ABSTRACT
BACKGROUND: The purpose of this in vitro study was to evaluate the efficacy of erythrosine and cyanidin-3-glucoside as photosensitizers in PDT for the elimination of Porphyromonas gingivalis (P. gingivalis) biofilms. METHODS: P. gingivalis biofilms were prepared from a chronic periodontitis subject. Erythrosine and cyanidin-3-glucoside were prepared and randomly allocated as follows: 110, 220, 330, and 440µM erythrosine; 101, 202, 303, and 404µM anthocyanin; and 440µM erythrosine+404µM cyanidin-3-glucoside. There were 18 PDT experimental groups (non-irradiated/irradiated with a 532-nm green light diode laser at 1.29J/cm2 for 60s). The 3 controls were grouped as follows: biofilms exposed to the photosensitizers alone, biofilms exposed to the laser alone, and biofilms exposed to 0.12% chlorhexidine. All sample groups were cultured at 1, 3 and 6h after PDT and incubated in an anaerobic chamber at 37°C for 4days. The surviving fraction was calculated from the log10 CFU/ml. The 330 and 440µM erythrosine and the 440µM erythrosine+404µM cyanidin-3-glucoside were mixed with spin traps (TEMPO, DMPO), and the electron spin resonance spectra were evaluated. RESULTS: The log10 CFU/ml measurements showed that the PDT groups with 330µM or 440µM erythrosine and 440µM erythrosine+404µM cyanidin-3-glucoside had statistically significant differences from the other groups (one-way ANOVA and Bonferroni's multiple comparison test, p- value≤0.05). CONCLUSIONS: PDT using 330µM erythrosine, 440µM erythrosine or 440µM erythrosine+404µM cyanidin-3-glucoside irradiated with the laser more effectively inhibited P. gingivalis in biofilms.
