Comparison of periodontal ligament cells responses to dense/ nanophase hydroxyapatite

Objectives: To investigate possible effects of nanophase powder of hydroxyapatite(nano-HA) on proliferation of periodontal ligament cells and compare with dense hydroxyapatite(dense-HA). Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved nanoparticles by scanning electron microscopy; transmission electron microscopy and energy disperse X-ray analyzer. The primary periodontal ligament cells were cultured with nanometer particle hydroxyapatite powder and dense particle hydroxyapatite(supplied by Long Ma chemical co Ltd of Xinjin, Chengdu, China). The effects on proliferation of periodontal ligament cell were examined in vitro with MTT(methyl thiazolil tetracolium) method. The intercellular effects were observed with scanning electron microscopy, transmission electron microscopy and energy disperse X-ray analyzer. In addition, the influence of two materials on osteoblast differentiation was determined by measurement of alkaline phosphatase activity and flow cytometry. Results: In 2,3,4 days after treated with nanoparticles of hydroxyapatite, the proliferating activity of the PDLC increased significantly, comparing with those with dense hydroxyaoatite and control but no significant difference was found between the dence hydroxyapatite and the control. The incubation for 5 days with nano-HA demonstrated significantly higher ALP activity (26.25±3.247) than that of the dense-HA(16.32±3.224)and the control (14.22±3.411). And in 8th day, result showed the values in nano-HA(28.67±4.208) was higher than those in dense-HA group(19.35±3.247) and the control(16.67±5.508). In FCM, distribution of ALP positive cells cultured with nanoparticles were significantly larger than other groups on day 5 and day 8. At the same time, intercellular engulf were found in the cultured cells with nanophase hydroxyapatite by electron microscopy. Conclusions: It shows that nanophase hydroxyapatite can promote proliferation and osteoblastic differentiation of periodontal ligament cells and it maybe become bioresorbable agent in bone restoration.