title: Femtosecond plasma mediated laser ablation has advantages over mechanical osteotomy of cranial bone.
abstract: BACKGROUND
  Although mechanical osteotomies are frequently made on the craniofacial skeleton, collateral thermal, and mechanical trauma to adjacent bone tissue causes cell death and may delay healing. The present study evaluated the use of plasma-mediated laser ablation using a femtosecond laser to circumvent thermal damage and improve bone regeneration.
  
  
  METHODS
  Critical-size circular calvarial defects were created with a trephine drill bit or with a Ti:Sapphire femtosecond pulsed laser. Healing was followed using micro-CT scans for 8 weeks. Calvaria were also harvested at various time points for histological analysis. Finally, scanning electron microscopy was used to analyze the microstructure of bone tissue treated with the Ti:Sapphire laser, and compared to that treated with the trephine bur.
  
  
  RESULTS
  Laser-created defects healed significantly faster than those created mechanically at 2, 4, and 6 weeks post-surgery. However, at 8 weeks post-surgery, there was no significant difference. In the drill osteotomy treatment group, empty osteocyte lacunae were seen to extend 699 ± 27 µm away from the edge of the defect. In marked contrast, empty osteocyte lacunae were seen to extend only 182 ± 22 µm away from the edge of the laser-created craters. Significantly less ossification and formation of irregular woven bone was noted on histological analysis for drill defects.
  
  
  CONCLUSIONS
  We demonstrate accelerated bone healing after femtosecond laser ablation in a calvarial defect model compared to traditional mechanical drilling techniques. Improved rates of early regeneration make plasma-mediated ablation of the craniofacial skeleton advantageous for applications to osteotomy.
authors.affiliation: Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Plastic and Reconstructive Surgery Division, Stanford University School of Medicine, Stanford, California 94305-5427, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Lo
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mackanos
authors.forename: Michael T
authors.initials: MT
authors.lastname: Chung
authors.forename: Jeong S
authors.initials: JS
authors.lastname: Hyun
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Montoro
authors.forename: Monica
authors.initials: M
authors.lastname: Grova
authors.forename: Chunjun
authors.initials: C
authors.lastname: Liu
authors.forename: Jenny
authors.initials: J
authors.lastname: Wang
authors.forename: Daniel
authors.initials: D
authors.lastname: Palanker
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Connolly
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Contag
authors.forename: Derrick C
authors.initials: DC
authors.lastname: Wan
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000528:radiation effects*; D053844:Lasers, Solid-State; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010027:Osteotomy / Q000379:methods*; D010294:Parietal Bone / Q000000981:diagnostic imaging / Q000502:physiology / Q000601:surgery* / Q000648:ultrastructure; D014057:Tomography, X-Ray Computed; D014945:Wound Healing / Q000528:radiation effects*