Dental caries, the most common oral disease, is a multifactorial disease caused by interactions among bacteria within the dental plaque, food, and saliva, resulting in tooth destruction. Streptococcus mutans has been strongly implicated as the causative organism in dental caries and is frequently isolated from human dental plaque. Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizer by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. Postantibiotic effect (PAE) is defined as the duration of suppressed bacterial growth following brief exposure to an antibiotic. In this study, the in vitro PAE of PDT using erythrosine and light emitting diode on S. mutans ATCC 25175 was investigated. The PAE of PDT for 1 s irradiation and 3 s irradiation were 1.65 h and 2.1 h, respectively. The present study thus confirmed PAE of PDT using erythrosine on S. mutans.

Low level light therapy (LLLT) is known to accelerate the process of wound healing, bone and cartilage formation, and to decrease tissue necrosis and inflammation. It also can be applicable to acute and chronic injury or degenerative disease. Despite forty- plus years of accumulating exprerience of the clinical efficacy of LLLT, their molecular biologic evidence is not fully elucidated. The aim of this review is to explore the role of the ROS system and its molecular biologic mechanism in related with inflammatory response, anti-apoptosis and angiogenesis during LLLT. We suggest that activation of ROS system explains many (if not most) of the observed response of cells to LLLT in vitro, and is likely to play a pivotal role in the response of animals and patients to LLLT for both experimental and clinical indications and diseases.

PDT is an established cancer treatment modality. This can be attributed to the attractive basic concept of PDT; Combination of two therapeutic agents, a photosensitizing drug and light, which are relatively harmless by themselves but when combined, cause more or less selective tumor destruction. Hematoporphyrin-derived photosensitizers are known to be stable and highly efficient. In this study, we conducted a series of experiments to develop light-induced anticancer drugs against oral cancer cells. We tested the cytotoxicity of photodin by MTT assay and observed cell death pattern (apoptosis or necrosis) by hoechst 33342 and propidium iodide staining methods after PDT. IC50 value of photodin was 0.65 ug/ml. At higher doses of photodin ( > 7.8 ug/ml), cancer cells died exclusively from necrosis after PDT. By contrast, at IC50 value, photodin induced cancer cell to undergo apoptotic cell death. The induction begins approximately 6 hours after PDT. We investigated intracellular localization of photodin by oral cancer cell via confocal laser scanning microscopy. Oral cancer cells dual-stained with photodin and organelle-specific fluorescence probes (Mitotracker, Lysotracker, ER-Tracker) revealed that an intracellular fluorescence distribution was restricted to cytoplasmic compartments with no detectable fluorescence in the nucleus. Confocal images of cells containing photodin were overlapped with the mitochondria-specific fluorescence probe images of the same cells. These results demonstrated that photodin may play the role of a photosensitizer for oral squamous cancer cells without swelling and inflammation. Therefore, photodin-based PDT is a suitable treatment for oral cavity carcinoma patients.

피부는 낮 동안 태양빛과 인공 빛에 끊임없이 노출되어 있으며, 그중 5%는 UV 영역, 50%는 가시광선, 나머지 45%는 적외선 영역으로 구성되어 있다. 이중 자외선의 피부에 대한 영향은 많은 연구가 되어 왔으나, 나머지 영역에 대한 연구는 미진한 실정이다. 이에, 가시광선에서 적외선 사이의 파장이 피부 섬유아세포에 어떤 영향을 미치는지 연구하고자 하였다. 광처리에 의한 효과는 광파장, 처리 시간, 광세기, 광조합 등 다양한 파라미 터들의 조합에 의해 그 효능이 결정되므로, 본 연구에서는 섬유아세포의 성장 및 콜라겐 합성과 관련된 기능을 촉진시킬 수 있는 광처리 조건을 찾아내고자 하였다. 가시광선과 적외선 영역 사이의 6개의 파장을 처리한 결과, 레드(630 nm)와 그린(520 nm) 파장에 의해 섬유아세포의 증식이 증가함을 확인하였다. 광처리 시간은 콜라겐 합성량 증가를 위해서는 10 min의 광처리가 30 min의 광처리 보다 적합한 조건이었다. 광세기는 0.05 ∼ 0.75 mW/cm2에서 6개의 광세기로 분할하여 실험한 결과, 레드 0.3 mW/cm2와 그린파장 0.15, 0.3 mW/cm2 세기가 type I collagen의 mRNA의 양을 증가시킬 수 있었다. 마지막으로 두 개 파장을 순차적으로 조합 처리하였을 때의 효과를 확인한 결과, 레드와 그린파장의 조합 조건은 섬유아세포의 수적증가를 목적으로 할 때 효율적인 방법이며, 콜라겐 합성에는 레드 단독처리가 보다 효과적인 방법이었다. 따라서 본 연구에서 제시하는 광처리 조건을 이용시 피부 세포의 성장이나 콜라겐 합성에 긍정적 영향을 유도할 수 있으며, 재생 및 피부 미용 등에 활용할 수 있는 가능성이 클 것으로 기대된다.