Photodynamic Therapy for Endodontic Disinfection

描述（由申请人提供）：根管治疗失败是由于根管系统的复杂性导致残留在根管内的残留细菌增殖而引起的，这使得仅使用器械和冲洗进行完全清创几乎是不可能的。我们的长期目标是开发光动力疗法（PDT）作为一种预防性技术，以消除器械和次氯酸钠（NaOCI）冲洗后残留的根管细菌。本研究所要检验的具体假设是，可见光可以实现快速和完全杀死残余根管微生物后，他们与光敏药物敏化。具体目标是：1.在离体牙的根管系统的表面和牙本质小管上，用常见于牙髓失败和/或感染的微生物形成单种和多种生物膜。我们将（i）通过扫描电子显微镜和共聚焦扫描激光显微镜来表征这些生物膜，并且我们将（ii）使用棋盘DNA-DNA杂交、聚合酶链反应（PCR）测定和培养来分析它们。2.探讨根管生物膜的光破坏作用。我们将（i）建立完全消除根管微生物生物膜的光和光敏剂参数，（ii）评估细菌杀灭，（iii）评估生物膜内细胞杀灭的分布。3.评估光动力疗法的安全性。我们将（i）确定治疗后人牙周膜和骨细胞的活力，（ii）确定治疗窗口，从而可以灭活微生物而不影响宿主细胞的活力，和iii）研究细胞凋亡的诱导。4.评价光动力疗法对离体人牙的抗菌效果。我们将使用新鲜拔出的受感染的人牙来评估光动力疗法对完全器械化和用NaOCl冲洗后的根管系统中残留细菌的影响。与公共卫生的相关性：在美国，每年有超过200万例因残留微生物而进行的根管再治疗。光动力疗法可能是一个连续的程序，以杀死残留的根管细菌后，他们的敏化与光敏药物和随后暴露于光。

DESCRIPTION (provided by applicant): Endodontic failures are caused by the proliferation of residual bacteria that are left behind within the root canal due to the complexity of the root canal system that makes complete debridement with instrumentation and irrigation alone almost impossible. Our long-term goal is to develop photodynamic therapy (PDT) as an adjunctive technique to eliminate residual root canal bacteria after instrumentation and irrigation with sodium hypochlorite (NaOCI). The specific hypothesis to be tested by this research is that visible light can achieve a rapid and complete killing of residual root canal microorganisms after their sensitization with a photoactive drug. The Specific Aims are to: 1. Develop mono- and multi-species biofilms with microorganisms that are common in endodontic failures and/or infections on the surface and in the dentinal tubules of root canal systems of extracted teeth. We will (i) characterize these biofilms by scanning electron microscopy and confocal scanning laser microscopy and we will (ii) analyze them using checkerboard DNA-DNA hybridization, polymerase chain reaction (PCR) assays and culture. 2. Investigate the photodestruction of root canal biofilms in vitro. We will (i) establish the parameters of light and photosensitizers for the complete elimination of root canal microbial biofilms, (ii) evaluate bacterial killing, and (iii) assess the distribution of cell killing within the biofilms. 3. Assess the safety of photodynamic therapy. We will (i) determine the viability of human periodontal ligament and bone cells after treatment, (ii) determine the therapeutic window whereby microorganisms can be inactivated without affecting host cell viability, and iii) investigate the induction of apoptosis. 4. Evaluate the antimicrobial effects of photodynamic therapy in human teeth ex vivo. We will use freshly extracted infected human teeth to evaluate the effect of photodynamic therapy on residual bacteria in the root canal system after complete instrumentation and irrigation with NaOCI. Relevance to public health: More than 2 million root canal re-treatments due to residual microorganisms are performed yearly in the US. Photodynamic therapy may be an adjunctive procedure to kill residual root canal bacteria after their sensitization with a photoactive drug and their subsequent exposure to light.