title: Implant-guided supracrestal alveolar bone growth using scaffolds, BMP-2, and novel scaffold-retaining device.
abstract: OBJECTIVE
  To evaluate the efficacy of various scaffold systems and a Ti scaffold-retaining device with and without non-glycosylated rhBMP-2 (BMP-2) for increasing the vertical alveolar bone growth in the intra-oral mini-pig model.
  
  
  METHODS
  Forty-eight Straumann Bone Level implants with hydrophilic (SLActive) surfaces were partially embedded in mandibles of 12 adult mini-pigs with the shoulder of the implant located 3 mm above the bone crest. Twenty-four implants were placed in conjunction with BMP-2 (50 μg) incorporated within resorbable scaffolds. Twenty-four additional control implants were placed with scaffolds only. Scaffolds were placed around the implant and stabilized with a newly developed Ti "umbrella" scaffold retainer. Scaffolds included (i) HA-coated collagen (Healos); (ii) biphasic HA/β-TCP crystals (Straumann Bone Ceramic, SBC); and (iii) SBC crystals infused with polyethylene glycol (PEG) hydrogel. Eight test and control pairs for each scaffold group were implanted. At 9 weeks, soft tissue healing was assessed and the extent of new vertical bone was evaluated with microCT and histomorphometry.
  
  
  RESULTS
  microCT analysis revealed a mean of 167 ± 47 mm3new supracrestal mineralized tissue volume formation around the test sites where BMP-2 was released from the scaffold whereas the control group (no BMP-2) showed a significantly lower mineralized tissue volume of 106 ± 55 mm3. The SBC+BMP-2 group had the highest mineralized tissue volume of 189 ± 36 mm3. Histomorphometry showed bone-to-implant contact of 54.5% for the test groups and 33.3% for the control groups and new vertical bone growth of 2.2 ± 1.0 and 1.0 ± 0.9 mm, respectively. The SBC+BMP-2 group again demonstrated the best outcome (2.7 ± 0.4 mm). The qualitative scoring of soft tissue dehiscence showed that the presence of BMP-2 yielded far superior outcomes, 0.63 vs. 1.75 for all control implant sites (with scores ranging from 0, reflecting no soft dehiscence, to 4, showing a completely exposed umbrella).
  
  
  CONCLUSIONS
  The release of BMP-2 from a SBC scaffold adjacent to a hydrophilic, rough Ti implant and scaffold retention umbrella consistently regenerated the greatest volume and height of new vertical bone along the length of the implant.
authors.affiliation: Department of Oral & Maxillofacial Surgery, Division of Implant Dentistry, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wen
authors.affiliation: Department of Craniofacial Sciences, Division of Oral & Maxillofacial Surgery, School of Dental Medicine, University of Connecticut, Farmington, CT, USA.
authors.forename: David
authors.initials: D
authors.lastname: Shafer
authors.affiliation: Department of head and neck, Stavanger University Hospital, Stavanger, Norway.
authors.forename: Peter
authors.initials: P
authors.lastname: Schleier
authors.affiliation: Department of Reconstructive Sciences, School of Dental Medicine, University of Connecticut, Farmington, CT, USA.
authors.forename: David
authors.initials: D
authors.lastname: Pendrys
authors.affiliation: Department of Reconstructive Sciences, Center for Biomaterials, School of Dental Medicine, University of Connecticut, Farmington, CT, USA.
authors.forename: Liisa
authors.initials: L
authors.lastname: Kuhn
authors.affiliation: Department of Reconstructive Sciences, Center for Biomaterials, School of Dental Medicine, University of Connecticut, Farmington, CT, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Freilich
mesh_terms: D000540:Alveolar Ridge Augmentation / Q000295:instrumentation / Q000379:methods*; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use*; D016557:Guided Tissue Regeneration, Periodontal / Q000379:methods*; D013552:Swine; D013556:Swine, Miniature; D054457:Tissue Scaffolds
chemical_list: D055396:Bone Morphogenetic Protein 2
keywords: Biomaterial scaffold; ng/rhBMP-2; scaffold retainer; vertical supracrestal bone growth