Finite element analysis of tooth movement under different retraction force and intrusive force in double-archwire lingual orthodontics system

Abstract

The objectives of this study were to evaluate the tooth movement tendency during space closure in maxillary anterior teeth by various combinations of retraction force and intrusive force in a double-archwire lingual orthodontic system. Mini-implant-double slot lingual orthodontics system models of the bilateral maxillary first premolar extraction cases were constructed. Three-dimensional finite element models of the maxilla were constructed with definite position mini-implants (8 mm) and power arms (6 mm). Different retraction forces(50gf、100gf、150gf)were applied with the help of a nickel-titanium closed coil spring on the plate side. Intrusive forces(0gf、50gf、100gf)were applied with the help of the mini-implant between the two central incisors, and the initial displacements of the maxillary anterior teeth were analyzed. Variable amounts of displacements like controlled tipping, uncontrolled tipping, lingual crown tipping, labial root tipping, extrusion and distal crown tipping were observed in all the models, and these tendencies increased as the magnitude of retraction force increased, and these tendencies decreased as the magnitude of intrusive force increased. When the intrusive force was greater than or equal to the retraction force, the maxillary central incisors showed the trend of lingual crown tipping and labial root tipping, resulting in uncontrolled tipping movement. In terms of horizontal changes, the increasing width of bilateral anterior teeth was observed, with canines showing the least increasing trend. Various combinations of retraction force and intrusive force in a double-archwire lingual orthodontic system provide a new choice for torque control of the anterior teeth. Although anterior mini-implants and elastics can achieve incisor intrusion and lingual root torque, they cannot achieve the expected torque without additional torque control methods.

Keywords:

• finite element models
• lingual orthodontics
• retraction force
• intrusive force
• torque control

Authors’ contributions

T.L: wrote the main manuscript text and prepared all figures and tables. All authors reviewed the manuscript; X.W: conception and design of the work, order of authors, confirming that data/figures/materials/code presentation accurately reflects the original. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval and consent to participate

This study was approved by the ethics committee of Shanxi Medical University School. Written informed consent was obtained from all subjects.

All methods were performed in accordance with the Declaration of Helsinki.

Availability of data and materials

All data generated or analysed during this study are included in this published article [and its supplementary information files].

Additional information

Funding

This work was supported by Shanxi Province Science and Technology Innovation Key Talent Team (202204051002034), Central guide local science and technology development funds (transfer of scientific and technological achievements) project (YDZJSX2021C011), Shanxi Province Key R&D Program (202102130501002) and Key country-specific science and technology cooperation projects of Shanxi Provincial Science and Technology Department (202204041101004).