Effect of laser on odontoblasts exposed to bleaching agents

The toxicity of the bleaching agents to pulp cells has been demonstrated in several papers. However, scant data are available about ways to reduce these toxic effects to pulp cells. The aim of this study was to evaluate the effects of low level laser irradiation on odontoblast-like cells treated or not with hydrogen peroxide (HP) MDPC-23 cells were seeded (12,500 cells/cm2) in wells of 24-well dishes. Eight groups were established according to the exposition to bleaching agent (none; HP/1h) and energy density applied (none; 4J/cm2; 10J/cm2; 15J/cm2). After the exposition to HP, the cells were irradiated. After 24 h of the treatment, the metabolism of the cells was evaluated by MTT assay and the data were analyzed statistically by two-way ANOVA and Tukey''s test (α=0,05). The statistical analysis detected a reduction on the cell metabolism on groups that. No cell metabolism difference was observed when those groups in which the non-treated cells submitted to laser irradiation were compared to the control group (p>0,05).

It was concluded that HP is capable to cause reduction on metabolism of the MDPC-23 cells, which was not modulated by the specific energy densities of LLL applied to these cells.