Cyclic fatigue behavior of nickel-titanium dental rotary files in clinical simulated root canals.
J Formos Med Assoc
; 116(4): 306-312, 2017 Apr.
Article
em En
| MEDLINE
| ID: mdl-27375047
ABSTRACT
BACKGROUND/PURPOSE:
Dental rotary instruments can be applied in multiple conditions of canals, but unpredictable fatigue fracture may happen. This study evaluated the fatigue lives of two batches of nickel-titanium (NiTi) dental rotary files operating in clinically simulated root canals.METHODS:
Single-step cyclic fatigue tests were carried out to assess the performance of two batches of NiTi files (ProTaper and ProFile) in nine combinations of simulated canals (cylinder radii 5 mm, 7.5 mm, and 10 mm, and insertion angles 20°, 40°, and 60°). Two-step cyclic fatigue tests were carried out in simulated root canals with the same radius by using the following two sets of insertion angles (20°, 40°), (20°, 60°), (40°, 20°), and (60°, 20°). Fracture surfaces were observed by scanning electron microscopy.RESULTS:
The single-step cyclic fatigue results showed that cyclic fatigue lives of the files decreased with increasing insertion angles or decreasing cylinder radius. The ProFile #25 .04 file was more fatigue resistant than the ProTaper F2 file. In two-step cyclic fatigue tests, the total fatigue lives were usually more than 100% when the files operated at a lower strain and then at a higher strain. By scanning electron microscopy, a larger area of fatigue striation corresponded to a longer fatigue life.CONCLUSION:
Cyclic fatigue life can be influenced by the strains and geometries of files. The fatigue life was prolonged when the files operated at a lower strain and then at a higher strain. However, the fatigue life was shortened if the loading sequence was reversed.Palavras-chave
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Base de dados:
MEDLINE
Assunto principal:
Titânio
/
Teste de Materiais
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Preparo de Canal Radicular
/
Níquel
Limite:
Humans
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article