Objective: The primary objective of the study was to assess the influence of externally applied 'command' set applications on the mechanical properties of several commercially available conventional glass ionomer cement (GIC).
Methods: Four different restorative GICs cements (Fuji IX FAST, Fuji IX, Ketac Molar Quick, Ketac Molar) were cured using three different methods, e.g. standard curing conditions (SC), ultrasonic excitation (UC) and by an external heat source (HC). The compressive strength of these samples was measured and the groups were compared using one-way ANOVA. A standard thermocouple (K-type) measured the temperature in GIC during curing.
Results: In general all experiments showed an increase in strength going from SC, UC to HC. Especially, the compressive strength of Fuji IX FAST and Ketac Molar increased by UC and HC compared to the SC values. The compressive strength of Fuji IX FAST as a function of time showed an increase in strength during 28d. There was a clear relationship between the temperature in the sample (SC<UC<HC) and the compressive strength of the GICs.
Significance: An increase in strength was found, especially at the early curing time. Enhanced material properties at early curing time can improve the survival rate of GICs in the clinical situation. Ultrasonic excitation can be used as a 'command' set method and improves the properties of GIC at early setting time.