Department of Conservative Dentistry and Periodontology, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.
Department of Physics, University of Cambridge, Cambridge, UK.
Photochem Photobiol Sci. 2019 May 15;18(5):1009-1019. doi: 10.1039/c8pp00223a.
Dental bleaching is an important part of aesthetic dentistry. Various strategies have been created to enhance the bleaching efficacy. As one such strategy, light-activated nanoparticles that enable localized generation of reactive oxygen species have been developed. Here, we evaluated the cellular response to experimental gels containing these materials in in vitro models. L-929 cells, 3T3 cells, and gingival fibroblasts were exposed to the gels at 50%, 10%, 2%, 0.4%, 0.08%, 0.016%, and 0.0032%. The gels contained TiO2/Ag nanoparticles, TiO2 nanoparticles, hydrogen peroxide (6% hydrogen peroxide), or no added component and were tested with and without exposure to light. Cells were exposed to gels for 24 h or for 30 min. The latter case mimics the clinical situation of a short bleaching gel exposure. Metabolic activity and cell viability were evaluated with MTT and neutral red assays, respectively. We found a dose-dependent reduction of formazan formation and neutral red staining with gels containing TiO2/Ag nanoparticles or TiO2 nanoparticles in the 24 h setting with and without illumination. The strongest reduction, which was not dose-dependent in the evaluated concentrations, was found for the gel containing hydrogen peroxide. Gels with TiO2 nanoparticles showed a similar response to gel without particles. TiO2/Ag gel showed a slightly higher impact. When the gels were removed by rinsing after 30 min of exposure without light illumination, gel containing TiO2/Ag nanoparticles showed a stronger reduction of formazan formation and neutral red staining than gel containing TiO2 particles. Exposure of cells for 30 min under illumination and consequent rinsing off the gels also showed that Ag-containing particles can have a higher impact on the metabolic activity and viability than particles from TiO2. Overall our results show that experimental bleaching gels containing TiO2/Ag or TiO2 nanoparticles are less cytotoxic than hydrogen peroxide-containing gel. When gels are removed, gel containing TiO2/Ag particles exhibit a stronger reduction of metabolic activity and viability than the gel containing TiO2.
牙齿漂白是美学牙科的重要组成部分。已经创造了各种策略来提高漂白效果。作为一种这样的策略，已经开发了能够局部产生活性氧的光激活纳米粒子。在这里，我们在体外模型中评估了含有这些材料的实验凝胶对细胞的反应。L-929 细胞、3T3 细胞和牙龈成纤维细胞在 50%、10%、2%、0.4%、0.08%、0.016%和 0.0032%的凝胶中暴露。凝胶含有 TiO2/Ag 纳米粒子、TiO2 纳米粒子、过氧化氢（6%过氧化氢）或未添加成分，并在有光和无光照射下进行测试。细胞用凝胶暴露 24 小时或 30 分钟。后一种情况模拟了临床短漂白凝胶暴露的情况。用 MTT 和中性红测定分别评估代谢活性和细胞活力。我们发现，在有光和无光照射下，含有 TiO2/Ag 纳米粒子或 TiO2 纳米粒子的凝胶在 24 小时设置中，随着凝胶浓度的增加，甲瓒形成和中性红染色的减少呈剂量依赖性。在评估的浓度下，不含过氧化氢的凝胶减少幅度最强，呈剂量依赖性。含有 TiO2 纳米粒子的凝胶表现出与无颗粒凝胶相似的反应。TiO2/Ag 凝胶的影响略高。当在无光照下暴露 30 分钟后用冲洗去除凝胶时，与含有 TiO2 颗粒的凝胶相比，含有 TiO2/Ag 纳米粒子的凝胶显示出更强的甲瓒形成和中性红染色减少。在光照下暴露细胞 30 分钟并随后冲洗掉凝胶也表明，含银颗粒对代谢活性和活力的影响可能高于 TiO2 颗粒。总的来说，我们的结果表明，含有 TiO2/Ag 或 TiO2 纳米粒子的实验性漂白凝胶比含过氧化氢的凝胶细胞毒性更小。当凝胶被去除时，含有 TiO2/Ag 颗粒的凝胶显示出比含有 TiO2 的凝胶更强的代谢活性和活力降低。
