Conference Paper

Antimicrobial Photodynamic Therapy: Chlorophyll as a Photosensitizer Against S. mutans.

June 2012

Conference: IADR General Session 2012

Authors:

Ana Cristina Godoi Zingra

University of São Paulo

Gabriel Barbério

São Paulo State University

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Objective: The aim of this work was to investigate the antimicrobial photodynamic therapy (aPDT) by using liquid chlorophyll as photosensitizer and Light Emitting Diode (LED) in the viability of S. mutans. Method: There were three experimental groups: G1: no exposure to LED nor to liquid chlorophyll (n=7); G2: with exposure only to liquid chlorophyll and not to LED (n=7); G3: with exposure to both LED and liquid chlorophyll (n=7). The bacterial growth of all groups was transferred to Petri plaques, and these were incubated in microaerophilic conditions for 48 hours. The colony-forming units (CFU), obtained by dilutions 102 and 103 of the bacterial inoculum, had been then counted. The results had been submitted to ANOVA and Bonferroni tests (p<0.05). Result: There was statistically significant reduction of CFU in the association of chlorophyll to LED. The CFU score was also reduced in the presence of chlorophyll only. Conclusion: The association of liquid chlorophyll and Photodynamic Therapy using LED was able to reduce the number of S. mutans. This result is important in order to bring a new perspective for clinical protocol to caries prevention in a forthcoming future.

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Conference Paper

Antimicrobial photodynamic therapy using LED against C. albicans

June 2012

Objective: This study evaluated specific effects of antimicrobial photodynamic therapy (aPDT) by using a low energy density and low time of application using toluidine blue as photosensitizer (PS) and a red light-emitting diode (rLED) irradiation on the viability of Candida albicans. Method: There were realized 28 assays. The toluidine blue was the PS and the light was from a LED (637 ± 15nm, ... [Show full abstract] 40mW, 1W/cm2). These assays were divided into the following experimental groups: submitted to light-emitting diode in the presence of the toluidine blue (n=7); submitted to light-emitting diode only (n=7); treated only with the toluidine blue (n=7); no exposure to light-emitting diode nor toluidine blue (n=7). Next, serial dilutions were prepared and seeded onto Sabouraud dextrose agar for the determination of the number of colony-forming units per milliliter (CFU/ml). The results were submitted to analysis of variance and the Tukey test (p<0.05). Result: aPDT with toluidine blue promoted a statistically significant reduction in the CFU number of C. albicans. The number of CFU was higher in the group submitted to LED only than in the group submitted to LED in the presence of the toluidine blue and it was higher for the group submitted to the toluidine blue than it was for the group submitted both to LED and toluidine blue. There was no significant statistical difference between the groups without PS. Conclusion: We show that LED with toluidine blue used for lower power and lower time had a fungicidal effect on C. albicans facilitating the clinical use of this therapy.

Conference Paper

In vitro Effectiveness of Photodynamic Antimicrobial Therapy against C. albicans

March 2010

Photodynamic antimicrobial therapy (PACT) is a treatment that uses specific wavelength light in order to cause cellular toxicity through the activation of a photosensitizing agent in the presence of oxygen. PACT has been employed in vitro studies to kill Candida albicans. Objective: The aim of the present study was to evaluate the effect of PACT on the viability of C. albicans (ATCC 10231), using ... [Show full abstract] toluidine blue O (TBO) as photosensitizer and a light emitting diode (LED, 630 nm) as light source. Methods: After adjust to 0.5 McFarland standard, 100 l C. albicans in broth were used in each one experimental condition as follows: (i) untreated C. albicans suspensions; (ii) C. albicans suspensions incubated with TBO without irradiation; (iii) C. albicans suspensions irradiated with 24 J/cm2 (1 min), 72 J/cm2 (3 min) or 120 J/cm2 (5 min) without TBO pre-incubation; and (iv) C. albicans suspensions incubated with TBO and irradiated with 24 J/cm2, 72 J/cm2 or 120 J/cm2. TBO 0.00025% was used to sensitize bacteria for 5 min in dark conditions. Immediately after, C. albicans were plated onto Sabouraud agar dishes for 48 h at 37oC to determine CFU counts. Results: There were significant differences among the groups (p<0.05). PACT using the conditions tested was effective in reducing the number of C. albicans when the samples were irradiated for 1 min and 3 min with LED. The number of CFU/ml was significantly reduced after the therapy, and the results of de control groups were depended on the irradiation time used. Conclusion: Values of CFU/mL were significantly decreased after using the different parameters of PACT. Therefore, C. albicans in broth can be killed after the use of PACT in vitro conditions. Further in vitro and in situ studies must be performed to show the action of PACT on C. albicans biofilms.