Garcez Aguinaldo S, Hamblin Michael R
Department of Oral Microbiology, São Leopoldo Mandic Institute and Dental School, Campinas SP, Brazil.
Department of Phototherapy, Wellman Center for Photomedicine, Massachusetts General Hospital, Boston MA, USA.
Eur Endod J. 2017 Nov 20;2(1):1-7. doi: 10.14744/eej.2017.17023. eCollection 2017.
Antimicrobial photodynamic therapy (aPDT) is a controversial approach for endodontic disinfection. The objective of this study was to test the photosensitiser (PS) concentration and assess the optical shielding phenomenon, the use of hydrogen peroxide (HO) and minimal energy irradiation to optimise endodontic aPDT for suggesting a protocol for clinical use.
Different parameters for aPDT were tested. Aqueous solutions of methylene blue (MB) at 50, 100, 150 and 300 μM were tested in vitro for optical shield and reactive oxygen species (ROS) production by the reduction of N,N-dimethyl-4-notrosoaniline (RNO) at 440 nm absorbance when irradiated using a diode laser (660 nm). Ten single-rooted teeth were inoculated with bioluminescent bacteria for 72 hours to form biofilms. Bioluminescence imaging was used to serially evaluate the minimum energy necessary during endodontic aPDT using MB and a diode laser coupled to an optical fibre for intracanal microbial reduction. In addition, teeth (n=21) infected with Enterococcus faecalis were treated with sequential combinations of endodontic aPDT and HO and the colony-forming unit (CFU) was determined.
ROS production was inversely proportional to the MB concentration in the solution due to quenching of MB. Optical shielding limited light penetration at high MB concentrations. The use of HO before aPDT achieved higher disinfection compared to conventional aPDT or when MB was irradiated in an HO solution. Energy irradiation of 9.6 J achieved a significant reduction and further light delivery did not produce further reduction.
PS concentration of about 50 μM, biofilm pre-treatment with HO for 1 min and energy irradiation around 10 J appear to be an effective protocol for endodontic aPDT.
抗菌光动力疗法（aPDT）是一种用于牙髓消毒的存在争议的方法。本研究的目的是测试光敏剂（PS）浓度，评估光屏蔽现象、过氧化氢（HO）的使用以及最小能量照射，以优化牙髓aPDT，从而提出一种临床使用方案。
测试了aPDT的不同参数。体外测试了浓度为50、100、150和300μM的亚甲蓝（MB）水溶液在使用二极管激光器（660nm）照射时，通过在440nm吸光度下还原N，N-二甲基-4-亚硝基苯胺（RNO）产生的光屏蔽和活性氧（ROS）。将十颗单根牙接种生物发光细菌72小时以形成生物膜。使用生物发光成像连续评估牙髓aPDT期间使用MB和耦合到光纤的二极管激光器进行根管内微生物减少所需的最小能量。此外，用粪肠球菌感染的牙齿（n = 21）接受牙髓aPDT和HO的序贯联合治疗，并测定菌落形成单位（CFU）。
由于MB的猝灭，溶液中ROS的产生与MB浓度成反比。光屏蔽限制了高MB浓度下的光穿透。与传统aPDT或在HO溶液中照射MB相比，在aPDT之前使用HO可实现更高的消毒效果。9.6J的能量照射实现了显著减少，进一步的光传递并未产生进一步减少。
约50μM的PS浓度、用HO对生物膜预处理1分钟以及约10J的能量照射似乎是牙髓aPDT的有效方案。
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