EFFECTS OF LOW INCIDENT ENERGY LEVELS OF INFRARED LASER IRRADIATION ON THE PROLIFERATION OF STREPTOCOCCUS MUTANS

抄録

This study was undertaken to determine whether the infrared (IR) beam of the gallium-arsenide (GaAs) laser at low reactive-level laser therapy (LLLT) levels has biostimulative effect on the oral flora as well as the tissue cell using spectrophotometeric assay, and to suggest an hypothesis on the mechanism of accelerated healing following low reactive-level laser therapy (LLLT) of the infected lesion according to the previously reported results that there were changes in the composition of various kinds of bacteria in addition to the decrease in the gingival inflammation. Eighty samples of Streptococcus mutans for 4 days were used and divided into four groups. (control, 1 min, 2 min, 3 min). Five samples of each group were sacrificed everyday for 4 days using a spectrophotometer to measure the optical density, and then the control and experimental groups were compared according to the time interval and irradiation time. Conclusions based on the results for this study were as follows: (l) Gallium-arsenide laser irradiation at LLLT levels stimulated the increase of bacterial growth. (2) The rate of increase of bacteria did not coincide with that of laser fluence and the biostimulative effect of LLLT on bacterial cells was most effective when the energy fluence was at 337.0 mJ at the parameters in this study.