Bactericidal effect of pulsed 1,064 nm Nd:YAG laser light on Staphylococcus epidermidis is of photothermal origin: an in vitro study.

ABSTRACT

BACKGROUND AND OBJECTIVE: The aim was to investigate the bactericidal effect of the 1,064 nm NdYAG laser on Staphylococcus epidermidis. MATERIAL AND METHODS: S. epidermidis was inoculated on agar plates and then exposed to pulsed laser light in three different modes with an uninterrupted train of pulses, or with two different repeated cycles of fractionated trains of pulses. The agar temperature was measured directly after uninterrupted radiation. RESULTS: A bacterial growth inhibition area of 0.3 cm(2) and maximum temperature of approximately 80 degrees C was observed after uninterrupted radiation at 2,000 J cm(-2). The corresponding figures after an exposure of 5,000 J cm(-2) were 0.9 cm(2) and 100 degrees C, respectively. No bacterial inhibition was observed after exposure to repeated cycles of 20 seconds of radiation followed by 60 seconds of rest. CONCLUSION: The antimicrobial effect of the 1,064 nm NdYAG laser light is caused by a photothermal rather than a photochemical effect.