Figure 3.
Effect of UV irradiation on the viability of cultured oral cells. HGF (15 PDL), HPC (16 PDL), HPLF (15 PDL), HSC-2, HSC-4 and Ca9-22 cells were A: exposed to UV irradiation (6 J/m2/min, 1 minute) for 2 min in 0, 0.05, 0.1, 0.2 or 0.4 ml of DMEM supplemented with 10% FBS (i), or PBS (−) (ii), or B: exposed for 30, 60, 120, 180 or 240 s in 0.1 ml PBS (−). After removing the medium or PBS (−), the cells were incubated for 48 hours in fresh culture medium. The viable cell number was then determined by MTT method, and expressed as a percentage that of control cells not exposed to UV irradiation. Each value represents the mean of three determinations.