牙科靜磁鐵在臨床應用上是近二十年的事。但由於矯正所使用的靜磁鐵是 屬於開放性的靜磁場，其對於生物體的細胞生長影響機制為何，目前仍不明 且缺乏深入的研究。此外，過去的研究及文獻也顯示，靜磁場對於細胞的影 響，會因細胞種類或環境的不同而有不同的結果。且靜磁場的刺激環境磁力 大小導致其細胞生長速率的增加或減緩之作用機制尚未明確且模糊不清。因 此，找出靜磁場刺激細胞後，其導致細胞生長速率的增加或減緩之作用機制 實為必需。雖然 Labes(1966) 曾提出靜磁場可能會影響細胞膜的脂質分子，但 卻從來沒有實驗去驗證過這個假說，因此靜磁場作用於細胞的哪個部分，目 前並不清楚。本研究選取纖維母細胞為研究對象，對前述之問題，在其暴露 於 0 到 4000 高斯的靜磁場 0 到 48 小時計算細胞數目增長情形，並以電子顯 微鏡觀察其超微結構，接者以免疫螢光酵素分析法進行 PGE2 的量測。此外
，細胞暴露於上述靜磁場時，細胞週期之變化亦利用流氏細胞儀來測定。結 果發現，暴露於靜磁場下的細胞數目在第 12 小時有最大的變化，在 1000 到 4 000 高斯時分別減少了 5.8%, 11.6% 和 20.9% 。而細胞週期並未有明顯的改變
，且 PGE2 釋放亦無變化，但在 4000 高斯之靜磁場作用下加入 IGF-I, PDGF- bb, TGF-β 之細胞數目分別較控制組少了 14.0%, 12.4% 和 15.4% 。而處理以 TNF-α 之細胞數目則多了 18.0% 。從此結果推論，靜磁場可能會影響細胞膜
，減緩生長因子作用但不影響到 DNA 層次，亦無 PGE2 增加之發炎反應副作 用產生。
牙科矯正用靜磁鐵磁場對細胞生長影響機制之探討
Static magnet has been used in the dental field for about 20 years. Clinical studies showed that magnets could not only offer force control and treatment convenience, it could also increase th e rate of tooth movement in orthodontic treatment. However, the effect of orthodontic static m agnetic field on growth stimulation of cell remains unclear and still need further study. In this study, our objective is to determine how the static magnet affects cell cycle and its mechanism . Cell number and viability of fibroblast (NIH-3T3) were tested under static magnetic field (S MF) exposure. Results showed that both cell number and viability of cells decreased when exp osed to SMF. However, no statistically significant difference was found between each cell cyc le phase when the cells were exposed to various strengths of SMF. In the growth factor experi ments, all growth factors IGF-I 、 TGF-βand PDGF were found to increase the cell number of the cells. However, when the cells were exposed to SMF, the effects of the IGF-I 、 TGF-βan d PDGF on cell number significantly decreased by 14.0% 、 15.4% and 12.4% (p<0.01) respe ctively. In contract, TNF-α did significantly increase the cell number of the cells with a percen tage of 18.0% (p<0.01) when exposed to SMF. The SEM images showed that no significantly changed when compared to control group after they were exposed to 4000 Gauss SMF within a period of 48 hours. According to these findings, we arrived at a hypothesis that SMF were ef fected of cell membrane. This interaction may affect the status of various transmembrane grow th factor receptors. When the growth factors cannot bind to its receptor, the proliferation rates of the cell decrease.
The effect of orthodontic static magnetic field on growth stimulation of cell
