title: A study on the morphological changes of the rat mandibular bone with TEA CO2 laser.
abstract: OBJECTIVE
  The purpose of this study was to investigate the morphological changes of the bone structure induced by transversely excited, atmospheric TEA pressure CO2 laser irradiation. Moreover, the healing process at 3 weeks was also observed.
  
  
  BACKGROUND
  It has been demonstrated that dental hard tissue can be removed by a long pulse of TEA CO2 laser irradiation with minimal thermal damage. However, there are few studies on the morphological changes of the TEA CO2 laser on bone tissue.
  
  
  METHODS
  The TEA CO2 laser was irradiated on the surface of the rat mandibular bone under the following irradiation conditions: wavelength, 10.6 microns; output, 95 mJ/pulse; pulse repetition rate, 1 Hz; irradiation time, 7.5 microseconds/shot; spot size, 0.8 x 1.5 mm; energy density, 7.9 J/cm2. Histological and scanning electron microscopic examinations were performed.
  
  
  RESULTS
  In the stereoscopic examination, a defect with clean-cut margins was produced. In the light microscopic examination, a basophilic line at the bottom of the defect was noted. Examining the defect with SEM, a smear-like appearance and cone structures were found. In the histological examination, a healing process by formation of new bones at the junction site was recognized.
  
  
  CONCLUSIONS
  These findings suggest that it is possible to remove bone tissues by TEA CO2 laser irradiation. However, a particle-like structure associated with a basophilic line and melted surface indicated that some thermal damage was produced during the laser irradiation.
authors.affiliation: Department of Endodontics, School of Dentistry, Showa University, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Hossain
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: H
authors.initials: H
authors.lastname: Tokonabe
authors.forename: N
authors.initials: N
authors.lastname: Matsumoto
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D007834:Lasers; D008297:Male; D008334:Mandible / Q000033:anatomy & histology* / Q000528:radiation effects* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar