title: Low-level laser effects on simulated orthodontic tension side periodontal ligament cells.
abstract: OBJECTIVE
  The purpose of this study was to analyze proliferation, inflammation, and osteogenic effects on periodontal ligament (PDL) cells after low-level laser therapy (LLLT) under simulated orthodontic tension conditions.
  
  
  BACKGROUND
  Low-level lasers affect fibroblast proliferation and collagen synthesis and reduce inflammation. Few studies have focused on the LLLT changes in the PDL caused by moving teeth.
  
  
  METHODS
  A human PDL cell line was cultured in a -100 kPa tension incubator. The PDL cells were treated with a 670 nm low-level diode laser, output power of 500 mW (continuous wave modus) for 2.5 or 5 sec, spot area 0.25 cm(2), corresponding to 1.25 and 2.5 J at an energy density of 5 or 10 J/cm(2), respectively. PDL cell viability was assayed by detecting the ability of the cells to cleave tetrazolium salt to formazan dye. Inflammation and osteogenic markers were analyzed by Western blot analysis.
  
  
  RESULTS
  PDL cell viablity increased in the experimental group, based on the ability of the cells to cleave tetrazolium salt at day 7 (p<0.05). The experimental group showed no difference in PDL cellular morphology compared with the control group. The inflammation markers inducible NO synthase (iNOS), cyclooxygenase (COX)-2 and interleukin (IL)-1 showed stronger expression in 5 and 10 J/cm(2) therapy at days 1 and 5, but decreased in expression at day 7. The osteogenic marker osteocalcin (OC) expression level was significantly higher at day 7 (p<0.05) than in the control cells.
  
  
  CONCLUSIONS
  LLLT significantly increased PDL cell proliferation, decreased PDL cell inflammation, and increased PDL OC activity under the tension conditions used in this study.
authors: Dental Department, Chung Shan Medical University Hospital. School of Dentistry, College of Oral Medicine, Chung Shan Medical University Taichung, Taiwan.
authors: Tsui-Hsien
authors: TH
authors: Huang
authors: Shiau-Lee
authors: SL
authors: Liu
authors: Chih-Lin
authors: CL
authors: Chen
authors: Ming-You
authors: MY
authors: Shie
authors: Chia-Tze
authors: CT
authors: Kao
mesh_terms: D049109:Cell Proliferation; D002470:Cell Survival; D051546:Cyclooxygenase 2 / Q000378:metabolism; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism; D028022:Low-Level Light Therapy; D015675:Osteocalcin / Q000378:metabolism; D010513:Periodontal Ligament / Q000166:cytology*; D014087:Tooth Movement Techniques
chemical_list: D007375:Interleukin-1; D015675:Osteocalcin; D051546:Cyclooxygenase 2