title: Tailor-made tricalcium phosphate bone implant directly fabricated by a three-dimensional ink-jet printer.
abstract: Rapid prototyping (RP) is a molding technique that builds a three-dimensional (3D) model from computer-aided design (CAD) data. We fabricated new tailor-made bone implants (TIs) from alpha-tricalcium phosphate powder using an RP ink-jet printer based on computed tomography (CT) data, and evaluated their safety and efficacy. CT data of the skulls of seven beagle dogs were obtained and converted to CAD data, and bone defects were virtually made in the skull bilaterally. TIs were designed to fit the defects and were fabricated using the 3D ink-jet printer with six horizontal cylindrical holes running through the implants, designed for possible facilitation of vascular invasion and bone regeneration. As a control, hydroxyapatite implants (HIs) were cut manually from porous hydroxyapatite blocks. Then, craniectomy was performed to create real skull defects, and TIs and HIs were implanted. After implantation, CT was performed regularly, and the animals were euthanized at 24 weeks. No major side effects were observed. CT analysis showed narrowing of the cylindrical holes; bony bridging between the implants and the temporal bone was observed only for TIs. Histological analysis revealed substantial new bone formation inside the cylindrical holes in the TIs, while mainly connective tissues invaded the porous structures in HIs. Bone marrow was observed only in TIs. Osteoclasts were seen to resorb regenerated bone from inside the cylindrical holes and to invade and probably resorb the TIs. These data suggest that TIs are a safe and effective bone substitute, possessing osteoconductivity comparable with that of HIs.
authors.affiliation: Division of Tissue Engineering, University of Tokyo Hospital, 7-3-1 Hongo, Tokyo 113-8655, Japan.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Igawa
authors.forename: Manabu
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Osamu
authors.initials: O
authors.lastname: Sugimori
authors.forename: Koutaro
authors.initials: K
authors.lastname: Shimizu
authors.forename: Kenji
authors.initials: K
authors.lastname: Yamazawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takato
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Nishimura
authors.forename: Shigeki
authors.initials: S
authors.lastname: Suzuki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Anzai
authors.forename: Ung-il
authors.initials: UI
authors.lastname: Chung
authors.forename: Nobuo
authors.initials: N
authors.lastname: Sasaki
mesh_terms: D000818:Animals; D018786:Bone Substitutes; D002130:Calcium Phosphates; D002516:Ceramics; D017076:Computer-Aided Design; D004285:Dogs; D017886:Durapatite; D008953:Models, Anatomic; D010316:Particle Size; D013718:Tensile Strength; D023822:Tissue Engineering / Q000379:methods*; D014057:Tomography, X-Ray Computed
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D017886:Durapatite; C018392:tricalcium phosphate