Characterization of calcium phosphate coatings doped with Mg, deposited by pulsed laser deposition technique using ArF excimer laser.

Calcium phosphate layers were deposited on Ti6Al4V substrates with TiN buffer layers by use of pulsed laser deposition method. With this technique three pressed pellets consisted of tricalcium phosphate (TCP, Ca(3)(PO(4))(2)), hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) and hydroxyapatite-doped with magnesium (HA with 4% of Mg and trace amount of (Ca,Mg)(3)(PO(4))(2)) were ablated using ArF excimer laser (lambda=193 nm). The using of different targets enabled to determine the influence of target composition on the nature of deposited layers. The obtained deposits were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction method (XRD). The obtained Fourier spectras revealed differences in terms of intensity of spectral bands of different layers. The analysis from XRD showed that Mg-doped HA layer has crystalline structure and TCP and HA layers composition is characterized by amorphous nature.

The kinetics of pentoxifylline release from drug-loaded hydroxyapatite implants.

Hydroxyapatite (HAP) was synthesized by the aqueous precipitation method from CaO and H3 PO4 as the reagents. The HAP powders, either subjected or not subjected to preliminary calcination, were mixed with a pore-creating medium and isostatically shaped at a pressure of 350 MPa to form cylindrical samples. A natural product such as flour served as a pore-creating medium. Sintering was performed in the air, at 1200 or 1250 degrees C. The employed procedure allowed for achieving microporous materials of pore sizes ranging from 0.1 to 15 microm and with open porosity values of 23-44%. It was demonstrated that the porosity of the obtained materials depended mainly on the amount of the added pore-creating medium and the temperature of sintering. The implants, shaped as hollow cylinders, were filled with 50 mg of pentoxifylline (PTX) as a model drug. Internal wells for drug placement were drilled in the samples using a high precision drill. The drug release study was performed in pH = 7.35 phosphate buffer, at 37 degrees C. The results showed that the amount and time of PTX release, as well as the lag time were mainly controlled by the open porosity of the carriers.

Kinetics of NMR cross-polarization from protons to phosphorus-31 in natural brushite.

Cross-polarization in natural brushite proceeds according to an isolated spin-pair kinetics.

Hardness and fracture toughness of dense calcium-phosphate-based materials.

Hardness, H, and fracture toughness, KIc, have been determined as well as fracture energy and embrittlement index, H/KIc for six calcium-phosphate ceramics differing in phase composition. These materials were produced from initial calcium-phosphate precipitates with Ca-P molar ratios ranging between 1.50 and 1.73, synthesized by wet methods. After uniaxial or isostatic moulding and thermal treatment at 1250 degrees C, the obtained dense sinters constituted mono-, bi- or triphase ceramic materials containing hydroxyapatite (HAp), beta-TCP, alpha-TCP and CaO. When comparing the investigated materials, the best parameters, i.e. relatively high hardness accompanied by high KIc, were observed in the case of a HAp-TCP composite, containing approximately 15 wt% HAp. It has been stated that free CaO occurring on the surface of the HAp samples obtained from powders with Ca-P ratios exceeding 1.67, transforms partially to CaCO3 due to contact with the surrounding atmosphere. The well shaped calcite crystals existing on the surfaces of such sinters significantly reduce hardness and increase fracture energy of the material when comparing both with the monophase HAp and the biphase HAp-TCP ceramics.

Long-term results of hydroxyapatite application in the treatment of periodontal osseous defects.

The aim of the present study was to evaluate in long-term clinical trials the effectiveness of hydroxyapatite (HA) bioceramics employed in dentistry in the treatment of periodontal osseous defects. The technology of obtaining the studied HA was developed at the Faculty of Material Science and Ceramics, University of Mining and Metallurgy, Cracow, Poland. A population of 90 patients was subjected to implantation of HA granules. The results of initial and final investigations based on periodontal indices, determination of osseous defects depth and X-ray studies were compared. The follow-up was 6 and 12 months, 2, 3 and as much as 4 years. All the studied parameters showed a significant improvement that was confirmed by statistical evaluation. Ceramic HA was found to be a fully and totally useful material in the reconstruction of periodontal defects. As demonstrated by X-ray studies, the reconstruction of osseous defects proceeded faster within the first 2 years and subsequently the process became slower.