Queen Mary & Westfield College

Abonetics Limited

Serena Michelle Best

William Bonfield

Iain Ronald Gibson

Lakhan Jee Jha

Jake E Barralet

Jose Domingos Da Silva Santos

The present invention provides a synthetic silicon-substituted apatite or hydroxyapatite which comprises 0.1% to 5% by weight of silicon. The silicon-substituted apatite or hydroxyapatite may be used as a synthetic bone material for use in bone substitution, implants, fillers and cements, coatings for metallic implants, and for making hydroxyapatite-polymer composites. The silicon-substituted apatite is prepared by reacting a calcium salt or calcium hydroxide with orthophosphoric acid or a salt of orthophosphoric acid in the presence of a silicon-containing compound, the molar ratio of calcium ions to phosphorous-containing ions being from 1:0.5 to 1:0.7 and the molar ratio of calcium ions to silicon-containing ions being at least 1:0.2, whereby a precipitate of a silicon-substituted apatite is formed. On heating and/or sintering the silicon-substituted apatite at a temperature of from 500&deg; C. to 1400&deg; C. part or substantially all of the silicon-substituted apatite transforms to silicon-substituted hydroxyapatite.

Silicon-substituted apatites and process for the preparation thereof

A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a green carbonated hydroxyapatite composition containing up to 20% by weight of CO.sub.3.sup.2- ions and having a green density of from 25 to 60% of the theoretical density at a temperature in the range of from 750.degree. to 1450.degree. C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, the sintering temperature being selected within the above range and the green composition being sintered for a period of time sufficient to cause the green composition to densify to at least 95% of the theoretical density.

Method for the preparation of carbonated hydroxyapatite compositions

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Ridgmont, United Kingdom

Serena Michelle Best