Department of Orthodontics, Juiz de Fora Federal University, Juiz de Fora, Minas Gerais, Brazil.
Am J Orthod Dentofacial Orthop. 2010 May;137(5):665-70. doi: 10.1016/j.ajodo.2008.07.017.
Ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade and release bisphenol-A and formaldehyde, respectively. More reliable tests are needed to assess the potential toxicity of these materials. In addition to traditional cytotoxicity tests, the study of nitric oxide (NO) cellular production stimulated by a specific material has been shown to be a reliable tool for evaluating cytotoxic potential. The purpose of this study was to assess, with esthetic brackets, cellular viability by 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide assay (Sigma, St. Louis, Mo) in the macrophage cell line J774 stimulated with interferon gamma. Interferon gamma is a key cytokine in the activation of macrophages, plays an important role in immunologic processes, and also quantifies NO production by these macrophages.
Well plates were seeded with 2 x 104 J774 cells per well, in a volume of 100 microL, resuspended in Roswell Park Memorial Institute Supplemented Medium 1640. The macrophage cell line J774 was stimulated with interferon gamma. Ceramic, polycarbonate, and polyoxymethylene brackets were added and kept in the culture for 24, 48, or 72 hours in 5% carbon dioxide at 37 degrees C; the control samples did not include brackets. At the end of each incubation period, the supernatant was collected for posterior NO quantification, and the cells were evaluated for cytotoxicity.
Cellular viability in all groups was higher at 72 hours than at 24 hours. The final means in the bracket groups did not show significant differences compared with the control group. NO production was significantly greater in all groups at the final time than at the initial time. However, the brackets with the interferon gamma stimulation did not result in greater NO production than did the cells in the control group.
陶瓷托槽在口腔中化学惰性，而聚碳酸酯和聚甲醛托槽则分别会降解并释放出双酚 A 和甲醛。需要更可靠的测试来评估这些材料的潜在毒性。除了传统的细胞毒性测试外，研究特定材料刺激下的一氧化氮（NO）细胞产生已被证明是评估细胞毒性潜力的可靠工具。本研究的目的是使用美学托槽，通过 3，（4，5-二甲基噻唑-2-基）-2，5-二苯基四唑溴盐测定法（Sigma，圣路易斯，密苏里州）评估 J774 巨噬细胞系在干扰素 γ刺激下的细胞活力。干扰素 γ是激活巨噬细胞的关键细胞因子，在免疫过程中发挥重要作用，还可以量化这些巨噬细胞产生的 NO。
将 2 x 104 J774 细胞接种于每孔 100 μL 的孔板中，悬浮于罗塞斯公园纪念研究所补充培养基 1640 中。用干扰素 γ刺激巨噬细胞系 J774。将陶瓷、聚碳酸酯和聚甲醛托槽加入并在 5%二氧化碳、37°C 的条件下保持培养 24、48 或 72 小时；对照组不包括托槽。在每个孵育期结束时，收集上清液用于后续 NO 定量，并评估细胞毒性。
所有组在 72 小时的细胞活力均高于 24 小时。支架组的最终平均值与对照组相比没有显著差异。所有组在最终时间的 NO 产量均显著高于初始时间。然而，与对照组相比，干扰素 γ 刺激下的支架并未导致更多的 NO 产生。
