上海交通大学学报（医学版）

上海交通大学学报（医学版） ›› 2024, Vol. 44 ›› Issue (8): 935-943.doi: 10.3969/j.issn.1674-8115.2024.08.001

• 牙颌面畸形专题 •    下一篇

替牙期无托槽隐形矫治器扩弓治疗改良设计的有限元分析

吕秦毅(), 高子琦, 冯青辰, 梅宏翔, 李娟()   

  1. 四川大学华西口腔医院正畸科，口腔疾病研究国家重点实验室，国家口腔疾病临床医学研究中心，成都 610041
  • 收稿日期:2024-03-05 接受日期:2024-06-05 出版日期:2024-08-28 发布日期:2024-08-27
  • 通讯作者: 李娟 E-mail:1375218618@qq.com;lijuan@scu.edu.cn
  • 作者简介:吕秦毅（1999—），男，苗族，学士；电子信箱：1375218618@qq.com。
  • 基金资助:
    国家自然科学基金(32271364);四川省重大科技专项项目(2022ZDZX0031);时代天使科研基金(SDTS21-4-01);四川大学华西口腔医院临床研究项目(LCYJ2019-22)

Optimizing arch expansion with clear aligners in the mixed dentition based on finite element analysis

LÜ Qinyi(), GAO Ziqi, FENG Qingchen, MEI Hongxiang, LI Juan()   

  1. Department of Orthodontics, West China Hospital of Stomatology, Sichuan University; State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Disease, Chengdu 610041, China
  • Received:2024-03-05 Accepted:2024-06-05 Online:2024-08-28 Published:2024-08-27
  • Contact: LI Juan E-mail:1375218618@qq.com;lijuan@scu.edu.cn
  • Supported by:
    National Natural Science Foundation of China(32271364);Major Special Science and Technology Project of Sichuan Province(2022ZDZX0031);Angelalign Scientific Research Fund(SDTS21-4-01);Clinical Research Project of West China Hospital of Stomatology, Sichuan University(LCYJ2019-22)

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摘要：

目的·借助有限元分析揭示无托槽隐形矫治器用于替牙期扩弓治疗时单颗牙位移方向、效率及力学荷载，并针对扩弓效率不足以及后牙颊倾等问题，设计扩弓过矫治和转矩补偿体系。方法·纳入替牙期志愿者1名，构建其颅上颌复合体三维模型以及隐形矫治体系，模拟无托槽隐形矫治器对上颌乳尖牙到第一恒磨牙施加颊向位移（工况1~4：分别为0.200、0.275、0.300、0.325 mm），同时施加颊向位移和根颊向转矩（工况1：颊向位移载荷0.200 mm，根颊向转矩0°；工况5：颊向位移载荷0.275 mm，根颊向转矩1.0°；工况6：颊向位移载荷0.300 mm，根颊向转矩1.3°；工况7：颊向位移载荷0.325 mm，根颊向转矩1.8°）。通过有限元分析，计算牙齿位移以及牙周膜的等效应力分布。结果·无托槽隐形矫治器扩弓治疗在替牙期主要表现为牙齿颊倾的牙性扩弓效应，且不同牙位的扩弓效率不同。在设定每侧0.200 mm的扩弓量时，上颌第一恒磨牙扩弓效率为51.86%，上颌第二乳磨牙为68.76%，上颌第一乳磨为73.48%，上颌乳尖牙为84.17%。通过设计扩弓过矫治（0.275、0.300、0.325 mm），能够有效提高扩弓效果。当扩弓过矫治量达到150%（0.300 mm）时，上颌第一恒磨牙、第二乳磨牙、第一乳磨牙和乳尖牙处扩弓效率分别提升为75.16%、99.96%、107.35%和122.37%；上颌第二乳磨牙、第一乳磨牙、乳尖牙处扩弓效率均接近100.00%。过矫治设计会加剧扩弓的牙性效应，使牙齿颊侧倾斜移动趋势加大，导致牙齿颊倾、腭尖下垂，上颌第一恒磨牙、第二乳磨牙、第一乳磨牙、乳尖牙的冠根位移差在扩弓过矫治量达到150%时，分别为-0.109、-0.134、-0.132、-0.298 mm。对不同牙位施加对应转矩补偿，可以对抗后牙颊倾。在扩弓过矫治量达到150%（0.300 mm）时，添加1.3°根颊向转矩，各牙位扩弓效率分别为56.15%、73.88%、79.49%、87.80%，而冠根位移差减小至-0.081、-0.097、-0.095、-0.208 mm。结论·无托槽隐形矫治器用于替牙期扩弓治疗时，存在后牙颊倾的不良反应，并且在不同牙位的扩弓效率不同。应根据不同牙位，分别设计不同的矫治策略。过矫治可以提高扩弓效率，但是需要配合根颊向转矩，从而实现牙齿整体颊侧移动。

