Tridimensional finite element analysis of teeth movement induced by different headgear forces.

Ivan Toshio Maruo,Orlando Motohiro Tanaka,Armando Yukio Saga,Marco André Argenta,Dauro Douglas De Oliveira,Hiroshi Maruo

doi:10.1186/s40510-016-0130-4

Abstract

BackgroundThis study aimed to simulate the actions of low-pull (LP), high-pull (HP), and combined pull (CP) headgears (HGs) and to analyze tooth movement tendencies through finite element analysis.MethodsTomographic slices of a human maxilla with complete permanent dentition were processed by reconstruction software, and the triangular surface mesh was converted into non-uniform rational B-spline (NURBS) curves. An HG facial bow was also modulated in 3D. The teeth and bone were considered to have isotropic and linear behavior, whereas the periodontal ligament was considered to have non-linear and hyperelastic behavior. Data regarding the application points, directions and magnitudes of forces were obtained from the literature and from a dolichofacial patient with class II, division 1 malocclusion, who was treated with a CP HG.ResultsThe CP HG promoted 37.1 to 41.1 %, and the HP HG promoted 19.1 to 31.9 % of LP distalization. The HP HG presented the highest intrusion, and the LP HG presented the highest extrusion of the first molar. The LP HG contracted the distal side, and the HP and CP HGs contracted the lingual and distobuccal roots of the second molar to a lesser degree.ConclusionsThe LP HG promotes the greatest distalization, followed by the CP and HP HGs; the LP HG causes greater extrusion of the first molar, and the HP HG causes greater intrusion of the first molar. The LP HG causes greater contraction of the second molar than the HP HG.

Highlights

This study aimed to simulate the actions of low-pull (LP), high-pull (HP), and combined pull (CP) headgears (HGs) and to analyze tooth movement tendencies through finite element analysis
It was observed that the forces were applied only at the first molars, all maxillary teeth moved, mainly the first and the second molars; under the three pulls, when the orthopedic-orthodontic forces were reduced to exclusively orthodontic forces, the distributions
Previous investigations of HGs utilizing finite element analysis (FEA) have focused on skeletal effects and modeled only the bone and the first molar [21], simplified the directions of the forces [21], or assumed the isotropic and linearly elastic behavior of the periodontal ligament (PDL) [28]

Summary

Introduction

This study aimed to simulate the actions of low-pull (LP), high-pull (HP), and combined pull (CP) headgears (HGs) and to analyze tooth movement tendencies through finite element analysis. While unilateral forces of 250 to 500 gf promote orthopedic-orthodontic effects As this methodology does not account for the biological properties of the periodontal ligament, teeth and bone, its results are limited. Cephalometric clinical studies [4, 5, 8], which compare initial and final results and facilitate patient follow-up using medical records, are useful and have limitations. As their samples consist of growing patients, it is difficult to isolate appliance effects from inherent craniofacial growth, as well as to distinguish orthopedic from orthodontic effects. There is the possibility of error when performing radiographs, cephalometric tracings, and measurements [9]

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