Avaliação in vitro das forças geradas por cadeias elásticas e molas fechadas de NiTi

• Autor(a) principal: Porto, Janise Bizarro Pereira
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional PUCRS
• Texto Completo: http://hdl.handle.net/10923/417
• topic: ODONTOLOGIA; ORTODONTIA; ORTOPEDIA FACIAL; MALOCLUSÃO; RETRAÇÃO (ODONTOLOGIA); DENTIÇÃO; RESISTÊNCIA DOS MATERIAIS

The aim of this in vitro study was to access the strength produced by the nickel titanium closed-coil springs from three different comercial brands (American Orthodontics®, TP orthodontics® and Morelli®) as well as elastomeric chains from two brands available in the market (American Orthodontics® – Memory Chain e Morelli® – conventional) when submitted to 50% and 100% distensions from initial length and then check their strength behavior within time. Both strength values were measured within five intervals of initial 3, 4, 6 and 9 weeks. The sample included 240 nickel titanium closed-coil springs and 80 of the elastomeric chains segments were divided into 16 groups according to the type of material, either nickel titanium closed-coil spring or elastomeric chains, commercial brand and distension submitted. Each group had 20 samples, distended in 50% or 100% from initial length and were kept distended on steel plates immersed in artificial salive solution at the steady temperature of 37ºC. The strength developed by the samples was assessed through a tension test carried out by a mechanic essay machine Emic DL2000® at a 0,5mm/minute speed. The results were submitted to statistical ANOVA and Tukey tests. The NiTi closed coil springs and elastomeric chains distended 50% of the initial length showed initial force between 126. 3 and 267. 5 gf and between 192. 6 and 267. 8 gf, respectively; in the end of nine weeks the average strength was between 131. 7 and 263 gf for the NiTi closed coil springs and between 123. 7 and 141. 3 gf for elastomeric chains. Distension of 100% of initial length of the average initial force produced by the NiTi closed coil springs was between 214. 3 and 451. 5 gf and elastomeric chains between 306. 6 and 380. 5 gf, after nine weeks of average strength remained between 196. 7 and 397. 3 gf for the NiTi closed coil springs and between 179. 4 and 189. 3 gf for elastomeric chains. Such results indicated.