LAUSR

This study aimed to evaluate type 1 collagen (COL1) gene expression by human pulp fibroblasts from primary teeth (HPF) after the variation of photobiomodulation (PBM) parameters. HPF were obtained from a biorepository, used at 4th passage, and irradiated (InGaAlP—660 nm) varying the power and application time according to the following groups: G1: 1.2 J cm−2–05 mW–10 s; G2: 2.5 J cm−2–05 mW–20 s; G3: 3.7 J cm−2–05 mW–30 s; G4: 5.0 J cm−2–05 mW–40 s; G5: 6.2 J cm−2–05 mW–50 s; G6: 2.5 J cm−2–10 mW–10 s; G7: 3.7 J cm−2–15 mW–10 s; G8: 5.0 J cm−2–20 mW–10 s; G9: 6.2 J cm−2–25 mW–10 s. The control group (G10) was not irradiated and maintained with DMEM + 10% SFB. RT-PCR was used to evaluate COL1 gene expression at 6, 12, and 24 h after irradiation. Intra- and intergroup comparisons were performed by two-way ANOVA followed by Tukey test (p 0.05). The energy densities from 2.5 to 5 J cm−2, regardless of the variation in PBM parameters, biomodulated the COL1 gene expression. At the energy density of 6.2 J cm−2, longer application time and smaller power changed the pattern of COL1 gene expression by pulp fibroblasts from human primary teeth.