INTRODUCTION: The purpose of this study was to assess the effects of sodium hypochlorite (NaOCl) immersion and sterilization on the cyclic fatigue resistance of heat-treated nickel-titanium (NiTi) rotary instruments. METHODS: Two hundred ten new 25/.06 Twisted Files (TFs; SybronEndo, Orange, CA) and Hyflex CM (Coltene Whaledent, Cuyahoga Falls, OH) files were divided into 7 groups (n = 15) for each brand. Group 1 (control group) included new instruments that were not immersed in NaOCl or subjected to autoclave sterilization. Groups 2 and 3 were composed of instruments dynamically immersed for 3 minutes in 5% NaOCl solution 1 and 3 times, respectively. Groups 4 and 5 consisted of instruments only autoclaved 1 and 3 times, respectively. Groups 6 and 7 recruited instruments that received a cycle of both immersion in NaOCl and sterilization 1 and 3 times, respectively. Instruments were subsequently subjected to a fatigue test. The surface morphology of fractured instruments was studied by field-emission scanning electron microscopy and x-ray energy-dispersive spectrometric (EDS) analyses. The means and standard deviations of the number of cycles to failure (NCF) were calculated and statistically analyzed using 2-way analysis of variance (P < .05). RESULTS: Comparison among groups indicated no significant difference of NCF (P > .05) except for the groups of TFs sterilized 3 times without and with immersion in NaOCl (P < .05). HyFlex CM files exhibited higher cyclic fatigue resistance than TFs when files were sterilized 3 times, independently from immersion in NaOCl (P < .05). EDS analysis showed the presence of an oxide-rich layer on the Hyflex CM files' external surface. No morphologic or chemical differences were found between files of the same brand subjected to different treatments. CONCLUSIONS: Repeated cycles of sterilization did not influence the cyclic fatigue of NiTi files except for TFs, which showed a significant decrease of flexural resistance after 3 cycles of sterilization. Immersion in NaOCl did not reduce significantly the cyclic fatigue resistance of all heat-treated NiTi files tested.
Cyclic Fatigue Resistance of Heat-treated Nickel-titanium Instruments after Immersion in Sodium Hypochlorite and/or Sterilization / Pedullà, E; Benites, A; La Rosa, Gm; Plotino, G; Grande, Nm; Rapisarda, E; Generali, L. - In: JOURNAL OF ENDODONTICS. - ISSN 0099-2399. - 44:4(2018), pp. 648-653.
Data di pubblicazione: | 2018 |
Data di prima pubblicazione: | 1-feb-2018 |
Titolo: | Cyclic Fatigue Resistance of Heat-treated Nickel-titanium Instruments after Immersion in Sodium Hypochlorite and/or Sterilization |
Autore/i: | Pedullà, E; Benites, A; La Rosa, Gm; Plotino, G; Grande, Nm; Rapisarda, E; Generali, L |
Autore/i UNIMORE: | |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1016/j.joen.2017.12.011 |
Rivista: | |
Volume: | 44 |
Fascicolo: | 4 |
Pagina iniziale: | 648 |
Pagina finale: | 653 |
Codice identificativo ISI: | WOS:000430035800023 |
Codice identificativo Scopus: | 2-s2.0-85041577622 |
Codice identificativo Pubmed: | 29397218 |
Citazione: | Cyclic Fatigue Resistance of Heat-treated Nickel-titanium Instruments after Immersion in Sodium Hypochlorite and/or Sterilization / Pedullà, E; Benites, A; La Rosa, Gm; Plotino, G; Grande, Nm; Rapisarda, E; Generali, L. - In: JOURNAL OF ENDODONTICS. - ISSN 0099-2399. - 44:4(2018), pp. 648-653. |
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