Comparison of the low level laser therapy effects on cultured human gingival fibroblasts proliferation using different irradiance and same fluence

Background and Objective: The low level laser therapy (LLLT) has been used in Dentistry to improve wound healing. In order to analyse the effect of LL LT on the in vitro proliferation of gingival fibroblasts we developed a pri mary culture of human gingival fibroblasts. Study Design/Materials and Methods: The cell line named LMF was grown in Du lbecco's Modified Eagle's medium (DME) with either 5% (nutritional deficit) or 10% fetal bovine serum (fbs). Laser irradiation was carried out with di ode lasers with the following wavelengths: 670 nm (L1), 780 nm (L2), 692 nm (L3), and 786 nm (L4). The fluence, was fixed in 2 J/cm(2). For growth ana lysis, control (not irradiated) and treated cultures (irradiated) were plat ed in 60 mm diameter culture dishes for 12 h before the irradiation. Results: We found that cells cultured in nutritional deficit condition grow n in medium supplemented by only 5% fbs presented a cell proliferation rate significantly smaller that cell grown in ideal culture conditions (10% fbs ). However, when irradiated, cells in nutritional deficit presented cell gr owth similar or higher than that of control cells grown in ideal culture co nditions. Using the same fluence, the infrared laser induced a higher cell proliferation than visible laser when the power outputs were different. How ever, lasers of equal power output presented similar effect on cell growth independently of their wavelengths. Conclusions: The LLLT acts by improving the in vitro fibroblast proliferati on and a smaller laser exposure time results in higher proliferation. (C) 2 001 Wiley-Liss, Inc.