title: Bio-degradation of a resorbable collagen membrane (Bio-Gide) applied in a double-layer technique in rats.
abstract: OBJECTIVE
  The aim of this study was to evaluate histologically the bio-degradation of two layers of Bio-Gide((R)) (BG) membrane, as compared with that of a single layer.
  
  
  METHODS
  Two circular calvarial bony defects, 5 mm in diameter, were made in 24 Wistar rats. BG membrane, labeled with biotin, was cut into 5-mm-diameter disks, and placed in defects either as a mono-layer membrane (MLM) or as a double-layer membrane (DLM). Rats were sacrificed after 4 or 9 weeks and histology was performed. Membranes were stained with horseradish peroxidase-conjugated streptavidin and aminoethyl carbazole as a substrate for detection of biotinylated collagen. The area of collagen and thickness of the residual membranes were measured by image analysis software. Statistical analysis was performed using the non-parametric Wilcoxon's signed-ranks test.
  
  
  RESULTS
  At 4-week collagen area per measurement window within the DLM sites (0.09+/-0.05 mm(2)) was significantly greater (P<0.01) than that in the MLM sites (0.047+/-0.034 mm(2)). At 9 weeks, the collagen area was also greater in the DLM sites (0.037+/-0.026 mm(2)) compared with that of the MLM sites (0.025+/-0.016 mm(2)); however, this difference did not reach statistical significance. The rate of membrane degradation, calculated as percent membrane lost compared with baseline, was similar for the DLM and MLM at both time points ( approximately 60% at 4 weeks and approximately 80% at 9 weeks). In addition, the residual DLM thickness at 4 weeks (475.5+/-73.77 mum) was significantly (P<0.01) greater than that of MLM (262.38+/-48.01 mum). At 9 weeks, membrane thickness was also greater in the DLM sites (318.22+/-70.45 mum) compared with that of the MLM sites (183.32+/-26.72 mum); however, this difference did not reach statistical significance. The reduction in thickness between 4 and 9 weeks was 30% for MLM and 33% for DLM.
  
  
  CONCLUSIONS
  The use of a double layer of BG membrane results in a barrier of increased collagen area and thickness, compared with application of a single layer.
authors.affiliation: Department of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. kavital@post.tau.ac.il
authors.forename: Avital
authors.initials: A
authors.lastname: Kozlovsky
authors.forename: Guy
authors.initials: G
authors.lastname: Aboodi
authors.forename: Ofer
authors.initials: O
authors.lastname: Moses
authors.forename: Haim
authors.initials: H
authors.lastname: Tal
authors.forename: Zvi
authors.initials: Z
authors.lastname: Artzi
authors.forename: Miron
authors.initials: M
authors.lastname: Weinreb
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Nemcovsky
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage*; D001861:Bone Regeneration / Q000187:drug effects*; D003094:Collagen / Q000008:administration & dosage*; D003399:Craniotomy; D005500:Follow-Up Studies; D048091:Guided Tissue Regeneration / Q000379:methods*; D008297:Male; D008567:Membranes, Artificial; D051381:Rats; D017208:Rats, Wistar; D012886:Skull / Q000601:surgery*; D014945:Wound Healing / Q000187:drug effects
chemical_list: C106416:Bio-Gide; D001672:Biocompatible Materials; D008567:Membranes, Artificial; D003094:Collagen