1 Department of Chemistry, Oregon State University, Corvallis, OR, USA.
2 Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA.
J Dent Res. 2019 Feb;98(2):194-199. doi: 10.1177/0022034518809086. Epub 2018 Nov 21.
The chemical microenvironment surrounding dental composites plays a crucial role in controlling the bacteria grown on these specialized surfaces. In this study, we report a scanning electrochemical microscopy (SECM)-based analytic technique to design and optimize metal ion-releasing bioactive glass (BAG) composites, which showed a significant reduction in biofilm growth. SECM allows positioning of the probe without touching the substrate while mapping the chemical parameters in 3-dimensional space above the substrate. Using SECM and a solid-state H and Ca ion-selective microprobe, we determined that the local Ca concentration released by different composites was 10 to 224 µM for a BAG particle size of <5 to 150 µm in the presence of artificial saliva at pH 4.5. The local pH was constant above the composites in the same saliva solution. The released amount of Ca was determined to be maximal for particles <38 µm and a BAG volume fraction of 0.32. This optimized BAG-resin composite also showed significant inhibition of biofilm growth (24 ± 5 µm) in comparison with resin-only composites (53 ± 6 µm) after Streptococcus mutans bacteria were grown for 3 d in a basal medium mucin solution. Biofilm morphology and its subsequent volume, as determined by the SECM imaging technique, was (0.59 ± 0.38) × 10 µm for BAG-resin composites and (1.29 ± 0.53) × 10 µm for resin-only composites. This study thus lays the foundation for a new analytic technique for designing dental composites that are based on the chemical microenvironment created by biomaterials to which bacteria have been exposed.
牙用复合材料周围的化学微环境在控制这些特殊表面生长的细菌方面起着至关重要的作用。在这项研究中，我们报告了一种基于扫描电化学显微镜（SECM）的分析技术，用于设计和优化释放金属离子的生物活性玻璃（BAG）复合材料，该技术显示出对生物膜生长的显著抑制作用。SECM 允许在不接触基底的情况下定位探针，同时在基底上方的三维空间中绘制化学参数。使用 SECM 和固态 H 和 Ca 离子选择性微探针，我们确定了在 pH 值为 4.5 的人工唾液中，不同复合材料释放的局部 Ca 浓度为 <5 至 150 µm 的 BAG 粒径为 10 至 224 µM。在相同的唾液溶液中，复合材料上方的局部 pH 值保持恒定。在唾液中，当 BAG 粒径为 <38 µm 且 BAG 体积分数为 0.32 时，Ca 的释放量最大。与仅含树脂的复合材料（53 ± 6 µm）相比，这种优化的 BAG-树脂复合材料在变形链球菌细菌在基础培养基粘蛋白溶液中生长 3 天后，对生物膜生长的抑制作用也非常显著（24 ± 5 µm）。通过 SECM 成像技术确定的生物膜形态及其随后的体积，BAG-树脂复合材料为（0.59 ± 0.38）×10 µm，而仅含树脂的复合材料为（1.29 ± 0.53）×10 µm。因此，这项研究为基于暴露于细菌的生物材料所创造的化学微环境来设计牙用复合材料的新分析技术奠定了基础。
