About half of the restorations made on teeth today are restorations of old
fillings, which explain the need for a better dental material. Recently
Calcium aluminates as dental materials, CACs, entered the market and have
shown good potentials. However their main disadvantage is slow development
of mechanical properties. By combining CACs with Glass ionomer cements,
GICs, that obtain most of their material properties during the first couple
of hours after placement, into a hybrid, this problem could be solved.
The main reason for believing in a successful hybridization is the similar
ion release taking place during the hydration and hardening processes in
both GICs and CACs. CACs dissolve into Ca and aluminate ions when mixed
with water, an analogue to the dissolution of glass in GICs into calcium
and aluminum ions when mixed with a Polyelectrolyte, most commonly Poly
(acrylic acid), PAA. With both a cross linking of the PAA and a hydrate
precipitation that contribute to the strength development, a rapid initial
strength would be obtained that continues to improve with time. The aim of
this thesis work was to explore the possibilities of manufacturing this
hybrid, a "Biomer", to optimize candidate compositions and to evaluate the
mechanical properties of the "Biomer"-candidates.
The work was divided into two parts: a pre-study was performed in order to
find suitable constituents for the Biomer and to determine whether the CAC
and the GIC reactions were compatible, and part two was the actual
manufacturing of the Biomer. During the pre-study it was concluded that the
two systems could co-react and that the hybrid should besides CA also
contain the commercial GIC ChemFlex, manufactured by Dentsply. As reactive
agent ChemFlex liquid, major constituent PAA, and distilled water
containing Li+ (accelerator) was used. Two candidates with different GIC-CA
compositions were tested in terms of mechanical properties and the
microstructure was imaged using scanning electron microscopy (SEM).
The conclusion made from the results obtained was that hybridization
between CAC- and GIC-systems was possible. The microstructure of the hybrid
was dense and showed well distributed grains The ...
