How do you make polyvinyl siloxane?
To create the material, the user simply mixes a colored putty (often blue or pink) with a white putty, and the chemical reaction begins. PVS with a wide variety of working and setting times is available commercially. Final set is noted when the product rebounds upon touching with a blunt or sharp instrument.
What are the two types of elastomeric impression materials that are available?
Four types of elastomeric impression materials are available in the market: addition silicone, also known as polyvinyl siloxanes (PVS), condensation silicone, polyether, and polysulfide. Elastomers can present in different consistencies, including putty, heavy body, medium body, and light body.
What is irreversible hydrocolloid?
A hydrosol of alginic acid whose physical state is changed by an irreversible chemical reaction, forming insoluble calcium alginate. This substance is called alginate or dental alginate. Alginate is used in dentistry as a primary impression material.
What is condensation silicone?
Condensation silicon is the first silicon material ever used in dentistry. It is commonly used to get impressions in the preparation of crowns, bridges, onlays, and inlays. In some cases, it’s used for an impression in the process of preparation for complete dentures.
Is alginate a reversible hydrocolloid?
Agar is a reversible hydrocolloid because it can pass repeatedly between highly viscous gel and low viscosity sol simply through heating and cooling. However, alginate once converted to the gel form cannot be converted back into the sol, and is therefore said to be irreversible hydrocolloid material (4).
Which is better addition or condensation silicone?
Conclusion: The addition silicones have better dimensional accuracy and stability than condensation silicones. An impression made from condensation silicone should be poured as soon as possible.
What is used as catalyst in polymerization of C silicone *?
When methyl chloride reacts with silicon in the presence of copper as a catalyst at a temperature 570 K, various types of methyl substituted chlorosilanes are formed. Hydrolysis of dimethyl dichloro silane i. e., (CH3)2SiCl2 followed by condensation polymerisation forms straight chain polymer i. e., silicone.
What are the different viscosities of different elastomeric material?
It is available in 4 viscosities: heavy, medium, light, and putty. Excellent detail reproduction, dimensional stability, and good tear strength are the qualities of elastomeric impression materials that made these materials used when a high degree of accuracy is essential .
Which hydrocolloid is irreversible?
The irreversible hydrocolloid employed in impression materials is some form of a soluble alginate. An alginate is a salt of alginic acid,, which is extracted from ma rine kelp.
What is the use of irreversible hydrocolloid?
Alginate, which is the most widely used irreversible hydrocolloid in dentistry, is an elastic impression material that is generally used for prosthodontic and orthodontic purposes.
What is the hydrocolloid and example?
Hydrocolloids that are commonly used as thickening are starch, xanthan, guar gum, locust bean gum, gum karaya, gum tragacanth, gum Arabic and cellulose derivatives. The gelling type hydrocolloids are alginate, pectin, carrageenan, gelatin, gellan and agar.
What is condensation type silicone?
What are the differences between addition and condensation polymerization?
Addition polymerization is the process of repeated addition of monomers that possess double or triple bonds to form polymers. Condensation polymerization is a process that involves repeated condensation reactions between two different bi-functional or tri-functional monomers.