模拟口腔环境下隐形矫治热塑性材料的力学性能、结构及化学成分的变化

Mechanical property,structural and compositional changes of orthodontic thermoplastic materials in simulated oral environment

目的研究在模拟口腔环境下,热处理、水和热等物理、化学因素对常用的正畸热塑性材料的成分、结构和力学性能的影响,从而认识材料的老化变化,为临床上正确选择和使用隐形矫治器,更精确的预测和控制牙齿移动提供一定的指导作用。方法将Erkodur材料用压膜机进行热软化处理(160℃),浸泡在人工唾液中,置于37℃恒温箱中老化,分别于浸泡12 h、3天、2周和4周后,测试观察其力学性能、分子结构(红外光谱,FTIR)、表面形貌和内部结构以及化学成分的变化。结果热处理后,材料的化学组成和一级结构没有发生明显的变化,但力学性能下降。37℃人工唾液浸泡后(最长4周),材料的一级结构仍没有明显的改变,但力学性能提升。结论模拟口腔环境并不改变Erkodur材料的一级结构,但其高级结构可能由于吸水膨胀而存在一定程度上的破损。因此,热塑性材料力学性能的变化主要来源于高分子聚合物的这些高级结构的改变。

Objective To evaluate the effect of heat treatment,water and heat on the composition,structure and mechanical properties of orthodontic thermoplastic materials in the simulated oral environment.Methods Erkodur materials were heat softened(160℃),soaked in artificial saliva,aged in a 37℃incubator,and then soaked for 12 hours,3 days,2 weeks and 4 weeks,respectively,and their mechanical properties and molecular structures(FTIR),surface morphology and internal structure(SEM and TEM)and chemical composition(STEM-XEDS)were observed.Results After heat treatment,the chemical composition and primary structure of the material did not change significantly,but the mechanical properties decreased.After immersion in artificial saliva at 37℃for 4 weeks,the primary structure of the material did not changed significantly,but the mechanical properties were improved.Conclusions The simulated oral environment does not change the primary structure of Erkodur,but its advanced structure may be damaged to some extent due to water swelling.Therefore,the changes of mechanical properties of thermoplastic materials are mainly due to the changes of these advanced structures of polymer.