title: Effects on periradicular periodontal tissues of root canal irradiation with Er:YAG laser in rats.
abstract: OBJECTIVE
  The effects of Er:YAG laser irradiation on the periodontal region during root canal preparation were evaluated using rats histopathologically.
  
  
  BACKGROUND
  The effects on periodontal tissues along the root surface and apical area during root canal preparation using Er:YAG laser irradiation in vivo are not clear.
  
  
  METHODS
  One hundred mesial root canals of mandibular first molars in rats were divided into four groups. In three of these groups, root canals were irradiated using an Er:YAG laser at 2 Hz and 34, 68, and 102 mJ/pulse for 30 sec. Non-irradiated canals served as controls. The effects of laser irradiation on the periodontal tissues along the root surface and apical area were evaluated at 0, 2 days, 1, 2, and 4 weeks after irradiation under light microscopy.
  
  
  RESULTS
  At 4 weeks after treatment, no inflammation or resorption was observed in any cases in the control or 34 mJ/pulse-irradiated groups. However, moderate to severe inflammation with resorption of root surface was observed in four of five cases (80%) in the 102 mJ/pulse-irradiated group, which was significantly different from the control (p < 0.01).
  
  
  CONCLUSIONS
  These results suggest that the effects on periodontal tissues during root canal preparation by Er:YAG laser irradiation after pulpectomy are minimal, if appropriate parameters are selected, and this is a potential therapy for human root canals of teeth.
authors.affiliation: Department of Endodontics, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan. yukimura@senzoku.showa-u.ac.jp
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kimura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yonaga
authors.forename: Masao
authors.initials: M
authors.lastname: Murakoshi
authors.forename: Keiko
authors.initials: K
authors.lastname: Yokoyama
authors.forename: Haruji
authors.initials: H
authors.lastname: Watanabe
authors.forename: Koukichi
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D001707:Biopsy, Needle; D003786:Dental Pulp Cavity / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure*; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D007834:Lasers; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D008855:Microscopy, Electron, Scanning; D009354:Neodymium; D010519:Periodontium / Q000473:pathology* / Q000528:radiation effects*; D010784:Photomicrography; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D018915:Root Canal Preparation; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D009354:Neodymium