Zinc Phosphate Cement: Uses & Properties

Zinc Phosphate Cement: Uses & Properties

 

Setting Reaction of Polycarboxylate Cement:

When powder and liquid are mixed, the surface of powder particles is attacked by the acid and releases zinc, magnesium, and tin ions. These ions bind to the polymer chain via carboxyl groups. They also react with carboxyl groups of adjacent polyacid chains to form cross-linked salts.

Advantages of Polycarboxylate Cement:

• It is less irritating to the pulp.
• It bonds chemically with the tooth structure.

Question  2.  Write in detail about the physical properties and uses of zinc phosphate cement. 
Or
Write a short answer on zinc phosphate cement.
Answer:

Physical Properties of Zinc Phosphate Cement.:

• Compressive strength: Zinc phosphate cement is stronger (103.5 MPa) than zinc oxide eugenol cement. The strength of zinc phosphate cement is sufficient when used as a base or luting agent. However, when it is exposed to the oral environment, for example, Temporary restorations, its brittleness and low strength cause it to fracture and disintegrate.
• Tensile Strength: The cement is weaker in tension (5.5 MPa) thus making it brittle.
• Modulus of elasticity: It is comparatively high (13.5 GPa) which makes it stiff and resistant to elastic deformation. This is necessary when it is employed as a luting agent for restorations that are subjected to high masticatory forces.
• Solubility and disintegration: In the mouth, they show greater disintegration over a period of time. When tested according to ADA specifications it shows low solubility (0.06% wt).
• Thermal properties: Zinc phosphate cement a good thermal insulator and may be effective in reducing galvanic shock
• Adhesion: The retention of a cemented restoration is by mechanical interlocking of the set cement with a surface roughness of the cavity and restorations.