Zinc Phosphate Cement: Composition, Manipulation, Uses

Dental Cement

Question  1. Classify dental cement. Write composition, manipulation, and uses of zinc phosphate cement.
Or
Classify cement. Write composition, manipulation, and uses of zinc phosphate cement.
Answer:

Cement: Dental cement are materials of comparatively low strength substance that harden to act as a base, liner, filling material, or adhesive to bind devices and prostheses to tooth structure or to each other.

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Classifiation of Cement:

Philips, Craig’s, and Coombe’s classifications are described as follows:

Craig’s Classification:

EC Coombe Classification:

• Acid-base reaction cement.
• Polymerizing materials:
  • Cyanoacrylates
  • Dimethacrylate polymers
  • Polymer ceramic composites.
• Other materials:
  • Calcium hydroxide
  • Gutt-percha
  • Varnishes.

Zinc Phosphate Cement:

Zinc phosphate is the oldest of the luting cements, the terms “crown and bridge” and “zinc oxyphosphate” have also been used for this cement.

Composition of Zinc Phosphate Cement:

Powder:

Liquid:

Manipulation of Zinc Phosphate Cement:

• Spatula used – Stainless steel
• Mixing time – 1 min 15 sec
• Dispense the cement – 1.4 gm / 0.5 ml

The steps involved in the manipulation of zinc phosphate cement are as follows:

• A cool glass slab is used in order to delay the settling and allow more powder to be incorporated before the matrix formation occurs.
• The liquid should be dispensed just before mixing.
• The powder is added in small increments.
• A large area is covered during mixing in order to dissipate the exothermic heat.
• Maximum amount of powder should be incorporated in the liquid to ensure minimum solubility and maximum strength.
• An appropriate consistency is attained by the addition of more powder to the liquid and not by allowing a thin mix to thicken.

Procedure of Zinc Phosphate Cement:

The powder is added in small increments (to adjust the consistency) mixing is done with stainless steel spatula using a brisk circular motion. Each increment is mixed for 15 to 20 seconds. A large area is covered during mixing in order to dissipate the exothermic heat. Maximum amount of powder should be incorporated in the liquid to ensure minimum solubility and
maximum strength.