Abstract: Optical parameters such as wavelength, power density and irradiation time have important effects on the bactericidal effect of phototherapy. This study aimed to explore the optimal optical parameters of LED phototherapy to inhibit the proliferation of oral bacteria, and provide a basis for the formulation of optical therapy for clinical oral bacterial infectious diseases. Enterococcus faecalis and Porphyromonas gingivalis were inoculated in 96-well plates and irradiated with the self-made 405 nm LED and 455 nm LED with power densities of 10 mW/cm2 and 40 mW/cm2. Energy densities of the LEDs ranged from 9.6 to 33.6 J/cm2. After 30 min, the bactericidal effect of phototherapy was evaluated by bacterial fluorescent staining or plate counting. The results showed that 405/455 nm LED had significant bactericidal effects on both kinds of bacteria. The maximum bacteriostatic rate (96.05±1.80)% of P. gingivalis was achieved with 405 nm LED with 40 mW/cm2 at light dose of 33.6 J/cm2. The maximum bacteriostatic rate (97.64±2.31)% of E. faecalis was achieved with 405 nm LED with 10 mW/cm2 at light dose of 33.6 J/cm2. It indicated that LED illumination can achieve significant bacteriostatic effects on common oral pathogens with appropriate optical parameters, while 405 nm LED with light dose of 33.6 J/cm2 could achieve the best effect in the study.
Key words: LED phototherapy; endogenous photosensitizer; Enterococcus faecalis; Porphyromonas gingivalis; oral infection
（Acta Laser Biology Sinica, 2022, 31(2): 104-113）