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Cyclic fatigue resistance of two reciprocating nickel–titanium instruments after immersion in sodium hypochlorite

2012; Wiley; Volume: 46; Issue: 2 Linguagem: Inglês

10.1111/j.1365-2591.2012.02100.x

1365-2591

Eugenio Pedullà, Nicola Maria Grande, Gianluca Plotino, Filippo Palermo, Gianluca Gambarini, E. Rapisarda,

Dental materials and restorations

Abstract Aim To assess resistance to cyclic fatigue of reciprocating nickel–titanium ( NiTi ) files ( R eciproc and W ave O ne) after immersion in NaOCl solution over several time periods. Methodology A total of 90 new R eciproc R25 and W aveOne P rimary were tested. The 45 files of the same brand were randomly assigned to three groups ( n = 15) and submitted to the following immersion protocol in 5% NaOCl at 37 °C for 16 mm: no immersion (control), 1 or 5 min dynamically. The dynamic immersion and the following cyclic fatigue tests were performed using the appropriate preset reciprocation modes (‘ RECIPROC ALL ’ or ‘ WAVEONE ALL ’) in a specially designed endodontic motor. Resistance to cyclic fatigue was determined by recording time to fracture ( T t F ) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. The artificial canal was manufactured reproducing the instrument's size and taper. Data were analysed by 2‐way analyses of variance. Results Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl . Reciproc R 25 was associated with a higher cyclic fatigue resistance in all groups compared to W ave O ne P rimary ( P < 0.0001). Conclusions Reciprocating dynamic immersion in NaOCl for 1 or 5 min did not reduce the cyclic fatigue resistance of NiTi files significantly. However, the type of reciprocating instrument influenced cyclic fatigue resistance with Reciproc R 25 being more resistant than W ave O ne P rimary.