The different irradiation parameters of carbon dioxide laser effects on periodontal ligament cells

/purpose: Photobiostimulation (PBS) can affect cellular functions. The objective of the present study was to evaluate the cellular changes in periodontal ligament (PDL) cells that received different carbon dioxide (CO₂) laser irradiation parameters under negative pressure culture.

The negative pressure-cultured PDL cells on normal medium and differentiation medium were subjected to continuous irradiation with a CO₂ laser at an energy density of 5 J/cm² or 10 J/cm². The irradiated PDL cells were harvested at Days 1, 5 and 7, and their viability was analyzed by the Presto Blue assay and the biologic markers alkaline phosphatase (ALP), bone sialopoietin (BSP), osteopontin (OPN), osteocalcin (OC), matrix metalloproteinase-3 (MMP-3) collagen I (Col I) and cyclooxygenase-2 (COX-2) expression by reverse transcription-polymerase chain reaction (RT-PCR).

The PDL cell viability showed that the differentiation medium groups were higher than the normal culture groups. The cell morphologies were all expressed as spindle type. The inflammatory markers in the laser-irradiated groups were higher on the first day and decreased on the seventh day (P < 0.05). Osteogenesis markers were highly expressed at different time periods (P < 0.05). The Col I and OPN genes were highly expressed on the first day, and the Col I high expression lasted until the seventh day. The OC gene was highly expressed on the seventh day. The effects of PDL cultured in differential medium and normal medium were the same in the present study.

A low-dose CO₂ laser continuously irradiating cultured PDL cells can induce osteogenesis and reduce cell inflammatory expression.