Department of Dental Materials, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
Am J Orthod Dentofacial Orthop. 2012 Jul;142(1):70-4. doi: 10.1016/j.ajodo.2012.02.025.
In this study, we evaluated the cellular viability of various esthetic, metallic, and nickel-free orthodontic brackets.
The sample was divided into 11 groups (n = 8): cellular control, negative control, positive control, metallic, polycarbonate, 2 types of monocrystalline ceramic, 3 types of nickel free, and polycrystalline ceramic brackets. Cell culture (NIH/3T3-mice fibroblasts) was added to the plates of 96 wells containing the specimens and incubated in 5% carbon dioxide at 37°C for 24 hours. Cytotoxicity was analyzed qualitatively and quantitatively. Cell growth was analyzed with an inverted light microscope, photomicrographs were obtained, and the results were recorded as response rates based on modifications of the parameters of Stanford according to the size of diffusion halo of toxic substances. Cell viability was analyzed (MTT assay); a microplate reader recorded the cell viability through the mitochondrial activity in a length of 570 nm. The values were statistically analyzed.
All tested brackets had higher cytotoxicity values than did the negative control (P <0.05), with the exception Rematitan and Equilibrium (both, Dentaurum, Ispringen, Germany) (P >0.05), suggesting low toxicity effects. The values showed that only polycarbonate brackets were similar (P >0.05) to the positive control, suggesting high toxicity.
The brackets demonstrated different ranges of cytotoxicity; nickel-free brackets had better biocompatibility than the others. On the other hand, polycarbonate brackets were made of a highly cytotoxic material for the cells analyzed.
本研究评估了各种美观、金属和无镍正畸托槽的细胞活力。
样本分为 11 组（n=8）：细胞对照、阴性对照、阳性对照、金属、聚碳酸酯、两种单晶陶瓷、三种无镍和多晶陶瓷托槽。将细胞培养物（NIH/3T3-小鼠成纤维细胞）添加到含有标本的 96 孔板中，并在 37°C 下在 5%二氧化碳中孵育 24 小时。定性和定量分析细胞毒性。用倒置相差显微镜分析细胞生长，获得照片，并根据斯坦福参数的大小根据有毒物质扩散晕的大小对反应率进行记录。通过线粒体活性在 570nm 波长处记录细胞活力。用酶标仪分析细胞活力（MTT 测定）。对细胞活力进行统计分析。
除 Rematitan 和 Equilibrium（均为 Dentaurum，Ispringen，德国）（P >0.05）外，所有测试的托槽的细胞毒性值均高于阴性对照（P <0.05），表明具有低毒性作用。结果表明，只有聚碳酸酯托槽与阳性对照相似（P >0.05），表明具有高毒性。
托槽表现出不同范围的细胞毒性；无镍托槽比其他托槽具有更好的生物相容性。另一方面，聚碳酸酯托槽由对分析细胞具有高细胞毒性的材料制成。
