The elemental analysis in the assessment of the osteointegration level of
carbonate hydroxyapatite
Bogusława Żywicka1, Anna Ślósarczyk2, Stanisław Pielka, Leszek Solski1
Jan Kuryszko3, Zofia Paszkiewicz2
1
Department of Experimental Surgery and Biomaterials Research, Wroclaw Medical
University; ul. Poniatowskiego 2, 53-326 Wrocław, Poland
2
Faculty of Materials Science and Ceramics, AGH University of Science and
Technology, ul. Mickiewicza 30, 30-30-059 Krakow, Poland
3
Department of Histology and Embryology, Agricultural University of Wroclaw, Poland
The main non-organic component of the bone is the bone apatite, which forms its 69% mass.
The standard compound, with the content similar to that of bone apatite, is the synthetic
hydroxyapatite with the following formula: Ca10(PO4)6(OH)2. The non-organic phase of the
bone is responsible for its hardness and rigidity, and along with the organic substrates also its
resistance for cracking. The bone apatite is non-stechiometric compound with the large
number of isomorphic links, including calcium ions, and as such could be regarded as
carbonate hydroxyapatite (CHAp). The important factor of the bone mineralization is the
molar ratio of calcium and phosphorus, which in the hard, mature bone is close to 1,71. The
higher content of phosphorus is related with high elasticity of the new bone and is often met
in the new callus up to 7 weeks old. In this work we evaluated the synthetic carbonate apatite
(CHAp) of the type AB, with the contents of calcium ions CO32 attached to groups PO43- and
OH-. Non-carbonate hydroxyapatite (HAp) was used as the control implant material. The
main target of this assessment was the elemental analysis of bone tissue surrounded the
implants as well as the histological and x-ray evaluation of the samples. The assessment was
carried out on albino New Zealand rabbits. The samples were deposited into femur bones for
the periods of 3 and 6 months. The microelemental analysis of the bone samples was done by
the EDS method using the peripheral device Roentec attached to scanning microscope LoeZeiss 435. After 3 months since implantation CHAp samples were surrounded by new bone
tissue with thin layers of fibrous-connective tissue, located mainly at the implant-tissue
interface. The ratio of ions Ca (9,61%) to ions P (6,50%) at the tested samples of callus was at
the level of 1,74, what could point out for the continuous mineralization process. Those places
at x-ray examination were described as being osteosclerotic. After 6 months since
implantation, CHAp samples were surrounded by new continuous bone layer with
characteristic similar to that of hard bone, and with the high content of ions Ca (34,24%) and
ions P (15,71%) with the ratio at 2,18. The control samples of HAp, after 3 months since
implantation were surrounded by the layer of connective tissue with visible bone trabecules.
This layer was of different thickness. The ratio of ions Ca (19,08%) to ions P (9,70%) at the
tested samples was at the level of 1,96. After 6 months since implantation the samples HAp
were surrounded by the layer of connective tissue interrupted by new bone tissue formation of
diverse thickness. The ratio of ions Ca (14,40%) to ions P (8,25%) at the tested samples was
1,74. In summary we can stated that the healing of CHAp into bone defects during the first
three months since their implantation, was characterized by continuous mineralization
process, which run faster as compared to that of HAp. In histological findings and after x-ray
examination we discovered the process which is quite representative for the bone rebuilding.
After six months since implantation the mineralization process was at the same level for both
tested materials. The continuous layer of new trabeculous bone which was present around the
samples of CHAp is the proof of the higher osteointegration properties of this material.
Key words: carbonate hydroxyapatite, osteointegration, elemental analysis