In vitro effect of simultaneous irradiation of 635 and 980 nm lasers on proliferation of periodontal ligament mesenchymal cells and their differentiation to osteoblasts
摘要
This study assessed the effect of photobiomodulation therapy (PBMT) by simultaneous irradiation of 635 and 980 nm lasers on proliferation of periodontal ligament (PDL) mesenchymal cells and their osteoblastic differentiation. In this in vitro study, PDL mesenchymal cells were cultured in osteogenic medium. The cells were subjected to PBM by 980 nm diode laser in the first group, PBM by 635 nm diode laser in the second group, and PBM by both lasers in the third group. Each group had two subgroups for one-time irradiation on day 1, and two irradiations on days 1 and 3. The control group did not receive any intervention. Cell proliferation was analyzed by the methyl thiazolyl tetrazolium (MTT) assay (days 1 and 3), apoptosis was assessed by DAPI staining (days 2 and 4), and osteoblastic differentiation was assessed by Alizarin red staining (day 14) and evaluation of expression of osteocalcin (OCN), osteopontin (OPN), and runt-related transcription factor 2 (RUNX2) osteogenic genes by real-time polymerase chain reaction (PCR). Data were analyzed by one-way ANOVA (α = 0.05). Cell viability was the highest in 980 nm laser group with one-time irradiation and 635 nm laser group with two irradiations on day 3. The lowest rate of apoptosis was noted in 635 nm laser group with two irradiations on day 4; this group also showed the best results in Alizarin red staining and the highest expression of all three genes (P < 0.05). PBM by 635 nm laser yielded more promising results regarding proliferation of PDL mesenchymal cells and their differentiation to osteoblasts.