ALGINATE IMPRESSION MATERIAL - DM

Purpose of impression materials

To make an accurate replica of the hard and soft oral tissues

Impression gives a ______ reproduction which may be filled with ______ to make a ______ cast

Negative

Dental Stone

Positive

Where does alginate come from

Where is it found?

Alginic Acid - Within cells of brown algae/seaweed

Alginate is ___% dry weight

40

Alginate is a linear ________ of what two things

Copolymer

B-D-Mannuronic Acid

a-L-Guluronic acid

What are the two phases of a colloidal solution

Dispersed and dispersion

In solutions, particles are _______

Dissolved

In a suspension, particles are ______

large and visible

Alginate is called a ______ _

Why?

Irreversible hydrocolloids

Once the paste sets to a gel, the process cannot be reversed

Sodium or Potassium Alginate Salt:

% and function

18

Dissolve in water

Calcium sulfate

% and function

14

Reacts with dissolved alginate to form insoluble calcium alginate

Sodium Phosphate

% and function

2

Retarde - Controls setting time

A faster setting alginate would have less _________

Sodium phosphate

Diatomaceous earth/silicate powder

% and function

56

Filler - controls consistency and flexibility

Potassium sulfate, potassium zinc fluoride, silicates or borates

% and function

10

Improves setting of gypsum - gives good surface to die

What is diatomaceous earth

What is it composed of?

Sedimentary rock that gets ground into a fine powder

Usually 80-90% silica with some alumina and iron oxide

What are the three types of mixing

Manual

Semi automatic

Automatic

Aqueous Elastic impression materials ______ in air and _____ in water

Contract

Expand

Aqueous elastic impression materials have _______ stability

Storage in 100% humidity preserves what

Dimensional

Normal water content

Jeltrate

Jeltrate dustless

Jeltrate plus

Chroma are all examples of alginate from what

Dentsply Sirona

Advantages of Alginate (2)

Hydrophilic

Low cost

Disadvantages of alginate (3)

Not as accurate

Poor tear strength

Pour immediately

Alternative alginates have improved what

Dimensional stability over time