Fabrication of chelate-setting hydroxyapatite cements from four kinds of commercially-available powder with various shape and crystallinity and their mechanical property

Abstract

Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ; HAp) is one of inorganic components of bone and teeth, and has an osteoconductivity and execellent biocompatibility. Thus, the HAp has been used as biomaterials for bone graftings. Clinically-used HAp cements are set on the basis of the acid-base reaction of Ca 4 O(PO 4 ) 2 and CaHPO 4 . This mechanism accompany the changes of pH during hardening, leading to inflammation around tissues, together with slow setting time. We have succeeded to develop novel HAp cement, which is created by mixing the HAp powder modified with inositol phosphate (IP6) and water. The present IP6-HAp cement is set based on the chelate-bonding of IP6 without the acid-base reaction. The IP6 is not only biocompatible but also has able to chelate to some metal ions as strongly as EDTA. In the present study, we fabricated four kinds of IP6-HAp cements using commercially-available HAp powders with diferent morphology and specific surface area (SSA): HAp-100 (fine particle), HAp-200 (hexagonal shape), HAp-400 (plate shape), and s-HAp (spherical shape). Among the cement specimens examined, the IP6/HAp-100 cement derived from HAp-100 powder had maximum compressive strength of 10 MPa under following condition: Powder/Liquid (P/L) ratio＝1/0.45[w/w]. The HAp-100 powder was composed of microcrystals with the highest SSA of 62.4 m 2 ･g -1 among the HAp powder used in the present work. On the other hand, the compressive strength of the IP6/HAp-200 cements showed the lowest value of 2 MPa under following condition: P/L ratio＝1/0.35[w/w]. The HAp-200 powder of a starting material was composed of hexagonal-shaped crystals, and had the lowest SSA of 7.0 m 2 ･g -1 . These results indicate that the compressive strength of novel IP6/HAp cements was affected by powder properties, especially, the morphology and SSA of starting HAp powders.

EFFECT OF THE ADDITION OF VARIOUS POLYSACCHARIDES ON THE MATERIAL PROPERTIES AND CYTOTOXICITY OF CHELATE-SETTING ^|^beta;-TRICALCIUM PHOSPHATE CEMENT

“…In general, calcium-phosphate cement (CPC) consists of two kinds of calcium-phosphate powders: acidic dicalcium phosphate dihydrate (CaHPO 4 •2H 2 O) and basic tetracalcium phosphate (Ca 4 O(PO 4 ) 2 ) 1 . These powders are mixed with suitable solvents, such as aqueous sodium hydrogen phosphate, to prepare cement paste.…”

“…One of the present authors and his coworkers have developed a novel CPC using inositol hexaphosphate (C 6 H 6 (OPO 3 H 2 ) 6 ; IP6) as a chelating agent 3,4 . IP6 is found in wheat, rice, corn, and soybean 5 and has a strong chelating capability to calcium ion, for example, ethylenediaminetetraacetic acid (EDTA).…”

“…We have also developed a novel biodegradable cement consisting of a β-TCP single phase based on our previous finding on the fabrication of HAp cement due to chelate-setting mechanism using IP6 3,4,6 . The β-TCP cement could be simply fabricated by mixing starting β-TCP powder surface-modified with IP6 and pure water 6 .…”

Fabrication of chelate-setting cement from hydroxyapatite powder prepared by simultaneously grinding and surface-modifying with sodium inositol hexaphosphate and their material properties

“…11) One of the present authors and his coworkers have developed a novel CPC using inositol hexaphosphate (C 6 H 6 (OPO 3 H 2 ) 6 ; IP6) as a chelating agent. 13), 14) IP6 is contained in grains of wheat, rice, corn, and soybean 15) and has a strong chelating capability to Ca 2+ ions, similar to ethylenediaminetetraacetic acid (EDTA). This newly-developed cement was fabricated by mixing HAp powders that were surface-modified with IP6 and suitable mixing solutions, and setting could be achieved by chelate-bonding of IP6 without acid-base reaction.…”

Evaluation of Powder Property of Calucium Phosphate

“…These calcium phosphate compounds are classified in this paper as that the materials of HAP are 'HAP series', those of -TCP, -TCP and TTCP are 'other calcium phosphate series'. HAP, -TCP, -TCP and TTCP made by our technology were utilized as reagents and raw materials for commercial products [4][5][6][7][8] .…”