title: Self-adjusting file cleaning-shaping-irrigation system improves root-filling bond strength.
abstract: BACKGROUND
  The aim of the present study was to assess the bond strength of root fillings in oval-shaped canals prepared with the self-adjusting file (SAF) system.
  
  
  METHODS
  A careful specimen selection resulted in 2 equal groups, each consisting of 12 extracted mandibular canines with oval canals that had vital pulps before extraction. One group was subjected to the SAF protocol, and the other group underwent conventional protocol, which was the ProTaper system with syringe-needle irrigation. Full-strength sodium hypochlorite was used as an irrigant for both groups. The teeth were obturated in a standardized way, filled with a lentulo spiral as the root filling, and then prepared for micropush-out assessment by using root slices of 1-mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min(-1). The Student's t test for pairwise comparisons was applied to assess the effect of each preparation technique on the push-out bond strength.
  
  
  RESULTS
  All specimens showed measurable adhesive properties to root dentin. In addition, no premature failure occurred. The group-by-location interaction was significant (P = .0071); thus, the group comparisons were dependent on the canal third. Overall, the push-out bond strength was the highest in the coronal third and the lowest in the apical third. SAF-prepared specimens displayed significantly higher bond strengths (P = .0012, 0.51-5.9 MPa).
  
  
  CONCLUSIONS
  The present study showed that SAF preparation markedly influenced root-filling push-out bond strength in oval-shaped canals. Further investigations are needed to provide a better understanding of the physicochemical modifications of the root dentin prepared with the SAF cleaning-shaping-irrigation system.
authors: Department of Endodontology, Grande Rio University, Rio de Janeiro, Rio de Janeiro, Brazil. endogus@gmail.com
authors: Gustavo
authors: G
authors: De-Deus
authors: Thais
authors: T
authors: Accorsi-Mendonça
authors: Leandro
authors: L
authors: de Carvalho e Silva
authors: Carlos Augusto de Souza
authors: CA
authors: Leite
authors: Diogo
authors: D
authors: da Silva
authors: Edson Jorge Lima
authors: EJ
authors: Moreira
mesh_terms: D000268:Adhesiveness; D016022:Case-Control Studies; D003481:Cuspid / Q000648:ultrastructure; D001840:Dental Bonding; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004853:Epoxy Resins / Q000627:therapeutic use; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D009339:Needles; D012387:Root Canal Filling Materials / Q000627:therapeutic use*; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000627:therapeutic use; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000627:therapeutic use; D013314:Stress, Mechanical; D013594:Syringes; D007507:Therapeutic Irrigation / Q000295:instrumentation; D019227:Tooth Apex / Q000648:ultrastructure
chemical_list: D004853:Epoxy Resins; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; C534916:epoxy resin-based root canal sealer; D012973:Sodium Hypochlorite