title: Hydroxyapatite crystallinity does not affect the repair of critical size bone defects.
abstract: OBJECTIVE
  The physicochemical properties of hydroxyapatite (HA) granules were observed to affect the biological behavior of graft materials. The aim of this work was to analyze the tissue response of two HA granules with different crystallinity and Ca/P ratio in vivo.
  
  
  METHODS
  The HA granules were produced in the Biomaterials Laboratory (COPPE/UFRJ). The testing materials were HA granules presenting a Ca/P molar ratio of 1.60 and 28% crystallinity (HA-1), and a Ca/P molar ratio of 1.67 and 70% crystallinity (HA-2). Both HAs were implanted into a critical-size calvaria rat defects.
  
  
  RESULTS
  To note, in the control group, the bone defects were filled with blood clot only. Descriptive and histomorphometric analyses after 1, 3, and 6 months postoperatively showed mild inflammatory infiltrate, mainly comprising macrophage-like and multinucleated giant cells, and an increase in the volume density of the fibrous tissues (p<0.05), which was in contrast to the similar volume density of the newly formed bone and biomaterials in relation to the control group.
  
  
  CONCLUSIONS
  Thus, we concluded that HA-1 and HA-2 are biocompatible and non-degradable, and that crystallinity does not affect bone repair of critical size defects.
authors.affiliation: Unigranrio University, Duque de Caxias, RJ, Brazil.
authors.forename: Marcio Baltazar
authors.initials: MB
authors.lastname: Conz
authors.forename: José Mauro
authors.initials: JM
authors.lastname: Granjeiro
authors.forename: Gloria de Almeida
authors.initials: Gde A
authors.lastname: Soares
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000627:therapeutic use; D001861:Bone Regeneration / Q000187:drug effects*; D018786:Bone Substitutes / Q000627:therapeutic use*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry* / Q000627:therapeutic use; D008422:Materials Testing; D051381:Rats; D012886:Skull / Q000033:anatomy & histology* / Q000601:surgery; D013997:Time Factors; D014945:Wound Healing
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D017886:Durapatite