title: Effects of femtosecond laser irradiation on osseous tissues.
abstract: OBJECTIVE
  Few studies have investigated femtosecond (fs) lasers for cutting bone tissue.
  
  
  METHODS
  A 775 nm, 1 kHz, 200 femtosecond, up to 400 microJ laser system was used to irradiate in vitro calcified cortical bone samples and bone tissue culture samples.
  
  
  RESULTS
  The ablation threshold in cortical bone was 0.69+/-0.08 J/cm(2) at 775 nm and 0.19+/-0.05 J/cm(2) at 387 nm. Plasma shielding experiments determined that the ablation plume and the plasma significantly affect material removal at high repetition rates and appear to generate thermal transients in calcified tissue. Confocal analysis revealed intact enzymatic activity on the surface of cells immediately adjacent to cells removed by fs laser irradiation.
  
  
  CONCLUSIONS
  These experiments demonstrate that fs lasers used for bone tissue cutting do not appear to generate significant temperature transients to inactivate proteins and that cellular membrane integrity is disrupted for only a few cell layers.
authors.affiliation: Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto, Ontario, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Girard
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: M R
authors.initials: MR
authors.lastname: Armstrong
authors.forename: B C
authors.initials: BC
authors.lastname: Wilson
authors.forename: C M L
authors.initials: CM
authors.lastname: Clokie
authors.forename: R J Dwayne
authors.initials: RJ
authors.lastname: Miller
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002470:Cell Survival; D006801:Humans; D007231:Infant, Newborn; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D012886:Skull / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D013194:Staining and Labeling
chemical_list: D000469:Alkaline Phosphatase