Journal Article

Initial forces generated by three types of thermoplastic appliances on an upper central incisor during tipping

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

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 31, issue 6, pages 625-631
Published in print December 2009 | ISSN: 0141-5387
Published online June 2009 | e-ISSN: 1460-2210 | DOI:
Initial forces generated by three types of thermoplastic appliances on an upper central incisor during tipping

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The force properties of thermoformed appliances have not been systematically investigated. Therefore, the aim of the present study was to quantify the forces delivered by thermoplastic appliances manufactured from three different materials, with the same thickness, on a central upper incisor, during tipping.

Five identical appliances were manufactured from three different materials all with a thickness of 1.0 mm (Ideal Clear®, Erkodur®, and Biolon®). For measuring the forces, an isolated measuring tooth, as part of a standardized resin model incorporated in a newly developed measuring device, was tipped in nine arc minute (degree) steps, from 0 to degrees in the vestibular and palatal directions around a rotational axis through the virtual apex, after positioning an appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of ±0.151 mm from the incisor edge were determined. Means and standard deviations (SDs) were calculated. The Kruskal–Wallis test for overall effects and the Wilcoxon two-sample test for individual group pairings were used (P < 0.05 significance level).

The mean Fx forces ranged from −2.82 N (SD 0.62) to 5.42 N (SD 0.56). The mean Fz forces were between −0.14 N (SD 0.52) and −2.3 N (SD 0.43). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the Biolon® appliance were found to be much greater (P < 0.01) than those of the other materials.

The forces delivered by the materials investigated were mostly higher than those stated in the literature.

Journal Article.  3295 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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