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Updated: Apr 19, 2026
LED-Based In Vitro Screening for Assessing Photoactivable Molecules in Bacterial Photodynamic Inactivation
Published on: January 24, 2025
Comparative evaluation of photodynamic therapy using LASER or light emitting diode on cariogenic bacteria: An in
Liliana Guimarães Oliveira Ricatto1, Luis Augusto Lopato Conrado2, Cecilia Pedroso Turssi1
1Department of Restorative Dentistry, São Leopoldo Mandic Institute and Research Center, Campinas, São Paulo, Brazil.
Objective:
The aim of this study was to evaluate in vitro the effect of photodynamic therapy (PDT) using LASER or light emitting diode (LED) on cariogenic bacteria (Streptococcus mutans [SM] and Lactobacillus casei [LC]) in bovine dentin.
Materials And Methods:
Twenty five fragments of dentin were contaminated with SM and LC strands and divided into five experimental groups according to the therapy they received (n = 5): C - control (no treatment), SCLED - no dye/LED application (94 J/cm(2)), SCLASER - no dye/LASER application (94 J/cm(2)), CCLED - dye/LED application (94 J/cm(2)) and CCLASER - dye/LASER application (94 J/cm(2)). The dye used was methylene blue at 10 mM. Dentin scrapes were harvested from each fragment and prepared for counts of colony forming units (CFU)/mL. The data were analyzed using Kruskal-Wallis, followed by Student-Newman-Keuls (α =0.05).
Results:
Regarding SM, groups CCLASER and CCLED showed a significant reduction in CFU/mL, which was statistically superior to the SCLASER, SCLED and C groups. Regarding LC, the groups CCLASER and CCLED caused a significant reduction in CFU/mL when compared with SCLASER, which showed intermediate values. SCLED and C had a lesser effect on reducing CFU/mL, where the former showed values similar to those of SCLASER.
Conclusions:
In conclusion, PDT combined with LASER or LED and methylene blue had a significant antimicrobial effect on cariogenic bacteria in the dentin.
