Mechanisms of cytotoxicity by initiators for dental polymerizing resin systems and application for photodiamic therapy.

樟脑酚(CQ)作为光引发剂广泛应用于牙科材料中，但其对人牙髓成纤维细胞(HPF)的细胞毒性，特别是还原剂甲基丙烯酸二甲氨基乙酯(DMA)和可见光(VL)照射对其的影响尚不清楚。因此，我们研究了CQ对HPF细胞的毒性和产生活性氧自由基(ROS)的作用。此外，还用两种不同的方法(二苯基苦味酰肼、DPPH和半乳糖氧基)测定了CQ的自由基产生活性。此外，用差示扫描量热法(DSC)研究了二棕榈酰磷脂酰胆碱(DPPC)脂质体作为生物膜模型在CQ诱导下的相变特性。并与具有长共轭基团的芳香族光引发剂9-荧酮(9F)进行了比较。VL照射的CQ增加了自由基的产生，而VL照射的9F增加了ROS的产生，并改变了DPPC的相变性质。与9F相比，CQ对HPF细胞的细胞毒性较小，但产生的自由基较多。在光敏剂中加入DMA，在不增加ROS和细胞毒性的情况下，增加了自由基的产生。综上所述，CQ/DMA在牙科树脂聚合中具有一定的应用价值。

Camphorquinone (CQ) is widely used as a photo-initiator in dental materials ; however, its cytotoxicity against human pulp fibroblasts (HPF) and particularly the effects of 2-dimethylaminoethyl methacrylate (DMA), a reducing agent, and visible-light (VL) irradiation on it remains unknown. So we investigated the cytotoxic and reactive oxygen species (ROS)-producing effects of CQ with or without DMA, in the presence or absence of VL on HPF cells. Also, the free-radical production activity of CQ was measured by 2 different methods (using diphenylpicryl hydrazyl, DPPH, and galvinoxyl). Furthermore, the phase-transition properties of dipalmitoylphosphatidyl choline (DPPC) liposomes, as a model for biomembranes, induced by CQ were investigated by differential scanning calorimetry (DSC). These findings were compared with those of 9-fluorenone (9F), an aromatic photo-initiator with long conjugated groups. CQ with VL irradiation increased the radical production, whereas 9F with VL irradiation increased ROS production, as well as changes in the DPPC phase-transition properties. The cytotoxicity of CQ toward HPF cells was smaller than that of 9F despite greater radical production. The addition of DMA to photosensitizer enhanced the free-radical production without in creasing ROS and cytotoxicity. In conclusion, CQ/DMA is valuable for polymerization of dental resins.