Low-energy diode laser irradiation reduced plasminogen activator activity in human periodontal ligament cells.

BACKGROUND AND
OBJECTIVE: The plasminogen activator (PA)-plasmin proteolytic system is implicated in the degradation of the extracellular matrix in inflammation. Since human periodontal ligament (PDL) cells produced high PA activity in response to mechanical stress, excessive mechanical stress to PDL cells such as occlusal trauma may induce collagen breakdown through activation of the PA-plasmin system. As low-energy laser irradiation has anti-inflammatory effects, we examined the effects of low-energy laser irradiation on the PA-plasmin system in stretched PDL cells in vitro. STUDY DESIGN/
MATERIALS AND METHODS: Human PDL cells obtained from healthy premolars were mechanically stretched and Ga-Al-As low-energy laser was irradiated (830 nm, 3.95 to 7.90 J/cm2) to the stretched cells.
RESULTS: PDL cells showed a marked elevation in PA activity in response to stretching, which was significantly inhibited by a laser irradiation in a dose-dependent manner (55-86%, p < 0.001). This effect could involve transcriptional events of tissue type (t) PA gene.
CONCLUSION: These results suggests that laser irradiation may reduce collagen breakdown around the PDL associated with traumatic occlusion.