Department of Orthodontics, Saint Louis University, Saint Louis, MO, USA.
Department of Orthodontics, Faculty of Dentistry, Alexandria University, Alexandria, Egypt.
BMC Oral Health. 2023 Jul 17;23(1):495. doi: 10.1186/s12903-023-03136-2.
To assess the possibility of extrusion of a maxillary central incisor with the use of buccal and lingual pressure columns in the absence of attachments, and to evaluate the forces and moments experienced by the teeth using both thermoformed and 3D-printed clear aligners.
A three-axis force and moment sensor (Aidin Robotics, Anyang, South Korea) was used to measure the forces and moments during extrusion of an upper left central incisor (UL1) and any forces experienced by the upper right central incisor (UR1) using thermoformed aligners and 3D-printed aligners. For the thermoformed aligners, the materials used were ATMOS® (American Orthodontics, Sheboygan, WI) and Zendura FLX® (Bay Materials LLC, Fremont, CA). 3D-printed aligners were fabricated using TC-85 clear photocurable resin (Graphy Inc., Seoul, South Korea). For each material type, three conditions were tested: Group 1: No attachment or pressure columns (control); Group 2: Attachment only; and Group 3: Pressure columns only. Each group was planned for 0.5 mm of extrusion on the UL1.
All force readings collected demonstrated statistically significant differences when compared by materials and when compared by groups, with a P value of < 0.001. In the absence of attachment or pressure columns (Group 1), ATMOS® and TC-85 groups exerted extrusive force on the UL1. However, significantly lower forces and moments were exerted by the TC-85 group in comparison to the ATMOS® and Zendura FLX® groups. In the presence of attachment (Group 2), all three ATMOS®, Zendura FLX® and TC-85 groups exerted extrusive force on the UL1, with the TA group showing different directions of faciolingual force, mesiodistal force and faciolingual inclination on the UR1 when compared to the other two thermoformed groups. Whereas in the presence of pressure columns (Group 3), only the TC-85 3D-printed aligner group exerted extrusive force. Thermoformed aligners generated significantly higher mean forces and moments than 3D-printed aligners. Significant levels of unintended forces and moments were present in all groups.
Force levels generated during extrusion with clear aligners are significantly lower with those 3D-printed using TC-85 than with those thermoformed using ATMOS® or Zendura FLX®. Attachments consistently generated extrusive forces, and may be an effective adjunct in achieving extrusion of incisors. Extrusion may be achieved without the use of attachments by utilizing pressure columns in 3D-printed aligners using TC-85. While different strategies can generate extrusive forces, there are significant unintended forces and moments.
评估在上颌中切牙无附件的情况下使用颊舌向压力柱产生外展的可能性，并使用热成型和 3D 打印透明矫正器评估牙齿所受的力和力矩。
使用三轴力和力矩传感器（Aidin Robotics，韩国安阳）测量上颌左中切牙（UL1）外展过程中的力和力矩，以及使用热成型矫正器和 3D 打印矫正器时上颌右中切牙（UR1）所受的任何力。对于热成型矫正器，使用的材料为 ATMOS®（美国正畸公司，Sheboygan，威斯康星州）和 Zendura FLX®（Bay Materials LLC，弗里蒙特，加利福尼亚州）。3D 打印矫正器使用 TC-85 透明光固化树脂（Graphy Inc.，首尔，韩国）制造。对于每种材料类型，测试了三种情况：第 1 组：无附件或压力柱（对照）；第 2 组：仅附件；第 3 组：仅压力柱。每组计划在上颌左中切牙上进行 0.5 毫米的外展。
所有力读数在材料之间和组之间比较时均具有统计学显著差异，P 值均小于 0.001。在无附件或压力柱（第 1 组）的情况下，ATMOS®和 TC-85 组对上颌左中切牙施加外展力。然而，TC-85 组施加的力和力矩明显低于 ATMOS®和 Zendura FLX®组。在有附件（第 2 组）的情况下，所有三个 ATMOS®、Zendura FLX®和 TC-85 组对上颌左中切牙施加外展力，与其他两个热成型组相比，TA 组在上颌右中切牙上显示出不同的颊舌向力、近远中向力和颊舌向倾斜方向。而在有压力柱（第 3 组）的情况下，仅 TC-85 3D 打印矫正器组对上颌左中切牙施加外展力。热成型矫正器产生的平均力和力矩明显高于 3D 打印矫正器。所有组均存在显著的非预期力和力矩。
与使用 ATMOS®或 Zendura FLX®热成型的矫正器相比，使用 TC-85 3D 打印的矫正器在进行矫正时产生的力水平明显较低。附件始终产生外展力，可能是实现切牙外展的有效辅助手段。在上颌左中切牙上使用 TC-85 3D 打印矫正器时，无需使用附件，可利用压力柱实现外展。虽然不同的策略可以产生外展力，但存在显著的非预期力和力矩。
