Department of Biomaterials Science and Turku Clinical Biomaterials Centre-TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4 B, 20520 Turku, Finland.
Department of Biomaterials Science and Turku Clinical Biomaterials Centre-TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4 B, 20520 Turku, Finland.
J Dent. 2016 Sep;52:70-8. doi: 10.1016/j.jdent.2016.07.009. Epub 2016 Jul 20.
This study evaluated several fiber- and matrix related factors and investigated different mechanical properties of discontinuous i.e. short fiber-reinforced composite (SFRC) (everX Posterior, eXP). These were compared with three conventional composites, microfilled G-ænial Anterior (GA), nanofilled Supreme XTE (SXTE) and bulk-fill Filtek Bulk-Fill (FBF).
Fracture toughness (KIC), flexural strength (FS), flexural modulus (FM), compressive strength (CS), diametral tensile strength (DTS), apparent horizontal shear strength (AHSS) and fracture work (Wf) were determined for each composite (n=8) stored dry or in water. SEM analysis of the fiber diameter (df) (n=6) and orientation (n=6) were performed. The theoretical critical fiber length (lfc) and the aspect ratio (l/d) of SFRC were calculated and the volume fraction of discontinuous fibers (Vf%) and the fiber length (lf) of SFRC were evaluated. The results were statistically analyzed with two-way ANOVA (α=0.05).
The mechanical properties of SFRC (eXP) were generally superior (p<0.05) compared with conventional composites. GA had the highest FM (p>0.05), whereas FBF had the highest AHSS (p<0.05). The fiber related properties Vf%, l/d, lf, lfc and df of eXP were 7.2%, 18-112, 0.3-1.9mm, 0.85-1.09mm and 17μm respectively. SEM results suggested an explanation to several toughening mechanisms provided by the discontinuous fibers, which were shown to arrest crack propagation and enable a ductile fracture. Water exposure weakened the mechanical properties regardless of material type. Wf was unaffected by the water storage.
The properties of this high aspect ratio SFRC were dependent on the fiber geometry (length and orientation) and matrix ductility.
The simultaneous actions of the toughening mechanisms provided by the short fibers accounted for the enhanced toughness of this SFRC, which toughness value matched the toughness of dentin. Hence, it could yield an inherently uniform distribution of stresses to the hard biological tissues.
本研究评估了几种纤维和基质相关因素，并研究了不同的机械性能不连续的即短纤维增强复合材料（SFRC）（everX 后，eXP）。这些与三种常规复合材料进行了比较，微填充 G-ænial 前牙（GA），纳米填充 Supreme XTE（SXTE）和块状填充 Filtek 块状填充（FBF）。
每种复合材料（n=8）均在干燥或水中储存时确定断裂韧性（KIC）、弯曲强度（FS）、弯曲模量（FM）、抗压强度（CS）、直径拉伸强度（DTS）、表观水平剪切强度（AHSS）和断裂功（Wf）。进行纤维直径（df）（n=6）和取向（n=6）的 SEM 分析。计算 SFRC 的理论临界纤维长度（lfc）和纵横比（l/d），并评估 SFRC 的不连续纤维体积分数（Vf%）和纤维长度（lf）。使用双因素方差分析（α=0.05）对结果进行统计分析。
SFRC（eXP）的机械性能一般优于常规复合材料（p<0.05）。GA 具有最高的 FM（p>0.05），而 FBF 具有最高的 AHSS（p<0.05）。eXP 的纤维相关性能 Vf%、l/d、lf、lfc 和 df 分别为 7.2%、18-112、0.3-1.9mm、0.85-1.09mm 和 17μm。SEM 结果表明，不连续纤维提供的几种增韧机制可以解释纤维取向和直径对纤维性能的影响，这些机制可以阻止裂纹扩展并实现韧性断裂。无论材料类型如何，水暴露都会削弱机械性能。水储存对 Wf 没有影响。
这种高纵横比 SFRC 的性能取决于纤维几何形状（长度和取向）和基质延展性。
短纤维提供的增韧机制的协同作用解释了这种 SFRC 的增强韧性，其韧性值与牙本质的韧性值相匹配。因此，它可以将应力均匀地分布到坚硬的生物组织中。
