Papers by Author: Zofia Paszkiewicz

Abstract: In the studies undoped HA and HA modified with 0.3; 0.6; 0.9; 1.8 wt % of Mg were prepared by the wet method. Introduction of magnesium into HA structure influenced its thermal stability as well as phase composition, sinterability, microstructure, flexural strength and chemical stability of the obtained calcium-phosphate ceramics. The presence of magnesium promoted the decomposition of HA to βTCP above 800°C. Beyond a certain limit (0.9 wt %), Mg ions caused formation of MgO in Mg-HA ceramics. Chemical stability of Mg modified HA below 0.9 wt % Mg under in vitro conditions was similar to that of the undoped hydroxyapatite. Biological studies showed that the number of cells cultured on the surface of HA samples with 1.8 wt % Mg additive, probably due to the MgO content, was lower than on the pure HA ceramics.

Abstract: Calcium phosphates (CaPs): hydroxyapatite (HA) and TCP are common biomaterials used in orthopedic, dental and maxillofacial surgery as bone fillers and also as drug carriers. Studies of the β→α TCP transformation and formation of mono-, bi- or three-phase CaPs materials: βTCP-αTCP-HA are of principal importance. Stability of calcium phosphate ceramics depends on many factors. Our dynamic studies by high temperature XRD measurements showed that monoclinic αTCP was a considerably stable phase after its creation completed at 1200°C. Different phase composition was obtained in technological conditions.

Abstract: The goal of our studies has been to determine under in vitro conditions the amount and rate of pentoxifylline release from the samples of modified hydroxyapatite [HAp-Ca10(PO4)6(OH)2] implants in the form of microporous blocks (heterogeneous system) as well as from hydroxyapatitegypsum pellets (homogeneous system). For the preparation of microporous hydroxapatite ceramics additives of calcium metaphosphate Ca(PO3)2 (5 and 10 wt. %) or hydrated magnesium orthophosphate Mg3(PO4)2·8H2O (10 wt. %) were used as modifiers. In the case of drug release from heterogeneous carriers, cylinders filled with 50 mg of PTX were used. In the homogeneous system the pellets made of HAp and CaSO4·1/2H2O powders with homogeneously incorporated of 50 mg PTX were applied. It has been shown that the process of drug release from multifunctional ceramic implants depends to a significant degree on the microstructure of the materials, and the type of carrier system (heterogeneous or homogeneous).