室温固化PMMA弯曲强度与断面激光共聚焦扫描微结构的关系

Relationship between flexural strength of room curing PMMA and cross-section observation under confocal laser scanning microscope

目的:比较4种室温固化聚甲基丙烯酸甲酯(PMMA)材料的弯曲强度,激光共聚焦扫描显微镜(CLSM)观察材料断面的物理构象,阐明宏观抗弯曲力与微观结构之间的关系。方法:4种室温固化PMMA材料的厂家分别为德山(硬衬型)、日进和贺利氏(纤维型)、上海齿科(单纯型),每种室温固化PMMA材料制备试件10个。根据ISO 1567标准,室温20℃条件下,按厂商提供的粉液比例,使用不锈钢模具制备试件,电子万能材料试验机上测定试件的弯曲强度,CLSM对试件断面进行图像重建观察断面微结构。结果:德山、日进、贺利氏和上海齿科生产的4种室温固化PMMA材料制作试件的弯曲强度分别为(41.00±12.22)、(87.80±14.82)、(76.30±7.51)和(81.20±8.93)MPa,德山、日进、贺利氏的弯曲强度两两比较差异均有统计学意义(P<0.05);上海齿科的弯曲强度与德山的弯曲强度比较差异有统计学意义(P<0.05),但与日进、贺利氏的弯曲强度比较差异无统计学意义(P>0.05)。试件断裂界面的三维重建图像分析,日进断面图像中微裂纹产生的完全程度、数量明显高于其他3种材料,贺利氏与上海齿科无明显差别,德山最低。结论:4种PMMA材料的弯曲强度以德山最低,日进近似最高,贺利氏与上海齿科相似;弯曲强度大的材料,其断裂界面产生微裂纹的完全性高且数量多。

Objective To compare the flexural strength of the four kinds of room curing denture materials of polymethyl methacrylate（PMMA）,and observe the physical conformation section through confocal laser scanning microscope（CLSM） in order to find the relationship between the macro-bending force and the microstructure.Methods Four room curing PMMA materials were produced by Tokuyama（hard-liner type）,Nisshin（fiber type）,Heraeus（fiber type）,and Shanghai dental（simple type）.Each of the room curing PMMA was prepared by a group of 10 specimens.According to ISO1567,room temperature 20℃ and vendors powder liquid ratio with the stainless steel molds were performed to prepare samples,flexural strength was measured on the test machine.The cross-section was analyzed with CLSM.Results The flexural strengths of four kinds of room curing PMMA were（41.00±12.22）,（87.80±14.82）,（76.30±7.51）,and（81.20±8.93） MPa,respectively;there wre significant differences in the flexural strengths between Tokuyama and Nisshin,Heraeus（P0.05）,there was significant difference between Shanghai dental and Tokuyama（P0.05）,but there was no significant difference between Shanghai dental and Nisshin,Heraeus（P0.05）.In the cross-section image of Nisshin group the complete degree and the number of micro-cracks were significantly higher than others,there was no significant difference between Heraeus and Shanghai dental,Tokuyama was the lowest.Conclusion Tokuyama has the lowest flexural strength,Nisshin maximum,Heraeus similarity with Shanghai dental.When the flexural strength of the material is stronger,there are more micro-cracks from the cross-section.