Balos Sebastian, Pilic Branka, Markovic Dubravka, Pavlicevic Jelena, Luzanin Ognjan
Assistant Professor and Deputy Head of Department, Department of Production Engineering, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
Associate Professor and Vice Dean, Department of Material Engineering, Faculty of Technology, University of Novi Sad, Novi Sad, Serbia.
J Prosthet Dent. 2014 Apr;111(4):327-34. doi: 10.1016/j.prosdent.2013.06.021. Epub 2013 Dec 18.
Poly(methyl-methacrylate) (PMMA) represents the most popular current denture material. However, its major drawbacks are insufficient ductility and strength.
The purpose of this study was to improve the mechanical properties of PMMA in denture base application by adding small quantities of nanosilica.
Silica nanoparticles were added to the liquid component of the tested materials. The standard heat polymerizing procedure was followed to obtain 6 PMMA--silicon dioxide (/SiO2) concentrations (0.023%, 0.046%, 0.091%, 0.23%, 0.46%, and 0.91% by volume). Microhardness and fracture toughness of each set of specimens was compared with the unmodified specimens. Furthermore, differential scanning calorimetry and scanning electron microscopy analyses were conducted, and the results obtained were correlated with the results of mechanical properties.
It was found that the maximum microhardness and fracture toughness values of the materials tested were obtained for the lowest nanosilica content. A nanosilica content of 0.023% resulted in an almost unchanged glass transition temperature (Tg), whereas the maximum amount of nanosilica induced a considerable increase in Tg. A higher Tg indicated the possible existence of a thicker interfacial layer caused by the chain immobility due to the presence of the particles. However, scanning electron microscopy results demonstrated extensive agglomeration at 0.91% nanosilica, which may have prevented the formation of a homogenous reinforced field. At a nanosilica content of 0.023%, no agglomeration was observed, which probably influenced a more homogenous distribution of nanoparticles as well as uniform reinforcing fields.
Low nanoparticle content yields superior mechanical properties along with the lower cost of nanocomposite synthesis.
聚甲基丙烯酸甲酯（PMMA）是目前最常用的义齿材料。然而，其主要缺点是延展性和强度不足。
本研究的目的是通过添加少量纳米二氧化硅来改善PMMA在义齿基托应用中的机械性能。
将二氧化硅纳米颗粒添加到测试材料的液体成分中。按照标准热聚合程序获得6种PMMA-二氧化硅（/SiO2）浓度（体积分数分别为0.023%、0.046%、0.091%、0.23%、0.46%和0.91%）。将每组试样的显微硬度和断裂韧性与未改性试样进行比较。此外，进行了差示扫描量热法和扫描电子显微镜分析，并将所得结果与机械性能结果相关联。
发现测试材料的最大显微硬度和断裂韧性值出现在纳米二氧化硅含量最低时。纳米二氧化硅含量为0.023%时，玻璃化转变温度（Tg）几乎不变，而纳米二氧化硅含量最高时，Tg显著升高。较高的Tg表明可能存在由颗粒导致的链运动受限而形成的较厚界面层。然而，扫描电子显微镜结果显示，纳米二氧化硅含量为0.91%时出现大量团聚，这可能阻止了均匀增强场的形成。纳米二氧化硅含量为0.023%时，未观察到团聚，这可能影响了纳米颗粒更均匀的分布以及均匀的增强场。
低纳米颗粒含量可产生优异的机械性能，同时降低纳米复合材料合成成本。
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