title: Bone regeneration by recombinant human bone morphogenetic protein-2 around immediate implants: a pilot study in rats.
abstract: OBJECTIVE
  Difficulties relating to bone regeneration that complicate immediate implant placement include buccal and/or lingual fenestrations, primary anchorage of the implants, and the need for protection from functional loading during the osseointegration period. The objective of this pilot study was to evaluate bone regeneration by recombinant human bone morphogenetic protein-2 (rhBMP-2) around immediate implants placed in maxillary sockets in rats.
  
  
  METHODS
  A total of 16 cylindric 0.8 x 1.8-mm commercially pure, solid titanium Implants were placed immediately after gentle extraction of the maxillary first molar teeth of 8 male Wistar rats. The sockets were randomly divided into 3 groups: group 1 (n = 6) received rhBMP-2 with polylactic acid/polyglycolic acid copolymer-coated gelatin sponge carrier; group 2 (n = 5) received only the carrier; and group 3 (n = 5) received no grafting materials following placement The rats were euthanized at 90 days postsurgery for microscopic analysis.
  
  
  RESULTS
  In group 1, the implant body remained submerged completely, including the coronal part, which was fully covered by a significant amount (30% of total height) of regenerated cortical bone, even though the implant could easily be pulled out by a tweezer at the time of placement. Close approximation between the implant surface and regenerated bone could also be detected, indicating good bone-to-implant contact. In contrast, only peri-implant bone regeneration occurred in group 2, and an approximate 0.3-mm coronal part of the implant remained exposed. When no grafting materials were used (group 3), almost one third of the total length of the implant was exfoliated out of the socket when no grafting materials were used.
  
  
  CONCLUSIONS
  Based on previous study and data from 16 sockets of the present study, it could be concluded that rhBMP-2 facilitated the regeneration of bone around immediate implants. In particular, the bone covering the coronal part could have been regenerated shortly after surgery, which helped to maintain the implant body inside the socket during the integration period in rats.
authors.affiliation: Department of Oral Health, National Institute of Public Health, Tokyo, Japan.
authors.forename: Khalrul
authors.initials: K
authors.lastname: Matin
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Senpuku
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Hanada
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Ozawa
authors.forename: Sadakazu
authors.initials: S
authors.lastname: Ejiri
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects*; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D004337:Drug Carriers; D006801:Humans; D019344:Lactic Acid; D008297:Male; D008852:Microradiography; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D010865:Pilot Projects; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors; D020390:Tooth Socket; D016212:Transforming Growth Factor beta
chemical_list: C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D015921:Dental Implants; D004337:Drug Carriers; D011108:Polymers; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid