How the photodynamic therapy application can influence the formation of different generations of Streptococcus mutans biofilm

• Grant number: 12/15314-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2012
• End date: November 30, 2013
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Alessandra Nara de Souza Rastelli
• Grantee: Vinicius Aparecido Zotesso
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Associated research grant: 98/14270-8 - Center for Optical and Photonics Science, AP.CEPID

Abstract

Regarding the methods to prevent dental caries, the chemical and mechanical control of dental biofilm have great importance in this process. Additionally to mechanical control, different chemical antimicrobial techniques have been used to control oral biofilms. In this sense, photodynamic antimicrobial chemotherapy (PACT) has been used because promotes bacterial death as a result of the photosensitization of microbial components and then has been used to provide the reduction or the control of different species of oral biofilms. However, few studies have investigated its efficacy over biofilms responsible for dental caries and mainly over different generations of Streptococcus mutans biofilm. Then, the purpose of this study will be to evaluate the effect of photodynamic therapy using one photosensitizer at different concentrations irradiated with different light doses over different generations of Streptococcus mutans biofilm. The biofilm will be induced on the enamel surface of bovine teeth slabs for 72 hours. PACT procedures were performed by the association between one photosensitizer based on curcumin at different concentrations (20, 40, and 80µM) and a visible RGB Biotable® (440 nm; doses of 15, 30, and 45 J/cm2) as a light source. Different experimental conditions will be tested: a) LED irradiation (L) in the presence of curcumin as a photosensitizer (PS) at different concentrations (PS+L+); b) LED irradiation only (PS-L+); c) treatment with photosensitizer (PS+L-); d) no LED irradiation or photosensitizer treatment (PS-L-), and e) application of chlorhexidine (C). The different treatments will be made in different Streptococcus mutans biofilm generations (immediately after, 6, 8, 12 and 24 hours after the first PACT application). After treatment, the strains were seeded onto BHI agar for determination of the number of colony-forming units (CFU/mL) and after that, the CFU/mm2 and percentage survival were calculated. The biofilm of each experimental Group will be stained with LIVE/DEAD® BacLightTM fluorescent dye (Molecular Probes, Eugene, OR, USA) to analyze the bacterial viability using a confocal laser scanning microscope (CLSM) before and after the different treatments. The results will be submitted to Analysis of Variance (ANOVA) and the Tukey test at 5% of the significant level.(AU)