Systematic Assessment of Synthesized Tri-magnesium Phosphate Powders (Amorphous, Semi-crystalline and Crystalline) and Cements for Ceramic Bone Cement Applications Nicole Ostrowski 1 , 4 , Vidisha Sharma 1 , 4 , Abhijit Roy 1 , 4 , Prashant N. Kumta 1 , 2, 3, 4, * 1 Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA 2 Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA 3 Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261, USA 4 Center of Complex Engineered Multifunctional Materials, University of Pittsburgh, Pittsburgh, PA 15261, USA article info Article history: Received 21 September 2014 Received in revised form 7 December 2014 Accepted 9 December 2014 Available online 20 February 2015 Key words: Amorphous magnesium phosphate Tri-magnesium phosphate Bone cement Bone regeneration Struvite Magnesium phosphate cements have come under investigation in recent years for use as an alternative to calcium phosphate cements for bone void repair applications. Evidence indicates that magnesium phosphate cements obtain higher initial strengths after cement reaction and resorption in more clinically appropriate time frames than commercially available calcium phosphate cements. In this study, amor- phous, partially amorphous and crystalline tri-magnesium phosphate powders were synthesized via an aqueous precipitation reaction with subsequent thermal treatment, and characterized using techniques such as X-ray diffraction and Fourier transform infrared spectroscopy. These materials were assessed for their functionality in cementing reaction with a 3.0 mol/L, pH 7.0 ammonium phosphate solution, including setting time and pH evolution in phosphate buffered saline solution. Results indicated that the amorphous and semi-crystalline tri-magnesium phosphate powders were highly reactive with the setting solution but resulted in mechanically weak cements, while the crystalline tri-magnesium phosphate powder reacted efficiently with the cement solution and were mechanically strong following the cement reaction. X-ray diffraction and scanning electron microscopy analyses indicated significant changes in the phase composition and morphology of the cements following incubation in phosphate buffered saline. These were perceived to be detrimental to the integrity of the amorphous and semi-crystalline tri-magnesium phosphate derived cements but not to those created with fully crystal- line tri-magnesium phosphate. The crystalline tri-magnesium phosphate material resulted in the most functional cement as this embodiment displayed the most clinically relevant setting time as well as the highest mechanical resilience and neutral pH during incubation in saline solution rendering them potentially viable as bone void fillers. Copyright © 2015, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved. 1. Introduction Bone substitutes are widely used in patients who require im- plantation to repair or remodel bone defects. These bone sub- stitutes can range from synthetic materials such as metals and polymers to natural polymeric and biologic materials including allografts and autografts [1,2] . Calcium phosphate based synthetic grafts are an excellent choice of bone replacement systems because these implants mimic the chemistry of the mineralized portion of human bone and have shown excellent biocompatibility [3,4] . Currently, there are calcium phosphate based bone cements clini- cally available, however these products are less than ideal. Optimal bone cements should display high biocompatibility and osteo- conductivity, strengths similar to natural bone, resorption rates in line with rapid bone remodeling, and clinically appropriate mix- ability, injectability, and setting times [4e6] . Brushite (CaHPO 4 ) based calcium phosphate bone cements, although readily resorbable, tend to display prohibitively fast setting rates and compressive strengths lower than natural bone. Hydroxyapatite (Ca 5 (PO 4 ) 3 (OH)) based calcium phosphate bone cements are capable of achieving * Corresponding author. Prof., Ph.D.; Tel.: þ1 412 648 0223; Fax: þ1 412 624 3699. E-mail address: pkumta@pitt.edu (P.N. Kumta). Contents lists available at ScienceDirect Journal of Materials Science & Technology journal homepage: www.jmst.org http://dx.doi.org/10.1016/j.jmst.2014.12.002 1005-0302/Copyright © 2015, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved. Journal of Materials Science & Technology 31 (2015) 437e444