title: Effects of 6 Single-File Systems on Dentinal Crack Formation.
abstract: BACKGROUND
  The purpose of this study was to compare the formation of microcracks after canal preparation performed with different single-file systems as One Shape (Micro-Mega, Besancon, Cedex, France), F6 SkyTaper (Komet Italia Srl, Milan, Italy), HyFlex EDM (Coltene/Whaledent AG, Altstatten, Switzerland), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (VDW, Munich, Germany), and WaveOne Gold (Dentsply Maillefer).
  
  
  METHODS
  Eighty-four human extracted mandibular central incisors (40-60 y) were selected and divided into 6 experimental groups (n = 12 teeth) and a control group (unprepared teeth): One Shape (group 1), F6 SkyTaper (group 2), HyFlex EDM (group 3), WaveOne (group 4), Reciproc (group 5), and WaveOne Gold (group 6). Roots were then sectioned at 3, 6, and 9 mm from the apex, and the surface was observed under a stereomicroscope. Data were analyzed using logistic regression (P < .05).
  
  
  RESULTS
  No cracks were observed in the control group. All the systems tested caused cracks, mainly in the apical section (3 mm). HyFlex EDM (33.3%) and WaveOne Gold (58.3%) showed fewer microcracks than other experimental groups (P < .01); however, no significant difference was found between them in crack formation (P > .05). There was no difference among the other experimental groups (P > .05).
  
  
  CONCLUSIONS
  All the instruments tested created dentinal cracks. Within the limitations of this study, the flexibility of nickel-titanium instruments because of heat treatment seems to have a significant influence on dentinal crack formation. HyFlex EDM and WaveOne Gold caused less microcracks than the other instruments tested.
authors.affiliation: Department of General Surgery and Surgical-Medical Specialties, University of Catania, Catania, Italy. Electronic address: eugeniopedulla@gmail.com.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Pedullà
authors.affiliation: Department of General Surgery and Surgical-Medical Specialties, University of Catania, Catania, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Genovesi
authors.affiliation: Department of General Surgery and Surgical-Medical Specialties, University of Catania, Catania, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Rapisarda
authors.affiliation: Department of General Surgery and Surgical-Medical Specialties, University of Catania, Catania, Italy.
authors.forename: Giusy R M
authors.initials: GR
authors.lastname: La Rosa
authors.affiliation: Catholic University of Sacred Heart, Rome, Italy.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Grande
authors.affiliation: Dental Hygiene Degree Course, "La Sapienza" University of Rome, Isernia, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.affiliation: Endodontics and Research Methodology, School of Dentistry, National University of Asuncion, Asuncion, Paraguay.
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Adorno
mesh_terms: D000328:Adult; D003762:Dental Instruments / Q000009:adverse effects*; D003799:Dental Stress Analysis; D003804:Dentin / Q000293:injuries* / Q000473:pathology; D004867:Equipment Design; D006801:Humans; D007180:Incisor; D008875:Middle Aged; D018915:Root Canal Preparation / Q000009:adverse effects* / Q000295:instrumentation
keywords: F6 SkyTaper; HyFlex EDM; Wave One Gold; microcracks; single-file system