title: Bone augmentation osteogenesis using hydroxyapatite and beta-tricalcium phosphate blocks.
abstract: OBJECTIVE
  In this study, we investigated the differences in osteogenesis and resorption between hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) implanted on the parietal bone of rats.
  
  
  METHODS
  HA and beta-TCP were used in blocks with macropores and micropores. They were implanted between the parietal bone and the cranial periosteum in rats. Osteogenesis around the implanted materials was investigated histopathologically and histomorphometrically at 1, 2, 4, 8, and 24 weeks after surgery.
  
  
  RESULTS
  At 2 weeks, osteogenesis from the parietal bone was observed around both materials, and new bone had attached directly to the surfaces of both materials. New bone grew into the pores of the upper regions of both materials with time. The beta-TCP block had a characteristic basophilic reticular structure in which the dissolution of the materials was observed close to the new bone. The HA blocks were stable for 24 weeks, whereas parts of the beta-TCP blocks were fractured and resorbed at 24 weeks. Histomorphometrically, the volume of new bone around HA was larger than that around beta-TCP. There was no remarkable change in the amount of remaining HA, but that of beta-TCP was decreased.
  
  
  CONCLUSIONS
  HA blocks in this model are suitable for onlay grafts because of its stability and osteogenesis, beta-TCP is not stable. Therefore, when beta-TCP blocks are used for onlay grafts, the mechanical stress on the recipient site should be taken into consideration because of resorption and fracture.
authors.affiliation: Graduate School of Dental Medicine, Hokkaido University, North 13 West 7, Kita-ku, Sapporo 060-8586, Japan. fujita@den.hokudai.ac.jp
authors.forename: Rumi
authors.initials: R
authors.lastname: Fujita
authors.forename: Atsuro
authors.initials: A
authors.lastname: Yokoyama
authors.forename: Takao
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Takao
authors.initials: T
authors.lastname: Kohgo
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology; D018786:Bone Substitutes; D002118:Calcium / Q000378:metabolism; D002130:Calcium Phosphates / Q000494:pharmacology*; D019245:Compressive Strength; D017886:Durapatite / Q000494:pharmacology*; D020007:Implants, Experimental; D008297:Male; D010012:Osteogenesis / Q000187:drug effects*; D010294:Parietal Bone; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate; D017886:Durapatite; C018392:tricalcium phosphate; D002118:Calcium