title: Ultrastructural analysis of root canal dentine irradiated with 980-nm diode laser energy at different parameters.
abstract: OBJECTIVE
  The purpose of this in vitro study was to investigate using the scanning electron microscope (SEM) the ultrastructural morphological changes of the radicular dentine surface after irradiation with 980-nm diode laser energy at different parameters and angles of incidence.
  
  
  BACKGROUND
  There have been limited reports on the effects of diode laser irradiation at 980 nm on radicular dentin morphology.
  
  
  METHODS
  Seventy-two maxillary canines were sectioned and roots were biomechanically prepared using K3 rotary instruments. The teeth were irrigated with 2 mL of distilled water between files and final irrigation was performed with 10 mL of distilled water. The teeth were then randomly divided into five groups (n = 8 each) according to their diode laser parameters: Group 1: no irradiation (control); group 2: 1.5 W/continuous wave (CW) emission (the manufacturer's parameters); group 3: 1.5 W/100 Hz; group 4: 3 W/CW; and group 5: 3 W/100 Hz. Laser energy was applied with helicoid movements (parallel to the canal walls) for 20 sec. Eight additional teeth for each group were endodontically prepared and split longitudinally and irradiation was applied perpendicularly to the root surface.
  
  
  RESULTS
  Statistical analysis showed no difference between the root canal thirds irradiated with the 980-nm diode laser, and similar results between the parameters 1.5 W/CW and 3 W/100 Hz (p > 0.05).
  
  
  CONCLUSIONS
  When considering different output powers and delivery modes our results showed that changes varied from smear layer removal to dentine fusion.
authors.affiliation: Department of Endodontics, University of Ribeirão Preto (UNAERP), Ribeirão Preto, SP, Brazil.
authors.forename: Melissa Andréia
authors.initials: MA
authors.lastname: Marchesan
authors.forename: Aldo
authors.initials: A
authors.lastname: Brugnera-Junior
authors.forename: Aline Evangelista
authors.initials: AE
authors.lastname: Souza-Gabriel
authors.forename: Silvio Rocha
authors.initials: SR
authors.lastname: Correa-Silva
authors.forename: Manoel D
authors.initials: MD
authors.lastname: Sousa-Neto
mesh_terms: D003786:Dental Pulp Cavity / Q000528:radiation effects* / Q000648:ultrastructure; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D007834:Lasers