Effect of the Antimicrobial Photodynamic Therapy on specific microorganism groups from dentin caries microcosms

Author(s)

Daniela Alejandra Cusicanqui Mendez

• Document type: Master's Dissertation
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2017-04-05

Examining board members

Thiago Cruvinel da Silva; Maria Cristina Borsato; Fernanda Lourenção Brighenti; Maria Aparecida de Andrade Moreira Machado

• Advisor: Thiago Cruvinel da Silva

Abstract

The antimicrobial photodynamic therapy (aPDT) has been proposed as an adjuvant therapy for dental caries, although there are not suitable protocols for its clinical application. The aim of this study was to evaluate the effect of the aPDT on the viability of specific microorganism groups and the production of lactic acid from dentin caries microcosms. Dentin samples were collected from three children and used as inoculum to produce biofilm microcosms. The biofilms were grown on bovine dentine discs in anaerobic conditions at 37oC for five days. Then, biofilms were treated by the association of methylene blue with a red LED (630 nm) or curcumin with a blue LED (455 nm). The viability of specific microorganisms was determined by the counts of colony-forming units (CFU) of total microorganisms (Trypticase Soy Agar Blood), total streptococci (Mitis Salivarius Agar), mutans streptococci (Mitis Salivarius Bacitracin Sucrose Agar) and total lactobacilli (Rogosa Agar). The spectrophotometry enzymatic method was used to determine the concentration of L-lactate in culture media. The statistical analysis was performed by KrusKal Wallis and post-hoc Dunns test (P<0.05). Both conditions of aPDT, methylene blue + red LED and curcumin + blue LED, reduced significantly the CFU counts of all microorganism groups. The dosedependent effect was observed only in the combination of methylene blue + red LED. The production of lactic acid depended on the combination of the dye and the LED used. The concentration of lactic acid was significantly reduced after the treatments with the combination of methylene blue with red LED when compared to control group. In contrast, the treatment with the dye alone did not interfere on the acidogenicity of microcosms. When the association of curcumin and blue LED was applied, no significant reductions were observed in the lactic acid concentrations. Therefore, the methylene blue-mediated aPDT was able to reduce the viability and the acidogenicity of dentin caries microcosms, whereas the curcumin-mediated aPDT reduced only the viability of microorganisms. (AU)

• FAPESP's process: 15/08595-9 - Effect of antimicrobial photodynamic therapy on specific microorganisms from dentin caries microcosms
• Grantee: Daniela Alejandra Cusicanqui Méndez
• Support Opportunities: Scholarships in Brazil - Master