Rat calvarial osteoblasts were treated with lanthanum chloride(LaCl_3) to explore its effect on the mineral crystalline phase during the process of osteoblast calcification in uitro.The results confirmed that La was readily deposited in the mineral component of the matrix.Employing high-resolution transmission electron microscopy and Fourier transform infrared microspectroscopy techniques,we demonstrated that features comparable to dicalcium phosphate dihydrate(DCPD) and octacalcium phosphate,and hydroxyapatite(HAP) were detected in the mineral phases in uitro.Particularly,LaCl_3 treatment retarded conversion from DCPD-like phase into HAP during mineralization.In addition,La was introduced in DCPD powder during wet chemical synthesis.When compared with that of La-free DCPD,the dissolution rate of La-incorporated DCPD was lower,thereby leading to a delayed DCPD-to-HAP phase transformation.Thus,it can be concluded that LaCl_3 treatment influences the kinetics of inorganic phase transition by decreasing the dissolution rate of DCPD. Rat calvarial osteoblasts were treated with lanthanum chloride (LaCl_3) to explore its effect on the mineral crystalline phase during the process of osteoblast calcification in uitro. The results confirmed that La was readily deposited in the mineral component of the matrix. Efficient fittings of high-resolution transmission electron microscopy and Fourier transform infrared microspectroscopy techniques, we demonstrated that features comparable to dicalcium phosphate dihydrate (DCPD) and octacalcium phosphate, and hydroxyapatite (HAP) were detected in the mineral phases in uitro. Particularly, LaCl 3 treatment retarded conversion from DCPD-like phase into HAP during mineralization. In addition, La was introduced in DCPD powder during wet chemical synthesis. Chen compared with that of La-free DCPD, the dissolution rate of La-incorporated DCPD was lower, leading to a delayed DCPD-to-HAP phase transformation.Thus, it can be bound that LaCl_3 treatment influences the kinetics of inorganic phase transitio n by decreasing the dissolution rate of DCPD.