Influence of Different Manufacturing Methods on the Cyclic Fatigue of Rotary Nickel-Titanium Endodontic Instruments.
Renata C.V. Rodrigues, DDS,* H elio P. Lopes, LD,† Carlos N. Elias, PhD,‡ Georgiana Amaral, PhD,§ Victor T.L. Vieira, DDS,‡ and Alexandre S. De Martin, PhD*Abstract
Introduction: The aim of this study was to evaluate, by static and dynamic cyclic fatigue tests, the number of cycles to fracture (NCF) 2 types of rotary NiTi instru- ments: Twisted File (SybronEndo, Orange, CA), which is manufactured by a proprietary twisting process, and RaCe files (FKG Dentaire, La Chaux-de-Fonds, Switzerland), which are manufactured by grinding. Methods: Twenty Twisted Files (TFs) and 20 RaCe files #25/.06 taper instruments were allowed to rotate freely in an artificial curved canal at 310 rpm in a static or a dynamic model until fracture occurred. Results: Measurements of the fractured fragments showed that fracture occurred at the point of maximum flexure in the midpoint of the curved segment. The NCF was signif- icantly lower for RaCe instruments compared with TFs. The NCF was also lower for instruments subjected to the static test compared with the dynamic model in both groups. Scanning electron microscopic analysis re- vealed ductile morphologic characteristics on the frac- tured surfaces of all instruments and no plastic deformation in their helical shafts. Conclusions: Rotary NiTi endodontic instruments manufactured by twisting present greater resistance to cyclic fatigue compared with instruments manufactured by grinding. The frac- ture mode observed in all instruments was of the ductile type.
(J Endod 2011;37:1553–1557)
Key Words
Cyclic fatigue, endodontic instruments, nickel-titanium, Twisted File, RaCe
Nenhum comentário:
Postar um comentário
Comentários