Lee In-Bog, Son Ho-Hyun, Um Chung-Moon
Department of Conservative Dentistry, College of Dentistry, Seoul National University, 28-2 Yeongeon-Dong, Chongno-ku, Seoul, South Korea.
Dent Mater. 2003 Jun;19(4):298-307. doi: 10.1016/s0109-5641(02)00058-1.
This research was undertaken to investigate the viscoelastic properties related to handling characteristics of five commercial flowable, two conventional hybrid and two condensable composite resins and to investigate the effect on the viscosity of filler volume fraction of composites.
A dynamic oscillatory shear test was used to evaluate the storage shear modulus (G'), loss shear modulus (G"), loss tangent (tan delta) and complex viscosity (eta(*)) of the composite resins as a function of frequency (omega)-dynamic frequency sweep test from 0.01 to 100 rad/s at 25 degrees C-using an Advanced Rheometric Expansion System. To investigate the effect on the viscosity of the composites of the filler volume fraction, the filler weight% and filler volume% were measured by the Archimedes' principle using a pyknometer.
The complex viscosity eta() of flowable composites was lower than that of the hybrid composites and significant differences were observed between brands. The complex viscosity eta() of condensable composites was higher than that of hybrid composites. The order of complex viscosity eta() at omega=10 rad/s in order of decreasing viscosity was as follows, Synergy compact, P-60, Z-250, Z-100, Aeliteflo, Tetric flow, Compoglass flow, Flow it and Revolution. The complex viscosity of flowable composites, normalized with respect to Z-100, was 0.04-0.56 but Synergy compact was 2.158 times higher than that of Z-100. The patterns of the change of loss tangent (tan delta) of the composite resins with increasing frequency were significantly different between brands. Phase angles delta ranged from 30.9 to 78.1 degrees at omega=10 rad/s. All composite resins exhibit pseudoplastic behavior with increasing shear rate. The relationships between the complex shear modulus G(), the phase angle delta, and the shear rate omega were represented by the frequency domain phasor form, G()(omega)=G()e(i delta)=G(*) 90 degree angle delta. Only a weak relationship was found between filler volume% and the viscosity of the composite resins.
This investigation shows that the viscoelasticity of composites in the same class is significantly different between brands. This rheologic property of composite resins influences the handling characteristics of the materials. The locus of frequency domain phasor plots in a complex plane is a valuable method of representing the viscoelastic properties of composite resins.
本研究旨在调查五种市售可流动复合树脂、两种传统混合型复合树脂和两种可压实复合树脂与操作特性相关的粘弹性特性，并研究复合材料填料体积分数对粘度的影响。
使用动态振荡剪切试验，在25℃下，使用高级流变扩展系统，以0.01至100 rad/s的频率进行动态频率扫描试验，评估复合树脂的储能剪切模量（G'）、损耗剪切模量（G"）、损耗角正切（tanδ）和复数粘度（η*）。为了研究填料体积分数对复合材料粘度的影响，使用比重瓶通过阿基米德原理测量填料重量百分比和填料体积百分比。
可流动复合树脂的复数粘度η低于混合型复合树脂，且不同品牌之间存在显著差异。可压实复合树脂的复数粘度η高于混合型复合树脂。在ω = 10 rad/s时，复数粘度η按粘度递减顺序排列如下：Synergy compact、P - 60、Z - 250、Z - 100、Aeliteflo、Tetric flow、Compoglass flow、Flow it和Revolution。以Z - 100为基准进行归一化处理后，可流动复合树脂的复数粘度为0.04 - 0.56，但Synergy compact比Z - 100高2.158倍。不同品牌的复合树脂损耗角正切（tanδ）随频率增加的变化模式存在显著差异。在ω = 10 rad/s时，相位角δ范围为30.9至78.1度。所有复合树脂均表现出随着剪切速率增加的假塑性行为。复数剪切模量G、相位角δ和剪切速率ω之间的关系由频域相量形式表示，即G*(ω)=G()e(iδ)=G() 90度角δ。在填料体积百分比与复合树脂粘度之间仅发现微弱的关系。
本研究表明，同一类复合材料的粘弹性在不同品牌之间存在显著差异。复合树脂的这种流变特性会影响材料的操作特性。复平面中频域相量图的轨迹是表示复合树脂粘弹性特性的一种有价值的方法。
