George Soja Sara, Reddy T R Jayaprakash, Kv Sujan Kumar, Chaudhary Gagan, Farooq Umar, Cherukuri Vishnupriya, Likitha Chadawala
Department of Orthodontics, MNR Dental College and Hospital, Telangana, IND.
Department of Dentistry, Dr. VRK Women's Medical College, Teaching Hospital and Research Center, Telangana, IND.
Cureus. 2022 Jun 15;14(6):e25976. doi: 10.7759/cureus.25976. eCollection 2022 Jun.
The effectiveness of orthodontic treatment depends on precise control of the anterior teeth during retraction in sliding mechanics. That is why researchers were interested in finding the appropriate loading conditions for sliding mechanics to govern anterior teeth's movement, such as the height of retraction force application and its location on the arch wire.
A FEM study was conducted to evaluate the type of movement of anterior teeth during en-masse retraction by applying 200 gms of force to each side of the maxillary arch with power arms set at various levels (4 mm, 6 mm, 8 mm) mesial to canine from mini-screw placed at a height of 8 mm between maxillary first molar and second premolar. A 3D model (FEM) of the maxillary arch was constructed to study the amount of labio-lingual tipping and bodily displacement of maxillary central incisor achieved.
When a 200-gm power was applied to the power arm, controlled lingual crown tipping was seen at the levels of 4 mm and 6 mm, in contrast to the level of 8 mm, where bodily displacement occurred, according to this evaluation. Conclusion: In sliding mechanics, the height of the power arm plays an important role in obtaining controlled lingual crown tipping or bodily displacement during retraction of anterior teeth.
正畸治疗的效果取决于在滑动机制内收过程中对前牙的精确控制。这就是为什么研究人员对寻找滑动机制的合适加载条件以控制前牙移动感兴趣，例如内收力施加的高度及其在弓丝上的位置。
进行了一项有限元分析（FEM）研究，通过将200克的力施加于上颌牙弓的每一侧，力臂设置在距尖牙不同水平（4毫米、6毫米、8毫米）的近中位置，力臂从位于上颌第一磨牙和第二前磨牙之间8毫米高度处的微型螺钉引出，以此评估整体内收过程中前牙的移动类型。构建了上颌牙弓的三维模型（有限元分析），以研究上颌中切牙实现的唇舌向倾斜和整体位移量。
根据该评估，当在力臂上施加200克的力时，在4毫米和6毫米水平观察到了可控的舌向冠倾斜，而在8毫米水平则发生了整体位移。结论：在滑动机制中，力臂的高度在获得前牙内收过程中可控的舌向冠倾斜或整体位移方面起着重要作用。
