Antimicrobial photodynamic therapy and its effect over biofilm responsible by dental caries

• Grant number: 15/21183-1
• Support type: Regular Research Grants
• Duration: February 01, 2016 - July 31, 2018
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal researcher: Alessandra Nara de Souza Rastelli
• Grantee: Alessandra Nara de Souza Rastelli
• Home Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Assoc. researchers: Clovis Grecco ; Marlus Chorilli ; Sebastião Pratavieira

Abstract

The aim of this study is to evaluate the effect of APDT using different photosensitizers in multi species biofilms (Streptococcus mutans, Streptococcus sobrinus and Actinomyces naeslundi) induced on the surface of hydroxyapatite discs for 7 days. Curcumin, curcuminoids, chlorin-e6 and zinc phthalocyanine incorporated or not in nanostructured liquid crystal precursors or not irradiated by LED (450 or 660nm) at energy density of 15J/cm2 will be used in concentrations previously determined by MIC and MIB. In addition, the dark cytotoxicity of photosensitizers as well as the mechanisms involved in photodynamic reaction by optical absorption, fluorescence and estimate the generation of singlet oxygen and OH- radicals will be performed. For the antibacterial activity we will use the technique for counting of colony forming units (CFU/mL), percentage of survival and metabolism of the biofilm by XTT test, biochemistry of biofilms, cell viability, architecture (3D structure, biovolume and thickness) and synthesis of polysaccharides by confocal Laser microscopy. Different conditions will be tested: a) irradiation LED (L ) + photosensitizer (P) (L+ P+); b ) LED irradiation only (L+P -); c) only photosensitizer (L- P+); d) no LED irradiation and without photosensitizer (L-P-) for all photosensitizers and e) chlorhexidine (C). Cytotoxicity in odontoblast cells culture will be also investigated for the photosensitizer that show the best results for CFU/mL and metabolism of biofilm by XTT test.After the results obtained during the previous experiments, the photosensitizer that provide the best results will be applied in artificial caries induced in fragments of bovine enamel and dentin by multi species biofilms associated with fluoride or bioactive glass in order to provide the remineralization of the dental surfaces. The results will be submitted to descriptive statistical analysis, analysis of variance (ANOVA) and Tukey's test at 5% significance level. If the data show not normality and homoscedasticity, the data will be submitted to non-parametric statistical analysis. (AU)