Effects of Skeletally Supported Anterior en Masse Retraction with Varied Lever Arm Lengths and Locations in Lingual Orthodontic Treatment: A 3D Finite Element Study.

Mohammad Ghannam,Beste Kamiloğlu,Vincenzo Iorio Siciliano

doi:10.1155/2021/9975428

Mohammad Ghannam, Beste Kamiloğlu + Show 1 more

Open Access

https://doi.org/10.1155/2021/9975428

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Journal: BioMed research international	Publication Date: May 17, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: Near East University

Abstract

Objective This study is aimed at analyzing different points of force application during miniscrew supported en masse retraction of the anterior maxillary teeth to identify the best line of action of force in lingual orthodontic treatment. Materials and Methods Three-dimensional (3D) finite element models were created to stimulate en masse retraction with different heights and positions of the miniscrew and lever arm to change the force application points; a 150 g retraction force was applied from the miniscrew to the lever arms, and the initial tooth displacements were analyzed. Results Lingual crown tipping and occlusal crown extrusion were seen at all heights and positions of the miniscrew and lever arm, but when the miniscrew height was at 8 mm and the power arm was located between the lateral incisors and canines, these tipping patterns were less than those obtained with a 4.5 mm high miniscrew and a lever arm located distal to the canines. Conclusion All miniscrew heights and lever arm positions showed initial lingual crown tipping and labial root tipping with occlusal crown extrusion. However, the 8 mm miniscrew height and the lever arm located between the lateral incisor and canine showed fewer amounts of these tipping patterns than a 4.5 mm miniscrew height and lever arm located distal to the canines. Therefore, this could be the preferred point of force application during en masse retraction in lingual treatment with additional torque control methods.

Highlights

With the increasing adoption of orthodontic treatment among adult patients, especially female, patient esthetic demands have been reportedly increasing [1]
The first generation of lingual orthodontic appliances was introduced by Kurz in the 1970s with his lingual edgewise appliance with an anterior bite plan and mesh pads to adapt to the tooth lingual surface and pretorqued archwire [3]
In measurements performed after application of the retraction force with the lever arm located distal to the canine with the miniscrew height at 4.5 mm, when the length of the lever arm was 6 mm, the maxillary incisors and canines showed lingual crown tipping, and labial root tipping increased significantly from the central incisors to the canines

Summary

Introduction

With the increasing adoption of orthodontic treatment among adult patients, especially female, patient esthetic demands have been reportedly increasing [1]. Fujita introduced lingual mushroom-shaped wires that were developed to overcome the difference in labiolingual thickness between the anterior and posterior teeth [4]. En masse retraction of the six maxillary anterior teeth as one unit to close an extraction space is a standard clinical practice procedure. To control the anchorage in the posterior teeth, miniscrews can be used to achieve maximal retraction of the anterior teeth during lingual orthodontic treatment [8]. Variations in the direction of the applied retraction will result in multiple movement patterns of the anterior teeth, which may lead to unfavorable outcomes. It is crucial to BioMed Research International understand the resultant effects of the different movement patterns during en masse retraction of the anterior maxillary teeth with the use of miniscrews in lingual orthodontics [8]

Methods

Results

Conclusion