Comparison between the effect of low-level laser therapy and low-intensity pulsed ultrasonic irradiation in vitro.

ABSTRACT

OBJECTIVE: The objective of this study was to compare the effect of low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) on fibroblast cell culture. Several methods, including ultrasound treatment and LLLT, are being used to facilitate tissue repair and healing processes. MATERIALS AND METHODS: L929 fibroblast cell cultures were irradiated with low-level laser energy and LIPUS. Cultures irradiated with ultrasound were divided into five groups group 1 control (did not receive irradiation); group 2 0.2 W/cm(2) in pulsed mode at 10% (19 duty cycle); group 3 0.6 W/cm(2) in pulsed mode at 10% (19 duty cycle); group 4 0.2 W/cm(2) in pulsed mode at 20% (28 duty cycle); and group 5 0.6 W/cm(2) in pulsed mode at 20% (28 duty cycle). Cultures irradiated with laser energy were divided into three groups group 1 control (did not receive irradiation); group 2 6 J/cm(2); and group 3 50 mJ/cm(2). Each group was irradiated at 24-h intervals, with the following incubation periods post-irradiation 24, 48, and 72 h; after each irradiation cycle the cultures were analyzed using MTT [3-(4.5-dimethylthiazol-2-yl)-2.5 diphenyltetrazolium bromide]. RESULTS: Analysis of results after LLLT and LIPUS demonstrated that the effect of laser therapy on fibroblast cell culture was greater than that of LIPUS (p < 0.05). CONCLUSION: Results demonstrated that LLLT significantly increased fibroblastic activity more than LIPUS. Therefore, in the first and second phases of tissue repair, laser treatment may be more effective than ultrasound treatment.