Objective

This work aimed at producing silica-blow-spun nanofibers containing silver nanoparticles (SiO₂/Ag) and investigating the effect of their incorporation in different proportions, with or without pre-treatment with a silane coupling agent, on the mechanical, physicochemical, and biological properties of a commercial composite low-viscosity bulk-fill resin.

Methods

The production of SiO₂/Ag nanofibers was confirmed by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). A portion of the produced nanofibers was silanized. Scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and agar diffusion tests against Streptococcus mutans were used to verify the differences between silanized and non-silanized nanofibers. Different proportions (0.5 wt% and 1 wt%) of silanized (SiO₂/Ag-0.5S and SiO₂/Ag-1S) and non-silanized (SiO₂/Ag-0.5NS and SiO₂/Ag-1NS) nanofibers were incorporated into the bulk-fill composite (Opus Bulk Fill Flow, FGM). A commercial composite was used as the control. Evaluation of the color parameters (L*, a*, and b*), radiopacity, contact angle, antimicrobial activity, Vickers microhardness, surface roughness (Sa and Sq), flexural strength, and SEM of the fractured surfaces were performed. The data were analyzed using the Mann–Whitney U test (fiber morphology), Kruskal-Wallis tests, with Dunn's post hoc test (antimicrobial activity of the specimen against S. mutans), Student’s t-test (disk diffusion), one-way ANOVA and Tukey (color, radiopacity, and contact angle), and two-way ANOVA and Tukey (microhardness, surface roughness, and flexural strength) tests. All statistical analyses were performed at a significance level of 1% (α = 0.01).

Results

Porous nanometric SiO₂/Ag fibers were successfully produced. The silanization process, confirmed by FTIR, increased the diameter and contact angle and reduced the growth inhibition halos of the nanofibers (p < 0.01). After the incorporation of nanofibers into the dental composite, all color parameters were altered in all the experimental groups (p < 0.01). All the groups presented adequate radiopacity values. No statistical difference was observed in the contact angles of the experimental composites (p > 0.01). The lowest microbial counts were obtained in the SiO₂/Ag-0.5S group; although no significant difference was observed with the control group (p < 0.01). The SiO₂/Ag-1S, SiO₂/Ag-0.5S, and SiO₂/Ag-0.5NS groups exhibited higher microhardness after 30 d of immersion in water (p < 0.01). The surface roughness (Sa-μm) resembled that of the control at baseline, except for the SiO₂/Ag-1NS group. For the baseline evaluation of flexural strength, all the experimental groups exhibited lower values than the control, except for SiO₂/Ag-0.5NS and SiO₂/Ag-0.5S, but after 30 d of immersion in water, there was no difference (p < 0.01).

Significance

The incorporation of 0.5% wt. of silanized nanofibers in the commercial composite (SiO₂/Ag-0.5S) seemed to be promising, especially for its greater inhibition of S. mutans, adequate roughness, and flexural strength, in addition to high hardness, even after aging in water.

中文翻译：

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掺入含有银纳米粒子 (SiO2/Ag) 的二氧化硅吹纺纳米纤维对低粘度填充复合树脂的机械、物理化学和生物性能的影响

客观的

这项工作旨在生产含有银纳米粒子 (SiO ₂ /Ag) 的二氧化硅吹纺纳米纤维，并研究它们以不同比例掺入，无论是否用硅烷偶联剂预处理，对机械、物理化学和商业复合低粘度填充树脂的生物学特性。

方法

通过透射电子显微镜（TEM）和能量色散X射线分析（EDX）证实了SiO ₂ /Ag纳米纤维的产生。一部分生产的纳米纤维被硅烷化。使用扫描电子显微镜 (SEM)、傅里叶变换红外光谱 (FTIR)、接触角测量和针对变形链球菌的琼脂扩散测试来验证硅烷化和非硅烷化纳米纤维之间的差异。不同比例（0.5 wt% 和 1 wt%）的硅烷化（SiO ₂ /Ag-0.5S 和 SiO ₂ /Ag-1S）和非硅烷化（SiO ₂ /Ag-0.5NS 和 SiO ₂/Ag-1NS) 纳米纤维被加入到散装填充复合材料中（Opus Bulk Fill Flow，FGM）。使用商业复合材料作为对照。对断裂表面的颜色参数（L*、a* 和 b*）、射线不透性、接触角、抗菌活性、维氏显微硬度、表面粗糙度（Sa 和 Sq）、弯曲强度和 SEM 进行了评估。使用 Mann-Whitney U 检验（纤维形态）、Kruskal-Wallis 检验、Dunn事后检验（样本对变形链球菌的抗菌活性）、Student's t-test（磁盘扩散）、单向方差分析和 Tukey（颜色、射线不透性和接触角）以及双向方差分析和 Tukey（显微硬度、表面粗糙度和弯曲强度）测试。所有统计分析均在 1% 的显着性水平 (α = 0.01) 下进行。

结果

成功制备了多孔纳米SiO ₂ /Ag纤维。由 FTIR 证实的硅烷化过程增加了纳米纤维的直径和接触角，并减少了纳米纤维的生长抑制光晕 (p < 0.01)。将纳米纤维掺入牙科复合材料后，所有实验组的所有颜色参数都发生了变化（p < 0.01）。所有组都呈现出足够的射线不透性值。实验复合材料的接触角没有观察到统计学差异（p > 0.01）。SiO ₂ /Ag-0.5S 组的微生物数量最少；尽管与对照组没有观察到显着差异（p < 0.01）。SiO ₂ /Ag-1S、SiO ₂ /Ag-0.5S和SiO ₂/Ag-0.5NS 组在水中浸泡 30 天后表现出更高的显微硬度（p < 0.01）。除了 SiO ₂ /Ag-1NS 组之外，表面粗糙度 (Sa-μm) 类似于基线处的对照。对于弯曲强度的基线评估，除SiO ₂ /Ag-0.5NS和SiO ₂ /Ag-0.5S外，所有实验组均表现出低于对照的值，但在水中浸泡30天后，没有差异(p < 0.01)。

意义

掺入 0.5% wt。商业复合材料（SiO ₂ /Ag-0.5S）中的硅烷化纳米纤维似乎很有前景，特别是它对变形链球菌的抑制作用更大，具有足够的粗糙度和弯曲强度，此外还具有高硬度，即使在水中老化后也是如此。