Bouillaguet Serge, Owen Brandi, Wataha John C, Campo Marino A, Lange Norbert, Schrenzel Jacques
Endodontics Unit, Section of Dental Medicine, University of Geneva, 19 rue B. Menn, 1205 Geneva, Switzerland.
Dent Mater. 2008 Aug;24(8):1070-6. doi: 10.1016/j.dental.2007.12.004. Epub 2008 Feb 19.
Disinfection of the tooth pulp-canal system is imperative to successful endodontic therapy. Yet, studies suggest that 30-50% of current endodontic treatments fail from residual bacterial infection. Photodynamic therapy using red-light chromophores (630 nm) to induce antimicrobial death mediated by generated reactive oxygen species (ROS) has been reported, but red-light also may thermally damage resident tissues. In the current study, we tested the hypothesis that several blue light chromophores (380-500 nm) generate intracellular reactive oxygen species but are not cytotoxic to mammalian cells.
THP1 monocytes were exposed to 10 microM of four chromophores (chlorin e6, pheophorbide-a, pheophorbide-a-PLL, and riboflavin) for 30 min before activation with blue light (27J/cm(2), 60s). After activation, intracellular ROS were measured using a dihydrofluorescein diacetate technique, and cytotoxicity was determined by measuring mitochondrial activity with the MTT method.
All photosensitizers produced intracellular ROS levels that were dependent on both the presence of the photosensitizer and blue light exposure. Riboflavin and pheophorbide-a-PLL produced the highest levels of ROS. Photosensitizers except riboflavin exhibited cytotoxicity above 10 microM, and all except pheophorbide-a-PLL were more cytotoxic after blue light irradiation.
The current study demonstrated the possible utility of blue light chromophores as producers of ROS that would be useful for endodontic disinfection.
牙髓-根管系统的消毒对于成功的牙髓治疗至关重要。然而，研究表明，目前30%-50%的牙髓治疗因残留细菌感染而失败。已有报道使用红光发色团（630nm）进行光动力疗法以诱导由产生活性氧（ROS）介导的抗菌死亡，但红光也可能对驻留组织造成热损伤。在本研究中，我们测试了以下假设：几种蓝光发色团（380-500nm）可产生活细胞内活性氧，但对哺乳动物细胞无细胞毒性。
用蓝光（27J/cm²，60秒）激活前，将THP1单核细胞暴露于10微摩尔的四种发色团（二氢卟吩e6、脱镁叶绿酸-a、脱镁叶绿酸-a-聚赖氨酸和核黄素）中30分钟。激活后，使用二氢荧光素二乙酸酯技术测量细胞内ROS，并通过MTT法测量线粒体活性来确定细胞毒性。
所有光敏剂产生的细胞内ROS水平均取决于光敏剂的存在和蓝光照射。核黄素和脱镁叶绿酸-a-聚赖氨酸产生的ROS水平最高。除核黄素外，光敏剂在浓度高于10微摩尔时表现出细胞毒性，且除脱镁叶绿酸-a-聚赖氨酸外，所有光敏剂在蓝光照射后细胞毒性更强。
本研究证明了蓝光发色团作为ROS产生剂在牙髓消毒中的潜在用途。
