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Properties of Injectable Apatite-Forming Premixed Cements



Yasushi Shimada, Laurence Chow, Shozo Takagi, Junji Tagami


A previously reported, premixed calcium phosphate cements (CPC) forms hydroxyapatite (HA) as the only product, but had a setting time greater than 60 min. This study investigated properties of fast-hardening HA-forming premixed CPCs. All cements consisted of two premixed pastes: (1) dicalcium phosphate anhydrous (DCPA) mixed with 1.5mol/L or 3.0mol/L NaH2PO4, and (2) tetracalcium phosphate in median particle sizes of 5μm (TTCP5) and17μm (TTCP17) mixed with glycerin. Mass fraction of TTCP5/(TTCP5+TTCP17) was used to control the cement hardening time. Equal volume of Pastes 1 and 2 were injected with the use of a two-barrel syringe fitted with a static mixer into sample molds. The molar Ca/P ratio of combined paste was approximately 1.5. Cements were characterized in terms of setting time (Gilmore needle), diametral tensile strength (DTS), and phase composition (powder X-ray diffraction, XRD). Setting time (in min; mean±sd; n=3) ranged from 68±3 for [NaH2PO4]=1.5mol/L and TTCP5 fraction=0 to 4.3±0.6 for [NaH2PO4]=3mol/L and TTCP5 fraction=1.0. Both the NaH2PO4 concentration and TTCP5 fraction and their interaction had significant (p<0.01) effects on setting time. DTS values (in MPa; n=5) ranged from 2.3±0.4 to 0.9±0.2. Both the NaH2PO4 concentration and TTCP5 fraction had significant (p<0.01) effects on DTS. XRD analysis showed that low crystallinity HA and unreacted DCPA were present in the 1-day specimens, and the extent of HA formation was increased with increasing TTCP5 fraction. Conclusion: Injectable HA-forming premixed CPCs with setting times from 4 to 70 min can be prepared by using DCPA and TTCP as the major ingredients. Compared to conventional powder/liquid cements, these premixed CPCs have the advantages of being easy to use, having good shelf-life, and controllable hardening times.
Journal of Research (NIST JRES) -


Dual-paste premixed calcium phosphate cement, dicalcium phosphate anhydrous, tetracalcium phosphate, crystallinity, hydroxyapatite formation, bone graft


Shimada, Y. , Chow, L. , Takagi, S. and Tagami, J. (2010), Properties of Injectable Apatite-Forming Premixed Cements, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed March 4, 2024)
Created April 9, 2010, Updated October 12, 2021