Calcium phosphate based cements can be moulded to irregular contours often encountered in medicine. Brushite cements are more soluble than hydroxyapatite (HA) in physiological conditions and as such can be more rapidly resorbed. The metastable nature of brushite means that it converts to HA following immersion in physiological conditions. This phase change reduces the resorption rate, resulting in long term stability. In this study, macropores were incorporated into brushite cement to accelerate degradation, preventing hydrolysis and long term stability. The incorporation of beads into the cement had no effect on the composition of the cement. By varying the proportion of beads in the cement, it was possible to control degradation and prevent the formation of HA within the cement. Interestingly, in the macroporous cement, after 14 days of aging, the only crystalline component was β-tricalcium phosphate, suggesting that an amorphous binding phase was formed following brushite dissolution; this phase may maintain the integrity of the cement.
BohnerM: ‘Calcium orthophosphates in medicine:from ceramics to calcium phosphate cements’, Injury, 2000, 31, (Suppl.4), 37–47.
2.
Wagoner JohnsonAJ, HerschlerBA: ‘A review of the mechanical behaviorof CaP and CaP/polymer composites for applications in bone replacement andrepair’, Acta Biomater., 2011, 7, (1), 16–30.
BohnerM, LemaitreJ, RingTA: ‘Effects of sulfate, pyrophosphate,and citrate ions on the physicochemical properties of cements made of beta-tricalciumphosphate–phosphoric acid–water mixtures’, J.Am. Ceram. Soc., 1996, 79, (6), 1427–1434.
XiaZD, GroverLM, HuangYZ, AdamopoulosLE, GbureckU, TriffittJT, SheltonRM, BarraletJE: ‘In vitro biodegradationof three brushite calcium phosphate cements by a macrophage cell-line’, Biomaterials, 2006, 27, (26), 4557–4565.
12.
ConstantzBR, BarrBM, IsonIC, FulmerMT, BakerJ, McKinneyLA, GoodmanSB, GunasekarenS, DelaneyDC, RossJ, PoserRD: ‘Histological, chemical, and crystallographicanalysis of four calcium phosphate cements in different rabbit osseous sites’, J.Biomed. Mater. Res., 1998, 43, (4), 451–461.
13.
RosseauS, LemaitreJ, BohnerM, FreiC: ‘Long term aging of brushite cementsin physiological conditions: an in-vitro study’, Proc.GRIBOI Conf., Shanghai, China, March2002,19.
14.
GroverLM, GbureckU, WrightAJ, BarraletJE: ‘Cement formulations in the calciumphosphate H2O–H3PO4–H4P2O7system’, J. Am. Ceram. Soc., 2005, 88, (11), 3096–3103.
15.
FleischH, MaerkiJ, RussellRGG: ‘Effect of pyrophosphate on dissolutionof hydroxyapatite and its possible importance in calcium homeostasis’, Proc.Soc. Exp. Biol. Med., 1966, 122, (2), 317–320.
16.
HingKA, RevellPA, SmithN, BucklandT: ‘Effect of silicon level on rate, qualityand progression of bone healing within silicate-substituted porous hydroxyapatitescaffolds’,Biomaterials, 2006, 27, (29), 5014–5026.
17.
CamaG, BarberisF, BotterR, CirilloP, CapurroM, QuartoR, ScaglioneS, FinocchioE, MussiV, ValbusaU: ‘Preparation and properties of macroporousbrushite bone cements’, Acta Biomater., 2009, 5, (6), 2161–2168.
18.
LoseeJE, KarmacharyaJ, GannonFH, SlempAE, OngG, HunenkoO, GordenAD, BartlettSP, KirschnerRE: ‘Reconstruction of the immature craniofacialskeleton with a carbonated calcium phosphate bone cement: Interaction withbioresorbable mesh’, J. Craniofac. Surg., 2003, 14, (1), 117–124.
19.
NilssonM, FernandezE, SardaS, LidgrenL, PlanellJA: ‘Characterization of a novel calciumphosphate/sulphate bone cement’, J. Biomed. Mater.Res., 2002, 61, (4), 600–607.
CurryNA, JonesDW: ‘Crystal structure of brushite, calciumhydrogen orthophosphate dihydrate – neutron-diffraction investigation’, J.Chem. Soc. A, 1971, 23A, 3725–3729.
23.
SchroederLW, DickensB, BrownWE: ‘Crystallographic studies of role ofMg as a stabilizing impurity in β-Ca3(PO4)2.Part 2 – refinement of Mg-containing β-Ca3(PO4)2’, J.Solid State Chem., 1977, 22, (3), 253–262.
BohnerM, TheissF, ApeltD, HirsigerW, HourietR, RizzoliG, GnosE, FreiC, AuerJA, von RechenbergB: ‘Compositional changes of a dicalciumphosphate dihydrate cement after implantation in sheep’, Biomaterials, 2003, 24, (20), 3463–3474.
26.
PenelG, LeroyN, van LanduytP, FlautreB, HardouinP, LemaitreJ, LeroyG: ‘Raman microspectrometry studies ofbrushite cement: in vivo evolution in a sheep model’, Bone, 1999, 25, (2), 81S–84S.
27.
TasAC, BhaduriSB: ‘Chemical processing of CaHPO4.2H2O:its conversion to hydroxyapatite’, J. Am. Ceram.Soc., 2004, 87, (12), 2195–2200.
