PDF(Pubmed)
Abstract：
UNASSIGNED: Overtreatment design of clear aligner treatment (CAT) in extraction cases is currently primarily based on the clinical experience of orthodontists and is not supported by robust evidence on the underlying biomechanics. This study aimed to investigate the biomechanical effects of overtreatment strategies involving different maxillary anterior teeth intrusion patterns during anterior teeth retraction by CAT in extraction cases.
UNASSIGNED: A finite element model of the maxillary dentition with the first premolar extracted was constructed. A loading method of clear aligners (CAs) based on the initial state field was proposed. The iterative method was used to simulate the long-term orthodontic tooth movement under the mechanical load exerted by the CAs. Three groups of CAs were utilized for anterior teeth retraction (G0: control group; G1: incisors intrusion group; G2: anterior teeth intrusion group). Tooth displacement and occlusal plane rotation tendency were analyzed.
UNASSIGNED: In G0, CAT caused lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, mesial tipping, and intrusion of the posterior teeth. In G1, the incisors showed minimal extrusion, whereas the canines showed increased extrusion and distal tipping tendency. G2 showed the smallest degree of posterior occlusal plane angle rotation, while the inclination tendency of the canines and second premolars decreased.
UNASSIGNED: 1. In CAT, tooth displacement tendency may change with increased wear time. 2. During anterior teeth retraction, the incisor intrusion pattern can provide effective vertical control for the lateral incisors but has little effect on the central incisors. Anterior teeth intrusion patterns can alleviate the inclination of canines and second premolars, resulting in partial relief of the roller-coaster effect.
UNASSIGNED: A finite element model of the maxillary dentition with the first premolar extracted was constructed. A loading method of clear aligners (CAs) based on the initial state field was proposed. The iterative method was used to simulate the long-term orthodontic tooth movement under the mechanical load exerted by the CAs. Three groups of CAs were utilized for anterior teeth retraction (G0: control group; G1: incisors intrusion group; G2: anterior teeth intrusion group). Tooth displacement and occlusal plane rotation tendency were analyzed.
UNASSIGNED: In G0, CAT caused lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, mesial tipping, and intrusion of the posterior teeth. In G1, the incisors showed minimal extrusion, whereas the canines showed increased extrusion and distal tipping tendency. G2 showed the smallest degree of posterior occlusal plane angle rotation, while the inclination tendency of the canines and second premolars decreased.
UNASSIGNED: 1. In CAT, tooth displacement tendency may change with increased wear time. 2. During anterior teeth retraction, the incisor intrusion pattern can provide effective vertical control for the lateral incisors but has little effect on the central incisors. Anterior teeth intrusion patterns can alleviate the inclination of canines and second premolars, resulting in partial relief of the roller-coaster effect.
摘要：
■在拔牙病例中进行的清晰矫正器治疗（CAT）的过度治疗设计目前主要基于正畸医生的临床经验，并且没有基础生物力学的有力证据支持。本研究旨在研究在拔牙病例中，CAT在前牙缩回过程中涉及不同上颌前牙侵入方式的过度治疗策略的生物力学影响。
■构建了拔除第一前磨牙的上颌牙列的有限元模型。提出了一种基于初始状态场的透明对准器加载方法。迭代方法用于模拟CA施加的机械载荷下的长期正畸牙齿移动。使用三组CA进行前牙回缩（G0：对照组；G1：门牙侵入组；G2：前牙侵入组）。分析了牙齿位移和咬合面旋转趋势。
■在G0中，CAT引起了门牙的舌状倾斜和挤压，犬齿的远端倾斜和挤压，中等小费，和后牙的侵入。在G1中，切牙显示出最小的挤压，而犬表现出增加的挤压和远端倾斜趋势。G2显示最小程度的后咬合平面角度旋转，而犬齿和第二前磨牙的倾斜趋势下降。
■1.在CAT,齿位移趋势可能随着磨损时间的增加而变化。2.在前牙缩回期间，切牙侵入模式可以为侧切牙提供有效的垂直控制，但对中切牙的影响很小。前牙侵入模式可以缓解犬齿和第二前磨牙的倾斜，导致过山车效应的部分缓解。
■构建了拔除第一前磨牙的上颌牙列的有限元模型。提出了一种基于初始状态场的透明对准器加载方法。迭代方法用于模拟CA施加的机械载荷下的长期正畸牙齿移动。使用三组CA进行前牙回缩（G0：对照组；G1：门牙侵入组；G2：前牙侵入组）。分析了牙齿位移和咬合面旋转趋势。
■在G0中，CAT引起了门牙的舌状倾斜和挤压，犬齿的远端倾斜和挤压，中等小费，和后牙的侵入。在G1中，切牙显示出最小的挤压，而犬表现出增加的挤压和远端倾斜趋势。G2显示最小程度的后咬合平面角度旋转，而犬齿和第二前磨牙的倾斜趋势下降。
■1.在CAT,齿位移趋势可能随着磨损时间的增加而变化。2.在前牙缩回期间，切牙侵入模式可以为侧切牙提供有效的垂直控制，但对中切牙的影响很小。前牙侵入模式可以缓解犬齿和第二前磨牙的倾斜，导致过山车效应的部分缓解。
