Oral Microbiology and Biomaterials Laboratory, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Via Pascal 36, 20133 Milan, Italy.
Poliklinik für Zahnärztliche Prothetik und Werkstoffkunde, Leipzig University, Liebigstraße 12, 04103 Leipzig, Germany.
Dent Mater. 2020 May;36(5):603-616. doi: 10.1016/j.dental.2020.03.016. Epub 2020 Mar 29.
Modern dentistry is increasingly focusing on digital procedures, including CAD/CAM technologies. New materials have to resist in a demanding environment that includes secondary caries occurrence. The current study hypothesized that the microbiological behavior of different RBCs for CAD/CAM applications is better than that of their counterparts for direct restorations due to differences in the surface characteristics.
Both direct and CAD/CAM RBCs were tested. Specimens were obtained from each group, polished, cleaned, stored in artificial saliva (1w), then sterilized under UV (24h). Specimens' surface was assessed using profilometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction; resin/filler content was assessed using thermogravimetry. After pre-incubation with sterile human saliva (24h), the microbiological behavior of the materials was assessed using four models: Streptococcus mutans adherence (2h), S. mutans biofilm formation in an orbital shaking bioreactor (24h), S. mutans biofilm formation in a continuous-flow bioreactor simulating shear forces (24h), and mixed-plaque formation in the bioreactor (24h). The viable biomass adhering to the specimens' surfaces was measured using a tetrazolium dye-based test. Statistical analysis included verification of normality of distribution and homoscedasticity, then Oneway ANOVA and Tukey's test (α=5%).
When using the bioreactor setup, CAD/CAM RBCs generally yielded lower S. mutans and mixed-plaque biofilm formation compared to direct RBCs. This difference was not evidenced in the first two microbiological models. Differences in manufacturing and curing processes rather than in materials' surface roughness and composition could explain these results.
CAD/CAM RBCs are promising materials from a microbiological point of view, featuring reduced biofilm formation on their surfaces when shear conditions similar to in vivo ones are present.
现代牙科越来越注重数字化程序，包括 CAD/CAM 技术。新的材料必须在包括继发龋发生的苛刻环境中具有抵抗力。目前的研究假设，由于表面特性的差异，CAD/CAM 应用的不同 RBC 的微生物行为优于直接修复的对应物。
测试了直接和 CAD/CAM RBC。从每组获得样本，抛光，清洁，储存在人工唾液（1w）中，然后用紫外线（24h）消毒。使用轮廓仪，扫描电子显微镜，能谱仪和 X 射线衍射评估样品表面；使用热重分析评估树脂/填料含量。在无菌人唾液（24h）预孵育后，使用四个模型评估材料的微生物行为：变形链球菌粘附（2h），在轨道摇床生物反应器中形成变形链球菌生物膜（24h），在模拟剪切力的连续流动生物反应器中形成变形链球菌生物膜（24h），以及在生物反应器中形成混合菌斑（24h）。使用基于四唑染料的测试测量附着在样品表面的活菌生物量。统计分析包括分布和同方差的正态性验证，然后是 Oneway ANOVA 和 Tukey 检验（α=5%）。
当使用生物反应器设置时，CAD/CAM RBC 通常比直接 RBC 产生的变形链球菌和混合菌斑生物膜形成率更低。在前两个微生物模型中没有证明这种差异。制造和固化过程的差异而不是材料的表面粗糙度和组成可以解释这些结果。
从微生物学的角度来看，CAD/CAM RBC 是有前途的材料，当存在类似于体内的剪切条件时，其表面的生物膜形成减少。