关键词: 扩弓治疗, 口腔正畸, 替牙期, 正畸矫治器，可摘式, 透明矫治器, 有限元分析

Abstract:

Objective ·To reveal the direction, efficiency, and mechanical load of single tooth displacement with clear aligners for expansion treatment during the transitional dentition period with the aid of finite element analysis. Additionally, overcorrection and torque compensation systems were designed to address insufficient expansion efficiency and buccal inclination of posterior teeth. Methods ·One volunteer in mixed dentition period was included to construct a three dimentional cranio-maxillary complex model and an invisible orthodontic system, simulating the buccal displacement (load 1?4: 0.200, 0.275, 0.300, 0.325 mm, respectively) and root buccal torque (load 1: buccal displacement load 0.200 mm, root buccal torque 0°; load 5: buccal displacement load 0.275 mm, root buccal torque 1.0°; load 6: buccal displacement load 0.300 mm, root buccal torque 1.3° and load 7: buccal displacement load 0.325mm, root buccal torque 1.8°) on the maxillary deciduous teeth to the first permanent molar with a non bracket invisible orthodontic appliance. Through finite element analysis, the tooth displacement and equivalent stress distribution of the periodontal membrane can be calculated. Results ·Expansion treatment with clear aligners in the transitional dentition phase primarily revealed the effect of buccal expansion of teeth; different teeth achieved different levels of expansion rate. At a set expansion amount of 0.200 mm per side, expansion efficiency in the maxillary first permanent molar was 51.86%, second primary molar 68.76%, first primary molar 73.48%, and primary cuspid 84.17%. By designing over-correction (0.275, 0.300, 0.325 mm), the results showed significant enhancement in expansion effect. When overcorrection length reached 150% (0.300 mm), expansion efficiency at the maxillary first permanent molar, second primary molar, first primary molar, and primary cuspid were 75.16%, 99.96%, 107.35%, and 122.37%, respectively. The expansion efficiency of maxillary second primary molar, first primary molar, and primary cuspid was close to 100.00%. The overcorrection design exacerbated the dental effects of expansion, intensifying the tendency for teeth to tilt toward the cheek side, leading to side effects such as buccal inclination and drooping of the palatal cusps. When the overcorrection amount for expansion reached 150%, the crown-root displacement in the upper first permanent molar, second primary molar, first primary molar, and primary cuspid were -0.109, -0.134, -0.132, and -0.298 mm, respectively. Applying specific torque compensation for different tooth positions can combat the buccal inclination of posterior teeth. At an overcorrection length of 150% (0.300 mm) with an added 1.3° root buccal torque, expansion efficiency was 56.15%, 73.88%, 79.49%, and 87.80%, respectively. While the crown-root displacement differences reduced to -0.081, -0.097, -0.095, and -0.208 mm. Conclusion ·When using clear aligners for expansion treatment during a transitional dentition period, side effects such as buccal inclination of posterior teeth exist. Furthermore, various teeth realize differing levels of expansion efficiency, necessitating the design of unique adjustment strategies according to different tooth positions. Overcorrection can improve expansion efficiency but needs to be coordinated with root buccal torque for the whole tooth to move buccally.

Key words: arch expansion, orthodontic treatment, mixed dentition, orthodontic appliance, removable, clear aligner, finite element analysis

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