title: Effect of Er, Cr: YSGG laser irradiation on Enterococcus faecalis in infected root canals.
abstract: OBJECTIVE
  The purpose of this study was to investigate the eradication of Enterococcus faecalis by high-power settings of Er, Cr:YSGG laser irradiation in root canals of extracted teeth.
  
  
  BACKGROUND
  The bacteria entering the root canal system invade dentinal tubules, resulting in persistent infections in root canals due to limited penetration of irrigation solutions into the dentinal tubules. The antibacterial effects of different lasers have been investigated in previous studies.
  
  
  METHODS
  Sixty newly extracted maxillary central incisors were enlarged chemomechanically and sterilized after removal of the smear layer. Root canals were inoculated with E. faecalis, and bacteria were incubated in root canals for 48 h. Samples were randomly divided into four groups, each containing 15 teeth. One group was considered as control with no intervention. Two groups were irradiated with 2- and 3-W output powers of Er, Cr:YSGG laser for 16 s. In the last group, the canals were irrigated with 1% sodium hypochlorite for 20 min.
  
  
  RESULTS
  In the laser groups at 2- and 3-W powers, the number of bacteria was reduced 2.4% and 1.53%, respectively, compared with the controls. No significant differences were found between the two laser groups (p > 0.05). The canals irrigated with 1% NaOCl solution demonstrated no bacterial growth.
  
  
  CONCLUSIONS
  According to the results of the present study, 2- and 3-W powers of Er, Cr:YSGG laser have antibacterial effects on E. faecalis in root canals of infected teeth; however, the effect is less remarkable than that of NaOCl solution.
authors.affiliation: The Department of Endodontics, Tabriz Dental School, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Yavari
authors.forename: Saeed
authors.initials: S
authors.lastname: Rahimi
authors.forename: Shahriar
authors.initials: S
authors.lastname: Shahi
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Lotfi
authors.forename: Mohammed H S
authors.initials: MH
authors.lastname: Barhaghi
authors.forename: Ali
authors.initials: A
authors.lastname: Fatemi
authors.forename: Majid
authors.initials: M
authors.lastname: Abdolrahimi
mesh_terms: D019551:Dental Disinfectants / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000382:microbiology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D013293:Enterococcus faecalis / Q000528:radiation effects*; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D028022:Low-Level Light Therapy; D012388:Root Canal Irrigants / Q000627:therapeutic use; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014076:Tooth Diseases / Q000628:therapy*
chemical_list: D019551:Dental Disinfectants; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite