthesized using calcium and phosphate salts. The brushite crystal growth occurs mainly along the (020) crystallographic plane. Brushite crystal is characterized by the presence of two structural water molecules. These two molecules are released at a temperature range between 80°C and 220°C to form monetite minerals.

In this chapter, brushite is used as a precursor to synthesize TTCP, the powder components of CPC. As a result of the solid reactions between brushite and calcium carbonate, at high temperature, 1500°C, a new CaP phase is called TTCP. This powder reacts with the phosphate-based solution at 37°C to form CDHA. Immersing this CPC in Hanks' Balanced Salt Solution results in the growth of nanofibrous crystals of CDHA layers on the surfaces of the CPC. The cultured CPC exhibits new connective tissues and throughout the CaP matrix. The CPC matrix contains bioactive CDH with both Ca and P, therefore this matrix provides an appropriate environment for MSCs growth and osteogenic differentiation.

Bioactive features of brushite-based materials affect cell adhesion, proliferation, and new bone formation. Bioactivity can be altered and controlled by the crystal structure and physical property of the scaffold. Bioactive characteristics are different depending on the produced type of CaP phases such as HAP, TCP, and ACP. These different bioactive characteristics are caused by the differences in Ca/P ratio, crystal structure, stability, and solubility. As mentioned above, brushite is often used with other CaP to control and improve their chemical, biological, and physical properties. Various applications have been exploited to actively utilize the bioactive features of brushite in bone regeneration.

*Brushite: Synthesis, Properties, and Biomedical Applications DOI: http://dx.doi.org/10.5772/intechopen.102007*
