title: Premixed rapid-setting calcium phosphate composites for bone repair.
abstract: Although calcium phosphate cement (CPC) is promising for bone repair, its clinical use requires on site powder-liquid mixing. To shorten surgical time and improve graft properties, it is desirable to develop premixed CPC in which the paste remains stable during storage and hardens only after placement into the defect. The objective of this study was to develop premixed CPC with rapid setting when immersed in a physiological solution. Premixed CPCs were formulated using the following approach: Premixed CPC = CPC powder + nonaqueous liquid + gelling agent + hardening accelerator. Three premixed CPCs were developed: CPC-monocalcium phosphate monohydrate (MCPM), CPC-chitosan, and CPC-tartaric. Setting time for these new premixed CPCs ranged from 5.3 to 7.9 min, significantly faster than 61.7 min for a premixed control CPC reported previously (p < 0.05). SEM revealed the formation of nano-sized needle-like hydroxyapatite crystals after 1 d immersion and crystal growth after 7 d. Diametral tensile strength for premixed CPCs at 7 d ranged from 2.8 to 6.4 MPa, comparable to reported strengths for cancellous bone and sintered porous hydroxyapatite implants. Osteoblast cells attained a normal polygonal morphology on CPC-MCPM and CPC-chitosan with cytoplasmic extensions adhering to the nano-hydroxyapatite crystals. In summary, fast-setting premixed CPCs were developed to avoid the powder-liquid mixing in surgery. The pastes hardened rapidly once immersed in physiological solution and formed hydroxyapatite. The cements had strengths matching those of cancellous bone and sintered porous hydroxyapatite and non-cytotoxicity similar to conventional non-premixed CPC.
authors.affiliation: American Dental Association Foundation, Paffenbarger Research Center, National Institute of Standards and Technology, 100 Bureau Drive Stop 8546, Gaithersburg, MD 20899-8546, USA.
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Carey
authors.forename: Hockin H K
authors.initials: HH
authors.lastname: Xu
authors.forename: Carl G
authors.initials: CG
authors.lastname: Simon
authors.forename: Shozo
authors.initials: S
authors.lastname: Takagi
authors.forename: Laurence C
authors.initials: LC
authors.lastname: Chow
mesh_terms: D016475:3T3 Cells; D000268:Adhesiveness; D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects* / Q000032:analysis / Q000737:chemistry* / Q000627:therapeutic use; D001843:Bone Cements / Q000009:adverse effects / Q000032:analysis / Q000737:chemistry* / Q000627:therapeutic use; D002130:Calcium Phosphates / Q000009:adverse effects* / Q000032:analysis / Q000737:chemistry* / Q000627:therapeutic use; D002470:Cell Survival / Q000187:drug effects*; D002484:Cementation / Q000379:methods; D004548:Elasticity; D050723:Fractures, Bone / Q000188:drug therapy; D006244:Hardness; D006801:Humans; D008420:Manufactured Materials / Q000032:analysis; D008422:Materials Testing; D051379:Mice; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D002130:Calcium Phosphates; C020243:calcium phosphate