title: Cranial particulate bone graft ossifies calvarial defects by osteogenesis.
abstract: BACKGROUND
  Cranial particulate bone graft heals inlay calvarial defects and can be harvested as early as infancy. The purpose of this study was to test the hypothesis that particulate bone promotes ossification primarily by osteogenesis.
  
  
  METHODS
  Freshly harvested particulate bone, devitalized particulate bone, and high-speed drilled bone dust from rabbit calvaria were assayed for metabolic activity (resazurin) and viable osteoblasts (alkaline phosphatase). A rabbit cranial defect model was used to test the effect of devitalizing particulate bone on in vivo ossification. A parietal critical-size defect was created and managed in three ways: (1) no implant (n = 6); (2) particulate bone implant (n = 6); and (3) devitalized particulate bone implant (n = 6). Micro-computed tomographic scanning was used to measure ossification 16 weeks later; histology also was studied.
  
  
  RESULTS
  Particulate bone contained more viable cells (0.94 percent transmittance per milligram) compared with devitalized particulate bone (0.007 percent) or bone dust (0.21 percent) (p = 0.01). Particulate bone had greater alkaline phosphatase activity (0.13 μU/μg) than devitalized particulate bone (0.000) or bone dust (0.06) (p = 0.01). Critical-size defects treated with particulate bone had more ossification (99.7 percent) compared with devitalized particulate bone implants (42.2 percent) (p = 0.01); no difference was found between devitalized particulate bone and the control (40.8 percent) (p = 0.9).
  
  
  CONCLUSIONS
  Particulate bone graft contains living cells, including osteoblasts, that are required to heal critical-size cranial defects. These data support the hypothesis that particulate bone promotes ossification primarily by osteogenesis.
authors.affiliation: Boston, Mass. From the Department of Plastic and Oral Surgery, Children's Hospital Boston, Harvard Medical School; the Program in Oral and Maxillofacial Pathology, Harvard School of Dental Medicine; and the Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School.
authors.forename: Aladdin H
authors.initials: AH
authors.lastname: Hassanein
authors.forename: Praveen R
authors.initials: PR
authors.lastname: Arany
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Couto
authors.forename: James E
authors.initials: JE
authors.lastname: Clune
authors.forename: Julie
authors.initials: J
authors.lastname: Glowacki
authors.forename: Gary F
authors.initials: GF
authors.lastname: Rogers
authors.forename: John B
authors.initials: JB
authors.lastname: Mulliken
authors.forename: Arin K
authors.initials: AK
authors.lastname: Greene
mesh_terms: D000818:Animals; D016025:Bone Transplantation; D002470:Cell Survival; D003399:Craniotomy; D004195:Disease Models, Animal; D010006:Osteoblasts / Q000502:physiology; D010012:Osteogenesis; D011817:Rabbits; D012886:Skull / Q000503:physiopathology* / Q000601:surgery*; D014182:Transplantation, Autologous; D014945:Wound Healing; D014947:Wounds and Injuries / Q000209:etiology / Q000628:therapy*