Effect of fluorides (KF and NaF) on the growth of dicalcium phosphate dihydrate (DCPD) crystal

Dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD also known as brushite) is the major component of hard tissues like bone, teeth and a medicine for calcium supply. The effect of sodium fluoride and potassium fluoride on the crystallization of DCPD in sodium meta silicate gel has been studied at room temperature under the physiological pH (7.4). Addition of fluorides reduces the crystal size and the number of crystals grown when compared to pure system. Among the two fluorides, the KF suppresses the crystal formation more drastically than that of NaF. In both the cases, the ‘Ca’ content in the DCPD crystals was found to be less when compared to its pure form. The crystal morphology, elemental composition and properties of the grown crystals were analyzed using SEM-EDAX, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermal analysis (TG-DSC).