J.Zivko-Babic*, Z. Schauperl1, Mehulic K, T.Ivanis, J.Panduric, H.Predanic-Gasparac (Faculty of Dentistry, 1Faculty of Mechanical and Nautical Engineering, Zagreb, Croatia)
IPS Empress ceramic is a two phases, fine crystalinic glass ceramic material, in which leucite is submitted in the glass matrix as a volume fraction.
The purpose of this study was to determine whether the cooling mode of both Empress based materials (for "Schicht" and "Mal" techniques) might be attributable to different phase share.
The base materials were pressed according to the manufacture's instructions. One muffle was cooled in the conventional manner by removing it from the furnace at maximum pressing temperature immediately and cooling at room temperature (normal cooled), while the second was quenched in cold water (fast cooled). The third muffle was cooled by interrupting power to the furnace and allowing it to cool inside the closed furnace (slow cooled). The specimens' surfaces were prepared with diamond paste and etched with 5% HF for 30 seconds and photographed under reflecting light of Olympus BHZ-UMA microscopy, under 200 and 1000 times magnitude. Share of each phase, porosity, foreign precipitations and roughness were analysed by employing the LECO 2001 device for automatic picture analysis.
Results, statistically elaborated, displayed a dependence of share and distribution of mentioned parameters on cooling condition.