Abstract
It is well known that bone tissues are affected by mechanical stimuli, and that osteocytes could be the key
to understanding the mechanisms of bone metabolism under mechanical stress. Low-power laser irradiation
stimulates wound healing in tissues, and we hypothesized that low-power laser irradiation, which is like
mechanical stimulation, can stimulate bone metabolism. The purpose of this study was to test whether lowpower
laser irradiation influences bone tissue. We used a carbon dioxide (CO2) laser, which is frequently used
in dental clinical situations, to examine the effects of low-power laser irradiation on osteocyte functions using
primary osteocyte-like cells.
Osteocyte-like cells were isolated from rat calvariae with enzyme digestion, and the cells received CO2
laser irradiation at doses of 0, 0.5, 1, and 2 W for 10 sec. Osteocyte-like cells isolated from calvariae exhibited
dendritic processes and expressed sclerostin and dentin matrix protein 1 (Dmp-1), which are characteristic of
osteocytes.
CO2 laser irradiation dose-dependently decreased sclerostin mRNA expression and increased Dmp-1 mRNA
expression. Furthermore, these effects were caused directly by laser irradiation without thermal damage.
These results suggest that low-power CO2 laser irradiation influences bone metabolism via osteocytes, and we
demonstrated the possibility of low-power CO2 laser irradiation for bone regeneration therapy.
