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

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.

Coeficientes de perda de carga em válvulas e acessórios no escoamento de fluídos não-newtonianos puramente viscosos e viscoelásticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação do sistema de força e estabilidade a longo prazo gerado por molas T do grupo B

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo clínico da retração de caninos e perda de ancoragem com a mola T do grupo A e estudos analíticos da mola T do grupo A e B

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamento mecânica da mola T de Beta-titânio: influência da marca comercial e do alivio de tensão estrutural

Pós-graduação em Ciências Odontológicas - FOAR

Relaxamento de tensão em molas T de Beta-Titânio: avaliação e uma possivel solução

Pós-graduação em Ciências Odontológicas - FOAR

Analysis of mesiodistal angulations of preadjusted brackets

Manufacturers offer various prescriptions of preadjusted brackets for use in the "straight-wire" orthodontic technique. However, the need to incorporate bends in the rectangular wires during orthodontic finishing has led to concerns regarding the type of prescription chosen and the credibility of information provided by the manufacturer. The aim of this study was to compare the slot angulations of Roth prescription preadjusted metallic brackets for the maxillary left central incisor and maxillary left canine. For each tooth type, 10 brackets of three commercial brands (GAC, Forestadent and Morelli) were selected. Two individual metal matrices for brackets and tooth positioning were made for each group of teeth. Captured images were obtained by standardized ortho-radial photography with a digital camera. Images were exported and analyzed with the Image J software package. One-way ANOVA and Tukey statistical analyses were performed at the 5% significance level. For brackets of the maxillary left central incisor, differences in mean angulation were observed between the Morelli and GAC groups (p < 0.01) and between the Forestadent and GAC groups (p < 0.01). For brackets of the maxillary left canine, differences in mean angulation were found between the Morelli and GAC groups (p < 0.01) and between the Morelli and Forestadent groups (p < 0.05). In conclusion, despite their same prescription name, the different brands exhibited significantly different angulation measurements.