Influence of thermoplastic appliance thickness on the magnitude of force delivered to a maxillary central incisor during tipping

Hahn, Wolfram; Dathe, Henning; Fialka-Fricke, Julia; Fricke-Zech, Susanne; Zapf, Antonia; Kubein-Meesenburg, Dietmar; Sadat-Khonsari, Reza

doi:10.1016/j.ajodo.2008.12.015

Cited by 72 publications

(74 citation statements)

References 18 publications

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“…Such a study is also crucial to better understand the orthodontic mechanism and process of Invisalign. In the past decade, various approaches or specific instruments have been developed to study the mechanical properties (including instantaneous forces and moments) of different thermoplastic materials in clinically-relevant situations [22][23][24] . This study developed a practical and economical temperature-controlled water bath system, which holds the specimen under a controllable environment.…”

Section: Discussionmentioning

confidence: 99%

Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

et al. 2013

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Mechanical properties are crucial for screening orthodontic thermoplastic materials for invisible aligners. However, most of previous studies were carried out within laboratory conditions which limit our understanding of the mechanical behaviors of aligners within oral environment. In this study, we studied the dynamic stress relaxation of thermoplastic materials by combination of Bose ElectroForce and a homemade temperature-controlled water bath. The 3-h stress relaxation curves of five orthodontic thermoplastic materials were measured within 37°C water bath as well as comparatively in ambient atmospheric environment (~20°C). The percentage residual stress at 0, 30, 60, 90, 120, 150, and 180 min was selected for statistical analyses. As expected, the experimental results showed that the residual stress within all five materials decreased with time, and that this process was significantly accelerated in the 37°C water bath (p<0.05). Compared with other materials, Erkodur and Masel exhibited slower relaxing rates in the 37°C water bath (p<0.05).

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Section: Discussionmentioning

confidence: 99%

Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

et al. 2013

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“…[17][18][19] Nevertheless, the forces at the lower range of activation are of lesser relevance, because the amount of movement is adapted to the width of the periodontal ligament (0.1-0.3 mm). 20,21 As postulated before, 5,6 a self-protecting mechanism might be responsible for a low rate of root resorption, even with appliances with an initial activation range of over 0.2 mm. 4,[17][18][19] This mechanism is probably based on the reduced fit of the appliance during increased activation.…”

Section: Discussionmentioning

confidence: 99%

“…2,3 Even though the movement of teeth with thermoplastic appliances has been clinically documented, the force delivery properties of these appliances have only been evaluated in a few in vivo 4 and in vitro studies of tipping movement. 5,6 The aim of the present study was to evaluate the forces and moments exerted by removable thermoplastic appliances produced by three different, hard thermoplastic materials, with the same thickness, on a maxillary central incisor during rotation in vitro.…”

Section: Introductionmentioning

confidence: 99%

Initial Forces and Moments Delivered by Removable Thermoplastic Appliances during Rotation of an Upper Central Incisor

Hahn

Engelke

Jung

et al. 2010

The Angle Orthodontist

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Objective: To determine the forces and moments delivered to a maxillary central incisor during rotation by three different thermoplastic appliances with identical thickness. Materials and Methods: Five identical appliances were manufactured from each of three materials (Ideal Clear 1.0 mm, Erkodur 1.0 mm, Biolon 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps to 62.5 degrees, 65 degrees, and 67.5 degrees (equivalent to an activation of 60.17 mm, 60.34 mm, and 60.51 mm of the incisor edge) in the clockwise and anticlockwise directions with the respective appliance fixed in place. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) were tested. Means and standard deviations for Tz and median and 25% and 75% quantiles for Fz were calculated. An analysis of variance (ANOVA) was performed. Results: The minimal moment was determined at a rotation of 20.17 mm (27.3 Nmm, 60.8), and the maximal moment at a deflection of 20.51 mm (271.8 Nmm. 62.5) was recorded. The minimal value for Fz was measured at an activation of 20.17 mm (0.0 N), and the highest intrusive forces were evaluated for a rotation of 20.51 mm (25.8 N). The particular material sometimes had a significant (P , .05) influence on the forces delivered and the moments. Conclusions: During rotation with aligners, an intrusive force can also be observed. The direction of rotation, and the materials used all exert an influence on the force delivery properties of the appliance.

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“…Proffit 28) stated that the ideal orthodontic forces are 0.35-0.60 N. Hahn et al 29) reported that the forces delivered by Erkodur were 3 to 11 times higher than the ideal forces. Barbagallo et al 30) revealed that Erkodur exerted a high level of force against the tooth to be moved at the initial stage followed by a rapid force diminish.…”

Section: Discussionmentioning

confidence: 99%

Preparation and characterization of thermoplastic materials for invisible orthodontics

et al. 2011

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PETG/PC/TPU polymer blend was prepared by mechanical blending. The mechanical properties of modified PETG/PC/TPU blend were characterized using a universal testing machine, and results were compared against two commercial thermoplastic products -Erkodur and Biolon. Blending modification improved the properties of PETG/PC/TPU. When blending ratio (wt%) was 70/10/20, PETG/PC/TPU exhibited optimal mechanical properties which exceeded those of Erkodur and Biolon. Tear strength was 50.23 MPa and elongation at break was 155.99%. Stress relaxation rate was 0.0136 N/s after 1 hour, which was significantly slower than Erkodur and Biolon (p<0.05). Water absorption rate was 0.57% after 2 weeks, which was significantly lower than Erkodur and Biolon (p<0.05).

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Influence of thermoplastic appliance thickness on the magnitude of force delivered to a maxillary central incisor during tipping

Cited by 72 publications

References 18 publications

Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

Initial Forces and Moments Delivered by Removable Thermoplastic Appliances during Rotation of an Upper Central Incisor

Preparation and characterization of thermoplastic materials for invisible orthodontics

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