Biomechanical Mechanism of Rocking-Chair Arch wire in En-Masse Retraction of Maxillary Anterior Teeth
10.16156/j.1004-7220.2025.04.009
- VernacularTitle:摇椅形唇弓滑动法整体内收上颌前牙的力学机制
- Author:
Jiaying HU
1
;
Jiali LIU
;
Zhen LIN
;
Jinquan GUO
;
Xie SHI
;
Jiehua SU
Author Information
1. 福建省口腔疾病研究重点实验室;福建省高校口腔医学重点实验室,福州 350002
- Publication Type:Journal Article
- Keywords:
orthodontics;
finite element analysis;
rocking-chair archwire(RCA);
sliding mechanics;
en-masse retraction
- From:
Journal of Medical Biomechanics
2025;40(4):858-865
- CountryChina
- Language:Chinese
-
Abstract:
Objective To establish a simplified simulation method of rocking-chair archwire(RCA),explore the biomechanical effect of RCA during anterior teeth retraction with sliding mechanics,and provide guidance for clinical treatment.Methods A standard 0.019 in×0.025 in(0.483 mm×0.635 mm)labial archwire was imported into ANSYS software and preloaded spring was used to simulate RCA at different angles to achieve parameterized modeling.A three-dimensional(3D)finite element model with labial straight wire appliance,teeth,periodontium and maxillary bone was established to analyze the displacement and force of anterior/posterior teeth under 1.5 N intra-arch traction combined with RCA at different angles.Results Preloading forces of 1.5,3,4.5,and 6 N in spring induced angles of approximately 5°,10°,15°,and 20° for RCA,demonstrating the flexibility and convenience of the parameterized modeling method.During intra-arch traction with increased angle of RCA,lingual crown displacement of the middle incisor gradually decreased,while the lateral incisor and canine showed decreased crown tipping and increased lingual root displacement;when the RCA angle was 20°,the lateral incisor and canine achieved almost bodily retraction.Meanwhile,premolars showed an extrusion tendency,while molars demonstrated distal crown tipping and intrusion tendency.As the RCA angle increased from 0° to 20°,intrusive force on the anterior teeth increased,and the moment-force ratio(M/F)at bracket level increased from 0 to near 9 mm.Conclusions RCA can effectively control the moving pattern of the maxillary anterior teeth and prevent their over-erection and extrusion during retraction with sliding mechanics.During intra-arch traction with rigid stainless steel archwire,theoretically RCA of 20° has sufficient torque control on the anterior teeth to achieve their en-masse retraction.
