Effects of photobiomodulation using 980 and 660 nm diode lasers on osteoprotegerin and RANKL expression in...

This study assessed the effects of photobiomodulation (PBM) with 980 and 660 nm low-level diode laser on the expression of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-Β ligand (RANKL) genes by human periodontal ligament stem cells (PDLSCs) under static loading. In this in vitro study, cultured human PDLSCs were randomly assigned to 8 groups; of which, 7 groups underwent static loading (2 g/cm² culture medium) by using glass slides for 48 h plus 660 nm laser irradiation in the beginning (group 1) or at the end (group 2) of loading, 660 nm laser irradiation in the beginning and at the end of loading (group 3), 980 nm laser irradiation in the beginning (group 4), or at the end (group 5) of loading, and 980 nm laser irradiation in the beginning and also at the end of loading (group 6) all with 4 J/cm² energy density for 16 s twice. In group 7 (pressure alone), the cells only underwent static loading. In group 8 (no pressure/no laser), the cells did not undergo static loading or laser irradiation, and were only incubated for 48 h. Expression of OPG and RANKL genes was analyzed by quantitative real-time polymerase chain reaction (PCR). PBM with 660 and 980 nm laser at the beginning of static loading with/without a repeat irradiation at the end caused upregulation of RANKL. PBM with 660 nm laser at the beginning of static loading with/without a repeat irradiation at the end caused upregulation of OPG. PBM with 980 nm laser at the end of loading caused upregulation of OPG. PBM with 660 nm diode laser at the beginning of static loading and a repeat irradiation at the end can cause upregulation of OPG and RANKL in human PDLSCs.