Comparison of the effects of continuous and pulsed blue light for reduction of Enterococcus faecalis biofilms

Mature biofilms exhibited minimal antimicrobial susceptibility. This study compares the decontamination effect of 450 nm continuous wave (CW) and pulsed wave (PW) blue diode laser with two different photosensitizers (curcumin and riboflavin) against mature Enterococcus faecalis biofilm model. Four irradiation parameter sets A (CW, peak power 0.4 W, and average fluence of 24 J/cm²), B (PW, duty cycle (DC) 50%, peak power 0.8 W, and average fluence of 24 J/cm²), C (CW, peak power 0.5 W, and average fluence of 30 J/cm²), and D (PW, DC 50%, peak power 1.0 W, and average fluence of 30 J/cm²) were used. The results showed that all irradiation parameters achieved a significant bacterial reduction compared to the control (p < 0.001). However, PW showed a more pronounced reduction effect than CW, with the difference being particularly marked at an average fluence of 30 J/cm². Curcumin or riboflavin without 450 nm blue diode laser irradiation had no antimicrobial effect (p > 0.05). PW light has the potential to improve the efficacy of a blue diode laser. However, the correct choice of parameters is required to achieve adequate laser fluence.