title: Histologic and histomorphometric evaluation of bone regeneration using nanocrystalline hydroxyapatite and human freeze-dried bone graft : An experimental study in rabbit.
abstract: OBJECTIVE
  Bone regeneration is an important concern in periodontal treatment and implant dentistry. Different biomaterials and surgical techniques have been used for this purpose. The aim of the present study was to compare the effect of nanocrystalline hydroxyapatite and human freeze-dried bone graft (FDBG) in regeneration of rabbit calvarium bony defects by histologic and histomorphometric evaluation.
  
  
  METHODS
  In this experimental study, three similar defects, measuring 8 mm in diameter, were created in the calvaria of 16 white New Zealand rabbits. Two defects were filled with FDBG and nanocrystalline hydroxyapatite silica gel, while the other one remained unfilled to be considered as control. All the defects were covered with collagen membranes. During the healing period, two animals perished; so 14 rabbits were divided into two groups: half of them were euthanized after 6 weeks of healing and the other half after 12 weeks. The specimens were subjected to histologic and histomorphometric examinations for assessment of the following variables: percentage of bone formation and residual graft material, inflammation scores, patterns of bone formation and type of newly formed bone.
  
  
  RESULTS
  The percentages of new bone formation after 6 weeks were 14.22 ± 7.85, 21.57 ± 6.91, and 20.54 ± 10.07% in FDBG, NanoBone, and control defects. These values were 27.54 ± 20.19, 23.86 ± 6.27, and 26.48 ± 14.18% in 12-week specimens, respectively. No significant differences were found in the amount of bone formation between the groups. With regard to inflammation, the control and NanoBone groups showed significantly less inflammation compared to FDBG at the 6-week healing phase (P = 0.04); this difference was not significant in the 12-week specimens.
  
  
  CONCLUSIONS
  Based on the results of this experimental study, both NanoBone and FDBG exhibited a similar effect on bone formation.
authors.affiliation: Department of Periodontics, Faculty of Dentistry, Shahed University, 37, Italia St., Vesal Ave., Tehran, 1417755351, Iran. sadeghi@shahed.ac.ir.
authors.forename: Rokhsareh
authors.initials: R
authors.lastname: Sadeghi
authors.affiliation: Department of Periodontics, Faculty of Dentistry, Golestan University of Medical Sciences, Gorgan, Golestan, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Najafi
authors.affiliation: Department of Periodontics, Faculty of Dentistry, Shahed University, 37, Italia St., Vesal Ave., Tehran, 1417755351, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Semyari
authors.affiliation: Department of Oral and Maxillofacial Pathology, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Mashhadiabbas
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects / Q000502:physiology*; D018786:Bone Substitutes / Q000627:therapeutic use; D016025:Bone Transplantation / Q000379:methods*; D015925:Cryopreservation / Q000379:methods; D017886:Durapatite / Q000627:therapeutic use*; D005612:Freeze Drying / Q000379:methods; D006801:Humans; D008297:Male; D053758:Nanoparticles / Q000627:therapeutic use*; D011817:Rabbits; D012887:Skull Fractures / Q000473:pathology* / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D017886:Durapatite
keywords: Animal models; Biocompatible materials; Bone regeneration; Inflammation; Osteogenesis