title: Biodegradation and tissue integration of various polyethylene glycol matrices: a comparative study in rabbits.
abstract: OBJECTIVE
  To test whether or not chemical and/or physical modifications of polyethylene glycol (PEG) hydrogels influence degradation time, matrix/membrane stability, and integration into surrounding hard and soft tissues.
  
  
  METHODS
  In 28 rabbits, six treatment modalities were randomly applied to six sites on the rabbit skull: a dense network PEG hydrogel (PEG HD), a medium-dense network PEG hydrogel (PEG MD), a medium-dense network PEG hydrogel modified with an RGD sequence (PEG MD/RGD), a medium-dense network PEG hydrogel modified with RGD with reduced carboxymethyl cellulose (PEG MD/RGD_LV), a loose network PEG hydrogel modified with RGD (PEG LD/RGD), and a collagen membrane (BG). Descriptive histology and histomorphometry were performed at 1, 2, 4, and 6 weeks.
  
  
  RESULTS
  PEG HD revealed the highest percentage of residual matrix at all time points starting with 47.2% (95% CI: 32.8-63.8%) at 1 week and ending with 23.4% (95% CI: 10.3-49.8%) at 6 weeks. The hydrogel with the loosest network (PEG LD/RGD) was stable the first 2 weeks and then degraded continuously with a final area of 8.3% (95% CI: 3.2-21.2%). PEG HD was the most stable and densely stained membrane, whereas PEG MD and PEG LD matrices integrated faster, but started to degrade to a higher degree between 2 and 4 weeks. PEG MD degradation was dependent on the addition of RGD and the amount of CMC.
  
  
  CONCLUSIONS
  Chemical and/or physical modifications of PEG hydrogels influenced matrix stability. PEG MD/RGD demonstrated an optimal balance between degradation time and integration into the surrounding soft and hard tissues.
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors.forename: Daniel S
authors.identifier: http://orcid.org/0000-0002-1764-7447
authors.initials: DS
authors.lastname: Thoma
authors.affiliation: Center of Dental Medicine, Oral Biotechnology & Bioengineering, University of Zurich, Zurich, Switzerland.
authors.forename: Franz E
authors.initials: FE
authors.lastname: Weber
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors.forename: Stefan P
authors.initials: SP
authors.lastname: Bienz
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Ge
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors.forename: Christoph H F
authors.initials: CHF
authors.lastname: Hämmerle
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Jung
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000378:metabolism*; D001861:Bone Regeneration; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000378:metabolism; D011092:Polyethylene Glycols / Q000378:metabolism*; D011817:Rabbits; D012886:Skull / Q000473:pathology / Q000601:surgery
chemical_list: D001672:Biocompatible Materials; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols
keywords: animal experiments (all MeSH terms); bone; bone regeneration; bone substitute; guided tissue regeneration; polyethylene glycols