Bactericidal effect of a 405-nm diode laser on Porphyromonas gingivalis

✍ Scribed by Y. Kotoku; J. Kato; G. Akashi; Y. Hirai; K. Ishihara

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 129 KB
• Volume: 6
• Category: Article
• ISSN: 1612-2011
• DOI: 10.1002/lapl.200910011

✦ Synopsis

The study was conducted to determine the effect of 405-nm diode laser irradiation on periodontopathic bacteria such as Porphyromonas gingivalis in vitro. A diluted suspension of P. gingivalis was irradiated directly with a 405-nm diode laser under conditions of 100 mW-10 sec, 100 mW-20 sec, 200 mW-5 sec, 200 mW-10 sec, 200 mW-20 sec, 400 mW-5 sec, 400 mW-10 sec, and 400 mW-20 sec. The energy density ranged from 2.0 to 16.0 J/cm 2 . The irradiated bacterial suspension was spread on a blood agar plate and growth of the colonies was examined after an anaerobic culture for 7 days. Bacterial growth was inhibited under all irradiation conditions, but the bactericidal effect of the 405-nm diode laser depended on the energy density. More than 97% of bacterial growth was inhibited with irradiation at an energy density > 4.0 J/cm 2 . The mechanism of the bactericidal effect is photochemical, rather than photothermal. These findings suggest that a 405-nm diode laser has a high bactericidal effect on P. gingivalis.

Survival ratio, %