OBJECTIVES 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. METHODS 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%). RESULTS 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. SIGNIFICANCE 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.

中文翻译：

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用于牙科CAD / CAM应用的树脂复合块可减少体外生物膜的形成。

目标现代牙科越来越关注数字程序，包括CAD / CAM技术。新材料必须在包括继发龋齿在内的苛刻环境中抵抗。目前的研究假设，由于表面特性的差异，用于CAD / CAM应用的不同RBC的微生物行为优于直接修复的RBC。方法直接和CAD / CAM RBCs都进行了测试。从每个组中获取标本，进行抛光，清洁，保存在人造唾液中（1瓦），然后在紫外线下消毒（24个小时）。使用轮廓仪，扫描电子显微镜，能量色散X射线光谱和X射线衍射来评估样品的表面；使用热重分析法评估树脂/填料含量。在与无菌人类唾液预温育（24h）后，使用四种模型评估材料的微生物学行为：变形链球菌粘附（2h），在轨道摇动生物反应器中变形链球菌生物膜形成（24h），变形链球菌生物膜形成。在连续流生物反应器中模拟剪切力（24h），并在生物反应器中形成混合菌斑（24h）。使用基于四唑鎓染料的测试来测量粘附到样品表面的活生物量。统计分析包括验证分布的正态性和均方差，然后进行单向方差分析和Tukey检验（α= 5％）。结果当使用生物反应器设置时，与直接RBC相比，CAD / CAM RBC通常产生较低的变形链球菌和混合斑块生物膜形成。在前两个微生物模型中没有发现这种差异。制造和固化过程的差异，而不是材料的表面粗糙度和组成的差异，可以解释这些结果。意义从微生物学的角度来看，CAD / CAM RBC是很有前途的材料，当存在与体内相似的剪切条件时，其表面生物膜形成减少。