Comparison of deflection forces of esthetic archwires combined with ceramic brackets

Abstract Coated archwires and ceramic brackets have been developed to improve facial esthetics during orthodontic treatment. However, their mechanical behavior has been shown to be different from metallic archwires and brackets. Therefore, the aim of this study was to compare the deflection forces in coated nickel-titanium (NiTi) and esthetic archwires combined with ceramic brackets. Material and Methods Non-coated NiTi (NC), rhodium coated NiTi (RC), teflon coated NiTi (TC), epoxy coated NiTi (EC), fiber-reinforced polymer (FRP), and the three different conventional brackets metal-insert polycrystalline ceramic (MI-PC), polycrystalline ceramic (PC) and monocrystalline ceramic (MC) were used. The specimens were set up on a clinical simulation device and evaluated in a Universal Testing Machine (Instron). An acrylic device, representative of the right maxillary central incisor was buccolingually activated and the unloading forces generated were recorded at 3, 2, 1 and 0.5 mm. The speed of the testing machine was 2 mm/min. ANOVA and Tukey tests were used to compare the different archwires and brackets. Results The brackets presented the following decreasing force ranking: monocrystalline, polycrystalline and polycrystalline metal-insert. The decreasing force ranking of the archwires was: rhodium coated NiTi (RC), non-coated NiTi (NC), teflon coated NiTi (TC), epoxy coated NiTi (EC) and fiber-reinforced polymer (FRP). At 3 mm of unloading the FRP archwire had a plastic deformation and produced an extremely low force in 2; 1 and 0.5 mm of unloading. Conclusion Combinations of the evaluated archwires and brackets will produce a force ranking proportional to the combination of their individual force rankings.

摘要 为优化正畸治疗期间的面部美观效果，科研人员已开发出涂层弓丝与陶瓷托槽。但已有研究表明，其力学性能与金属弓丝及金属托槽存在显著差异。因此，本研究旨在对比涂层镍钛（NiTi）美学弓丝与陶瓷托槽组合后的偏转力情况。
材料与方法 本次实验选用未涂层镍钛弓丝（NC）、铑涂层镍钛弓丝（RC）、聚四氟乙烯涂层镍钛弓丝（TC）、环氧涂层镍钛弓丝（EC）、纤维增强聚合物（FRP）弓丝，以及三种传统托槽：金属嵌体多晶陶瓷托槽（MI-PC）、多晶陶瓷托槽（PC）与单晶陶瓷托槽（MC）。将试件安装于临床模拟装置，并通过万能试验机（Instron）开展性能评估。采用模拟右上颌中切牙的丙烯酸酯装置进行颊舌向加载，记录3mm、2mm、1mm及0.5mm卸载位移下产生的卸载力。试验机加载速度设定为2mm/min。采用方差分析（ANOVA）与Tukey检验对不同弓丝及托槽组进行对比分析。
结果 托槽的卸载力由高到低排序为：单晶陶瓷托槽、多晶陶瓷托槽、金属嵌体多晶陶瓷托槽。弓丝的卸载力由高到低排序为：铑涂层镍钛弓丝（RC）、未涂层镍钛弓丝（NC）、聚四氟乙烯涂层镍钛弓丝（TC）、环氧涂层镍钛弓丝（EC）与纤维增强聚合物（FRP）弓丝。当卸载位移为3mm时，纤维增强聚合物（FRP）弓丝发生塑性变形，在2mm、1mm及0.5mm卸载位移下产生的力值极低。
结论 本研究所评估的弓丝与托槽组合所产生的力值排序，与其各自单独的力值排序呈正比关系。