矯正用金屬於含氟溶液之腐蝕機械效應與生物學效應

The corrosive mechanism of orthodontic metal and its biologic effects in fluoride solution

高嘉澤(Chia-Tze Kao)

指導教授 ： 周明勇

中山醫學大學/醫學院/醫學研究所/博士(2006年)

https://doi.org/10.6834/CSMU.2006.00017

摘要

矯正用之金屬材料應用於臨床治療上最常見為金屬矯正支架(metal bracket)與矯正金屬線(metal wire)。矯正中，為了預防蛀牙與保持牙周之健康，氟化物之使用非常頻繁，金屬矯正裝置於此環境下可能會發生腐蝕，腐蝕後釋出之物質是否對於人體組織有影響，以及當腐蝕後之裝置是否會影響臨床上矯正牙齒之移動等問題乃是值得研究與探討之主題。本研究目的在於探討（ㄧ）、金屬矯正支架與金屬矯正線於含氟化物下之腐蝕性變化；（二）、由腐蝕之金屬矯正裝置釋出物（即金屬離子溶液），對於細胞之生物相容性；（三）、由腐蝕之金屬矯正裝置於模擬口腔中之環境，比較矯正支架與矯正金屬線組合下之摩擦力大小，以提供臨床上治療或是材料研究上改進之參考。
研究材料採用為市面上常見之矯正用之四種廠牌金屬矯正支架，採用之矯正金屬矯正線為不鏽鋼線、鎳鈦線和鈦鉬線。腐蝕之浸泡溶液為人工唾液（Sali lube, Sinphar, Ilan, Taiwan, pH6.75）、調整酸鹼值之人工唾液（pH4）和氟化鈉溶液（APF, pH 3.5）。所有金屬材料於實驗前均以超音波去離子水清洗，再以酒精（ethyl alcohol）除去表面之油質。本研究分為三部份，其方法如下：（一）以電化學分析金屬線與矯正支架之腐蝕程度、以電子顯微鏡觀察表面結構，以金屬原子吸收光譜儀分析釋出之金屬溶液中金屬離子之釋出變化；（二）以MTT分析金屬釋出液作用於細胞後之存活率；以DNA裂片分析探討細胞基因之傷害；以西方墨點法分析細胞內蛋白訊號釋出之變化；（三）以萬能試驗機測試矯正支架與金屬線之靜摩差力與動摩差力。
研究結果顯示：（一）發現當矯正金屬線與金屬矯正支架於含氟之酸性環境下會產生腐蝕效應，本身金屬表面結構上會有腐蝕現象出現。不同條件下有不同之釋出金屬離子濃度，不同廠牌之金屬矯正支架有不同量之金屬離子釋出。於pH 4人工唾液與pH3.5 APF條件下鎳離子、鉻離子與鐵離子之釋出量顯著增加(p<0.05)。（二）當矯正金屬於含有氟化物之酸性液體中，發生腐蝕後之釋出液體會對於U2OS細胞與HGF 細胞造成細胞毒性，隨著釋出液濃度增加細胞之存活率下降(p<0.05)；釋出液對於U2OS細胞作用較HGF 細胞作用敏感。當細胞與矯正金屬釋出液作用，因毒性發生死亡之途徑，研究結果顯示矯正金屬線可能由於凋亡之出現，而矯正支架則未見造成細胞凋亡。於矯正金屬線萃取液對U2OS 細胞之訊息傳遞研究，經西方墨點分析結果發現均有出現ERK, Caspase 3, JNK 和p53蛋白環帶。矯正金屬支架腐蝕萃取液經西方墨點分析結果發現有p53 和caspase 3之環帶出現，未見有ERK和JNK出現。（三）於腐蝕後之矯正支架與矯正金屬線之摩擦力研究，發現摩擦力均因氟化物處理而有增加 (p<0.05)。靜摩擦力均大於動摩擦力，大小次序為TMA線＞NiTi線＞不?袗?線(p<0.05)。
結語：矯正金屬於酸性或是含有氟化物之環境下會產生腐蝕現象並釋出金屬離子，於試管中之研究結果認為釋出物對於細胞會造成傷害，且腐蝕之裝置對於牙齒移動之影響因子之ㄧ摩擦力也會造成影響，因此於臨床上建議可選擇不易腐蝕之矯正支架、矯正中之患者減少使用含氟化合物之口腔保健用品。

關鍵字

金屬矯正支架 ； 金屬矯正線 ； 生物相容性 ； 腐蝕 ； 摩擦力

並列摘要

The metal bracket and metal wire are the most often application materials in orthodontic treatment. In orthodontic treatment patient, the oral hygiene is difficult to maintain. To prevent the dental caries and maintain the periodontal health, the fluoride application is to be a routine prevention works in clinical care or home care. In the oral environment, orthodontic attachments are exposed to a number of potentially damaging physical and chemical agents, such conditions possibly contributing to corrosion of the metal components of the appliance. The purpose of the present study was to evaluate the surface corrosion effects of the metal brackets and wires, the biocompatibility of the elution which was from the fluoride corroded metal brackets and wires and compared the levels of friction resistance between metal brackets and orthodontic wires after immersion in fluoride solutions. Materials and methods:
Four brands of metal bracket and four dimensions of wires were used in this study. The artificial saliva and fluoride contained medium were used as the corrosion solution. The metal materials were cleaned before the test. The electrochemical analyze was to evaluate the corrosion effects. The atomic absorption assay was used to analysis the metal ion released from the media. The MTT assay was used to analyze the cytotoxicity of the elute solution. The DNA fragmentation assay was used to analysis gene toxicity. The mitogen activated protein kinase expression on cell was analyzed by western blot assay. The universal testing machine was used to evaluate the friction force on corroded metal bracket and wires. The data were all collected and analyzed by one way ANOVA. The results were followed by the Student-Newman-Keuls multiple comparison of means ranking at P < 0.05 to determine differences between the different groups. Results were as the follows: The polarization curve showed orthodontic metal could be corroded in acid environment and in acid fluoride medium. SEM observation showed pit corrosion. Ni, Cr, Fe, Ti ions was found in the metal ion released solution. . The amount of the metal ions release was found higher in salivary (pH4) + APF (pH3.5) media. The cytotoxicity was found as the concentration of the elute solution increased. The Apoptosis mechanism appeared in metal wire elutes but not in brackets elutes. ERK, Caspase 3, JNK and p53 were expressed on wire elutes, but only p53 and caspase 3 expressed on bracket elutes. The friction force was increased as the corrosion happened on bracket and wire. The statistic friction force was higher than kinetic friction force. In conclusion: The application of fluoride on orthodontic metal should be caution on its corrosion behaviour, especially in acid environment. Although there is no clinical side effects reported on patient except nickel allergy. But in present in vitro study showed elutes can decrease the cell viability and affect the tooth movement on friction. The suggestion is to replace wire after orthodontic treatment. Further investigation can be focused on the in vivo evaluation and clinical study on the slide effects of friction.

並列關鍵字

metal bracket ； metal wire ； corrosion ； biocompatibility ； frictional force

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