EVALUATION OF PHOTODYNAMIC THERAPY IN MICROORGANISMS ASSOCIATED WITH ORAL INFECTIONS: IN VITRO STUDY

Abstract

This study aimed to investigate the effectiveness of Photodynamic Therapy (PDT) in vitro against oral microorganisms, with emphasis on Streptococcus viridans. These microorganisms are associated with oral bacteremia and infectious endocarditis, highlighting the importance of exploring alternative treatments in light of the challenges of antibiotic therapy, such as side effects and microbial resistance. A quantitative experimental approach was conducted, testing different energy levels on S. viridans colonies. A red diode laser (660 nm) was used in combination with methylene blue 0.01% as the photosensitizer. The applied energy levels were 9 J (90s), 10 J (100s), 13 J (130s), 16 J (160s), and 18 J (180s). Samples were cultured in appropriate media and exposed to PDT under controlled conditions, following standardized protocols to assess post-treatment microbial viability. Lower energy levels (9 J and 10 J) had limited effects. It is concluded that PDT is a promising alternative for the control of S. viridans, particularly at higher energy doses, with potential as an adjuvant therapy for oral infections, reducing antibiotic dependence and microbial resistance risks. Further studies are required to optimize parameters and evaluate in vivo efficacy.