牙科复合材料已成为修复牙齿的标准填充材料,但是在放置这些修复物的过程中,包括许多纳米尺寸颗粒的大量可吸入复合粉尘(<5μm)可能在患者和牙科操作者的呼吸区域中释放。在这里,我们使用肺泡巨噬细胞模型系统测试了几种复合颗粒的可吸入部分的细胞毒性作用。方法:复合粉尘是按照临床方案产生的,在无菌环境下收集灰尘颗粒。灰尘分散在流体中,和5μm过滤以富集可吸入部分。石英DQ12和刚玉用作阳性和阴性对照,分别。四种浓度(22.5μg/ml,45μg/ml,将90μg/ml和180μg/ml)应用于NR8383肺泡巨噬细胞。光学和电子显微镜用于颗粒的亚细胞定位。测试培养上清液中乳酸脱氢酶的释放,葡糖醛酸酶,TNF-α,和H2O2。
悬浮颗粒的表征显示了许多纳米尺寸的颗粒,但也有许多高体积的颗粒,其中大部分可以通过过滤来删除。即使在最高浓度(180μg/ml),细胞从培养容器的底部完全清除沉降颗粒。因此,在细胞内部观察到纳米和微米级颗粒的混合物,它们被限制在吞噬溶酶体中。过滤后的颗粒部分引起了很大程度上均匀的剂量依赖性反应,仅在最高浓度时与对照相比升高,这等于120μg/细胞的平均细胞剂量。由于H2O2和TNF-α的剂量依赖性释放,确定了低的炎症潜力。然而,与阳性对照相比,H2O2和TNF-α的释放水平仍然中等,但是它们的释放曲线取决于复合材料的类型。
肺泡巨噬细胞能够吞噬可吸入复合粉尘颗粒包容性纳米颗粒。由于NR8383细胞耐受五种材料中每种材料的相对较高的细胞负荷(60pg/细胞),细胞毒性或炎症的迹象最小,可吸入复合粉尘的毒性潜力似乎很低。这些结果让牙科人员放心,但是需要更多的研究来表征实际的暴露和吸收,特别是纯纳米部分。
Dental composites have become the standard filling material to restore teeth, but during the placement of these restorations, high amounts of respirable composite dust (<5 μm) including many nano-sized particles may be released in the breathing zone of the patient and dental operator. Here we tested the respirable fraction of several composite particles for their cytotoxic effect using an alveolar macrophage model system. METHODS: Composite dust was generated following a clinical protocol, and the dust particles were collected under sterile circumstances. Dust was dispersed in fluid, and 5-μm-filtered to enrich the respirable fractions. Quartz DQ12 and corundum were used as positive and negative control, respectively. Four concentrations (22.5 μg/ml, 45 μg/ml, 90 μg/ml and 180 μg/ml) were applied to NR8383 alveolar macrophages. Light and electron microscopy were used for subcellular localization of particles. Culture supernatants were tested for release of lactate dehydrogenase, glucuronidase, TNF-α, and H2O2.
Characterization of the suspended particles revealed numerous nano-sized particles but also many high volume particles, most of which could be removed by filtering. Even at the highest concentration (180 μg/ml), cells completely cleared settled particles from the bottom of the culture vessel. Accordingly, a mixture of nano- and micron-scaled particles was observed inside cells where they were confined to phagolysosomes. The filtered particle fractions elicited largely uniform dose-dependent responses, which were elevated compared to the control only at the highest concentration, which equaled a mean cellular dose of 120 pg/cell. A low inflammatory potential was identified due to dose-dependent release of H2O2 and TNF-α. However, compared to the positive control, the released levels of H2O2 and TNF-α were still moderate, but their release profiles depended on the type of composite.
Alveolar macrophages are able to phagocytize respirable composite dust particle inclusive nanoparticles. Since NR8383 cells tolerate a comparatively high cell burden (60 pg/cell) of each of the five materials with minimal signs of cytotoxicity or inflammation, the toxic potential of respirable composite dust seems to be low. These results are reassuring for dental personnel, but more research is needed to characterize the actual exposure and uptake especially of the pure nano fraction.