Department of Orthodontics and Craniofacial Orthopedics, University Medicine Greifswald, 17475, Greifswald, Germany.
Department for Prosthodontics, Gerostomatology and Biomaterials, University Medicine Greifswald, Greifswald, Germany.
Clin Oral Investig. 2023 May;27(5):2163-2173. doi: 10.1007/s00784-023-04912-8. Epub 2023 Feb 15.
To investigate the effect of layer height of FFF-printed models on aligner force transmission to a second maxillary premolar during buccal torquing, distalization, extrusion, and rotation using differing foil thicknesses.
Utilizing OnyxCeph™ Lab (Image Instruments GmbH, Chemnitz, Germany, Release Version 3.2.185), the following movements were programmed for the second premolar: buccal torque (0.1-0.5 mm), distalization (0.1-0.4 mm), extrusion (0.1-0.4 mm), rotation (0.1-0.5 mm), and staging 0.1 mm. Via FFF, 91 maxillary models were printed for each staging at different layer heights (100 µm, 150 µm, 200 µm, 250 µm, 300 µm). Hence, 182 aligners, made of polyethylene terephthalate glycol (PET-G) with two thicknesses (0.5 mm and 0.75 mm), were prepared. The test setup comprised an acrylic maxillary model with the second premolar separated and mounted on a sensor, measuring initial forces and moments exerted by the aligners. A generalized linear model for the gamma distribution was applied, evaluating the significance of the factors layer height, type of movement, aligner thickness, and staging on aligner force transmission.
Foil thickness and staging were found to have a significant influence on forces delivered by aligners, whereas no significance was determined for layer height and type of movement. Nevertheless, at a layer height of 150 µm, the most appropriate force transmission was observed.
Printing aligner models at particularly low layer heights leads to uneconomically high print time without perceptible better force delivery properties, whereas higher layer heights provoke higher unpredictability of forces due to scattering. A z-resolution of 150 µm appears ideal for in-office aligner production combining advantages of economic print time and optimal force transmission.
利用 OnyxCeph™ Lab（Image Instruments GmbH，德国开姆尼茨，版本 3.2.185），研究在使用不同箔片厚度的情况下，FFF 打印模型的层厚对颊向转矩、远移、外展和旋转过程中矫治器力传递到第二上颌前磨牙的影响。
针对第二前磨牙，在 OnyxCeph™ Lab 中编程以下运动：颊向转矩（0.1-0.5mm）、远移（0.1-0.4mm）、外展（0.1-0.4mm）、旋转（0.1-0.5mm）和阶段 0.1mm。通过 FFF，在不同的层厚（100μm、150μm、200μm、250μm、300μm）下为每个阶段打印 91 个上颌模型。因此，用聚对苯二甲酸乙二醇酯（PET-G）制成两种厚度（0.5mm 和 0.75mm）的 182 个矫治器。测试装置包括一个上颌丙烯酸模型，分离并安装第二前磨牙在传感器上，测量矫治器施加的初始力和力矩。应用伽马分布的广义线性模型，评估层厚、运动类型、矫治器厚度和阶段对矫治器力传递的因素的显著性。
发现箔片厚度和阶段对矫治器施加的力有显著影响，而层厚和运动类型则没有确定意义。然而，在层厚为 150μm 时，观察到最适当的力传递。
在特别低的层厚下打印矫治器模型会导致打印时间极长，而力传递性能没有明显提高，而较高的层厚会由于散射而导致力的不可预测性增加。150μm 的 z 分辨率对于结合经济打印时间和最佳力传递优势的诊室用矫治器生产似乎是理想的。
