Silicon, calcium and phosphate effect on human dental pulp cell cultures

Abstract

This study was designed to investigate the odontogenic effects of Silicon, Calcium and Phosphorous on human dental pulp cells (hDPCs). hDPCs derived from extracted pristine teeth were cultured in growth media with supplements of Si 25ppm, Si 25ppm+Ca 8.3ppm, Si 25ppm+Ca 8.3ppm+P 4.16ppm, Si 50ppm, Si 50ppm+Ca 16.7ppm, Si 50ppm+Ca 16.7ppm+P 8.3ppm and media without additional supplement as control, for the time intervals of 16 hours, 7, 12, and 21 days. Also, HDPCs were cultured in growth media with supplements of inorganic phosphate (Pi) in 0 ppm, 2 ppm, 4 ppm, 5 ppm, 8 ppm, for the time intervals of 16 hours, 7, 14, and 21 days. Cell proliferation rates were measured by the optical density of crystal violet dye stained cells. ALP activity was measured by fluorometric assay. Expression of Dentin Sialoprotein (DSP) was measured by ELISA. Mineralization of cultures was measured by Alizarin Red staining. Culture with 50ppm supplemental Si at day 21 yield significantly higher levels of ALP activity, DSP expression and mineralization (P<0.05) compared to the control group and other supplemented groups. Cultures with 2, 4, 5 and 8 ppm supplemental Pi yield significantly higher levels of ALP activity (P<0.05) compared to the control group at day 7. Cultures with 5 ppm Pi supplement showed significantly higher levels of DSP expression (P<0.05) compared to the control group and the other groups at day 7. Cultures with Si 25ppm+Ca 8.3ppm supplemental and Si 50ppm+Ca 16.7ppm supplemental displayed significantly higher cell proliferation rates compared to the control group at day 12 and at day 21 (P<0.05). Cultures with 2, 4 and 5 ppm supplemental Pi displayed significantly higher cell proliferation rates compared to the control group at day14 (P<0.05) and at day 21 (P<0.05). Supplemental silicon in concentration of 50 ppm could significantly induce differentiation and mineralization of normal human dental pulp cells. Calcium has a synergetic effect in up-regulating the proliferation rates. Supplemental Pi in concentration of 5 ppm could significantly induce proliferation and odontogenesis of hDPCs. This is the first report to demonstrate Si, Ca and P induced odontogenesis of hDPCs cultures.