title: Osteoclast-like cells on deproteinized bovine bone mineral and biphasic calcium phosphate: light and transmission electron microscopical observations.
abstract: OBJECTIVE
  The occurrence of multinucleated giant cells (MNGCs) on bone substitute materials has been recognized for a long time. However, there have been no studies linking material characteristics with morphology of the MNGCs. The aim was to analyze the qualitative differences of MNGCs on two commercially available calcium phosphate bone substitute materials retrieved from bone defects.
  
  
  METHODS
  Six defects were prepared bilaterally in the mandibular body of three mini pigs. The defects were randomly grafted with either deproteinized bovine bone mineral (DBBM) or biphasic calcium phosphate (BCP). After a healing period of four weeks, bone blocks were embedded in LR White resin. Three consecutive sections per defect were analyzed as follows: two with light microscopy using toluidine blue and tartrate-resistant acid phosphatase (TRAP) staining and one with transmission electron microscopy.
  
  
  RESULTS
  Multinucleated giant cells appeared on both biomaterials. On BCP, MNGCs had a flat morphology and were not observed in resorption lacunae. On DBBM, the MNGCs appeared more round and were often found in shallow concavities. MNGCs on both biomaterials demonstrated a varying degree of TRAP staining, with a tendency toward higher staining intensity of MNGCs on BCP. At the ultrastructural level, signs of superficial dissolution of BCP together with phagocytosis of minor fragments were observed. MNGCs on the surface of DBBM demonstrated sealing zones and ruffled borders, both features of mature osteoclasts.
  
  
  CONCLUSIONS
  MNGCs demonstrated distinctly different histological features depending on the bone substitute material used. Further research is warranted to understand the clinical implications of these morphological observations.
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.|Department of Oral & Maxillofacial Surgery, Copenhagen University Hospital (Rigshospitalet), Copenhagen Ø, Denmark.
authors.forename: Simon S
authors.initials: SS
authors.lastname: Jensen
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.|Laboratory of Oral Cell Biology, School of Dental Medicine, University of Bern, Bern, Switzerland.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Gruber
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Buser
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.|Robert K. Schenk Laboratory of Oral Histology, School of Dental Medicine, University of Bern, Bern, Switzerland.
authors.forename: Dieter D
authors.initials: DD
authors.lastname: Bosshardt
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002417:Cattle; D008334:Mandible / Q000601:surgery; D046529:Microscopy, Electron, Transmission; D010010:Osteoclasts / Q000648:ultrastructure*; D013194:Staining and Labeling; D013552:Swine; D013556:Swine, Miniature
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; C020243:calcium phosphate
keywords: biphasic calcium phosphate; bone regeneration; degradation; deproteinized bovine bone mineral; osteoclast