Objective

The viscosity of dental resin composites is important in their formulation and clinical use; it depends on the filler particle size and loading. We intend to study the viscosity and conversion of composites made of low dispersity spherical silica fillers.

Methods

Experimental dental resin composites were formulated using low dispersity spherical silica particles of graded sizes (75, 150, 500, 350, 500, 1000 nm) at several loading levels with resins based on Bis-GMA and UDMA. Their rheological properties and double bond conversion were measured with a rheometer and differential scanning calorimeter, respectively.

Results

The complex viscosity of the unpolymerized pastes can be fit to an extended Krieger–Dougherty equation that includes an adjustment factor to account for filler particle surface area. This relationship is also extended to estimate the degree of conversion, where the calculated or experimental viscosity is used to predict the resulting conversion.

Significance

The enhanced understanding of the relationship of filler size, composite viscosity, and monomer conversion will allow improved accuracy in the prediction of the properties of dental resin composite formulations to obtain ideal viscosity for their clinical use and a high degree of conversion.

中文翻译：

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牙科复合材料中树脂粘度和单体转化率与填料粒径的关系

客观的

牙科树脂复合材料的粘度在其配方和临床应用中很重要。这取决于填料的粒径和载量。我们打算研究由低分散度球形二氧化硅填料制成的复合材料的粘度和转化率。

方法

实验性牙科树脂复合材料是使用具有低分散度的球形二氧化硅颗粒（尺寸分别为75、150、500、350、500、1000 nm）在几种负载水平下使用基于Bis-GMA和UDMA的树脂配制的。用流变仪和差示扫描量热仪分别测量它们的流变性质和双键转化率。

结果

可以将未聚合浆料的复数粘度拟合为扩展的Krieger-Dougherty方程，该方程包括一个考虑填料颗粒表面积的调整因子。该关系也被扩展以估计转化率，其中使用计算的或实验的粘度来预测所得的转化率。

意义

对填料尺寸，复合材料粘度和单体转化率之间关系的加深了解将提高牙科树脂复合材料配方的性能预测中的准确性，从而获得其临床应用的理想粘度和高转化率。