The influence of environmental conditions on the material properties of setting glass-ionomer cements.

OBJECTIVES

Aim of this study was to investigate the influence of temperature on the setting time and compressive strength of two conventional glass-ionomer cements (GIC's) and to determine the influence of storage medium, oil or water and storage time.

MATERIALS AND METHODS

Two conventional GIC's, Ketac Molar (3 M-ESPE Dental Products, Seefeld, Germany) and Fuji IX Fast (GC Corp., Tokyo, Japan) were used to perform flow property tests and compression tests. Flow property measurements were performed using a displacement rheometer at six different temperatures. From the results of the rheometer tests, the working times and setting times could be determined. The samples for the compressive tests were stored at four different temperatures and in two different media. Testing took place at five time intervals reaching from 1 h to 3 months.

RESULTS

The results of rheometer tests showed that a temperature increase speeded up the setting reaction significantly. The compressive strength results showed a jump in time as a result of the higher curing temperature but no long-term strength effect was observed. Materials curing in oil reached a significantly higher compressive strength compared to storage in water and Fuji IX Fast is significantly stronger than Ketac Molar.

SIGNIFICANCE

It was concluded that a temperature between 333 and 343 K almost sets conventional GIC's on command and improves the early compressive strength.