Zinc phosphate cement the one of the oldest and widely used cements, and is commonly used for luting permanent metal restorations and as a base. It is a high-strength cement base, mixed from zinc oxide powder and phosphoric acid liquid. Due to its low initial pH, it may cause pulpal irritation, especially where only a thin layer of dentin exists between the cement and the pulp; thus is especially important to follow the correct procedures and precautions when using zinc phosphate cement.