title: Histological and TEM examination of early stages of bone healing after Er:YAG laser irradiation.
abstract: OBJECTIVE
  The aim of this study was to analyze the early healing process of bone tissue irradiated by Er:YAG laser and compare it with that treated by mechanical drilling and CO(2) laser.
  
  
  BACKGROUND
  Er:YAG laser has a great potential for cutting hard tissues as it is capable of ablation with less thermal damage.
  
  
  METHODS
  Twenty-four male Wistar rats were used for this study. The calvarial bone of rats was exposed and straight grooves were prepared by Er:YAG laser, mechanical bur and continuous wave CO(2) laser. Four rats each were sacrificed at six time points: 10 min, 6 and 24 h and 3, 7, and 14 days post-surgery. Sections were prepared for light and transmission electron microscopic (TEM) observations.
  
  
  RESULTS
  Compared to mechanical bur and CO(2) groups, the inflammatory cell infiltration adjacent to the irradiated bone surface, fibroblastic reaction, and revascularization were more pronounced in the Er:YAG laser-irradiated tissues. A cell-rich granulation tissue with fibroblasts and osteoblasts was predominant in 7-day specimens of Er:YAG laser group. Histopathological analysis of 14-day specimens in the Er:YAG group also revealed significantly greater new bone formation, compared with the mechanical bur and CO(2) laser groups.
  
  
  CONCLUSIONS
  Initial bone healing following Er:YAG laser irradiation occurred faster than that after mechanical bur and CO(2) laser. Er:YAG laser treatment may be advantageous for wound healing of bone tissue, presumably by providing a favorable surface for cell attachment.
authors.affiliation: Periodontology, Department of Hard Tissue Engineering, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. amir.peri@tmd.ac.jp
authors.forename: Amir
authors.initials: A
authors.lastname: Pourzarandian
authors.forename: Hisashi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Akira
authors.initials: A
authors.lastname: Aoki
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.forename: Katia M
authors.initials: KM
authors.lastname: Sasaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nitta
authors.forename: Isao
authors.initials: I
authors.lastname: Ishikawa
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002245:Carbon Dioxide / Q000627:therapeutic use; D003399:Craniotomy; D046508:Culture Techniques; D004195:Disease Models, Animal; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D017348:Microscopy, Electron, Scanning Transmission; D009354:Neodymium; D010012:Osteogenesis / Q000502:physiology / Q000528:radiation effects*; D010294:Parietal Bone / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure*; D011336:Probability; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D014945:Wound Healing / Q000502:physiology / Q000528:radiation effects*
chemical_list: D002245:Carbon Dioxide; D009354:Neodymium