title: Bilayer hydroxyapatite scaffolds for maxillofacial bone tissue engineering.
abstract: OBJECTIVE
  The frequency of alveolar ridge resorption and crestal bone loss emphasizes the clinical need for bone graft substitutes to improve local bone quality prior to dental implant placement. Microcomputed tomography has been extensively employed to estimate bone quality more objectively (ie, quantitatively) by relating it to architectural parameters. In the present study, the mechanical properties of open cellular fully interconnected bilayer hydroxyapatite scaffolds, which mimicked the cortical shell/trabecular core architecture of human bone, were investigated for suitability as bone graft substitutes for maxillofacial reconstruction.
  
  
  METHODS
  Hydroxyapatite scaffolds with different architectures were fabricated using polymeric template pore sizes of 450 or 340 μm for the inner trabecular cores and 200 or 250 μm for the outer cortical shells in three different core-to-shell volume ratios. The architectural and mechanical properties and fluid permeability of the scaffolds were compared to reported values for maxillofacial bone.
  
  
  RESULTS
  Whereas the elastic moduli of the scaffolds were comparable, their compressive strength was observed to be in the lower range of human mandibular trabecular bone. The microcomputed tomography architectural indices for the scaffolds were comparable to those of human trabecular bone at different locations in the human body, including the maxilla and mandible. Scaffold compressive strength, elastic modulus, and fluid conductance were 0.3 to 2.3 MPa, 40.9 to 668.1 MPa, and 8.8 to 49.9 x 10-10 m3s-1Pa-1, respectively.
  
  
  CONCLUSIONS
  Open-pore bilayer scaffolds can be fabricated to exhibit sufficient mechanical integrity for maxillofacial bone graft applications to match specific bone site architecture while providing sufficient permeability to sustain bone regeneration.
authors.affiliation: Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA. teja.guda@gmail.com
authors.forename: Teja
authors.initials: T
authors.lastname: Guda
authors.forename: Sunho
authors.initials: S
authors.lastname: Oh
authors.forename: Mark R
authors.initials: MR
authors.lastname: Appleford
authors.forename: Joo L
authors.initials: JL
authors.lastname: Ong
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D018786:Bone Substitutes / Q000737:chemistry; D019245:Compressive Strength; D017886:Durapatite / Q000737:chemistry*; D055119:Elastic Modulus; D006244:Hardness; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology; D008437:Maxilla / Q000033:anatomy & histology; D055595:Mechanical Phenomena; D019647:Oral Surgical Procedures; D010539:Permeability; D016062:Porosity; D011474:Prosthesis Design; D012212:Rheology; D013499:Surface Properties; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*; D055114:X-Ray Microtomography
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D017886:Durapatite