title: Effect of laser-activated irrigation of 1320-nanometer Nd:YAG laser on sealer penetration in curved root canals.
abstract: BACKGROUND
  The purpose of this study was to investigate the efficacy of laser-activated irrigation (LAI) of 1320-nm neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser on sealer penetration into dentinal tubules in the presence of 5.25% sodium hypochlorite (NaOCl) or 17% ethylenediaminetetraacetic acid (EDTA).
  
  
  METHODS
  The curved root canals (>20°) from 63 extracted human molars (negative control, n = 3) were prepared to size #30.06 with NaOCl irrigation. Teeth were divided into 4 groups (n = 15) as follows: group N, NaOCl irrigation without LAI; group E, EDTA irrigation without LAI; group NL, LAI with NaOCl; group EL, LAI with EDTA. In all groups, the laser fiber was inserted and withdrawn 4 times for 5 seconds each. Teeth were obturated with gutta-percha and fluorescent-labeled sealer. Transverse sections at 2 and 5 mm from root apex were examined with confocal laser scanning microscopy, and the percentage of sealer penetration into dentinal tubules was measured.
  
  
  RESULTS
  Groups E, NL, and EL showed higher percentage of sealer penetration than group N (P < .05). With NaOCl as irrigant, LAI (group NL) resulted in significantly higher amount of sealer penetration than nonactivated group (group N) in both levels (P < .05). However, with EDTA, no significant differences in sealer penetration were observed between the laser-activated group (group EL) and its nonactivated counterpart (group E) in both levels (P > .05).
  
  
  CONCLUSIONS
  The 1320-nm Nd:YAG laser activation with either NaOCl or EDTA was much better than NaOCl irrigation alone and as effective as EDTA final flush for sealer penetration into dentinal tubules. Additional use of laser with EDTA did not improve the quality of obturation in the curved canals.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Moon
authors.forename: Hyeon-Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Kwang-Shik
authors.initials: KS
authors.lastname: Bae
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Baek
authors.forename: Won-Jun
authors.initials: WJ
authors.lastname: Shon
authors.forename: WooCheol
authors.initials: W
authors.lastname: Lee
mesh_terms: D002614:Chelating Agents / Q000528:radiation effects / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D004492:Edetic Acid / Q000528:radiation effects / Q000627:therapeutic use; D004853:Epoxy Resins / Q000737:chemistry / Q000627:therapeutic use; D005456:Fluorescent Dyes; D006171:Gutta-Percha / Q000737:chemistry / Q000627:therapeutic use; D006801:Humans; D006813:Humidity; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D018613:Microscopy, Confocal; D008963:Molar; D012387:Root Canal Filling Materials / Q000737:chemistry / Q000627:therapeutic use*; D012388:Root Canal Irrigants / Q000528:radiation effects / Q000627:therapeutic use*; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012973:Sodium Hypochlorite / Q000528:radiation effects / Q000627:therapeutic use; D013696:Temperature; D007507:Therapeutic Irrigation / Q000379:methods; D013997:Time Factors
chemical_list: D002614:Chelating Agents; D004853:Epoxy Resins; D005456:Fluorescent Dyes; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; C534916:epoxy resin-based root canal sealer; D006171:Gutta-Percha; D004492:Edetic Acid; D012973:Sodium Hypochlorite