Compressive Strength of Five High-Viscosity Glass Ionomer Cements

Objectives: The aim of the present research was to compare in vitro the compressive strength of five glass ionomer cements: Ketac Molar Easymix, Ketac Universal (3M), GC Fuji IX, GC EQUIATM Fil (GC corporation), and Maxxion R (FGM); after 24 hours, 7 days and 2 months after the mixing process.
Methods: Five high-viscosity glass ionomer cements were selected for the present in vitro study: Ketac Molar Easymix^TM, Ketac Molar Universal^TM (3M), GC Fuji IX _GP, GC EQUIA^TM Fil (GC Corporation), and Maxxion R (FGM), recommended for the Atraumatic Restorative Treatment (ART). The mixing process was performed strictly respecting the manufacturer recommendations.
The analysis unit was made of glass ionomer cylinders of 2mm high and 4mm in diameter, prepared with a metallic matrix. 15 samples were created for each study group, obtaining a total of 225 samples. The sample size was determined by the Stata^®12 Software, using the formula for the mean comparisons, with a C.I. of 95% and a statistical power of 80% obtaining the mean values and the S.D. of a previous research.
Results: After 24 hours, EQUIA Fil (GC Corporation) showed the highest compressive strength values (299.80 MPa), however, after 7 days the compressive strength felled dramatically for the five groups. After 2 months, the value still decrease but at a lower rate, where Ketac Universal ^TM HM (3M) showed the highest values of compressive strength among the five groups (75.48 MPa).
Conclusions: The encapsulated material EQUIA Fil (GC Corporation) showed the highest values of compressive strength after 24 hours, value that felled as the other four groups with time. After 2 months, the hand-mixed glass ionomer cement Ketac Universal^TM HM (3M) showed the highest values of compressive strength.