title: Morphological and atomic analytical studies on enamel and dentin irradiated by an erbium, chromium:YSGG laser.
abstract: OBJECTIVE
  The purposes of this study were to investigate the morphological and atomic analytical changes and to evaluate the cutting effect on dental hard tissues of this laser in vitro.
  
  
  BACKGROUND
  There have been few reports on morphological and atomic analytical study of dental hard tissues after erbium,chromium:yttrium,scandium,gallium,garnet (Er,Cr:YSGG) laser irradiation.
  
  
  METHODS
  Eighteen extracted human molars were sectioned into 3-mm-thick slices, which were irradiated with water-air spray by an Er,Cr:YSGG laser at 6.0 W and 20 Hz for 5 sec for enamel and 5.0 W and 20 Hz for 5 sec for dentin. The samples were then morphologically observed and examined atomic-analytically.
  
  
  RESULTS
  Regular holes having sharp edges and smooth walls, but no melting or carbonization, were observed in both samples. An atomic analytical examination showed that the calcium ratio to phosphorus showed no significant changes between the lased areas and unlased areas (p > 0.01).
  
  
  CONCLUSIONS
  These results showed that the Er,Cr:YSGG laser has a good cutting effect on dental hard tissues and offers advantages of no burning or melting after laser irradiation.
authors.affiliation: Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan.
authors.forename: D G
authors.initials: DG
authors.lastname: Yu
authors.forename: Y
authors.initials: Y
authors.lastname: Kimura
authors.forename: J
authors.initials: J
authors.lastname: Kinoshita
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D003743:Dental Enamel / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure*; D003804:Dentin / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure*; D006801:Humans; D066298:In Vitro Techniques; D028022:Low-Level Light Therapy