Análise comparativa do comportamento mecânico dos instrumentos rotatórios de NiTi fabricados com a tecnologia CM, M-Wire e com o fio de NiTi convencional

• Ano de defesa: 2014
• Autor(a) principal: Ligia Carolina Moreira Braga
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: instrumentos CM; Instrumentos rotatórios de NiTi; Resistência torcional; M-Wire; Resistência à fadiga; Instrumentos e aparelhos odontológicos; Resistência de materiais; Endodontia/instrumentação; Tratamento do canal radicular/instrumentação; Ligas dentárias; Instrumentos odontológicos; Ligas de níquel-titânio
• Link de acesso: http://hdl.handle.net/1843/BUOS-9MYK43

The mechanical properties of the endodontic instruments are affected by factors such as diameter, design, chemical composition and thermo-mechanical treatments applied during the manufacturing process. The objective of this study is to compare the physical, chemical and structural properties and mechanical behavior of Typhoon and Hyflex instruments, which have a controlled memory (CM) compared to ProFile Vortex instruments, manufactured with M-Wire, and EndoWave and ProTaper Universal, manufactured with conventional NiTi wires. The chemical components have all been analyzed with X-Ray energy spectroscopy (EDS) and the transformation temperatures obtained with differential scanning calorimeter (DSC). Images from the longitudinal and transversal sections were used for determining the diameter and the area 3 mm away from the tip (D3 and A3), the position where the mechanical requests are focused on during the clinical use and the instruments are apprehended in the tests. The mechanical behavior has been evaluated through simulation of flexion and torsion until rupture accordingly to the ISO 3630-1, and flexural fatigue test until fracture. The instruments Hyflex CM, Typhoon CM, ProFile Vortex, ProTaper Universal e EndoWave showed similar chemical composition. However, the average values of transformation temperatures of the CM instruments and ProFile Vortex were significantly higher than other systems tested. In the fatigue tests, the Hyflex and Typhoon CM instruments showed a fatigue life significantly higher (p = 0.000) than ProFile Vortex instruments, fabricated with M-Wire, and these were significantly higher (p = 0.000) than ProTaper Universal and EndoWave systems, manufactured with conventional NiTi alloy. Among the CM instruments, it was observed that the Hyflex system was significantly higher (p = 0.000) than Typhoon. The Hyflex CM and Typhoon CM instruments were significantly more flexible, possibly due to thermal they have been subjected during manufacture, resulting in softening of the alloy treatments. The ProTaper Universal F2 instruments showed maximum torque values significantly higher (p = 0.034) of those Typhoon CM instruments, similar cross section, although the former have A3 significantly higher (p = 0.000). The Hyflex CM and Endowave instruments showed similar maximum torque values (p = 0.228) and also mean values of A3 (p = 0.276). Whereas instruments have similar diameters and geometry, the thermomechanical treatment performed in CM instruments represented an important improvement in the mechanical properties of the instruments, when compared with rotary systems manufactured with M-Wire and conventional NiTi wires. Regarding torsional strength, application of heat treatments seemed not influence the mechanical behavior of the instruments CM studied.