- 學位論文
抗氧化劑對牙科用光聚合樹脂起始劑造成中國倉鼠細胞株細胞-遺傳毒性的保護作用
Protective effects of antioxidants on cytotoxicity and genotoxicity induced by photoinitiators in CHO cells
摘要
光聚合樹脂系統的光起始劑 (photoinitiator) 【包含光敏劑(photosensitizer) 及還原劑(reducing agent)】 被廣泛應用於牙科的填補材料，即使光起始劑為了更適用於人體已在物理性質上做很大的改進，但光照聚合過程中產生許多的自由基與口腔粘膜及牙髓組織等的傷害有關聯性。目前常用的光敏劑，樟腦酮 (camphorquinone, CQ) 及芴酮 (9-fluorenone, 9F) 至今仍少有研究探討其是否會有細胞-遺傳毒性。 本篇研究利用靈敏度極高的微小核法 (micronucleus assay) 分析CQ在二甲對甲苯胺 (N, N-dimethyl-p-toluidine, DMT) 的存在下有、無照光及9F在有無DMT的存在與有、無照光的條件下探討中國倉鼠卵巢(chinese hamster ovary, CHO)細胞的細胞-遺傳毒性。我們的研究結果顯示CQ在DMT的存在下，無論有、無照光都能顯著的增加微小核 (MNs) 數目及延長細胞週期 (p<0.05)，且照光組之細胞-遺傳毒性比不照光組增加 (p<0.05)，而9F無論在有無DMT的存在及有、無照光的條件下，均呈現統計意義地減少細胞分裂阻斷增生指數 (CBPI) 及增加MNs數目的結果。為了進ㄧ步探討CQ及9F光起始劑所造成之細胞-遺傳毒性的主要原因是否與自由基的產生有關聯，所以本篇研究以10 mM N-乙醯基半胱氨酸 (N-acetyl-L-cysteine, NAC), 2 mM抗血酸劑 (ascorbic acid) 及2 mM生育醇 (α-tocopherol) 等抗氧化劑加入CHO細胞。結果顯示這些抗氧化劑均能對抗CQ及9F光起始劑減少CHO細胞之CBPI及增加MNs數目的作用。結論：CQ及9F光起始劑均會造成染色體斷裂和/或整個染色體延遲及延長細胞週期，而抗氧化劑對其所造成的細胞毒性及遺傳毒性可產生抑制作用。所以CQ及9F光起始劑可能經由氧自由基造成CHO細胞的細胞-遺傳毒性。
並列摘要
The visible-light (VL) polymerizing resin system with photoinitiators (photosensitizer and reducing agent) is widely used in modern dentistry as restorative materials, bonding agents, cements, and prosthetic and orthopaedic devices. In this chemical reactions which generates many free radicals between the photosensitizers and reducing agents during VL irradiation. There is growing concern that camphorquinone (CQ) and 9-Flurorenone (9F) may produce genetic damage by inducing mutation. We used micronucleus assay to analyze for the induction of chromosomal aberrations and lapping whole chromosome in CHO cells. Our data demonstrated that an increase in the numbers of MN and prolonged cell cycle were observed by the treatment CQ/DMT with or without VL irradiation (p<0.05). In addition, VL irradiated CQ/DMT was found to exhibit significantly increase cytotoxicity and genotoxicity as compared with CQ/DMT alone (p<0.05). Also an increase in the numbers of MN and prolonged cell cycle were observed by the treatment with 9F with or without DMT in the presence or absence of VL irradiation. Furthermore, to determine whether oxidative stress could modulate the MN induced by CQ/DMT with or without VL irradiation and 9F with or without DMT in the presence or absence of VL irradiation in CHO cells, cells were pre-treated with various antioxidants 10 mM N-acetyl-L-cysteine (NAC), 2 mM ascorbic acid and 2 mM α-tocopherol. The pre-treatment with antioxidants could diminish not only the prolonged cell cycle but also the decreased frequency of MN which is induced by CQ/DMT with or without VL irradiation and 9F with or without DMT in the presence and absence VL irradiation in CHO cells. Our findings provide the evidences for induction of MN by CQ/DMT with or without VL irradiation and 9F with or without DMT in the presence and absence VL irradiation in CHO cells, indicating clastogenic activity of CQ and 9F resin system in vitro. Moreover, NAC, ascorbic acid and α-tocopherol act as the antagonists against the cytotoxicity and genotoxicity of CQ/DMT with or without VL irradiation and 9F with or without DMT in the presence and absence VL irradiation. Thus, antioxidants could prevent oxidative damage induce by CQ and 9F resin system.