Novel magnesium phosphate cements with high early strength and antibacterial properties

• Published in: Acta biomaterialia Vol. 7; no. 4; pp. 1853 - 1861
• Main Authors: Mestres, Gemma, Ginebra, Maria-Pau
• Format: Journal Article Publication
• Language: English
• Published: England Elsevier Ltd 01-04-2011
• Subjects: ammonia; ammonium compounds; Anti-Bacterial Agents - pharmacology; Antibacterial properties; Assaigs de materials; biocompatible materials; Biomedical Laboratory Science; Biomedicinsk laboratorievetenskap; Bone cement; Bone Cements - chemistry; calcium phosphates; cement; civil engineering; Colony Count, Microbial; Compressive Strength - drug effects; Dental cement; Enginyeria dels materials; heat production; Humans; magnesium; Magnesium Compounds - chemistry; Magnesium Compounds - pharmacology; magnesium oxide; Magnesium phosphate cement; Materials science; Materials Testing; Metal·lúrgia; Microbial Sensitivity Tests; Microscopy, Electron, Scanning; mixing; Particle Size; Phosphates - chemistry; Phosphates - pharmacology; sodium borate; sodium phosphate; Streptococcus - drug effects; Streptococcus sanguinis; Struvite; Surface Properties - drug effects; Temperature; Time Factors; X-Ray Diffraction; Àrees temàtiques de la UPC; Dental cement; Bone cement; Antibacterial properties; Struvite; Magnesium phosphate cement
• ISSN: 1742-7061; 1878-7568; 1878-7568
• DOI: 10.1016/j.actbio.2010.12.008

Magnesium phosphate cements (MPCs) have been extensively used as fast setting repair cements in civil engineering. They have properties that are also relevant to biomedical applications, such as fast setting, early strength acquisition and adhesive properties. However, there are some aspects that should be improved before they can be used in the human body, namely their highly exothermic setting reaction and the release of potentially harmful ammonia or ammonium ions. In this paper a new family of MPCs was explored as candidate biomaterials for hard tissue applications. The cements were prepared by mixing magnesium oxide (MgO) with either sodium dihydrogen phosphate (NaH2PO4) or ammonium dihydrogen phosphate (NH4H2PO4), or an equimolar mixture of both. The exothermia and setting kinetics of the new cement formulations were tailored to comply with clinical requirements by adjusting the granularity of the phosphate salt and by using sodium borate as a retardant. The ammonium-containing MPC resulted in struvite (MgNH4PO4·6H2O) as the major reaction product, whereas the MPC prepared with sodium dihydrogen phosphate resulted in an amorphous product. Unreacted magnesium oxide was found in all the formulations. The MPCs studied showed early compressive strengths substantially higher than that of apatitic calcium phosphate cements. The Na-containing MPCs were shown to have antibacterial activity against Streptococcus sanguinis, which was attributed to the alkaline pH developed during the setting reaction.