Oral Microbiology and Biomaterials Laboratory, Department of Biomedical, Surgical and Dental Sciences, University of Milan, via Pascal, 36, 20133 Milan, Italy.
Oral Microbiology and Biomaterials Laboratory, Department of Biomedical, Surgical and Dental Sciences, University of Milan, via Pascal, 36, 20133 Milan, Italy.
Dent Mater. 2022 Sep;38(9):1470-1481. doi: 10.1016/j.dental.2022.06.032. Epub 2022 Jul 7.
Innovative, nanotechnologies-featuring dental materials for CAD/CAM applications are becoming available. However, the interaction with the oral environment poses critical challenges to their longevity. The present study evaluated specific physical-chemical properties and antimicrobial potential of a CAD/CAM graphene-doped resin before and after accelerated aging protocols.
Graphene nanofibers (GNF)-doped (<50 ppm) PMMA (GPMMA) and control PMMA CAD/CAM discs were used. Specimens underwent aging procedures of their bulk (thermo- and load-cycling) and surface (24 h-immersion in absolute ethanol), then they were tested for flexural strength, ultimate tensile strength, sorption/solubility, and methyl-methacrylate elution. Surface characterization included x-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface roughness, microhardness, and scanning electron microscopy (SEM). Adherence of Streptococcus mutans and Candida albicans, and biofilm formation (continuous-flow bioreactor) by the same strains and an artificial oral microcosm were investigated.
GNF-doping improved the physical-chemical bulk properties of the PMMA resin. Surface aging reduced microhardness and increased the roughness of both test and control materials. Surfaces displayed signs of swelling and degradation at SEM. Microbiological data of non-aged surfaces showed that GNF-doping significantly reduced biofilm formation by all tested strains despite having no impact on microbial adherence. After aging, microbial adherence was higher on GPMMA surfaces, while biofilm formation was not promoted.
GNF-doping improved the material's performance and influenced its antimicrobial potential. This strategy seems a valuable option to overcome the effects of surface degradation induced by aging on the antimicrobial potential of PMMA resin.
具有创新性的纳米技术的牙科材料越来越多地应用于 CAD/CAM 技术。然而，这些材料与口腔环境的相互作用对其耐久性提出了严峻的挑战。本研究评估了 CAD/CAM 技术中添加石墨烯的树脂的特定物理化学性能和抗菌潜力，分别在加速老化前后进行了测试。
使用了掺杂了石墨烯纳米纤维（GNF）的（<50ppm）聚甲基丙烯酸甲酯（GPMMA）和对照 PMMA CAD/CAM 圆盘。样品进行了体相（热循环和负载循环）和表面（24 小时浸泡在无水乙醇中）老化处理，然后对其进行了弯曲强度、拉伸强度、吸湿性/溶解性和甲基丙烯酸甲酯洗脱测试。表面特性分析包括 X 射线衍射、傅里叶变换红外光谱、X 射线光电子能谱、表面粗糙度、显微硬度和扫描电子显微镜（SEM）。检测了变异链球菌和白色念珠菌的黏附力，以及在相同菌株和人工口腔微环境下的生物膜形成（连续流动生物反应器）。
GNF 掺杂改善了 PMMA 树脂的物理化学性能。表面老化降低了两种测试材料的显微硬度，增加了表面粗糙度。SEM 显示表面出现了肿胀和降解的迹象。未经老化的表面微生物学数据表明，尽管 GNF 掺杂对微生物黏附没有影响，但显著减少了所有测试菌株的生物膜形成。老化后，GPMMA 表面的微生物黏附增加，但生物膜形成未得到促进。
GNF 掺杂改善了材料的性能并影响了其抗菌潜力。这种策略似乎是克服老化引起的表面降解对 PMMA 树脂抗菌潜力的影响的一种有价值的选择。
