Cements based on Phosphoric acid-Zinc Phosphate Cement and SilicoPhosphate Cement


Introduction
One group of widely used cements is based on the vigorous reaction which occurs between certain basic oxides and phosphoric acid to form phosphate salt of low solubility.

Zinc phosphate cements

Composition:
            These materials are generally supplied as a powder and liquid which are mixed together by hand.
            The major reactive component of the powder is zinc oxide.

Composition of zinc phosphate cements:

Powder

Zinc oxide

Approximately 90% as main active ingredient
Other metallic oxides
Approximately 10 % concentration
Liquid

Aqueous solution of phosphoric acid
50-60 %
AIPO4
Zn3(PO4)2
Up to 10% As buffers

Manipulative variables:
            The powder/liquid ratio depends on the application. For cavity lining a puttylike consistency having a powder/liquid ratio of about 3.5:1 is used.
The powder is the best incorporated into the liquid in small increments until the desired consistency is reached.
Mixing is easier if carried out on a cooled glass mixing slab.

Properties:
            Providing the materials are manipulated correctly. The phosphate cements have sufficient working time to allow placement of a cavity lining or cement lute before the viscosity has increased markedly. There is a minimum setting time of 2.5 minutes for luting cements and 2 minutes for lining cements. Phosphate cement are not adhesive to tooth substance or to restorative materials.

Silicophosphate cements.

Silicophosphate cements are, essentially hybrids of zinc phosphate and silicate materials. They are supplied as a powder and liquid. The liquid  is an aqueous solution of phosphoric acid whilst the powder is mixture of zinc oxide and black cupper oxide. The settings reaction is similar to that for zinc phosphate materials.
The two properties which distinguish these products from simple zinc phosphate materials are their black appearance and their bactericidal effects, produced by the presence of cupper.
Previous
Next Post »

1 comments:

Click here for comments
August 10, 2013 at 2:34 AM ×

Thanks best sharing for more list visit site Zinc Dust Exporters - Manufacturer and Supplier of Zinc dust India
transpek-silox

Selamat Reshma Mulchandani dapat PERTAMAX...! Silahkan antri di pom terdekat heheheh...
Balas
avatar
admin
Thanks for your comment

Popular Posts

Gadget

This content is not yet available over encrypted connections.