Influence of Firing Condition for Fracture Toughness, Color Stability and Firing Shrinkage of Porcelain-fused-to-titanium.

An experiment was conducted to determine fracture toughness, color stability, and firing shrinkage of porcelain-fused-to-titanium in relation with firing conditions. Titanium (VT), Duceratin (DD), Titanbond (OT) and Titan (NT) were examined under firing temperatures of 10, 20, and 30°C higher than the reference temperature, respectively, with either 1, 3, or 5 rounds of firing.The results were as follows:1. With the rise in firing temperature, the fracture toughness level was decreased in VT and increased in NT, while the level remained constant in DD and OT. Repeat firing also influenced the fracture toughness level, which was reduced in VT and OT with increasing number of firings, though the level remained constant in NT and DD.2. When the color obtained at the reference firing temperature was regarded as the standard color, the color difference ΔE* from the standard was observed in all except for VT at 10°C higher than the reference temperature. In addition, when the color obtained by one firing was taken as the standard color, the color difference ΔE* from the standard was recognized in all repeat firings.3. The degree of linear shrinkage was increased in VT and decreased in NT, with the rise in firing temperature and increasing number of rounds of firing, but it remained constant in DD and OT.