title: [Study on bone regeneration with two different ratios of nano-hydroxyapatite and collagen grafts after tooth extraction in dogs].
abstract: OBJECTIVE
  To compare the effect of bone regeneration with two different ratios of nano-hydroxyapatite(nHA)/collagen(Col) (nHAC) after tooth extraction in canine.
  
  
  METHODS
  Two kinds of nHAC grafts were prepared with different nHA/collagen ratio of 3∶7 and 5∶5. Eighteen male healthy adult dogs had been randomly divided into three groups. Immediately after extraction of the mandibular second premolars, each kind of nHAC was implanted into extraction sockets as follow: Group A, nHA/Col=3∶7(12 sites); Group B, nHA/Col=5∶5(12 sites); Group C, blank control group(12 sites). The bone repairing abilities of the two grafts such as vertical distance of alveolar, CT values, general observation, histological observation, trabecular volume fraction and porosity were separately analyzed at 1st, 3rd and 6th month, respectively (each group had 4 sites in different time periods).
  
  
  RESULTS
  nHAC were absorbed gradually after they were implanted into alveolar bone defect and were replaced by new bone. The vertical distance of alveolar bone in Group A([15.76±0.28] mm) was significant higher than that in Group B([14.88±0.36] mm), and CT values of Group A([879±31] HU) were higher than those in Group B([718±29] HU) (P<0.05). The trabecular bone volume percentage of Group A([22.2±0.4]%) was higher than that in Group B([20.3±0.4]%), and the bone porosity of Group A([23.6±0.9]%) was lower than that in Group B([27.6±0.6]%) (P<0.05). In addition, the vertical distance, CT values and the trabecular bone volume percentage of Group C was lower than those in Group A and B, but the bone porosity of Group C was higher.
  
  
  CONCLUSIONS
  The nHAC with nHA/collagen ratio of 3∶7 could better promote bone regeneration than nHAC with the nHA/collagen ratio of 5∶5 did.
authors.affiliation: Department of Prosthodontics, Affiliated Stomatological Hospital of Liaoning Medical University, Jinzhou 121000, China.
authors.forename: Yanfu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Prosthodontics, Affiliated Stomatological Hospital of Liaoning Medical University, Jinzhou 121000, China.
authors.forename: Chengyue
authors.initials: C
authors.lastname: Wang
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
authors.forename: Shaogang
authors.initials: S
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Fuzhai
authors.initials: F
authors.lastname: Cui
mesh_terms: D000818:Animals; D001861:Bone Regeneration; D003094:Collagen / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004285:Dogs; D017886:Durapatite / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D053758:Nanoparticles; D011897:Random Allocation; D023822:Tissue Engineering; D014081:Tooth Extraction
chemical_list: D003094:Collagen; D017886:Durapatite