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.

We previously reported that materials leached from bioactive glass (BG) and vitamin D3 induced the formation of nodules on cultured periodontal-ligament fibroblasts (PLF). In this study, we have investigated the relationship between the conditions of the materials and nodule formation, analyzed morphologically, and also studied whether the production of nodules was specific to cultured PLF. PLF and skin fibroblasts were cultured in the presence or absence of BG. The amounts of calcium, phosphate, sodium and silicon in the culture medium and the number of nodules were measured at the 55th day. The nodules were observed microscopically and analyzed using an X-ray microanalyzer. In PLF, nodules were formed regardless of the presence or absence of BG; however, they were more numerous in the presence of BG. In skin fibroblasts, nodules were not observed. The amounts of calcium and silicon were higher in the presence of BG, while the amount of phosphate was lower. The nodules appeared crystalline with a spongy structure and contained calcium and phosphorus. Our results show that the nodules were associated with PLF and precipitated by the materials (higher concentrations of calcium and silicon), and they were spongy crystal composed of calcium and phosphorus.

The cell occlusive effects on human gingival fibroblasts of degradable lactic acid-glycolic acid copolymer membranes (noncoated membranes) and membranes coated with a sucrose ester of fatty acid (coated membranes) were studied and compared with those of expanded polytetrafluoroethylene (e-PTFE) membranes. The membranes were immersed in a culture medium periodically for 21 days and interposed into a chemotaxis chamber, and the fibroblasts then were cultured in the chamber for another 7 days. The passage rate of cells through the membranes was calculated and the change in surface structure of each membrane after immersion for 28 days was observed by an environmental scanning electron microscope. The passage rate of coated membranes (3.4+/-2.2%) was significantly lower than that of noncoated (25.7+/-5.1%) at the 28th day whereas the passage rate of e-PTFE membranes was 0.8-1.5%. Many pores were observed on the noncoated membranes before immersion while the coating material covered most of the pores on the coated membranes. The average pore size of the noncoated membranes was larger than that of the coated membranes at day 28. The structure of the e-PTFE membranes underwent no change. The passage rate of the coated membranes was not different from the e-PTFE membranes, suggesting an effect that might be useful for a guided tissue regeneration procedure.

The effects of bioactive glass and vitamin D3 on cultured fibroblasts derived from periodontal-ligament, with respect to their proliferation and alkaline-phosphatase activity were studied. The cells were cultured with or without the bioactive glass and/or vitamin D3, then the number and alkaline-phosphatase activity of the cells were measured periodically until the 33rd day. Formation of mineralized deposits was assessed by staining with alizarin red and von Kossa staining techniques. Fewer fibroblasts grew when they were cultured in the presence of bioactive glass and/or vitamin D3 as compared to those cultures without them. Alkaline-phosphatase activity was greater in the fibroblasts cultured with bioactive glass and vitamin D3 than in the cells grown without them. Mineralized deposits assessed by alizarin red and von Kossa staining techniques were observed microscopically around the fibroblasts cultured with bioactive glass and/or vitamin D3. A nodule visible after drying was evident only when both bioactive glass and vitamin D3 were present in culture. The results showed that although the bioactive glass and vitamin D3 decreased cell proliferation, they increased the alkaline-phosphatase activity of the fibroblasts which formed a nodule, suggesting an effect which might be useful for implant materials.

summary 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 ceil 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.