Fig. 4.

Effect of 310 nm UVB-LED on human gingival epithelial cells. Ca9–22 cells were seeded at a density of 2 × 10⁴ cells/well in 96-well cell culture plates. The cells were irradiated by a UV-LED (265 nm or 310 nm) for 60–240 s and were incubated for 24 h. Cytotoxicity of UV LED irradiation to the cells was measured by WST-8 assay. (n = 3, means ± SE; **P < 0.01 vs. 0 s,*P < 0.05 vs. 0 s)