title: Low-temperature particulate calcium phosphates for bone regeneration.
abstract: BACKGROUND
  Low-temperature synthesized calcium phosphates are produced by mixing calcium phosphate powders in an aqueous solution resulting in a precipitated phase. These compounds can be formulated in several forms (e.g. injectable cements and implantable blocks), and are commonly used as bone substitutes and drug delivery systems for the treatment of bone defects. As bone substitutes, calcium phosphates in general offer the advantages of being biocompatible and osteoconductive.
  
  
  OBJECTIVE
  The present work employed a machine-based process to derive a reproducible preparation method for low-temperature calcium phosphate particulate (LTCP). The in vivo outcomes of LTCP were compared with those of three commercially available bone substitutes by histomorphometric measurements of bone formation and material degradation in a rat femur implantation model.
  
  
  METHODS
  Specifically, LTCP, anorganic bovine bone (AB), bioactive glass (BG), and demineralized bone matrix (DBM) were implanted in defects created in the distal aspect of rat femora. Reparative bone and particulate volumes of these biomaterials were evaluated post-operatively using micro-computed tomography and histological analyses at 3, 6, 12, and 16 weeks.
  
  
  CONCLUSIONS
  Results showed that, despite invoking bone formation, AB, BG, and DBM were found un-resorbed in situ at 16 weeks. Conversely, LTCP showed an early increase in bone formation as well as clear evidence of complete degradation and reparative bone remodelling, resulting in the total reconstitution of the marrow cavity and marrow tissue.
  
  
  CONCLUSIONS
  LTCP promoted increased early bone formation, associated with an improved degradation rate, compared with the other three bone-substitute biomaterials tested.
authors.affiliation: Faculty of Dentistry, University of Toronto, Toronto, ON, Canada M5G 1G6.
authors.forename: M V F
authors.initials: MV
authors.lastname: Araújo
authors.forename: V C
authors.initials: VC
authors.lastname: Mendes
authors.forename: P
authors.initials: P
authors.lastname: Chattopadhyay
authors.forename: J E
authors.initials: JE
authors.lastname: Davies
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001857:Bone Matrix / Q000637:transplantation; D001861:Bone Regeneration / Q000187:drug effects*; D018786:Bone Substitutes / Q000494:pharmacology*; D002130:Calcium Phosphates / Q000494:pharmacology*; D003080:Cold Temperature; D018360:Crystallography, X-Ray; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D005898:Glass; D008297:Male; D008422:Materials Testing; D008903:Minerals; D010316:Particle Size; D016062:Porosity; D051381:Rats; D017208:Rats, Wistar; D055114:X-Ray Microtomography
chemical_list: C077540:Bio-Oss; C073544:Biogran; D018786:Bone Substitutes; D002130:Calcium Phosphates; D008903:Minerals