Fumes Ana Caroline, Romualdo Priscilla Coutinho, Monteiro Rachel Maciel, Watanabe Evandro, Corona Silmara Aparecida Milori, Borsatto Maria Cristina
Department of Pediatric Clinics, Ribeirão Preto Dental School, University of Sao Paulo (USP), Ribeirão Preto, SP, Brazil.
Departamento de Clínica Infantil, Faculdade de Odontologia de Ribeirão Preto-USP, Av. do Café, s/n, Monte Alegre, Ribeirão Preto, SP, 14040-904, Brazil.
Lasers Med Sci. 2018 Jan;33(1):67-73. doi: 10.1007/s10103-017-2336-1. Epub 2017 Sep 30.
The aim of the present study was to evaluate, in vitro, the effect of different pre-irradiation times of the photosensitizer in photodynamic therapy in biofilms formed by Streptococcus mutans and Candida albicans, through the evaluation of the microbial load. The factors under study were as follows: times of pre-irradiation of the photosensitizer in three levels (1, 2, or 5 min). For the control of the cariogenic dental biofilm with antimicrobial photodynamic therapy (aPDT), methylene blue (0.01%) was used in association with the diode laser (InGaAlP) with a wavelength of 660 nm. Chlorhexidine digluconate (0.12% CHX) and saline were used as positive and negative controls, respectively. The study design was carried out in complete and randomized blocks. The sample consisted of 15 S. mutans biofilms cultures, randomly divided into five groups and 15 C. albicans cultures, also divided into five groups. The experiment was performed in triplicate (n = 3) and the response variables were obtained through quantitative analysis of bacterial viability, expressed in colony-forming units (CFU) per square millimeter of the specimen area. The data were analyzed with the aid of the ANOVA one-way test and Tukey's post-test. All analyses were performed using the Graph Pad Prism 4.0 program, with a significance level of 5%. For the S. mutans group, only the saline solution presented a statistically significant difference when compared to the other treatments (p < 0.05), that is, the treatment with aPDT, irrespective of the irradiation time applied, was similar to the treatment with CHX and both were more effective in reducing cariogenic biofilm compared to saline. For the group of C. albicans, there was no statistical difference between the groups (p > 0.05). Therefore, it can be concluded that the treatment with aPDT reduced the number of CFUs of S. mutans in a similar way to CHX, independently of the pre-irradiation time applied. No effect of this therapy or of the different pre-irradiation times on the C. albicans biofilm could be observed. In this way, the pre-irradiation time of 1 min can be used to reduce the microbial load of S. mutans.
本研究的目的是通过评估微生物载量，在体外评价光动力疗法中光敏剂不同预照射时间对变形链球菌和白色念珠菌形成的生物膜的影响。所研究的因素如下：光敏剂的预照射时间分为三个水平（1、2或5分钟）。为了用抗菌光动力疗法（aPDT）控制致龋性牙生物膜，使用亚甲蓝（0.01%）与波长为660nm的二极管激光器（InGaAlP）联合使用。葡萄糖酸洗必泰（0.12%CHX）和生理盐水分别用作阳性和阴性对照。研究设计采用完全随机区组设计。样本包括15个变形链球菌生物膜培养物，随机分为五组，以及15个白色念珠菌培养物，也分为五组。实验重复进行三次（n = 3），通过对细菌活力的定量分析获得反应变量，以每平方毫米标本面积的菌落形成单位（CFU）表示。数据借助单因素方差分析和Tukey事后检验进行分析。所有分析均使用Graph Pad Prism 4.0程序进行，显著性水平为5%。对于变形链球菌组，与其他处理相比，仅生理盐水呈现出统计学显著差异（p < 0.05），即，无论应用何种照射时间，aPDT处理与CHX处理相似，且二者在减少致龋生物膜方面均比生理盐水更有效。对于白色念珠菌组，各处理组之间无统计学差异（p > 0.05）。因此，可以得出结论，aPDT处理以与CHX相似的方式减少了变形链球菌的CFU数量，与所应用的预照射时间无关。未观察到该疗法或不同预照射时间对白色念珠菌生物膜有影响。这样，1分钟的预照射时间可用于降低变形链球菌的微生物载量。
