Determination of the force systems produced by different configurations of tear drop orthodontic loops

• Autor(a) principal: Thiesen, Guilherme
• Data de Publicação: 2013
• Outros Autores: Shimizu, Roberto Hideo [UNESP], do Valle, Caio Vinicius Martins, do Valle-Corotti, Karyna Martins, Pereira, Jefferson Ricardo, Conti, Paulo Cesar Rodrigues
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1590/S2176-94512013000200007; http://hdl.handle.net/11449/76367
• topic: Biomechanics; Orthodontic space closure; Orthodontics; Tooth extraction

Objective: To determine the mechanical characteristics of teardrop loop with and without helix fabricated using different metal alloy compositions (stainless steel and beta-titanium), submitted to different intensities of bends preactivation (0° and 40°), and with different cross-sectional dimension of the wire used to build these loops (0.017 x 0.025-in and 0.019 x 0.025-in). Methods: Eighty loops used to close spaces were submitted to mechanical tests. The magnitudes of horizontal force, the moment/force ratio, and the load/deflection ratio produced by the specimens were quantified. Loops were submitted to a total activation of 5.0 mm and the values were registered for each 1.0 mm of activation. For statistic data analysis, a analysis of variance was performed and a Tukey's Multiple Comparison test was used as supplement, considering a 5% level of significance. Results: In general, teardrop loops with helix produced lower magnitudes of horizontal force and load/deflection ratio, and higher moment/force ratio than teardrop loops without helix. Among all analyzed variables, metal alloy composition presented greater influence in the horizontal force and in the load/deflection ratio. The moment/force ratio showed to be more influenced by the preactivation of loops for space closure. © 2013 Dental Press Journal of Orthodontics.