title: Novel use of cranial epidural space in rabbits as an animal model to investigate bone volume augmentation potential of different bone graft substitutes.
abstract: BACKGROUND
  The success of bone augmentation to a major degree depends on the biomechanics and biological conditions of the surrounding tissues. Therefore, an animal model is needed providing anatomical sites with similar mechanical pressures for comparing its influence on different biomaterials for bone regeneration. The present report describes the new bone formation associated to biomaterial in a bursa created in the epidural space, between dura mater and cranial calvaria, under the constant pressure of cerebrospinal fluid.
  
  
  METHODS
  Five adult California rabbits were used for the trial. In each animal, two bursae were created in the epidural spaces, in the anterior part of the skull, below both sides of the interfrontal suture. The spaces between dura mater and cranial calvaria were filled with in-situ hardening biphasic calcium phosphate containing hydroxyapatite and beta tricalcium-phosphate (BCP), in-situ hardening phase-pure beta-tricalcium phosphate (β-TCP) or without any biomaterials (sham). After 90 days, the animals were sacrificed, and the defect sites were extracted and processed for histomorphometric analysis by optical and backscattered electron microscopy.
  
  
  RESULTS
  The cranial epidural spaces created (n = 10) could be preserved by the application both BCP (n = 3) and β-TCP biomaterials (n = 3) in all experimental sites. The sites augmented with BCP showed less new bone formation but a trend to better volume preservation than the sites augmented with β-TCP. However, the bone in the BCP sites seemed to be more mature as indicated by the higher percentage of lamellar bone in the sites. In contrast, the created space could not be preserved, and new bone formation was scarce in the sham-operated sites (n = 4).
  
  
  CONCLUSIONS
  The experimental bursae created bilaterally in the epidural space allows comparing objectively bone formation in relation to biomaterials for bone regeneration under permanent physiological forces from cerebrospinal fluid pressure.
authors.affiliation: Biomedical Department, Universidad de Antofagasta, Antofagasta, Chile.|Odontology Department, Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Ivan
authors.initials: I
authors.lastname: Valdivia-Gandur
authors.affiliation: Department of Oral and Maxillofacial Surgery, Georg-August-Universität, Göttingen, Germany.
authors.forename: Wilfried
authors.initials: W
authors.lastname: Engelke
authors.affiliation: Department of Oral and Maxillofacial Surgery, Georg-August-Universität, Göttingen, Germany. victor.beltran@ufrontera.cl.|Faculty of Dentistry, Universidad de La Frontera, Temuco, Chile. victor.beltran@ufrontera.cl.|Clinical Investigation and Dental Innovation Center (CIDIC), Dental School, Universidad de La Frontera, Av. Francisco Salazar 01145, Temuco, Chile. victor.beltran@ufrontera.cl.
authors.forename: Víctor
authors.initials: V
authors.lastname: Beltrán
authors.affiliation: Faculty of Dentistry, Universidad de La Frontera, Temuco, Chile.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Borie
authors.affiliation: Faculty of Dentistry, Universidad de La Frontera, Temuco, Chile.
authors.forename: Ramón
authors.initials: R
authors.lastname: Fuentes
authors.affiliation: Muscular and Skeletal Pathology Research, Human Anatomy and Embryology Unit, Universitat de Barcelona, Barcelona, Spain.
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Manzanares-Céspedes
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects* / Q000502:physiology; D018786:Bone Substitutes / Q000494:pharmacology*; D016025:Bone Transplantation / Q000379:methods; D002130:Calcium Phosphates / Q000494:pharmacology; D004195:Disease Models, Animal; D004824:Epidural Space / Q000601:surgery; D006882:Hydroxyapatites / Q000494:pharmacology; D007150:Immunohistochemistry; D010012:Osteogenesis / Q000502:physiology*; D011817:Rabbits; D011897:Random Allocation; D012680:Sensitivity and Specificity; D012886:Skull / Q000601:surgery
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; D006882:Hydroxyapatites; C485817:beta-tricalcium phosphate; C074950:hydroxyapatite-beta tricalcium phosphate
keywords: BCP; Beta-tricalcium phosphate; Bi-phasic calcium phosphate; Bone augmentation; Epidural space; Hydroxyapatite; Rabbit; Sinus floor elevation