title: Low-dose rhBMP2/7 heterodimer to reconstruct peri-implant bone defects: a micro-CT evaluation.
abstract: OBJECTIVE
  To delineate the dynamic micro-architectures of bone induced by low-dose bone morphogenetic protein (BMP)-2/7 heterodimer in peri-implant bone defects compared to BMP2 and BMP7 homodimer.
  
  
  METHODS
  Peri-implant bone defects (8 mm in diameter, 4 mm in depth) were created surrounding SLA-treated titanium implants (3.1 mm in diameter, 10 mm in length) in minipig's calvaria. We administrated collagen sponges with adsorbed low-dose (30 ng/mm(3) ) BMP2/7 to treat the defects using BMP2, BMP7 or no BMP as controls.2, 3 and 6 weeks after implantation, we adopted micro-computer tomography to evaluate the micro-architectures of new bone using the following parameters: relative bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), connectivity density, and structure mode index (SMI). Bone implant contact (BIC) was also revealed histologically.
  
  
  RESULTS
  Consistent with 2 and 3 weeks, after 6 weeks post-operation, BMP2/7 resulted in significantly higher BV/TV (63.033 ± 2.055%) and significantly lower SMI (-4.405 ± 0.500) than BMP2 (BV/TV: 43.133 ± 2.001%; SMI: -0.086 ± 0.041) and BMP7 (BV/TV: 41.467 ± 1.850%; SMI: -0.044 ± 0.016) respectively. Significant differences were also found in Tb.N, Tb.Th and Tb.Sp at all time points. At 2 weeks, BMP2/7 resulted in significantly higher BIC than the controls.
  
  
  CONCLUSIONS
  Low-dose BMP2/7 heterodimer facilitated more rapid bone regeneration in better quality in peri-implant bone defects than BMP2 and BMP7 homodimers.
authors.affiliation: School/Hospital of Stomatology, Zhejiang University, Hangzhou, China.
authors.forename: Jingxiao
authors.initials: J
authors.lastname: Wang
authors.forename: Yuanna
authors.initials: Y
authors.lastname: Zheng
authors.forename: Juan
authors.initials: J
authors.lastname: Zhao
authors.forename: Tie
authors.initials: T
authors.lastname: Liu
authors.forename: Lixia
authors.initials: L
authors.lastname: Gao
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Gu
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage / Q000502:physiology*; D055419:Bone Morphogenetic Protein 7 / Q000008:administration & dosage / Q000502:physiology*; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D016348:Osseointegration / Q000187:drug effects / Q000502:physiology*; D055503:Protein Multimerization; D011994:Recombinant Proteins; D012886:Skull / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology*; D013552:Swine; D013556:Swine, Miniature; D055114:X-Ray Microtomography
chemical_list: C525718:BMP2 protein, human; C525819:BMP7 protein, human; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D015921:Dental Implants; D011994:Recombinant Proteins