Department of Orthodontics, University Medical Centre of Regensburg, Regensburg, Germany.
Am J Orthod Dentofacial Orthop. 2010 Mar;137(3):362-7. doi: 10.1016/j.ajodo.2008.12.020.
Polymer brackets still have some disadvantages because of decreased wear resistance and hardness. The aim of this study was to investigate the mechanical properties of alternative bracket polymers; urethane-dimethacrylate, high-density polyethylene, and an experimental bracket polymer (EBP) consisting of polyethylene and a copolymer were tested. Polycarbonate and polyoxymethylene brackets served as controls.
The mechanical properties of urethane-dimethacrylate, high-density polyethylene, EBP, polycarbonate, and polyoxymethylene bracket materials were evaluated after thermocycling (6000 x 5 degrees C-55 degrees C) in a mastication device before testing. Three medium-wear, fracture toughness, and Vickers hardness tests were performed.
High-density polyethylene had the highest values of wear and the lowest values of fracture toughness and Vickers hardness. The urethane-dimethacrylate bracket material and the EBP had better mechanical properties than polycarbonate. The polyoxymethylene bracket material had the highest values of fracture toughness and Vickers hardness, and the lowest values of wear compared with the other investigated polymers.
High-density polyethylene seems to be unsuitable as bracket material because it demonstrated excessive wear and insufficient fracture toughness. Polyoxymethylene had the best performance during mechanical testing.
聚合物托槽仍存在一些缺点，因为其耐磨性和硬度降低。本研究的目的是研究替代托槽聚合物的力学性能；测试了聚氨酯二甲基丙烯酸酯、高密度聚乙烯和由聚乙烯和共聚物组成的实验性托槽聚合物（EBP）。聚碳酸酯和聚甲醛托槽作为对照。
在咀嚼装置中进行热循环（6000×5°C-55°C）后，对聚氨酯二甲基丙烯酸酯、高密度聚乙烯、EBP、聚碳酸酯和聚甲醛托槽材料的力学性能进行评估，然后进行三种中磨损、断裂韧性和维氏硬度测试。
高密度聚乙烯的磨损值最高，断裂韧性和维氏硬度最低。与聚碳酸酯相比，聚氨酯二甲基丙烯酸酯托槽材料和 EBP 具有更好的力学性能。与其他研究的聚合物相比，聚甲醛托槽材料具有最高的断裂韧性和维氏硬度值，以及最低的磨损值。
高密度聚乙烯似乎不适合作为托槽材料，因为它表现出过度磨损和不足的断裂韧性。在力学测试中，聚甲醛表现最佳。
