title: Treatment of circumferential defects with osseoconductive xenografts of different porosities: a histological, histometric, resonance frequency analysis, and micro-CT study in dogs.
abstract: BACKGROUND
  Finding the most effective method of minimizing the gap effect in alveolar crest remodeling constitutes a clinical challenge for immediate implant technique.
  
  
  OBJECTIVE
  To evaluate the effectiveness of osseoconductive xenografts with different porosities in the crestal bone region, with and without guided bone regeneration, over immediate implant installation.
  
  
  METHODS
  Five bone defects (6 mm in diameter/4 mm depth) were prepared on one side of the mandibles of twelve dogs. Implants of 3.3 × 10 mm were installed on the mesial side of each defect, providing a 2.7-mm distal gap. Defects were randomly filled with autogenous bone, coagulum, a deproteinized bovine bone mineral (DBBM) block, a DBBM sponge, or DBBM granules. The same procedures were performed on the opposite side after 8 weeks. Collagen membranes were used to cover the defects on half of the sides. The animals were sacrificed after 8 weeks. The outcomes were evaluated by histology, histomorphometric analysis, resonance frequency analysis, and micro-CT analysis.
  
  
  RESULTS
  The histomorphometry showed the DBBM sponge to provide similar bone formation to autogenous bone at 8 weeks without a membrane. The coagulum rendered better bone formation at 16 weeks (membrane) (p < .05). The DBBM block exhibited the poorest results between treatments (8 and 16 weeks, with or without membrane). Micro-CT analysis revealed increasing bone surface values in sites with DBBM granules, followed by the DBBM sponge (8 weeks without membrane) and autogenous bone at 8 weeks with membrane (p < .05). Porosity analysis of the biomaterials showed the highest number, volume, and surface area of closed pores in DBBM granules. The DBBM block presented the highest volume of open pores, open porosity, and total porosity.
  
  
  CONCLUSIONS
  The high-porosity block (DBBM block) failed to provide greater bone repair within the defect. Biomaterials with lower porosity (DBBM sponge and granules) showed similar or higher bone formation when compared with autogenous bone.
authors.affiliation: University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Antonio Azoubel
authors.initials: AA
authors.lastname: Antunes
authors.forename: Gustavo Augusto
authors.initials: GA
authors.lastname: Grossi-Oliveira
authors.forename: Evandro Carneiro
authors.initials: EC
authors.lastname: Martins-Neto
authors.forename: Adriana Luisa Gonçalves De
authors.initials: AL
authors.lastname: Almeida
authors.forename: Luiz Antonio
authors.initials: LA
authors.lastname: Salata
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000473:pathology / Q000517:prevention & control*; D000539:Alveolar Process / Q000601:surgery*; D000818:Animals; D016723:Bone Remodeling; D018786:Bone Substitutes / Q000494:pharmacology; D016025:Bone Transplantation / Q000379:methods*; D003094:Collagen / Q000494:pharmacology; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D004285:Dogs; D064593:Heterografts; D008334:Mandible; D008567:Membranes, Artificial; D016062:Porosity; D014945:Wound Healing; D055114:X-Ray Microtomography
chemical_list: D018786:Bone Substitutes; D015921:Dental Implants; D008567:Membranes, Artificial; D003094:Collagen
keywords: animal study; bone defects; guided bone regeneration; immediate implants; osseointegration