片状玻璃填料增强的低收缩耐水解光固化复合树脂的研究

Fracture and secondary caries are the two main reasons for treatment failure of posterior light-cured resin composite restoration. The underlying root causes lie in the limitations of the materials: low mechanical strength, high polymerization shrinkage, and large thermal expansion coefficient. How to improve the performance of the materials is the key to ensure the durability of resin composite restoration. It is and will continue to be a problem to solve in resin composite research and clinical applications for a long time. A potential solution is to reinforce the composite with glass flake fillers to improve its mechanical strength, reduce its thermal expansion coefficient, and to minimize water penetration and the consequential effects on the composite. In this study, a glass flake filler with a better barrier effect combined with spherical nano filler, along with Bis-GMA modified, polysubstituted silsesquioxane was added to the conventional composite substrate. By screening such synthetic composites through a comprehensive performance evaluation, we were able to identify the best formulations for light-cured resin composite. One innovation in this study is using an etching method to reduce the thickness of the glass flake filler, increase the diameter to thickness ratio, and thus enhance the binding with the resin matrix. Another innovation is synthesizing Bis-GMA-modified polysubstituted silsesquioxane to improve the compatibility with acrylic resin. The objective of this study is to find a method to enhance the mechanical properties and reduce polymerization shrinkage and thermal expansion coefficient of light-cured resin composite, and eventually to improve the overall performance of resin composite and the clinical outcomes of resin composite restoration.

断裂和继发龋是导致后牙光固化复合树脂修复治疗失败的两个主要原因，而断裂和继发龋的根本原因在于材料本身的机械强度低、固化收缩及热膨胀系数大，如何对材料的这些性能加以改进和提高，是保证复合树脂修复耐久性的关键，也是复合树脂科研和临床应用领域目前及今后相当长时间内亟待解决的问题。 用片状玻璃填料增强树脂可以提高树脂的机械强度及降低热膨胀系数，同时减小水对树脂的渗透和影响，有可能解决上述问题。本研究采用阻隔效应较好的片状玻璃填料结合球形纳米填料，并将多取代的Bis-GMA改性的倍半硅氧烷加入传统树脂基质内，通过对合成树脂的综合性能评价，筛选确定最佳的光固化复合树脂配方。 研究的创新性在于采用蚀刻方法降低片状玻璃填料的厚度，增加径厚比，同时加强与树脂基质的结合；合成多取代的Bis-GMA改性的倍半硅氧烷，改善与丙烯酸树脂的互容性。以期增强树脂的机械强度，降低固化收缩及热膨胀系数，提高临床治疗效。

研究背景：. 光固化复合树脂是后牙龋坏修复首选材料，但断裂仍是造成修复失败的原因之一。树脂容易被唾液，细菌微生物酶分解,树脂的吸水和溶解特性将影响修复体的临床使用寿命。水环境作用下商品树脂的力学强度下降25%~86%。为了提高复合树脂的长期力学性能，本项目设计合成一种新型光固化复合树脂，将POSS-MA与传统基质配伍使用，同时采用玻璃鳞片与Ba-Al-SiO2作为无机填料，合成一种新型耐老化光固化复合树脂。.主要研究内容: .（1）新型光固化树脂基质的合成与性能表征；（2）新型光固化复合树脂的合成与性能表征；（3）新型复合树脂综合性能评价。.重要结果和数据及科学意义.（1）通过向Bis-GMA/TEGDMA体系中掺入POSS-MA，树脂基质的弯曲性能、压缩强度和硬度显着增加；但当加入量增至10wt％时，双键转化率和力学性能显著下降。SEM结果显示加入POSS-MA后基质断裂面由光滑变得凹凸不平，呈撕裂态，与力学性能增强密切相关。.（2）无机填料总含量控制在65wt%,通过调节片状玻璃/Ba-Al-SiO2质量比，采用1wt%光引发剂，1.75wt%POSS-MA,32.25wt% BisGMA/TEDMA，58wt%玻璃鳞片和7wt% Ba-Al-SiO2的复合树脂具有最佳综合性能，挠曲强度可达到134.88 MPa（ISO标准为80MPa）；吸水值和溶解值分别为10.96μg/mm3和2.31μg/mm3，低于ISO标准40μg/mm3 和7.5μg/mm3；而且固化深度超过2mm，可满足临床要求。POSS-MA和玻璃鳞片赋予树脂良好的耐磨性能。.（3）MTT结果显示新型复合树脂具有较低的细胞毒性；经6个月长期水浸泡力学行性能试验，作为对照的6种商品树脂硬度和弯曲性能明显下降，而新型复合树脂力学性能相对稳定，挠曲强度仍保持在120 MPa左右；14400次往复摩擦磨损结果显示磨损深度约为57μm，耐磨性能高于大多数商品树脂。热膨胀系数及固化收缩性能等参数位于所有实验对照组的树脂的值的中上游水平。. 研究结果显示，采用POSS-MA和片状玻璃能够明显提高复合树脂的综合性能及耐久性，弥补目前复合树脂存在的一些不足，为今后商品复合树脂的研发提供参考依据和一定的指导意义。