Faltermeier Andreas, Rosentritt Martin, Faltermeier Rupert, Müssig Dieter
Department of Orthodontics, University Medical Centre, Regensburg, Germany.
Eur J Orthod. 2007 Jun;29(3):304-9. doi: 10.1093/ejo/cjm025. Epub 2007 May 19.
In spite of their popularity in fulfilling aesthetic requirements, plastic brackets still present some disadvantages because of their low elastic modulus, decreased fracture toughness, and reduced wear resistance. Fibre-reinforced composites are well established in dentistry and consist of a polymer matrix in which reinforcing fibres are embedded. Stress is transferred from the polymer matrix to the fibres which present a high tensile strength. Hence, the mechanical properties of polymers could be improved. The purpose of this study was to compare fracture strength, fracture toughness and flexural strength of an experimental fibre-reinforced bracket material, an SiO(2) filler-reinforced bracket and an unfilled plastic bracket material (control group). Experimental brackets and specialized bars were manufactured. Tests were performed after thermal cycling (5 degrees C/55 degrees C) the samples in an artificial oral environment of a device to simulate mastication. Statistical evaluation was undertaken. The median, 25th and 75th percentiles were calculated and a Mann-Whitney U-test was performed. In this study two findings were obvious. (1) Filler reinforcement of plastic brackets improved fracture strength and fracture toughness in comparison with the unfilled bracket material. (2) Glass fibre reinforcement of orthodontic bracket materials resulted in the greatest enhancement of the mechanical properties in comparison with the other test groups. Therefore, the application of glass fibres in plastic brackets is a successful method to enhance fracture strength.
尽管塑料托槽在满足美学需求方面很受欢迎，但由于其低弹性模量、降低的断裂韧性和耐磨性，仍然存在一些缺点。纤维增强复合材料在牙科领域已得到广泛应用，由嵌入增强纤维的聚合物基体组成。应力从聚合物基体传递到具有高拉伸强度的纤维上。因此，可以改善聚合物的机械性能。本研究的目的是比较一种实验性纤维增强托槽材料、一种SiO(2)填料增强托槽和一种未填充塑料托槽材料（对照组）的断裂强度、断裂韧性和弯曲强度。制作了实验性托槽和专用棒材。在模拟咀嚼的装置的人工口腔环境中对样品进行热循环（5摄氏度/55摄氏度）后进行测试。进行了统计评估。计算了中位数、第25百分位数和第75百分位数，并进行了曼-惠特尼U检验。在本研究中有两个明显的发现。(1) 与未填充托槽材料相比，塑料托槽的填料增强提高了断裂强度和断裂韧性。(2) 与其他测试组相比，正畸托槽材料的玻璃纤维增强导致机械性能的最大提高。因此，在塑料托槽中应用玻璃纤维是提高断裂强度的一种成功方法。
