title: A feasibility study evaluating an in situ formed synthetic biodegradable membrane for guided bone regeneration in dogs.
abstract: OBJECTIVE
  The aim was (1) to evaluate the soft-tissue reaction of a synthetic polyethylene glycol (PEG) hydrogel used as a barrier membrane for guided bone regeneration (GBR) compared with a collagen membrane and (2) to test whether or not the application of this in situ formed membrane will result in a similar amount of bone regeneration as the use of a collagen membrane.
  
  
  METHODS
  Tooth extraction and preparation of osseous defects were performed in the mandibles of 11 beagle dogs. After 3 months, 44 cylindrical implants were placed within healed dehiscence-type bone defects resulting in approximately 6 mm exposed implant surface. The following four treatment modalities were randomly allocated: PEG+autogenous bone chips, PEG+hydroxyapatite (HA)/tricalcium phosphate (TCP) granules, bioresorbable collagen membrane+autogenous bone chips and autogenous bone chips without a membrane. After 2 and 6 months, six and five dogs were sacrificed, respectively. A semi-quantitative evaluation of the local tolerance and a histomorphometric analysis were performed. For statistical analysis, repeated measures analysis of variance (ANOVA) and subsequent pairwise Student's t-test were applied (P<0.05).
  
  
  RESULTS
  No local adverse effects in association with the PEG compared with the collagen membrane was observed clinically and histologically at any time-point. Healing was uneventful and all implants were histologically integrated. Four out of 22 PEG membrane sites revealed a soft-tissue dehiscence after 1-2 weeks that subsequently healed uneventful. Histomorphometric measurement of the vertical bone gain showed after 2 months values between 31% and 45% and after 6 months between 31% and 38%. Bone-to-implant contact (BIC) within the former defect area was similarly high in all groups ranging from 71% to 82% after 2 months and 49% to 91% after 6 months. However, with regard to all evaluated parameters, the PEG and the collagen membranes did not show any statistically significant difference compared with sites treated with autogenous bone without a membrane.
  
  
  CONCLUSIONS
  The in situ forming synthetic membrane made of PEG was safely used in the present study, revealing no biologically significant abnormal soft-tissue reaction and demonstrated similar amounts of newly formed bone for defects treated with the PEG membrane compared with defects treated with a standard collagen membrane.
authors.affiliation: Department of Fixed and Removable Prothodontics and Dental Material Science, University of Zurich, Zurich, Switzerland. ronald.jung@zzmk.uzh.ch
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Jung
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Lecloux
authors.forename: Eric
authors.initials: E
authors.lastname: Rompen
authors.forename: Christian F
authors.initials: CF
authors.lastname: Ramel
authors.forename: Daniel
authors.initials: D
authors.lastname: Buser
authors.forename: Christoph H F
authors.initials: CH
authors.lastname: Hammerle
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use; D001861:Bone Regeneration / Q000502:physiology*; D018786:Bone Substitutes / Q000627:therapeutic use; D016025:Bone Transplantation; D002130:Calcium Phosphates / Q000627:therapeutic use; D003094:Collagen; D015921:Dental Implants; D004285:Dogs; D017886:Durapatite / Q000627:therapeutic use; D005240:Feasibility Studies; D005260:Female; D048091:Guided Tissue Regeneration / Q000379:methods*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008264:Macrophages / Q000473:pathology; D008334:Mandible / Q000473:pathology / Q000601:surgery; D008336:Mandibular Diseases / Q000473:pathology / Q000601:surgery*; D008567:Membranes, Artificial; D016348:Osseointegration / Q000502:physiology; D011897:Random Allocation; D013997:Time Factors
chemical_list: C106416:Bio-Gide; D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; D015921:Dental Implants; D008567:Membranes, Artificial; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D003094:Collagen; D017886:Durapatite; C018392:tricalcium phosphate