title: Evaluation of dentin root canal permeability after instrumentation and Er:YAG laser application.
abstract: OBJECTIVE
  Smear layer removal with EDTA from root canal walls allows greater cleaning and disinfection of root canals. However, because Er:YAG laser acts on the removal of the smear layer, the objective of investigation was to analyze in vitro the effect of Er:YAG laser on dentin root canal wall permeability after endodontic instrumentation and irrigation with water or sodium hypochlorite and Er:YAG laser application.
  
  
  METHODS
  A total of 25 extracted human maxillary incisors were divided into five groups: Group I, instrumentation with deionized distilled water as the irrigating solution; Group II, instrumentation with 1% sodium hypochlorite as the irrigating solution; Group III, instrumentation with deionized distilled water as the irrigating solution and Er:YAG laser application; Group IV, instrumentation with 1% sodium hypochlorite solution as the irrigating solution and Er:YAG laser application; Group V, instrumentation only up to #20 file with deionized distilled water as the irrigating solution and Er:YAG laser irradiation. The laser parameters were 15 Hz, 140 mJ, total energy 42 J, 300 pulses (Kavo Key Laser). Copper sulfate (10%) was used to evaluate dentin permeability. The penetration of copper ions into the dentinal tubules was observed using 1% rubeanic acid, which reveals copper ions, forming a stained compound ranging in color from deep blue to black. Transverse sections (500-microm thick) were obtained with a diamond disk from the cervical, middle, and apical thirds.
  
  
  RESULTS
  The instrumentation of the root canal that used water as the irrigating solution followed by Er:YAG laser irradiation promoted the greatest increase in dentin permeability. The use of Er:YAG laser, 1% sodium hypochlorite + Er:YAG, and 1% sodium hypochlorite used alone showed an intermediate capacity of increasing dentin permeability. The use of water as the irrigating solution without Er:YAG laser promoted the least dentin permeability.
  
  
  CONCLUSIONS
  The use of water as the irrigating solution after instrumentation and Er:YAG laser irradiation was an effective procedure for increasing dentin permeability.
authors.affiliation: Dental School of Ribeirão Preto, University of São Paulo, 14040-904, Ribeirão Preto SP, Brazil. pecora@forp.usp.br
authors.forename: J D
authors.initials: JD
authors.lastname: Pecora
authors.forename: A
authors.initials: A
authors.lastname: Brugnera-Júnior
authors.forename: A L
authors.initials: AL
authors.lastname: Cussioli
authors.forename: F
authors.initials: F
authors.lastname: Zanin
authors.forename: R
authors.initials: R
authors.lastname: Silva
mesh_terms: D003786:Dental Pulp Cavity / Q000502:physiology / Q000528:radiation effects*; D003806:Dentin Permeability / Q000502:physiology / Q000528:radiation effects*; D006801:Humans; D007834:Lasers; D018915:Root Canal Preparation / Q000295:instrumentation*; D007507:Therapeutic Irrigation; D014867:Water
chemical_list: D014867:Water