title: Guided bone augmentation around a titanium bone-anchored hearing aid implant in canine calvarium: an initial comparison of two barrier membranes.
abstract: BACKGROUND
  The placement of a bone-anchored hearing aid (BAHA) implant in young children may be hampered by the presence of thin, poor-quality calvarial bone. The use of extraskeletal guided skull bone augmentation around the titanium implant is one potential solution.
  
  
  OBJECTIVE
  To compare the effectiveness of a collagen membrane BioSISt (Cook Biotech Inc., Lafayette, IN, USA) and a PGA/PLA barrier membrane, Osseoquest (W.L. Gore & Associates, Flagstaff, AZ, USA) in promoting extraskeletal bone formation, when combined with cancellous bone graft, around a titanium implant in the canine calvarium. The quality and quantity of bone tissue was compared.
  
  
  METHODS
  A 4-mm titanium BAHA implant was placed in the cranial parietal bone of 11 dogs. The implant protruded from the bone surface by a measured distance. Two groups, each of three dogs, received an implant, cancellous bone graft, and either a BioSISt or Osseoquest membrane. Three dogs received implant and bone graft (positive controls), and two received an implant only (negative controls). Samples were retrieved at 3, 6, and 9 months after placement. Undecalcified histologic and histomorphometric assessments were made of the augmented bone thickness, and bone gain factors were calculated for each sample group.
  
  
  RESULTS
  The process of osseointegration of the implants was ongoing and increased over time. Bone generation occurred with both test membranes and the early trabecular bone that formed, matured, and remodelled to compact bone at 9 months. BioSISt membrane samples showed superior quality and quantity of augmented bone compared with Osseoquest samples that exhibited thinner bone with persistent inflammation. Quantitatively, the BioSISt samples showed statistically greater new bone contact and bone area than both the positive and negative controls, whereas Osseoquest samples did not. The bone gain factor was statistically greater for BioSiSt samples when compared to the positive and negative controls whereas the Osseoquest samples were not.
  
  
  CONCLUSIONS
  In this study, the collagen BioSISt membrane promoted bone formation of superior quality and quantity compared with the polyglycolic/polylactic acid-based Osseoquest membrane and positive and negative controls over 9 months. Further investigation of the use of the collagen BioSISt membrane for cranial bone augmentation is warranted.
authors.affiliation: Companion Animal Science, School of Veterinary Science, The University of Queensland, Brisbane, Australia. s.sommerlad@uq.edu.au
authors.forename: Susan
authors.initials: S
authors.lastname: Sommerlad
authors.forename: Deborah
authors.initials: D
authors.lastname: Mackenzie
authors.forename: Carina
authors.initials: C
authors.lastname: Johansson
authors.forename: Rick
authors.initials: R
authors.lastname: Atwell
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D015519:Bone Density / Q000502:physiology; D001861:Bone Regeneration / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology; D016025:Bone Transplantation; D003094:Collagen; D004146:Dioxanes; D004285:Dogs; D048091:Guided Tissue Regeneration; D006310:Hearing Aids; D020007:Implants, Experimental; D019344:Lactic Acid; D008567:Membranes, Artificial; D016348:Osseointegration / Q000502:physiology; D010294:Parietal Bone / Q000473:pathology / Q000601:surgery*; D011091:Polyesters; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D011897:Random Allocation; D013997:Time Factors; D014025:Titanium
chemical_list: D001672:Biocompatible Materials; D004146:Dioxanes; D008567:Membranes, Artificial; D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C443643:trimethylene carbonate; C033616:poly(lactide); D003094:Collagen; D014025:Titanium