Laboratory of Biomaterials, Center for Studies in Health and Disease Sciences, School of Dentistry, Benito Juárez Autonomous University of Oaxaca, Oaxaca de Juárez, Mexico.
Technological Institute of Toluca, Metepec, Mexico.
Dent Med Probl. 2020 Jul-Sep;57(3):239-246. doi: 10.17219/dmp/121973.
The incorporation of an antibacterial agent into an adhesive could improve its clinical performance. Some nanoparticles (NPs), including copper nanoparticles (Cu NPs), display an antibacterial effect. Therefore, Cu NPs could act as a nanofiller when added to an adhesive.
The aim of this study was to evaluate the antibacterial activity, cytotoxicity and shear bond strength (SBS) of an experimental dental adhesive with Cu NPs.
Different concentrations (0.0050 wt%, 0.0075 wt% and 0.0100 wt%) of Cu NPs were added to the adhesive. The distribution of Cu NPs in the polymer matrix was observed based on transmission electron microscope (TEM) images. The antimicrobial activity of the adhesive + Cu NPs was evaluated with the agar disk diffusion test against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Streptococcus mutans (S. mutans). The cytotoxicity assay was performed by means of the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method with human pulp cells (HPC). Additionally, the SBS tests were carried out (n = 31) and the modes of fracture were registered. The vestibular and lingual surfaces of each tooth were randomly assigned to the study groups (group I - control adhesive; group II - adhesive + 0.0100 wt% Cu NPs). The samples were statistically analyzed (p ≤ 0.05).
The adhesive + 0.0100 wt% Cu NPs showed inhibition zones against the strains under study that were similar to, or slightly smaller than, the halos produced by chlorhexidine (CHX) and specific drugs for each strain (30 μg of cefotaxime against S. mutans and S. aureus, and 1.25/3.75 μg of sulfamethoxazole/ trimethoprim against E. coli). The control adhesive was moderately cytotoxic (relative cell viability of 36.7 ±0.8%), being more cytotoxic than Cu NPs themselves (58.3 ±0.1%). A significantly higher SBS was obtained for the adhesive + 0.0100 wt% Cu NPs (6.038 ±2.95 MPa) than for the control group (3.278 ±1.75 MPa). The modes of fracture in group I were almost equally distributed between adhesive and cohesive failures whereas in group II, the failure was mainly cohesive.
The results of this study suggest that incorporating Cu NPs into an adhesive improves its SBS and provides it with antibacterial properties, without increasing its inherent cytotoxicity - 2 desirable characteristics for the dental adhesives of composites.
将抗菌剂掺入胶粘剂中可以改善其临床性能。一些纳米粒子（NPs），包括铜纳米粒子（Cu NPs），具有抗菌作用。因此，Cu NPs 可以作为纳米填料添加到胶粘剂中。
本研究旨在评估含有 Cu NPs 的实验性牙科胶粘剂的抗菌活性、细胞毒性和剪切结合强度（SBS）。
将不同浓度（0.0050wt%、0.0075wt%和 0.0100wt%）的 Cu NPs 添加到胶粘剂中。通过透射电子显微镜（TEM）图像观察 Cu NPs 在聚合物基质中的分布。采用琼脂圆盘扩散试验评估胶粘剂+Cu NPs 对金黄色葡萄球菌（S. aureus）、大肠杆菌（E. coli）和变形链球菌（S. mutans）的抗菌活性。通过 MTT（3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴化物）法进行细胞毒性试验，使用人牙髓细胞（HPC）。此外，进行了 SBS 测试（n=31）并记录了断裂模式。每颗牙的颊侧和舌侧表面随机分配到研究组（I 组-对照胶粘剂；II 组-胶粘剂+0.0100wt%Cu NPs）。对样本进行了统计学分析（p≤0.05）。
与对照胶粘剂相比，胶粘剂+0.0100wt%Cu NPs 对研究菌株产生的抑菌环相似或略小，与洗必泰（CHX）和每种菌株的专用药物（针对 S. mutans 和 S. aureus 的 30μg 头孢噻肟，针对 E. coli 的 1.25/3.75μg 磺胺甲噁唑/甲氧苄啶）产生的抑菌环相似或略小。对照胶粘剂具有中度细胞毒性（相对细胞活力为 36.7±0.8%），比 Cu NPs 本身（58.3±0.1%）更具细胞毒性。与对照组（3.278±1.75MPa）相比，胶粘剂+0.0100wt%Cu NPs 的 SBS 显著提高（6.038±2.95MPa）。I 组的断裂模式几乎均匀分布在胶粘剂和内聚失效之间，而在 II 组中，失效主要是内聚性的。
本研究结果表明，将 Cu NPs 掺入胶粘剂中可以提高其 SBS，并赋予其抗菌性能，而不会增加其固有细胞毒性-这是复合材料牙科胶粘剂的两个理想特性。
