title: Alveolar ridge augmentation using implants coated with recombinant human growth/differentiation factor-5: histologic observations.
abstract: OBJECTIVE
  In vitro and in vivo preclinical studies suggest that growth/differentiation factor-5 (GDF-5) may induce local bone formation. The objective of this study was to evaluate the potential of recombinant human GDF-5 (rhGDF-5) coated onto an oral implant with a purpose-designed titanium porous oxide surface to stimulate local bone formation including osseointegration and vertical augmentation of the alveolar ridge.
  
  
  METHODS
  Bilateral, critical-size, 5 mm, supraalveolar peri-implant defects were created in 12 young adult Hound Labrador mongrel dogs. Six animals received implants coated with 30 or 60 microg rhGDF-5, and six animals received implants coated with 120 microg rhGDF-5 or left uncoated (control). Treatments were alternated between jaw quadrants. The mucoperiosteal flaps were advanced, adapted, and sutured to submerge the implants for primary intention healing. The animals received fluorescent bone markers at weeks 3, 4, 7, and 8 post-surgery when they were euthanized for histologic evaluation.
  
  
  RESULTS
  The clinical examination showed no noteworthy differences between implants coated with rhGDF-5. The cover screw and implant body were visible/palpable through the alveolar mucosa for both rhGDF-5-coated and control implants. There was a small increase in induced bone height for implants coated with rhGDF-5 compared with the control, induced bone height averaging (+/-SD) 1.6+/-0.6 mm for implants coated with 120 microg rhGDF-5 versus 1.2+/-0.5, 1.2+/-0.6, and 0.6+/-0.2 mm for implants coated with 60 microg rhGDF-5, 30 microg rhGDF-5, or left uncoated, respectively (p<0.05). Bone formation was predominant at the lingual aspect of the implants. Narrow yellow and orange fluorescent markers throughout the newly formed bone indicate relatively slow new bone formation within 3-4 weeks. Implants coated with rhGDF-5 displayed limited peri-implant bone remodelling in the resident bone; the 120 microg dose exhibiting more advanced remodelling than the 60 and 30 microg doses. All treatment groups exhibited clinically relevant osseointegration.
  
  
  CONCLUSIONS
  rhGDF-5-coated oral implants display a dose-dependent osteoinductive and/or osteoconductive effect, bone formation apparently benefiting from local factors. Application of rhGDF-5 appears to be safe as it is associated with limited, if any, adverse effects.
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration, Department of Periodontics & Oral Biology, Medical College of Georgia School of Dentistry, Augusta, GA 30912, USA. gpolimeni@hotmail.com
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Polimeni
authors.forename: Ulf M E
authors.initials: UM
authors.lastname: Wikesjö
authors.forename: Cristiano
authors.initials: C
authors.lastname: Susin
authors.forename: Mohammed
authors.initials: M
authors.lastname: Qahash
authors.forename: Richard H
authors.initials: RH
authors.lastname: Shanaman
authors.forename: Hari S
authors.initials: HS
authors.lastname: Prasad
authors.forename: Michael D
authors.initials: MD
authors.lastname: Rohrer
authors.forename: Jan
authors.initials: J
authors.lastname: Hall
mesh_terms: D000540:Alveolar Ridge Augmentation / Q000379:methods*; D000818:Animals; D020099:Coated Materials, Biocompatible; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D017267:Dental Prosthesis Design; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D055428:Growth Differentiation Factor 5 / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008297:Male; D016348:Osseointegration / Q000187:drug effects*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013499:Surface Properties; D014025:Titanium; D014716:Vertical Dimension
chemical_list: D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D055428:Growth Differentiation Factor 5; D011994:Recombinant Proteins; C009495:titanium dioxide; D014025:Titanium