Finite element analysis of the effect of power arm locations on tooth movement in extraction space closure with miniscrew anchorage in customized lingual orthodontic treatment

doi:10.1016/j.ajodo.2018.08.025

American Journal of Orthodontics and Dentofacial Orthopedics

Volume 156, Issue 2, August 2019, Pages 210-219

https://doi.org/10.1016/j.ajodo.2018.08.025 Get rights and content

Highlights

•
Biomechanics of tooth movement in customized lingual orthodontics is important.
•
Maxillary anterior tooth retraction with miniscrew anchorage requires careful planning.
•
Distal canine power arms are unfavorable for controlling torque and intercanine width.
•
Power arms midway between the lateral incisors and canines provide better control.
•
Extra torque control methods will still be needed.

Introduction

More patients are choosing customized orthodontic appliances because of their excellent esthetics. It is essential that clinicians understand the biomechanics of the tooth movement tendency in customized lingual orthodontics. This study aimed to evaluate the tooth movement tendency during space closure in maxillary anterior teeth with the use of miniscrew anchorage in customized lingual orthodontics with various power arm locations.

Methods

Three-dimensional finite element models of the maxilla were created with miniscrews and power arms; the positions were varied to change the force directions. A retraction force (1.5 N) was applied from the top of the miniscrews to the selected points on the power arm, and the initial displacements of the reference nodes of the maxillary teeth were analyzed.

Results

After applying force in different directions, power arms located at the distal side of the canines led to larger initial lingual crown tipping and occlusal crown extrusion of the maxillary incisors compared with power arms located at the midpoint between the lateral incisors and canines, and caused a decreasing trend of the intercanine width.

Conclusions

In customized lingual orthodontic treatment, power arms located at the distal side of the canines are unfavorable for anterior teeth torque control and intercanine width control. Power arms located at the midpoint between the lateral incisors and canines can get better torque control, but still cannot achieve excepted torque without extra torque control methods, no matter whether its force application point is higher than, lower than, or equal to the level of the top of the miniscrews.

Section snippets

Material and methods

One healthy adult orthodontic patient was selected as the subject of this study. The selection criteria were as follows: permanent dentition, bilateral maxillary first premolar extraction, completed alignment and leveling, normal tooth morphology and symmetric arch, without dental caries, periodontal disease, or tooth loss, and without previous orthodontic treatment. Cone-beam computed tomography (CBCT) was used to obtain the patient's maxillary scanning image, and the scan slice thickness was

Results

When the power arms were located at the midpoint between the lateral incisors and canines with the miniscrews located between the first molar and the second molar, after applying 1.5 N retraction force the maxillary central incisors showed tendencies of lingual crown tipping and labial root tipping, and these tendencies decreased as the vertical distance between force application points on the power arm and the archwire plane increased from 6 mm to 10 mm. The maxillary canines showed tendencies

Discussion

In theory, the anchorage value in lingual orthodontics is greater than in labial orthodontics, because the force acting on the anterior teeth passes through the lingual side of the center of resistance of the anterior teeth in lingual orthodontics and produces a lingual crown torque to the anterior teeth and a distal uprighting force on the posterior teeth throughout the retraction process, which increases the anchorage value of the molars.13, 14 However, Lawson¹⁵ suggested that there was no

Conclusions

In customized lingual orthodontic treatment with miniscrew anchorage, compared with power arms located at the midpoint between the lateral incisors and canines, power arms located at the distal side of the canines will lead to larger initial lingual crown tipping, labial crown tipping, and occlusal crown extrusion of the maxillary anterior teeth in the sagittal and vertical planes, and a decreasing trend of the intercanine width in the transverse plane. Therefore, power arms located at the

Acknowledgment

The authors express their gratitude to the Riton Biotechnology Co for providing the software which was essential for this study.

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Effect of power arm length combined with additional anterior torque on the axial orientation of the maxillary incisors during en-masse retraction: A finite element analysis
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This study aimed to clarify the effect of power arm length combined with additional torque incorporated into the archwire on the controlled movement of the anterior teeth using the finite element method.
An adult patient requiring medium anchorage after extraction of the maxillary first premolars was selected for this study. The power arms were placed between the lateral incisor and the canine at 3 levels: 3 mm, 6 mm, and 9 mm. A 150 g of retraction force was applied from each height of the anterior hook to the first molar tube, with 0°, 5°, and 10° of applied lingual root torque on the incisors.
A 3-mm hook with 10° of applied torque, a 6-mm hook with 5° of applied torque, or a 9-mm hook with no extra torque constituted the best combinations targeted at controlling the inclination of incisors during retraction. Extrusion and distal tipping of the canine were observed. Moreover, mesial tipping and mesiopalatal rotation of the molar were unavoidable. Finally, intercanine and intermolar widths were decreased.
Adding extra torque on the incisors or using high torque brackets is recommended for patients with maxillary first premolar extraction.
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: Yi Feng and Wei-Dong Kong are joint first authors and contributed equally to this work.

: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.

: Funding: Science and Technology Planning Project of Guangdong Province, China (grants 2015A020214015, 2016A020220015).

View full text

Original articleFinite element analysis of the effect of power arm locations on tooth movement in extraction space closure with miniscrew anchorage in customized lingual orthodontic treatment

Highlights

Introduction

Methods

Results

Conclusions

Section snippets

Material and methods

Results

Discussion

Conclusions

Acknowledgment

Keys to success in lingual therapy. Part 1

J Clin Orthod

New orthodontic treatment with lingual bracket mushroom arch wire appliance

Am J Orthod

A new bracket system for lingual orthodontic treatment. Part 1: Theoretical background and development

J Orafac Orthop

Finite element analysis of the effect of force directions on tooth movement in extraction space closure with miniscrew sliding mechanics

Am J Orthod Dentofacial Orthop

Finite element analysis of miniscrew placement in mandibular alveolar bone with varied angulations

Eur J Orthod

A validated finite element method study of orthodontic tooth movement in the human subject

J Orthod

Torque control of the maxillary incisors in lingual and labial orthodontics: a 3-dimensional finite element analysis

Eur J Orthod

Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis

Am J Orthod Dentofacial Orthop

Displacement and stress distribution of the maxillofacial complex during maxillary protraction with buccal versus palatal plates: finite element analysis

Eur J Orthod

Initial force systems during bodily tooth movement with plastic aligners and composite attachments: A three-dimensional finite element analysis

Angle Orthod

Stress distribution and displacement by different bone-borne palatal expanders with micro-implants: a three-dimensional finite-element analysis

Eur J Orthod

Original article
Finite element analysis of the effect of power arm locations on tooth movement in extraction space closure with miniscrew anchorage in customized lingual orthodontic treatment