Universidade de São Paulo, SP, Brazil.
Braz Oral Res. 2010 Oct-Dec;24(4):460-6. doi: 10.1590/s1806-83242010000400015.
This in vitro study aimed to analyze the effect of different parameters of phototherapy with low intensity laser on the viability of human dental pulp fibroblasts under the effect of substances released by bleaching gel. Cells were seeded into 96 wells plates (1 x 10³ cells/well) and placed in contact with culture medium conditioned by a 35 % hydrogen peroxide bleaching gel for 40 minutes, simulating the clinical condition of the in-office bleaching treatment. Cells cultured in ideal growth conditions served as positive control group (PC), and the cells grown in conditioned medium and non-irradiated served as negative control group (NC). Cells grown in conditioned medium were submitted to a single irradiation with a diode laser (40 mW, 0.04 cm²) emitting at visible red (660 nm; RL) or near infrared (780 nm; NIR) using punctual technique, in contact mode and energy densities of 4, 6 or 10 J/cm². The cell viability was analyzed through the MTT reduction assay immediately and 24 hours after the irradiation. The data was compared by ANOVA followed by the Tukey's test (p ≤ 0.05). The cell viability increased significantly in 24 hours within each group. The PC presented cell viability significantly higher than NC in both experimental times. Only the NIR/10 J/cm² group presented cell viability similar to that of PC in 24 hours. The phototherapy with low intensity laser in defined parameters is able to compensate the cytotoxic effects of substances released by 35 % hydrogen peroxide bleaching gel.
本体外研究旨在分析低强度激光光疗的不同参数对人类牙髓成纤维细胞活力的影响，这些细胞受到漂白凝胶释放物质的影响。将细胞接种到 96 孔板中（1x10³个细胞/孔），并与 35%过氧化氢漂白凝胶的条件培养基接触 40 分钟，模拟临床诊室漂白治疗的情况。在理想生长条件下培养的细胞作为阳性对照组（PC），在条件培养基中生长且未辐照的细胞作为阴性对照组（NC）。在条件培养基中生长的细胞采用单点照射技术，用二极管激光（40 mW，0.04 cm²）进行照射，发射可见红光（660nm；RL）或近红外光（780nm；NIR），接触模式和能量密度分别为 4、6 或 10 J/cm²。通过 MTT 还原测定法立即和辐照后 24 小时分析细胞活力。通过方差分析（ANOVA）比较数据，然后进行 Tukey 检验（p≤0.05）。在每个组内，24 小时内细胞活力显著增加。在两个实验时间点，PC 的细胞活力均显著高于 NC。只有 NIR/10 J/cm²组在 24 小时时的细胞活力与 PC 相似。在定义的参数下，低强度激光光疗能够补偿 35%过氧化氢漂白凝胶释放物质的细胞毒性作用。
