Low-level Laser Therapy Effects on Pulp Cells from Human Primary Teeth

The aim of this study was to verify the influence of different energy densities of low-level laser therapy (LLLT) on the viability and proliferation of pulp fibroblasts of human primary teeth (HPF).Cultures of fibroblast were irradiated with LLLT according to experimental groups: I (1.2 J/cm 2 ), II (2.5 J/cm 2 ), III (3.7 J/cm 2 ), IV (5.0 J/cm 2 ), V (6.2 J/cm 2 ), and VI (not irradiated).Cell viability was determined 6 and 24 hours after of irradiation using 3-(4, 5-dimethyl-2-thiazolyl) -2, 5-diphenyl -2H-tetrazolium bromide (MTT) assay.Cell proliferation was assessed through sulforhodamine B (SRB) assay after 24, 48, and 72 hours of irradiation.Data were submitted to two-way analysis of variance (ANOVA) and Tukey test (p < 0.05).After 6 hours of irradiation, group III exhibited the greatest cell viability compared with other groups.After 24 hours, group I exhibited the smallest absorbance value compared with group VI.To cell proliferation, 24 and 48 hours after irradiation, all groups showed similar results to those of group VI.After 72 hours, group I showed lower cell proliferation than the others.Group V exhibited results very similar to those of group VI.This study suggests that different energy densities of LLLT influenced the viability and proliferation of HPF.