Novel Zinc Containing Phosphate Glasses for Glass–Ionomer Cements for Bone Cement Applications
Abstract
Glass‐ionomer cements (GICs) are acid base reaction cements used in dentistry
for restorative applications. In conventional GICs aluminosilicate glass is used to react
with a polyalkenoic acid such as poly acrylic acid. Glass–ionomer cements have the
potential to be used for bone cement applications, however there is a concern over
the neurotoxicity of aluminium in the glass component of these cements. In this work
zinc containing phosphate glass based glass–ionomer cement has been developed for
the bone cement application. In this relation structure of zinc containing phosphate
glasses in the system Na2O:CaO:ZnO:P2O5 ranging from metaphosphate compositions
to invert phosphate compositions has been examined. Various advanced techniques in
solid state nuclear magnetic resonance (NMR) such as dipolar recoupling and solid
state NMR of low quadrupolar nuclei (67Zn and 43Ca) and neutron diffraction have
been employed. Special emphasis has been focused on structural role of zinc in glasses
of different composition and the effect of different cations on coordination of zinc
along with the effect on phosphate tetrahedra. 67Zn and 43Ca solid state NMR spectra
of selected glass samples have been successfully acquired at ultrahigh field 900 MHz
using Solid Echo pulse sequence. In addition solid state NMR spectra of two
polymorphs of crystalline Zn(PO3)2 have also been acquired at 850 MHz using DFS–
WURST–QCPMG pulse sequence in order to distinguish between the magnitude and
orientation of electric field gradient (EFG) of zinc in octahedral and tetrahedral
coordination.
Structure determined through various techniques has been related to the
dissolution behaviour of glass compositions from metaphosphate to invert phosphate.
A decrease in pH of surrounding medium has been observed due to the presence of
zinc. Insertion of ZnO4 tetrahedra between PO4 tetrahedra has been observed in invert
phosphate glasses with high zinc oxide content which renders them suitable for glass–
ionomer cements. Glass–ionomer cement from glass composition
10Na2O:50ZnO:10CaO:30P2O5 and hydroxyapatite and, acrylic acid and vinyl
phosphonic acid co‐polymer has been produced successfully.
Authors
Kanwal, NasimaCollections
- Theses [4490]