Influence of different concentrations of potassium iodide associated with methylene blue on the reduction of microorganisms in multispecies biofilm

• Grant number: 23/04809-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): August 01, 2023
• Effective date (End): July 31, 2024
• Field of knowledge: Health Sciences - Dentistry - Pediatric Dentistry
• Principal Investigator: Carolina Steiner Oliveira Alarcon
• Grantee: Érica de Sousa Pereira
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

Dental caries is the most prevalent oral disease and has a multifactorial etiology mediated by frequent sugar intake and the individual's susceptibility to biofilm formation. The dental biofilm is formed by a diversified microbial community and its treatment is challenging, since it depends on the patient's collaboration. Antimicrobial photodynamic therapy is a promising alternative, but new strategies, such as different formulations of the photosensitizer, aim to improve the antimicrobial action of the therapy. The aim of this study will be to test the antimicrobial action of TFDA, mediated by 0.005% methylene blue (AM) associated with different concentrations of potassium iodide (KI) and with different pre-irradiation times, against microorganisms organized in a multispecies biofilm. Ninety bovine incisors will be used to obtain specimens and subsequent biofilm formation using a microcosm model, from an inoculum formed by human saliva. The specimens will be divided into eight groups (n=3, in triplicate), with NaCl 0.9% and chlorhexidine 0.2% as negative and positive control groups, respectively. The KI concentrations will be 50, 75 and 100 mM, in two times of pre-irradiation of the photosensitizer of 5 or 10 minutes. The irradiation will be performed by a low-power laser (GaAlAs, Ž = 660 nm) in continuous mode, with a beam (Ø = 0.09 cm2) focused at 2.0 mm from the biofilm, with a power of 100 mW, 18 J of energy for 180 s. After the treatments, the biofilm of each block will be collected and the colony forming units (CFU/ml) will be counted. The data obtained will be checked for normality and homoscedasticity, using the Shapiro-Wilk and Levene tests, respectively, and the most appropriate test will be selected for comparison, with a significance level of 5%.