Calcium and silicon from bioactive glass concerned with formation of nodules in periodontal-ligament fibroblasts in vitro

Previously, the authors reported that bioactive glass promoted formation of nodules in cultured periodontal-ligament fibroblasts and high concentrations of calcium and silicon were detected in the culture medium. Herein, the effects of bioactive glass, calcium alone and calcium and silicon for formation of nodules on the periodontal-ligament fibroblasts are examined. The cells were cultured with bioactive glass, without bioactive glass, calcium and silicon, with calcium alone and with calcium and silicon. The cell growth, alkaline-phosphatase activity, amount of pro-collagen type I and the number of nodules were measured periodically until the 21st day. The cell growth rate with calcium and silicon was the highest, however the rate with bioactive glass and calcium alone were similar to that without them. The alkaline-phosphatase activity and the amount of pro-collagen showed peaks at the 11th day. At the peak, the alkaline-phosphatase activity with bioactive glass or calcium and silicon, and the pro-collagen with bioactive glass was higher than without them. The number of nodules with bioactive glass, calcium alone or calcium and silicon was greater than without them. These findings suggested that the combination of calcium and silicon released from bioactive glass was concerned with the formation of nodules on the periodontal-ligament cells.