title: Long-term effect of pulsed Nd:YAG laser irradiation on cultured human periodontal fibroblasts.
abstract: OBJECTIVE
  The purpose of this study was to investigate the long-term effect of Nd:YAG laser irradiation on cultured human periodontal fibroblasts (hPF).
  
  
  METHODS
  The cultured hPF were irradiated by pulsed Nd:YAG laser. The power delivery was 50 mJ x 10 pps (pulse per second) with irradiation duration 60, 120, 180, or 240 seconds. The viability and collagen content of laser-irradiated hPF were assessed on day 5 after laser treatment. Light microscope and transmission electron microscope (TEM) were used to observe cytomorphological change. The irradiated hPF cultured in mineralizing medium for 28 days were examined by alizarin red S and Von Kossa stain.
  
  
  RESULTS
  The cellular viability and collagen content of hPF decreased after Nd:YAG laser irradiation. Cell damage was noted with retraction of cellular processes, loss of normal architecture, and lysis of some cells. However, survived hPF proliferated and migrated to the cell-debris-associated deposits. The electron-dense cytoplasm and amorphous organelles in laser-damaged cells was revealed by TEM. In vitro mineralization was demonstrated in the long-term laser-irradiated hPF cultured in mineralizing medium.
  
  
  CONCLUSIONS
  Nd:YAG laser irradiation induced partial loss of cellular viability and collagen content. The co-existence of viable cells and progressive degeneration of laser-damaged cells was associated with the in vitro mineralization of hPF.
authors.affiliation: School of Dentistry, National Taiwan University Hospital and School of Dentistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Yi-Jane
authors.initials: YJ
authors.lastname: Chen
authors.forename: Jiiang-Huei
authors.initials: JH
authors.lastname: Jeng
authors.forename: Chung-Chen
authors.initials: CC
authors.lastname: Jane Yao
authors.forename: Min-Huey
authors.initials: MH
authors.lastname: Chen
authors.forename: Lein-Tuan
authors.initials: LT
authors.lastname: Hou
authors.forename: Wan-Hong
authors.initials: WH
authors.lastname: Lan
mesh_terms: D002113:Calcification, Physiologic / Q000528:radiation effects; D002478:Cells, Cultured; D003094:Collagen / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D007834:Lasers; D046529:Microscopy, Electron, Transmission; D010513:Periodontal Ligament / Q000166:cytology / Q000528:radiation effects*
chemical_list: D003094:Collagen