BackgroundThe objective of the present study was to specify an optimum force system for intrusion and extrusion of maxillary central incisor and to compare the effects of bracket positioning at different heights from the incisal edge in Labial Orthodontics (LaO) and Lingual Orthodontics (LiO).MethodsA mathematical model of maxillary central incisor with normal inclination was developed. Four cases of heights of bracket slot from incisal edge were considered both in LaO and LiO viz. 3 mm, 4 mm, 5 mm and 6 mm. Based on a mathematical model, an optimum force system consisting of an intrusive or extrusive force (F) and a moment (M) was devised and moment (M) to force (F) ratio (M:F ratio) was estimated in each case. Then, three-dimensional Computer Aided Design (CAD) models of incisor and surrounding structures were prepared. To validate an optimum force system, finite element analysis was carried out and force system with derived M:F ratio was applied in each case.ResultsIn finite element analysis, results were shown in the form of vector graph of nodal displacements along with undeformed and deformed models. The desired intrusion or extrusion of incisor was observed. Thus, force system devised from a mathematical model was validated with finite element analysis in each case.ConclusionTo achieve intrusion or extrusion, M:F ratios required in LaO were same i.e. 8:1 for aforementioned heights of bracket slot from incisal edge but different in LiO i.e. 0:1, 1:1, 2:1 and 3:1 for the heights of 3 mm, 4 mm, 5 mm and 6 mm respectively.

Abhishek Madhukar Thote

School of Mechanical Engineering

Engineering and Technology

Rashmi V. Uddanwadiker

Krishna Sharma

Sunita Shrivastava

MIT-World Peace University (MIT-WPU) is a top educational institute located in Pune, India. It is recognized within&nbsp;UGC under Government of Maharashtra Act No. XXXV 2017.&nbsp;

It is part of the MIT group of institutions (established in 1983) which covers 10+ campuses across India and has more than 50,000+ students enrolled across various disciplines at a given point of time. The institute houses 15 schools ranging from Engineering &amp; Technology, Design, Pharmacy, Commerce, Governance among others. It offers undergraduate, postgraduate and PhD programs among different disciplines.&nbsp;

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MIT World Peace University

Computers in biology and medicine

The objective of this study was to devise an optimum force system to achieve en-masse retraction of six maxillary anterior teeth in lingual orthodontics (LiO). First, the set of equations was developed based on the mathematical computation to estimate optimum parameters of force system. Then, the computer software based on this mathematical computation was developed for the ease of estimation of force system. The verification of force system obtained with computer software was accomplished by three-dimensional finite element analysis (FEA). In FEA, it was clear that the desired en-masse retraction of six maxillary anterior teeth in LiO was achieved as observed from the vectors of nodal displacements as well as positions of undeformed and deformed models. In this way, mathematically computed optimum force system was verified with FEA. For orthodontists, the developed computer software accurately estimates the required force system according to mathematical computation. It simplifies the task of computation for orthodontists. The orthodontists can easily operate this computer software as it is user-friendly. Further, in-vivo validation of this study is required in future before clinical application.

Molecular & Cellular Biomechanics

Optimum en-masse retraction of six maxillary anterior teeth in lingual orthodontics: a numerical investigation with 3-dimensional finite element analysis

ObjectiveApproximately 50% patients with a deep bite possess anatomically extruded mandibular canines. The objective of this study was to specify the required toe (θ) of the vertical segment of a cantilever from the distal aspect to achieve pure intrusion of a mandibular canine with a segmented arch in lingual orthodontics. Additionally, the optimum magnitude of the required intrusive force by a cantilever was determined assuming non-linear, hyper-elastic behaviour of periodontal ligament (PDL).MethodsThe geometrical model of a mandibular canine tooth was developed and the mathematical equation was devised to evaluate θ (positive value: toe-in, negative value: toe-out) based on certain input parameters. To verify this numerical study by finite element analysis (FEA), total eight different positions of point of force application (Pf) on bracket top (occlusal) surface were considered based on different values of input parameters.ResultsThe results were displayed in terms of nature of tooth movement and Von-Mises (equivalent) stresses generated in the PDL. Additionally, the optimum magnitude of the required intrusive force within the biological limit of a mandibular canine was determined from FEA considering the strength of PDL and factor of safety.ConclusionsThe numerical study was developed to compute the value of required toe angle (θ) of the vertical segment of a cantilever for different morphologies of a mandibular canine as well as different positions of Pf. From FEA, the optimum range of an intrusive force within the biological limit of a mandibular canine was found to be 20–30 g.

Biocybernetics and Biomedical Engineering

Pure intrusion of a mandibular canine with segmented arch in lingual orthodontics: A numerical study with 3-dimensional finite element analysis

Background:Approximately 50% patients with a deep bite possess anatomically extruded mandibular canines. Objective:The objective of this study was to specify an optimum toe (Θ) of the vertical segment of a cantilever from the distal aspect to achieve pure intrusion of a mandibular canine with the segmented arch in lingual orthodontics (LiO). Methods:The geometrical model of a mandibular canine was developed to compute the required values of Θ (positive values – toe-in, negative values – toe-out). Different positions of the cantilever attachment on the lingual bracket top (occlusal) surface were considered according to different heights (h) from the cusp of a canine i.e. 2, 3, 4 and 5 mm in each case of horizontal distance (x) from canine surface i.e. 2 and 3 mm. In x=2mm case, the required values of Θ at h=2,3,4 and 5mm were −5°, 0°, +6° and +11° respectively. While, in x=3mm case, the required values of Θ at h=2,3,4 and 5mm were 0°, +5°, +12° and +17° respectively. Results:In finite element analysis (FEA), the computed values of Θ were verified by displaying the results of a mandibular canine movement in the form of vectors of nodal displacements along with undeformed and deformed models. Conclusions:In the cases of x=2mm and 3mm, no toe angles were required at heights h=3mm and 2mm respectively. Hence, these can be considered as better positions of the cantilever attachment than others.

Bio-Medical Materials and Engineering

Optimum pure intrusion of a mandibular canine with the segmented arch in lingual orthodontics

Computer Methods in Biomechanics and Biomedical Engineering

Biomechanical analysis and comparison of 12 dental implant systems using 3D finite element study

The Angle Orthodontist

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

Acta Odontologica Scandinavica

Changes in maxillary incisor dental pulp blood flow during intrusion by mini-implants

Seminars in Orthodontics

Orthodontic extrusion for implant site development revisited: A new classification determined by anatomy and clinical outcomes

American Journal of Orthodontics and Dentofacial Orthopedics

Effect of bracket slot and archwire dimensions on anterior tooth movement during space closure in sliding mechanics: A 3-dimensional finite element study

Optimum force system for intrusion and extrusion of maxillary central incisor in labial and lingual orthodontics

Journal	Data powered by TypesetComputers in biology and medicine
Publisher	Data powered by TypesetElsevier
ISSN	00104825
Open Access	No