title: The Antibacterial Effect of Nd:YAG Laser Treatment of Teeth with Apical Periodontitis: A Randomized Controlled Trial.
abstract: BACKGROUND
  The aim of this blind, in vivo, randomized controlled trial was to evaluate the antibacterial effect of Nd:YAG laser irradiation in endodontic treatment of single-rooted teeth with apical periodontitis. The hypothesis was that mechanical enlargement of the root canal and Nd:YAG laser irradiation would yield more negative bacterial samples than conventional treatment.
  
  
  METHODS
  Forty-one patients (45 teeth) were allocated to the laser (n = 22) or control (n = 23) group. The teeth in the laser group were instrumented, irrigated with saline, and irradiated with Nd:YAG laser according to a standard protocol. The teeth in the control group were similarly instrumented but irrigated with 1% unbuffered sodium hypochlorite and 15% EDTA solution. Bacterial samples were taken before and after treatment, blinded, and immediately sent for culturing and analysis.
  
  
  RESULTS
  The initial bacterial samples were positive in 20 of 22 teeth in the laser group and 18 of 23 (P = .414) in the control group. After the initial treatment, negative bacterial samples were found in 11 teeth in the laser group and 13 (P = .768) in the control group. After 2 to 4 days with no antibacterial dressing in the root canals, 5 teeth in the laser group and 9 (P = .337) in the control group yielded negative bacterial samples.
  
  
  CONCLUSIONS
  After intervention, neither the test group nor the control group yielded predictable negative bacterial samples. Thus, the results failed to verify the hypothesis that Nd:YAG laser irradiation would yield significantly more negative bacterial samples than conventional irrigation with 1% unbuffered sodium hypochlorite solution.
authors.affiliation: Department of Endodontics, Specialist Clinic Kaniken, Public Dental Health Service, Uppsala, Sweden. Electronic address: maria.granevik.lindstrom@regionuppsala.se.
authors.forename: Maria
authors.initials: M
authors.lastname: Granevik Lindström
authors.affiliation: Department of Endodontics, Faculty of Odontology, Malmö University, Malmo, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Wolf
authors.affiliation: Department of Endodontics, Faculty of Odontology, Malmö University, Malmo, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Fransson
mesh_terms: D000368:Aged; D001419:Bacteria / Q000528:radiation effects; D004202:Disinfectants / Q000008:administration & dosage / Q000627:therapeutic use; D005260:Female; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000382:microbiology / Q000601:surgery*; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000627:therapeutic use; D007507:Therapeutic Irrigation / Q000379:methods
chemical_list: D004202:Disinfectants; D012973:Sodium Hypochlorite
keywords: Endodontics; root canal therapy; sodium hypochlorite; solid-state lasers; treatment outcome