Water sorption of newly formulated resin-modified and conventional glass ionomer cements

Abstract EN

Background: Chemical bonding of glass ionomer cements to tooth structure may be affected by dimensional changes associated with water absorbed by the material when it is in service inside the oral environment.

The aim of this work was to measure the amount of water absorbed by new formulated cements and compare it with cements with old formula and two commercial cements.

MATERIALS AND METHODS: Four types of cements were prepared, two were resin-modified light-cured(l and 2)and two were conventional chemical-cured (4 and 5).

Two commercial cements were used, the first was light-cured cement 3 (Vivaglass) and the second was chemical-cured cement 6 (Nikang).

Five specimens with 9mm diameter and 4mm height were produced for each type of cement.

The weight of each specimen was recorded after 24 hours before immersing in distilled water using very sensitive weight measuring balance with a precision + 2 mg.

A desiccator was used to absorb water from the specimen material for 24 hours.

Then the weight of each specimen was recorded.

The specimens were immersed in 20 milliliters of distilled water at room temperature (25°C + 2).

The weight of each specimen was then recorded after different immersing times of five minutes, 10 minutes, 15 minutes, 30 minutes, 60 minutes, one day, three days, one week, 10 day, and two weeks, until no more water absorbed.

The value of water sorption was calculated and the final value was rounded to the nearest 0.1 mg/cm2.

RESULTS: Resin modified cements showed higher values of water sorption than those of conventional types of glass ionomer cements.'The highest value of short-term water sorption test was recorded for cements (5) followed by cement (2).

While the lowest value of water sorption was recorded for cement (3) CONCLUSSION: Resin-modified cements absorb more water than conventional cements.

Changing the powder formula had no clear effect on water sorption, while the resinous components of the liquid had direct effect on water sorption of the tested cements.