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http://hdl.handle.net/1843/ZMRO-877K5F| Type: | Dissertação de Mestrado |
| Title: | Caracterização dimensional e comportamento mecânico de instrumentos rotatórios de NiTi PROFILE GT e PROFILE GT Series X |
| Authors: | Isabella Faria da Cunha Peixoto |
| First Advisor: | Maria Guiomar de Azevedo Bahia |
| First Co-advisor: | Vicente Tadeu Lopes Buono |
| First Referee: | Dagoberto Brandao Santos |
| Second Referee: | Marta Chaves Craveiro de Melo |
| Abstract: | Neste trabalho foi avaliada, a resistencia a fadiga e o comportamento em torcao de instrumentos ProFile GT (Dentsply-Maillefer, Baillagues, Suica) e ProFile GT Series X (GTX) (Dentsply Tulsa Dental, Oklahoma, USA). A composicao quimica da liga NiTi foi analisada semi-quantitativamente por espectroscopia de energia de raios-X (EDS), as fases presentes foram identificadas atraves de analises por difratometria de raios-XDRX, as temperaturas de transformacao identificadas por calorimetria exploratoria diferencial (DSC) e o acabamento superficial foi avaliado por microscopia eletronica devarredura (MEV). A avaliacao dimensional foi realizada atraves de fotografias dos instrumentos pelo software Image-Pro Plus 6.0. Os instrumentos foram divididos em dois grupos: Grupo experimental de fadiga, com 20 instrumentos novos GT e GTX de calibre 20 e taper .06 (n=10) ensaiados ate a ruptura em dispositivo de bancada defadiga, para determinacao do numero de ciclos ate a fratura (NCF). Grupo experimental de torcao com 20 instrumentos novos GT e GTX de calibre 20 e taper .04 (n=10) ensaiados em torcao ate a ruptura, para determinacao dos valores medios de torque maximo e de deflexao angular ate a fratura. Os resultados obtidos foram analisados estatisticamente pelo teste ANOVA (95% de confiabilidade). Todos osinstrumentos apresentaram caracteristicas superficiais satisfatorias. A composicao quimica foi a mesma em todos os instrumentos analisados, aproximadamente 50,5%Ni-49,5%Ti atomica. Os difratogramas, de GT e GTX, apresentaram apenas a presenca da austenita (fase À, de estrutura B2) e as temperaturas de transformacaovariaram, sugerindo possiveis diferencas nos tratamentos termicos dos fios. Os instrumentos GTX 20/.06 apresentaram resistencia a fadiga significativamente maior, quando comparados aos instrumentos GT 20/.06. Os instrumentos GT 20/.04 apresentaram valores de torque maximos significativamente maiores que os instrumentos GTX, embora menores valores de deflexao angular ate a fratura. Considerando que os dois instrumentos apresentam geometria e diametros similares,e possivel que o tratamento termico utilizado na liga (M-Wire) tenha influenciado o comportamento mecanico dos instrumentos analisados neste estudo. |
| Abstract: | The purpose of this study was to compare the flexural fatigue and torsional resistance of ProFile GT (Dentsply-Maillefer, Baillagues, Switzerland) and ProFile GT Series X (GTX) (Dentsply Tulsa Dental, Oklahoma, USA) instruments, taking into account theirstructural and dimensional characteristics. The instrument diameter at each millimeter from the tip and pitch length were the dimensional parameters measured. Chemical composition was determined by energy-dispersive x-ray spectroscopy and phase constitution by x-ray diffraction. Vickers microhardness measurements were performedto assess instrument strength. One group of 20/.06 GT and GTX instruments (n = 10 each) was tested until failure in a flexural fatigue test device, whereas another group of 20/.04 files (n = 10 each) was tested in torsion based on ISO 3630-1. GT and GTX instruments showed approximately the same chemical composition, namely 51at%Ni-49at%Ti (56wt%Ni-44wt%Ti) and contained mainly the â-phase. GTX instruments showed higher intensity x-ray diffraction peaks and a statistically higher Vickers microhardness. There was a significant decrease in the diameter of GTX in relation to GT instruments from D6 to D9 for 20/.04 instruments and from D4 to D7 for 20/.06 instruments. Pitch length increased along the active part of both instruments, with asteeper increase in GTX. In general, GT Series X instruments were significantly more resistant to flexural fatigue than were similar GT instruments (p < 0.001) but exhibited lower torsional strength (p < 0.001). Different structural and dimensional characteristics were found in GTX instruments in comparison with GT instruments; this is probably thecause for their higher flexural fatigue resistance and lower torsional strength. |
| Subject: | Ligas de níquel-titânio Endodontia/instrumentação instrumentos odontológicos Endodontia |
| language: | Português |
| Publisher: | Universidade Federal de Minas Gerais |
| Publisher Initials: | UFMG |
| Rights: | Acesso Aberto |
| URI: | http://hdl.handle.net/1843/ZMRO-877K5F |
| Issue Date: | 29-Jun-2009 |
| Appears in Collections: | Dissertações de Mestrado |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| disserta__o_mestrado_isabella_faria_da_cunha_peixoto.pdf | 4.2 MB | Adobe PDF | View/Open |
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