Abstract
The injectability of Portland cement (PC) with several citrate additives was investigated for use in clinical applications such as vertebroplasty (stabilization of a fractured vertebra with bone cement) using a syringe. A 2-wt % addition of sodium or potassium citrate with PC significantly improved cement injectability, decreased cement setting times from over 2 h to below 25 min, while increasing the compressive strength to a maximum of 125 MPa. Zeta-potential measurements indicated that the citrate anion was binding to one or more of the positively charged species causing charged repulsion between cement particles which dispersed aggregates and caused the liquefying effect of the anion. Analysis of the hydrating phases of PC indicated that the early strength producing PC phase (ettringite) developed within the first 2 h of setting following addition of the citrate anion, while this did not occur in the control cement (PC only). Within 24 h ettringite developed in PC as well as calcium–silicate–hydrate (C–S–H), the major setting phase of PC, whereas cements containing citrate did not develop this phase. The evidence suggested that in the presence of citrate the cements limited water supply appeared to be utilized for ettringite formation, producing the early strength of the citrate cements. The present study has demonstrated that it is possible to modify PC with citrate to both improve the injectability and crucially reduce the setting times of PC while improving the strength of the cement. © 2014 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1799–1808, 2014.
Highlights
IntroductionNamely alite and belite, constitute approximately 75 wt % of the cement clinker phase of Portland cement (PC).[1]
Calcium silicates, namely alite and belite, constitute approximately 75 wt % of the cement clinker phase of Portland cement (PC).[1]
The present study has demonstrated that it is possible to modify PC with citrate to both improve the injectability and crucially reduce the setting times of PC while improving the strength of the cement
Summary
Namely alite and belite, constitute approximately 75 wt % of the cement clinker phase of Portland cement (PC).[1]. Since PC-based mineral trioxide aggregate was Food and Drug Administration approved for endodontic use in the late 1990s, there has been an increased interest in the wider use of PC as a biomaterial It has been investigated as a drug delivery system for antibiotics used to treat bone diseases such as osteomyelitis,[8] as a high strength hybrid material in combination with zinc[9] and for formation of apatite on exposure to simulated body fluid when combined with zirconium.[10] PCs are durable, possess high compressive strengths and can set in aqueous environments such as those found in vivo.[11,12,13] PC would be suited for loadbearing applications such as vertebroplasty, which involves the subcutaneous injection of a stabilizing bone cement into fractured or even collapsed vertebrae.[14] Polymethylmethacrylate (PMMA) is the bone cement routinely used for vertebroplasty, PMMA has a compressive strength of 79 MPa and a setting time of 15–20 min setting time.[15] In order to make PC a possible candidate for use as an alternative to PMMA for vertebroplasty, the cement needs to be developed to a similar strength and setting time.[16] There are hereby two key challenges which need to be addressed before PC can be considered as a suitable bone cement for applications such as vertebroplasty. The addition of micro fiber material such as polypropylene has been
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