Mechanical properties of orthodontic wires on ceramic brackets associated with low friction ligatures

Abstract Introduction Few studies investigated the mechanical properties of orthodontic wires on ceramic brackets associated the ligatures. Objective This study aimed to compare the load-deflection of orthodontic wires with round section of 0.016” made of stainless steel (SS), nickel-titanium (NiTi) and glass fiber-reinforced polymer composite (GFRPC). Material and method Sixty specimens obtained from 10 sectioned pre-contoured arches (TP Orthodontics), were divided into 3 groups of 20 according to each type of material (1 esthetic-type wire and 2 not esthetic) and length of 50 mm. The methodology consisted of a 3-point bending test using esthetic ceramic brackets (INVU, TP Orthodontics, Edgewise, 0.022”x 0.025”) as points of support. The tensile tests were performed on a mechanical test machine, at a speed of 10 mm/min, deflection of 1 mm, 2 mm and 3 mm. Friedman’s Non Parametric Multiple comparisons test was used (P<0.05). Result The nickel-titanium wire presented smaller load/ deflection compared with stainless steel. GFRPC wires had lower strength values among all groups evaluated (P

摘要与引言：目前鲜有研究探讨配套结扎丝的陶瓷托槽下正畸弓丝的力学性能。
研究目的：本研究旨在对比三种材质的0.016英寸圆形截面正畸弓丝的载荷-挠度特性，三种材质分别为不锈钢（stainless steel, SS）、镍钛（nickel-titanium, NiTi）以及玻璃纤维增强聚合物复合材料（glass fiber-reinforced polymer composite, GFRPC）。
材料与方法：从10根经切割的预成型弓丝（TP Orthodontics）中获取60个试样，按材质类型分为3组，每组20个（含1种美观型弓丝与2种非美观型弓丝），试样长度为50mm。本研究采用三点弯曲试验，以美观型陶瓷托槽（INVU, TP Orthodontics, Edgewise, 0.022"×0.025"）作为支撑支点。测试在机械试验机上进行，加载速度设为10mm/min，分别施加1mm、2mm、3mm的挠度。数据分析采用弗里德曼非参数多重比较检验，检验水准为P<0.05。
结果：镍钛弓丝的载荷-挠度值低于不锈钢弓丝；在所有评估组中，玻璃纤维增强聚合物复合材料弓丝的强度值最低（P