The impact of photobiomodulation therapy by diode lasers at wavelengths of 450 nm, 980 nm and their combinations on the proliferation and differentiation of periodontal ligament mesenchymal stem cells

This study was conducted to investigate the effects of photobiomodulation utilizing a 450, 980 nm laser and a combination of these wavelengths on the growth and differentiation of periodontal ligament mesenchymal stem cells (PDLMSCs). PDLMSCs were cultured and assessed in four groups. The first one received 450 nm, the second 980 nm. Each received 4 J/cm 2 of radiation. Third group: 2 J/cm 2 from 450 nm blue laser and 2 J/cm 2 from 980 nm laser hit cells with total energy density of 4 J/cm 2 . All irradiations were done once. Control was the fourth non-irradiated group. Cell viability/proliferation was measured using MTT. RT-PCR measured osteogenic markers like alkaline phosphatase (ALP), RUNT-related transcription factor 2 (RUNX2), and osteopontin (OPN), osteocalcin (OCN). The Alizarin red test was used to measure colonization. Annexin V measured viable, early, and late apoptosis and necrosis. Data analysis used a one-way analysis of variance. In the MTT experiment on days 2 and 4, the 980 nm group had the highest cell proliferation rate, but the mix group had a control group-like rate on day 4. RT-PCR showed that the 980 nm group differentiated highest, followed by the 450 nm group at a lower rate. In contrast, the mixed group showed results similar to or lower than the control except for OPN expression. 980 nm group had the most alizarin red mineralization. The mixed group had the most apoptosis. It was demonstrated that 450 nm and 980 nm laser photobiomodulation increased PDLMSC proliferation and osteogenic differentiation. Combining these wavelengths did not affect cell growth or differentiation.