PDF(Pubmed)
Abstract：
OBJECTIVE: To analyze the biomechanical system of anterior retraction with clear aligner therapy (CAT) with and without an anterior mini-screw and elastics.
METHODS: Models including a maxillary dentition (without first premolars), maxilla, periodontal ligaments (PDLs), attachments, and aligners were constructed and imported to finite element software. Three model groups were created: (1) control (CAT alone), (2) labial elastics (CAT with elastics between the anterior mini-screw and buttons on central incisors), and (3) linguoincisal elastics (CAT with elastics between the anterior mini-screw and precision cuts on the lingual sides of the aligner). Elastic forces (0-300 g, in 50 g increments) were applied.
RESULTS: CAT alone caused lingual tipping and extrusion of the incisors. Labial elastics caused palatal root torquing and intrusion and mesial tipping of the central incisors, while linguoincisal elastics produced palatal root torquing and intrusion of both central and lateral incisors. Second premolars were intruded in all three groups, with less intrusion in the linguoincisal elastics group. For the control group, stress was concentrated on both labial and lingual root surfaces, alveolar ridge, and cervical and apical PDLs. Stress was more concentrated in the labial elastics group and less concentrated in the linguoincisal elastics group.
CONCLUSIONS: CAT produced lingual tipping and extrusion of incisors during anterior retraction. Anterior mini-screws and elastics can achieve incisor intrusion and palatal root torquing. Linguoincisal elastics are superior to labial elastics with a lower likelihood of buccal open bite. Root resorption and alveolar defects may occur in CAT, more likely for labial elastics and less likely for linguoincisal elastics.
METHODS: Models including a maxillary dentition (without first premolars), maxilla, periodontal ligaments (PDLs), attachments, and aligners were constructed and imported to finite element software. Three model groups were created: (1) control (CAT alone), (2) labial elastics (CAT with elastics between the anterior mini-screw and buttons on central incisors), and (3) linguoincisal elastics (CAT with elastics between the anterior mini-screw and precision cuts on the lingual sides of the aligner). Elastic forces (0-300 g, in 50 g increments) were applied.
RESULTS: CAT alone caused lingual tipping and extrusion of the incisors. Labial elastics caused palatal root torquing and intrusion and mesial tipping of the central incisors, while linguoincisal elastics produced palatal root torquing and intrusion of both central and lateral incisors. Second premolars were intruded in all three groups, with less intrusion in the linguoincisal elastics group. For the control group, stress was concentrated on both labial and lingual root surfaces, alveolar ridge, and cervical and apical PDLs. Stress was more concentrated in the labial elastics group and less concentrated in the linguoincisal elastics group.
CONCLUSIONS: CAT produced lingual tipping and extrusion of incisors during anterior retraction. Anterior mini-screws and elastics can achieve incisor intrusion and palatal root torquing. Linguoincisal elastics are superior to labial elastics with a lower likelihood of buccal open bite. Root resorption and alveolar defects may occur in CAT, more likely for labial elastics and less likely for linguoincisal elastics.
摘要：
目的：分析带有和不带有前微型螺钉和弹性件的清晰对准器治疗（CAT）的前回缩的生物力学系统。
方法：包括上颌牙列（无第一前磨牙）的模型，上颌骨,牙周韧带（PDL），附件,和对齐器被构造并导入到有限元软件中。创建三个模型组：（1）对照（单独使用CAT），（2）唇松紧带（CAT在前微型螺钉和中央切牙上的纽扣之间带有松紧带），和（3）舌面弹性（CAT在前微型螺钉和矫正器舌侧的精密切口之间具有弹性）。弹力(0-300g,以50g的增量)进行应用。
结果：单独使用CAT会引起切牙的舌侧倾斜和挤压。唇弹性引起腭根扭转和侵入以及中央切牙的内侧倾斜，而舌尖弹性产生腭根扭转和中央和侧切牙的侵入。所有三组都侵入了第二前磨牙，在舌弹性组中的侵入较少。对于对照组，应力集中在唇和舌根表面，牙槽脊,和子宫颈和根尖PDL。应力更集中在唇弹性组中，而较少集中在舌弹性组中。
结论：CAT在前缩过程中产生了舌侧倾斜和门牙挤压。前微型螺钉和弹性件可以实现切牙侵入和腭根扭转。腹股沟弹性优于唇弹性，颊张开咬伤的可能性较低。在CAT中可能发生牙根吸收和肺泡缺损，唇弹性的可能性更大，舌弹性的可能性更小。
方法：包括上颌牙列（无第一前磨牙）的模型，上颌骨,牙周韧带（PDL），附件,和对齐器被构造并导入到有限元软件中。创建三个模型组：（1）对照（单独使用CAT），（2）唇松紧带（CAT在前微型螺钉和中央切牙上的纽扣之间带有松紧带），和（3）舌面弹性（CAT在前微型螺钉和矫正器舌侧的精密切口之间具有弹性）。弹力(0-300g,以50g的增量)进行应用。
结果：单独使用CAT会引起切牙的舌侧倾斜和挤压。唇弹性引起腭根扭转和侵入以及中央切牙的内侧倾斜，而舌尖弹性产生腭根扭转和中央和侧切牙的侵入。所有三组都侵入了第二前磨牙，在舌弹性组中的侵入较少。对于对照组，应力集中在唇和舌根表面，牙槽脊,和子宫颈和根尖PDL。应力更集中在唇弹性组中，而较少集中在舌弹性组中。
结论：CAT在前缩过程中产生了舌侧倾斜和门牙挤压。前微型螺钉和弹性件可以实现切牙侵入和腭根扭转。腹股沟弹性优于唇弹性，颊张开咬伤的可能性较低。在CAT中可能发生牙根吸收和肺泡缺损，唇弹性的可能性更大，舌弹性的可能性更小。
