Asymmetric headgear for differential molar movement: a study using finite element analysis

Squeff, Luciana Rougemont; Ruellas, Antônio Carlos de Oliveira; Penedo, Norman Duque; Elias, Carlos Nelson; Sant'Anna, Eduardo F.; Casaccia, Giovana Rembowski; Gomes, Janaína Cristina; Gouvêa, Jayme Pereira de

doi:10.1179/14653120723130

Cited by 5 publications

(7 citation statements)

References 25 publications

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“…For the AHG, the first molar on the active side, with or without a third molar, presented with a large amount of distal tipping. This was expected since the vector of the distalizing force passed below the first molar's centre of resistance, and was in agreement with the findings of previous studies 27,28 . However, similar to the UZG, the amount of first molar distal tipping was smaller in the model with third molars than that in the model without.…”

Section: Discussionsupporting

confidence: 91%

“…On the other hand, the passive side of the AHG showed distalization and distal tipping of the molars because distalization forces were applied, albeit unequally, on both sides. In our study, the asymmetric headgear system was created by elongating the outer arm in the active side following the method described by Squeff et al 27 In another study, molar displacement was evaluated after application of asymmetric headgear with differential shortening of one side in association with differential expansion of the other side of the outer bow 31 . Distalization forces were applied by the two asymmetric force systems (equal and unequal).…”

Section: Discussionmentioning

confidence: 99%

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A 3D finite element analysis of maxillary molar distalization using unilateral zygoma gear and asymmetric headgear

Alosman

Bayome

Vahdettin

2020

Orthod Craniofacial Res

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Objective The aims of this study were (a) to evaluate the displacement and stress distribution in the maxillary dentition associated with the use of two different unilateral distalization appliances—unilateral zygoma gear (UZG) appliance and asymmetric headgear (AHG)—in non‐growing patients; and (b) to assess the effects of fully erupted maxillary third molars on the distalization of the first molar with both appliances by using three‐dimensional finite element analysis. Settings and sample population Two 3D models of the maxilla were created: one with third molars and one without. Next, two distalizing appliances (UZG and AHG) were added to each model to create four models. Materials and methods Distalization forces were applied, and the resultant displacements were recorded at the mesiobuccal and distolingual cusps and palatal root apex of each molar and the incisal edge root apex of the central incisors. The resulting von Mises stress distributions were evaluated. Results With the UZG, the first molar showed greater root distalization than the crown in the model with the third molar, whereas the model without the third molar showed distalization and distal tipping of the first molar. With the AHG, the first molar showed a large amount of distal tipping in the model without a third molar. However, this tipping was less than that in the model with third molars. Conclusion The presence of completely erupted third molars decreased the amount of uncontrolled distal tipping in both appliances. UZG can be considered as an effective option for maxillary molar distalization.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

A 3D finite element analysis of maxillary molar distalization using unilateral zygoma gear and asymmetric headgear

Alosman

Bayome

Vahdettin

2020

Orthod Craniofacial Res

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“…Previous investigations of HGs utilizing 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 PDL [ 28 ]. Our study tried to overcome these limitations by not only modeling the maxilla, the maxillary teeth, and the HG but also by respecting the viscoelastic behavior of the PDL.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2016

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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.

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“…Finite element analysis is proved to be effective in different applications in Orthodontics 3 . Because experimental technique in human or animal are limited, finite element analysis is a good solution to simulate the effect of different appliances on the dental structures.…”

Section: Discussionmentioning

confidence: 99%

“…Different treatment modalities have been introduced to distalize maxillary molars to overcome patient compliance, such as palatal bar, repelling magnets, Nitinol coil spring, K-loops, superelastic wires, Wilson arches, Jones jig appliances, pendulum appliances, distal jet appliances and recently temporary anchorage devices (TAD) 1 . Compared with these appliances, headgear is the better choice because of restricting effect of maxillary growth and dental movement to correct Class II relationship 3 . In some instances, there is unilateral Class II malocclusion (Class II subdivision), in which one side presents Class II molar relationship, while the other side is Class I.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two asymmetric headgear force systems: A finite element analysis

Sadeghi

Hedayati

Mousavi-Fard

2019

Dental Press J. Orthod.

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Objective: The aim of this study was to evaluate the effect of displacement patterns of the molar teeth in response to different asymmetric headgear loading using 3D finite element method. Methods: A series of twenty-five facebow with different left vs. right outer bow length and different expansion of left vs. right were designed. The non-favored side (right side) was shortened at intervals of 10 mm, and favored side (left side) was expanded 10 degree greater than right side and 5 degree expansion were successively added. At the first phase, each side received 200-g load, implying the neck strap to displace toward shorter arm. At the second phase, a total of 400-g load was applied to the ends of the outer bow. Because of the neck strap displacement, the shorter arm received greater load than the left side, the magnitude of the applied force to each side depended on difference of left vs. right outer bow length and expansion. Results: All systems were effective in promoting asymmetric distal movement of the molars. However, the asymmetrical facebow with the 40 mm shortening and 25 degree expansion outer bow when unequal force applied could be used in asymmetric mechanics. Medial and occlusal displacing forces were observed in all systems. Conclusions: Both equal and unequal force application is effective for molar distalization. Expansion of the outer bow in the affected side and shortening of the outer bow in the normal side were effective to produced differential distal molar movement.

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Asymmetric headgear for differential molar movement: a study using finite element analysis

Abstract: The simulated computer model used in this investigation suggests that a face-bow with a symmetrically soldered joint and arms of equal lengths used in combination with a transpalatal arch is the best headgear option when asymmetric movement of upper molars is desired.

Cited by 5 publications

References 25 publications

A 3D finite element analysis of maxillary molar distalization using unilateral zygoma gear and asymmetric headgear

A 3D finite element analysis of maxillary molar distalization using unilateral zygoma gear and asymmetric headgear

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

Comparison of two asymmetric headgear force systems: A finite element analysis

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