Cyclic Fatigue of Different Nickel-Titanium Rotary Instruments: A Comparative Study

Since the introduction of nickel-titanium alloy to endodontics, there have been many changes in instrument design, but no significant improvements in the raw material properties, or enhancements in the manufacturing process. Recently, a new method to produce nickel-titanium rotary (NTR) instruments has been developed, in an attempt to obtain instruments that are more flexible and resistant to fatigue. NTR instruments produced using the process of twisting (TF, SybronEndo, Orange, CA) were compared to NTR instruments from different manufacturers produced by a traditional grinding process. The aim of the study was to investigate whether cyclic fatigue resistance is increased for TF NTR files. Tests were performed with a cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (P< .05). In the mean number of cycles to failurewhen compared to the other tested 06-25 NTR. Hence, it can be concluded that size 06-25 TF NTR instruments were found to be significantly more resistant to fatigue than those produced with the traditional grinding process

Vantaggi e limiti del nichel-titanio in endodonzia.

Aggiornamento Monografic

Radiographic and rheological properties of a new endodontic sealer

A new dual-cured resin sealer has recently been proposed as an innovative endodontic filling material. Being a new endodontic material, no in vitro research has been published yet on Real Seal's (RS) physical properties. Therefore, theaim of the present study was to evaluate and compare radiopacity and rheological properties of the RS sealer with those of currently available endodontic sealers (Roeko Seal Automix and Bioseal). All tests strictly followed American National Standards Institute/American Dental Association (ANSI/ADA) specification No. 57, which indicates test methods and establishes minimal requirements of flow, film thickness and radiopacity of endodontic sealers. Results showed that significant differences were found among sealers in the different test methods. However, RS showed values complying with ANSI/ADA specification No. 57 requirements in all tests. Hence, the new RS sealer exhibited radiographic and rheological properties suitable for clinical use