Original Research Articles
Vol. 33 No. 1 (2026)
Antimicrobial effect of the photodynamic therapy on caries lesion: an in vitro study
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All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
Published: 16 April 2026
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The current evidence suggests that antimicrobial photodynamic therapy (aPDT) with the application of methylene blue as a photosensitizer and red laser activation is suitable for disinfecting carious tissue. However, since many dental practices lack access to lasers, a standard dental curing light could be an alternative light source. This study evaluated the use of fuchsin as a photosensitizer in aPDT and a blue light-emitting diode (LED) dental curing light for the disinfection of carious dentin. Sixty permanent third molars were selected, cut to obtain flat dentin surfaces, and subjected to a 15-day cariogenic challenge with Streptococcus mutans. The specimens were allocated into four groups (n=15): no disinfection; fuchsin; blue LED irradiation; and aPDT (fuchsin plus blue LED irradiation). S. mutans counts were obtained in the remaining carious dentin from all specimens across all groups. Results were analyzed by the Kruskal-Wallis test (Student-Newman-Keuls). The percentage reduction in microbial load was 96.07% for aPDT, 88.85% for LED alone, and 85.46% for fuchsin alone. SEM demonstrated a greater reduction in microbial burden after aPDT with fuchsin and blue LED light, with removal of the smear layer and exposure of dentin tubules. Fuchsin-mediated aPDT using blue LED irradiation significantly reduced microbial load and may represent a viable alternative for the disinfection of carious tissue, particularly in settings without access to laser devices.
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Supporting Agencies
This study was supported by undergraduate research scholarships from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundo de Apoio à Iniciação Científica/Reitoria PUC-Campinas (Brazil), which were essential for enabling student participation in scientific research, as well as for supporting the execution of laboratory procedures and data collection, thereby contributing to the advancement of knowledge in this field.How to Cite
Antimicrobial effect of the photodynamic therapy on caries lesion: an in vitro study. (2026). Laser Therapy, 33(1). https://doi.org/10.4081/ltj.2026.436
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