title: Biodegradation, soft and hard tissue integration of various polyethylene glycol hydrogels: a histomorphometric study in rabbits.
abstract: OBJECTIVE
  (i) To evaluate biodegradation, hard and soft tissue integration using various polyethylene glycol (PEG) hydrogels; (ii) to evaluate the influence of arginine-glycine-aspartic acid (RGD) on two types of PEG hydrogels.
  
  
  METHODS
  In seven rabbits, six treatment modalities were randomly applied subperiosteally on the skull: (1) a dense network PEG hydrogel (PEG1), (2) PEG1 modified with RGD (PEG1-RGD), (3) a looser network PEG hydrogel (PEG2), (4) PEG2 modified with RGD (PEG2-RGD), (5) a collagen membrane, and (6) a polylactide/polyglycolide/trimethylene carbonate membrane. The animals were sacrificed at 14 days. Histomorphometric analyses were performed on undecalcified Epon sections using a standardized region of interest. For statistical analysis, paired t-test and signed rank test were applied.
  
  
  RESULTS
  PEG1 and PEG1-RGD remained intact and maintained the shape. PEG2 and PEG2-RGD completely degraded and were replaced by connective tissue and bone. The largest amount of mineralized tissue was found for PEG2-RGD (21.4%), followed by PEG 2 (9.5%). The highest percentage of residual hydrogel/membrane was observed for PEG1-RGD (55.6%), followed by PEG1 (26.7%).
  
  
  CONCLUSIONS
  Modifications of the physico-chemical properties of PEG hydrogels and the addition of RGD influenced soft and hard tissue integration and biodegradation. PEG1 showed an increased degradation time and maintained the shape. The soft tissue integration was enhanced by adding an RGD sequence. A high turn-over rate and extensive bone regeneration was observed using PEG2. The addition of RGD further improved bone formation and soft tissue integration.
authors.affiliation: Clinic for Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, Zurich, Switzerland. daniel.thoma@zzmk.uzh.ch
authors.forename: D S
authors.initials: DS
authors.lastname: Thoma
authors.forename: K
authors.initials: K
authors.lastname: Subramani
authors.forename: F E
authors.initials: FE
authors.lastname: Weber
authors.forename: H U
authors.initials: HU
authors.lastname: Luder
authors.forename: C H F
authors.initials: CH
authors.lastname: Hämmerle
authors.forename: R E
authors.initials: RE
authors.lastname: Jung
mesh_terms: D020341:Absorbable Implants; D000595:Amino Acid Sequence; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001847:Bone Diseases / Q000473:pathology / Q000601:surgery; D001857:Bone Matrix / Q000473:pathology; D001861:Bone Regeneration / Q000502:physiology; D002113:Calcification, Physiologic / Q000502:physiology; D055598:Chemical Phenomena; D003094:Collagen / Q000737:chemistry; D003238:Connective Tissue / Q000473:pathology; D004146:Dioxanes / Q000737:chemistry; D005347:Fibroblasts / Q000473:pathology; D005624:Frontal Bone / Q000473:pathology / Q000601:surgery; D020100:Hydrogels / Q000737:chemistry*; D019344:Lactic Acid / Q000737:chemistry; D008567:Membranes, Artificial; D009842:Oligopeptides / Q000737:chemistry; D010012:Osteogenesis / Q000502:physiology; D010294:Parietal Bone / Q000473:pathology / Q000601:surgery; D011092:Polyethylene Glycols / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011817:Rabbits; D011897:Random Allocation; D050151:Subcutaneous Fat / Q000473:pathology; D013499:Surface Properties; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D004146:Dioxanes; D020100:Hydrogels; D008567:Membranes, Artificial; D009842:Oligopeptides; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D011092:Polyethylene Glycols; C443643:trimethylene carbonate; C047981:arginyl-glycyl-aspartic acid; D003094:Collagen