Qiang Ruyue, Wu Junjie, Gao Jie, Chen Haiwen, Xu Jianing, Jin Zuolin, Ma Yanning
State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi Key Laboratory of Stomatology, Department of Orthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032, China.
Department of Orthodontics, Shanxi Medical University School and Hospital of Stomatology, Taiyuan, 030001, China.
BMC Oral Health. 2025 Apr 13;25(1):558. doi: 10.1186/s12903-025-05945-z.
In clear aligner treatment (CAT), closure of the premolar space is achieved by reducing aligner length. Posterior anchorage preparation is effective in preserving molar angulation; however, the resulting distal tipping can contribute to anterior anchorage loss. This study aims to identify an approach that balances anterior torque compensation with posterior anchorage preparation in CAT.
Two finite element models were developed to simulate en-masse incisor retraction using clear aligners (CAs). Model 1 simulated first premolar extraction cases, while Model 2 simulated second premolar extraction cases. In Step I, only distal tipping was applied to the posterior teeth as an anchorage preparation strategy. In Step II, a positive torque of 0.08 degrees was introduced to the incisors to simulate torque compensation in a single orthodontic step.
In Model 1, the maxillary lateral incisor and mandibular central incisor tipped further lingually compared to cases without posterior anchorage preparation. The posterior terminal teeth showed a tendency to tip mesially in Step I, which was partially reduced with anterior torque compensation in Step II. In Model 2, all incisors had a stronger tendency to tip lingually in Step I. Molar anchorage control improved with incisor torque compensation of 0.08 degrees. Tipping was more pronounced in the maxillary arches compared to the mandibular arches. Posterior anchorage loss was greater in Model 2, while Model 1 showed more pronounced anchorage loss in anterior teeth.
Posterior anchorage preparation alone increases the risk of anterior anchorage loss. Combining this approach with incisor torque compensation helps distribute the anchorage burden more effectively. As an advanced approach, anterior and posterior anchorage management should be strategically coordinated and adapted to the number of orthodontic steps required in premolar extraction cases treated with CAs.
Not applicable.
在透明矫治器治疗（CAT）中，通过缩短矫治器长度来关闭前磨牙间隙。后牙支抗预备对于保持磨牙角度有效；然而，由此产生的远中倾斜可能导致前牙支抗丧失。本研究旨在确定一种在CAT中平衡前牙转矩补偿与后牙支抗预备的方法。
建立两个有限元模型，以模拟使用透明矫治器（CA）进行整体切牙内收。模型1模拟拔除第一前磨牙的病例，模型2模拟拔除第二前磨牙的病例。在步骤I中，仅对后牙施加远中倾斜作为支抗预备策略。在步骤II中，对切牙施加0.08度的正转矩，以模拟在单个正畸步骤中的转矩补偿。
在模型1中，与未进行后牙支抗预备的病例相比，上颌侧切牙和下颌中切牙舌向倾斜更明显。后牙在步骤I中有近中倾斜的趋势，在步骤II中通过前牙转矩补偿部分减轻。在模型2中，所有切牙在步骤I中舌向倾斜的趋势更强。切牙转矩补偿0.08度后，磨牙支抗控制得到改善。与下颌牙弓相比，上颌牙弓中的倾斜更明显。模型2中的后牙支抗丧失更大，而模型1在前牙中表现出更明显的支抗丧失。
单独进行后牙支抗预备会增加前牙支抗丧失的风险。将该方法与切牙转矩补偿相结合有助于更有效地分配支抗负担。作为一种先进的方法，前牙和后牙支抗管理应进行策略性协调，并适应CA治疗的前磨牙拔除病例所需的正畸步骤数量。
不适用。
