Cel It was found that formation of SiF(4) could be prevented by incorporation of at least one non-bridging oxygen per silicon and sufficient aluminium to bond the fluorine present. Strong correlations were found between the fluorine content of the glass and the fluoride released from the set cements. Ion release studies demonstrated that the major mechanism of ion release was via ion exchange where a fluoride ion in the cement is exchanged for a hydroxyl ion in the aqueous medium, rather than the accepted counter ion model where an alkali cation is released in conjunction with a fluoride ion from the set cement. Strong correlations were established between the glass composition and the setting and working times of the resulting cement pastes as well as with the mechanical properties. Sodium and phosphate were shown to disrupt the crosslinking of the polyacrylate matrix. The aluminium to silicon ratio of the glass was not found to be as significant as previously thought and this is believed to result from PO(4) tetrahedra locally charge balancing AlO(4) tetrahedra, as well as glass degradation occurring via phosphorus-oxygen bond hydrolysis in addition to aluminium-oxygen bond hydrolysis. Biocompatibility studies in vivo with decalcified sections indicated the cements were osteoconductive and the osteoconductivity increased with the sodium and fluorine content of the glass. Implant studies using a rabbit model and undecalcified sections indicated that the bone formed near the implant was poorly mineralised and had the appearance of osteomalacia. This was associated with the aluminium content of the cement. Aluminium was found at sites distant from the implant particularly with implants placed in the unset state. The ability of the cements to bond to bone in push-out tests was no better than existing acrylic bone cements, largely as a result of the inhibition of mineralisation adjacent to the implanted cement.The planned research is directed at developing a new generation of glass polyalkenoate cements formed from reacting ion leachable fluoro-alumino-silicate glass with poly(acrylic acid). The new cements will be based on novel glass compositions and will be designed for use as:1. Posterior dental filling materials that can bond to dentine and enamel and have a fracture toughness comparable to the existing amalgams.2. Bone cements that stimulate bone growth and can chemically bond to bone as well as the alloys used for prosthesis.3. An insitu setting bone substitute that can bond to bone and be readily moulded to shape by the surgeon.Completion of this project should yield major social benefits for elderly edentulous patients and for the younger arthritic patient, as well as resulting in improved posterior dental fillings.The project may also result in environmental benefits for the ceramic tile industry in reducing hydrofluoric acid emmissions. Dziedzina nauki natural scienceschemical sciencesinorganic chemistryalkali metalsnatural scienceschemical sciencesinorganic chemistrypost-transition metalsengineering and technologymaterials engineeringnatural scienceschemical sciencesinorganic chemistryhalogensmedical and health sciencesmedical biotechnologyimplantsartificial bone Program(-y) FP3-BRITE/EURAM 2 - Specific programme (EEC) of research and technological development in the field of industrial and materials technologies, 1990-1994 Temat(-y) 1.4.5 - Biomaterials Zaproszenie do składania wniosków Data not available System finansowania CSC - Cost-sharing contracts Koordynator UNIVERISTY OF LIMERICK Wkład UE Brak danych Adres PLASSEY TECHNOLOGICAL PARK LIMERICK Irlandia Zobacz na mapie Koszt całkowity Brak danych Uczestnicy (2) Sortuj alfabetycznie Sortuj według wkładu UE Rozwiń wszystko Zwiń wszystko London Hospital Medical College Zjednoczone Królestwo Wkład UE Brak danych Adres Turner Street E1 2AD London Zobacz na mapie Koszt całkowity Brak danych University of Sheffield Zjednoczone Królestwo Wkład UE Brak danych Adres Western Bank S10 2TN Sheffield Zobacz na mapie Koszt całkowity Brak danych
