title: Bone regeneration using a synthetic matrix containing enamel matrix derivate.
abstract: OBJECTIVE
  The aim of the present study was to test whether the delivery of enamel matrix derivate (EMD) via synthetic polyethylene glycol (PEG)-based hydrogels with and without RGD sequences enhances bone formation in vivo.
  
  
  METHODS
  In each of 10 rabbits, four titanium cylinders were placed on the external cortical bones of their calvaria. The following four treatment modalities were randomly allocated: One of the four cylinders was left empty (control), the other three were filled with a combination of PEG matrix with hydroxyapatite/tricalciumphosphate (HA/TCP) granules and EMD in a concentration of 100 μg/ml (test 1) or 500 μg/ml (test 2) or 500 μg/ml and RGD peptide (test 3). After 8 weeks, the animals were sacrificed and ground sections were obtained for histological analysis. For statistical analysis, the Kruskal-Wallis test was applied (P<0.05).
  
  
  RESULTS
  The histomorphometric analysis revealed a statistically larger area fraction of newly formed bone in the EMD 500/RGD group (54.8±14.5%) compared with the control group (28.7±10.3%) and the EMD 500 group (31.2±14.1%) and non-significantly higher area fraction compared with the EMD 100 group (38.2±10.4%). The percentage of mineralized bone showed no statistically significant differences among the four groups. The mean percentage of mineralized bone was 13.6±3.3% in the control group, 14.2±5.8% in the EMD 100 group, 11.69±5.9% in the EMD 500 group and 15.66±5.2% in the EMD 500/RGD group. No statistically significant difference regarding the bone-to-graft contact between the EMD 100 group (23±15.7%), the EMD 500 group (22.2±14.6%) and the EMD 500/RGD group (21.6±8.8%) was observed.
  
  
  CONCLUSIONS
  The combination of a PEG matrix containing EMD with HA/TCP granules had no effect on the formation of mineralized bone tissue in rabbit calvaria. The addition of RGD peptide to the PEG/EMD 500 combination increased the area fraction of newly formed bone compared with the other treatment groups. Further studies are indicated to study a possible synergistic effect of EMD and RGD.
authors.affiliation: Center for Dental and Oral Medicine and Cranio-Maxillofacial Surgery, Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Plattenstrasse 11, Zurich, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Schneider
authors.forename: Franz E
authors.initials: FE
authors.lastname: Weber
authors.forename: Christoph H F
authors.initials: CH
authors.lastname: Hämmerle
authors.forename: Andreas
authors.initials: A
authors.lastname: Feloutzis
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Jung
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects*; D002130:Calcium Phosphates / Q000494:pharmacology; D003743:Dental Enamel / Q000737:chemistry*; D017886:Durapatite / Q000494:pharmacology; D020100:Hydrogels / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011817:Rabbits; D011897:Random Allocation; D012886:Skull / Q000601:surgery; D018709:Statistics, Nonparametric; D014025:Titanium
chemical_list: D002130:Calcium Phosphates; D020100:Hydrogels; D011092:Polyethylene Glycols; D017886:Durapatite; D014025:Titanium