Do miniscrews remain stationary under orthodontic forces?

Liou, Eric Jein-Wein; Pai, Betty C. J.; Lin, James Cheng-Yi

doi:10.1016/j.ajodo.2003.06.018

Cited by 398 publications

(275 citation statements)

References 17 publications

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“…On the upper part of the blocks, resin of density 40 pounds per cubic foot (pcf) (0.62 g/cm 3 ) was used in layers of thickness 1.0, 2.0, and 3.0 mm. Resin of density 20 pcf (0.32 g/cm 3 ) was used in the lower portion of the blocks to simulate bone marrow (Figure 2). Uniform blocks made from 40 pcf density resin were also used to simulate bone areas of greater density.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the use of a stable anchorage unit that is independent of cooperation and has no side effects on adjacent teeth has been studied in recent years 1 through the use of conventional implants, miniplates, or mini-implants (MIs). 2,3,4 MIs constitute a more versatile and easy-to-use resource; they have good primary stability but are not completely stationary. 2,3 MI stability is directly related to the thickness and quality of the cortical bone.…”

Section: Introductionmentioning

confidence: 99%

“…2,3,4 MIs constitute a more versatile and easy-to-use resource; they have good primary stability but are not completely stationary. 2,3 MI stability is directly related to the thickness and quality of the cortical bone.…”

Section: Introductionmentioning

confidence: 99%

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Influence of cortical thickness on the stability of mini-implants with microthreads

et al. 2015

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The objective of this study was to assess the influence of cortical thickness and bone density on the insertion torque of a mini-implant (MI) with microthreads. Mini-implants with lengths of 6 and 8 mm in the active part were inserted into synthetic bone blocks (polyurethane resin). The density of these blocks was 20 pounds per cubic foot (pcf), simulating bone marrow, and that of blocks 1, 2, and 3-mm-thick blocks was 40 pcf, simulating cortical bone. Blocks with uniform density of 40 pcf were also used to simulate bone areas of greater density. Insertion torque was quantified with a universal testing machine (EMIC). For both MIs, increasing insertion torque was associated with increasing cortical bone thickness. For the same MI length, significant differences were observed among all assessed groups. The insertion torque of the 6-mm-long MI inserted in a 3-mm-thick cortical bone was equivalent to that of the 8-mm-long MI inserted in a 1-mm-thick cortical bone. MIs inserted in bone blocks of greater density presented insertion torque values almost twice as high as those in other groups. The shorter MI, the lower the insertion torque, and the greater the cortical bone thickness, the greater the insertion torque. To minimize fracture risk, the size of MI should be selected according to the insertion site.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of cortical thickness on the stability of mini-implants with microthreads

et al. 2015

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“…Studies have shown that implants remain stable and thus serve as an absolute anchorage unit [1,23]. Therefore fixed nodes were used for force application.…”

Section: Discussionmentioning

confidence: 99%

En-masse Retraction of the Maxillary Anterior Teeth by Applying Force from Four Different Levels – A Finite Element Study

Keluskar

Revankar³

2014

JCDR

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Objective: To find out if it is possible to control maxillary anterior teeth in sagittal and vertical plane during retraction by altering the vertical levels of force application in the posterior region, i.e. identifying the type of movement of the maxillary anterior teeth which occurs when force would be applied from four different levels i.e. High, Medium, and Low pull Implants and from a conventional Molar hook and also to quantify the retraction and intrusion components of force thus setting a guideline for the implant height placement. Materials and Methods:A Finite Element Model of maxillary dentition along with alveolar bone, brackets and wire was developed with defined material properties. The model was analysed to calculate the displacement when force was applied from different levels.Results: From all points of force application, anterior teeth tipped lingually in the sagittal plane, whereas in the vertical plane extrusion was seen when retracted from molar hook and intrusion was seen when retracted from implants. For every mm of apical displacement of implant, the retraction component of force reduces approximately by around 1% and intrusion component of force increases approximately by around 0.3%. Conclusion:Based on the results of this study we can reckon that by changing the position of implant in vertical plane one will have very little effect on the type of tooth movement. As the point of force application moves apically, type of tooth movement in the sagittal plane remained almost constant and in vertical plane intrusion is slightly increased.

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“…Como o mini-implante não precisa sofrer osteointegração, ou seja, não há união ao osso, é tolerada mobilidade de até 0,5mm [9], dependendo do tipo, período e direção da força aplicada e da qualidade e quantidade de osso no local de instalação. Mini-implantes com mobilidade mínima podem ser usados como ancoragem utilizando-se uma força unidirecional menor que 200 gf [4].…”

Section: Estabilidade Sucesso E Falhaunclassified

Distribuição de tensões em mini-implantes ortodônticos

Dobranszki

Neto

Dobranszki³

et al. 2010

Matéria (Rio J.)

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RESUMOO objetivo deste trabalho foi avaliar a distribuição de tensões na resina em contato com os filetes de roscas de mini-implantes cilíndricos e cônicos, submetidos à carga lateral e torção de inserção. Um modelo fotoelástico foi confeccionado com gelatina transparente, para simular o osso alveolar. O modelo foi observado com um polariscópio plano e fotografado antes e após a ativação dos mini-implantes com força lateral e de inserção. A aplicação de cargas laterais provocou momentos fletores nos mini-implantes, aparecimento de franjas isocromáticas ao longo dos filetes do corpo dos mini-implantes e no ápice. Quando foi aplicado o torque de inserção, verificou-se a concentração de tensões próxima ao ápice. Concluiu-se que:(1) o mini-implante cilíndrico apresentou maior concentração de tensões no ápice, e (2) o mini-implante cônico apresentou maior concentração de tensões nos filetes de rosca apicais.Palavras-chaves: distribuição de tensões, fotoelasticidade, mini-implantes, ancoragem absoluta. Stress distribution in orthodontic mini-implants ABSTRACTThe objective of this study was to evaluate the stress distribution in the resin in contact with the spirals of cylindrical and conical mini-implants, when submitted to lateral load and insertion torsion. A photoelastic model was fabricated using transparent gelatin to simulate the alveolar bone. The model was observed with a plane polariscope and photographically recorded before and after activation of the two screws with a lateral force and torsion. The lateral force application caused bending moments on both miniimplants, with the uprising of fringes or isochromatics, characteristics of stresses, along the threads of the mini-implants and in the apex. When the torsion was exerted in the mini-implants, a great concentration of stress upraised close to the apex. The conclusion was that, comparing conical with cylindrical mini-implants under lateral load, the stresses were similar on the traction sides. The differences appear (1) on the apex, where the cylindrical mini-implant showed a greater concentration of stress, and (2) along the spirals, in the compression side, where the conical mini-implant showed a greater concentration of stress. The greater part of the stress produced by both mini-implants, after torsion load in insertion, were concentrated on the apex. With the cylindrical mini-implant, the greater concentration of tension was close to the apex, while with the conical one, the stresses were distributed along a greater amount of apical threads.

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Do miniscrews remain stationary under orthodontic forces?

Cited by 398 publications

References 17 publications

Influence of cortical thickness on the stability of mini-implants with microthreads

Influence of cortical thickness on the stability of mini-implants with microthreads

En-masse Retraction of the Maxillary Anterior Teeth by Applying Force from Four Different Levels – A Finite Element Study

Distribuição de tensões em mini-implantes ortodônticos

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