CC BY-NC-ND 4.0 · Eur J Dent 2017; 11(01): 041-047
DOI: 10.4103/ejd.ejd_272_16
Original Article
Dental Investigation Society

Influence of reuse and cervical preflaring on the fracture strength of reciprocating instruments

Claudio Maniglia-Ferreira
1   Department of Endodontics, Course of Dentistry, University of Fortaleza, Fortaleza, CE, Brazil
,
Fabio de Almeida Gomes
1   Department of Endodontics, Course of Dentistry, University of Fortaleza, Fortaleza, CE, Brazil
,
Tatyana Ximenes
1   Department of Endodontics, Course of Dentistry, University of Fortaleza, Fortaleza, CE, Brazil
,
Murilo Alves Teixeira Neto
1   Department of Endodontics, Course of Dentistry, University of Fortaleza, Fortaleza, CE, Brazil
,
Thiane Elys Arruda
1   Department of Endodontics, Course of Dentistry, University of Fortaleza, Fortaleza, CE, Brazil
,
Giovani Gonçalves Ribamar
2   Department of Metallurgical and Materials Engineering, Faculty of Chemical Engineering, Federal University of Ceará, Fortaleza, CE, Brazil
,
Luis Flávio Gaspar Herculano
2   Department of Metallurgical and Materials Engineering, Faculty of Chemical Engineering, Federal University of Ceará, Fortaleza, CE, Brazil
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Publikationsverlauf

Publikationsdatum:
25. September 2019 (online)

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ABSTRACT

Objective: This study sought to assess the influence of cervical preflaring and reuse after resterilization, on fracture strength and plastic deformation and/or surface cracking in reciprocating nickel–titanium [NiTi] endodontic instruments after root canal instrumentation of extracted human teeth. Materials and Methods: Forty engine-driven reciprocating NiTi instruments (20 Reciproc® [RC], VDW; 20 WaveOne® [WO], Dentsply) were used in root canal instrumentation of extracted human molars. A total of 485 human upper molars with similar anatomical features were selected and randomly distributed across four groups according to the instrumentation procedures performed (G1 and G3: RC; G2 and G4: WO). Reciprocating instruments were used as per manufacturer instructions. In groups G3 and G4, cervical preflaring was performed prior to instrumentation. After each use of each instrument, sterilization was repeated and scanning electron microscope (SEM) images were obtained to check for plastic deformations and/or cracks on instrument surfaces. Each instrument was used repeatedly until fracture occurred. Results: Regardless of flaring, RC files exhibited greater fracture strength than WO instruments (P<0.01) with and without preflaring. Cervical preflaring significantly reduced the risk of instrument fracture (P<0.01). No plastic deformations were observed before fracturing. However, cracks were found on WO instruments shortly after their first use. RC and WO instruments resisted fracturing after autoclave sterilization. Conclusions: Cervical preflaring allowed a significant increase in the number of times RC and WO files could be reused safely.