The physical–mechanical performance of the new Ketac™ Molar Easymix compared to commercially available glass ionomer restoratives

Objectives To evaluate the time dependence of physical–mechanical performance of glass ionomer restoratives. Methods The physical–mechanical properties of Ketac™ Molar Easymix in comparison to four handmix glass ionomer restoratives were evaluated by testing the compressive and flexural strength, acid erosion and solubility. By testing the properties in the early and late setting phase it was determined how fast the level of material characteristics is achieved. IR spectroscopy was used for monitoring the acid–base reaction. Results The compressive strength after 1 and 24 h setting time show that Ketac™ Molar Easymix and Fuji IX demonstrate a significantly higher performance. Ketac™ Molar Easymix exhibits by far the highest flexural strength 1 h after start of setting. After 24 h, it remains at this high level and only Vitro Molar and Fuji IX come close. Ketac™ Molar Easymix and Fuji IX show the lowest solubility in neutral media after 24 h and 7 d. It is remarkable that the solubilities of Ionofil® Molar, Vitro Molar and Vidrion R stored in water for 24 h are higher than those of Ketac™ Molar Easymix and Fuji IX obtained after 7 d water immersion. In acidic media Ketac™ Molar Easymix is least prone to acid erosion. Conclusions For clinical success of a filling material the early achievement of a high physical–mechanical performance is mandatory to minimize the risk of early damage to a restoration. With the high flexural strength reached after 1 h combined with the lowest susceptibility for acid-attack and solubility in water, Ketac™ Molar Easymix, from 3M ESPE, provides the best performance of any materials tested.