Fong Hao, Dickens Sabine H, Flaim Glenn M
Department of Chemistry and Chemical Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701-3995, USA.
Dent Mater. 2005 Jun;21(6):520-9. doi: 10.1016/j.dental.2004.08.003. Epub 2004 Dec 10.
The aim of this study was to explore novel polymeric dental restorative composites, in which polyhedral oligomeric silsesquioxane methacrylate monomer (POSS-MA) was used to partially (or completely) replace the commonly used base monomer 2,2'-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA).
The composites were cured (hardened) by photo-initiated free radical polymerization. Mechanical properties (i.e. flexural strength, Young's modulus and diametral tensile strength) of the composites were tested by a universal mechanical testing machine; photopolymerization induced volumetric shrinkage was measured using a mercury dilatometer; and near infrared (NIR) technique was used to study the degree of methacrylate double bond conversion and photopolymerization rate.
Small percentage POSS-MA substitution of Bis-GMA (i.e. mass fraction of 10% or less) in the resin system improved the mechanical properties of the composites; while large amount substitution led to less desirable mechanical properties, lower methacrylate double bond conversion, and slower photopolymerization rate. Statistical examinations showed the maximum flexural strength of the composites occurred when 10% (mass fraction) of Bis-GMA was replaced by POSS-MA, while the highest modulus occurred when the mass fraction of POSS-MA was 2%.
Polymeric dental restorative composites with improved mechanical properties may be designed by judicious choice of monomer (POSS-MA, Bis-GMA and TEGDMA) compositions.
本研究旨在探索新型聚合物牙科修复复合材料，其中使用多面体低聚倍半硅氧烷甲基丙烯酸酯单体（POSS-MA）部分（或完全）替代常用的基础单体2,2'-双-[4-(甲基丙烯酰氧基丙氧基)-苯基]-丙烷（Bis-GMA）。
复合材料通过光引发自由基聚合进行固化（硬化）。使用万能机械试验机测试复合材料的机械性能（即弯曲强度、杨氏模量和径向拉伸强度）；使用汞膨胀仪测量光聚合引起的体积收缩；并使用近红外（NIR）技术研究甲基丙烯酸酯双键转化率和光聚合速率。
在树脂体系中用小百分比的POSS-MA替代Bis-GMA（即质量分数为10%或更低）可改善复合材料的机械性能；而大量替代会导致不太理想的机械性能、较低的甲基丙烯酸酯双键转化率和较慢的光聚合速率。统计检验表明，当10%（质量分数）的Bis-GMA被POSS-MA替代时，复合材料的弯曲强度最大，而当POSS-MA的质量分数为2%时，模量最高。
通过明智地选择单体（POSS-MA、Bis-GMA和TEGDMA）组成，可以设计出具有改善机械性能的聚合物牙科修复复合材料。
