Impression Materials in Dentistry
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Questions and Answers

What is the primary characteristic of impression plaster as an impression material?

  • It is elastic and can be used in various cases.
  • It is rigid and suitable for edentulous patients only. (correct)
  • It has a long setting time of 10 minutes.
  • It provides excellent detail for undercut areas.

Which of the following is NOT a property of ideal impression materials?

  • Long setting time (correct)
  • Dimensionally stable after setting
  • Good flow
  • Pleasant taste, odour, and color

What is the primary use of Type I brown cake impression compound?

  • Creating a custom tray for fixed prosthesis
  • Taking primary impressions for edentulous patients (correct)
  • Bite registration for dentulous patients
  • Border molding for dentures

What happens to impression compound when heated?

<p>It becomes soft and can be manipulated. (B)</p> Signup and view all the answers

Which ingredient is used in impression compound primarily for lubrication?

<p>Stearic acid (B)</p> Signup and view all the answers

What is the setting time range for impression plaster?

<p>3-5 minutes (D)</p> Signup and view all the answers

Type II green stick impression compound is primarily used for which purpose?

<p>Border molding of custom trays (A)</p> Signup and view all the answers

Why is impression material required to have good flow properties?

<p>To capture fine details accurately. (A)</p> Signup and view all the answers

What is the primary characteristic of alginate irreversible hydrocolloid?

<p>It is irreversible once set. (B)</p> Signup and view all the answers

What is the recommended action if alginate impressions are not poured within 30 minutes?

<p>They may dry out and shrink. (D)</p> Signup and view all the answers

What happens to setting time when using more powder in alginate mixing?

<p>It makes the material set faster. (D)</p> Signup and view all the answers

What is the primary use of light body additional silicone elastomer impression material?

<p>To take final impressions for crowns and bridges (A)</p> Signup and view all the answers

What is a characteristic of Agar reversible hydrocolloid?

<p>It can be reused by heating. (A)</p> Signup and view all the answers

Which characteristic is NOT true about putty additional silicone elastomer impression material?

<p>It should be mixed with latex gloves on (A)</p> Signup and view all the answers

In what scenario is Zinc Oxide Eugenol (ZOE) most appropriately used?

<p>As a temporary filling in edentulous patients. (B)</p> Signup and view all the answers

Which type of additional silicone elastomer is most likely to provide excellent surface detail?

<p>Light body (C)</p> Signup and view all the answers

What distinguishes the fast-setting alginate from the normal-setting alginate?

<p>It sets more quickly with a setting time of 1-2 minutes. (B)</p> Signup and view all the answers

Which feature is NOT associated with alginate?

<p>High detail production in impressions. (A)</p> Signup and view all the answers

What is one major disadvantage of using additional silicone elastomer materials?

<p>It can be expensive (B)</p> Signup and view all the answers

What is the consequence of leaving an alginate impression for more than 24 hours?

<p>It may experience dimensional distortion. (A)</p> Signup and view all the answers

When using medium body additional silicone elastomer material, what is a correct characteristic to note?

<p>It can be used alone or in combination for final impressions (A)</p> Signup and view all the answers

What is the primary advantage of using polysulfide elastomer elastic impression material?

<p>Good flexibility (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of polyether elastomer elastic impression material?

<p>Long working time (A)</p> Signup and view all the answers

What is a disadvantage associated with silicone elastomer elastic impression materials?

<p>High cost (A)</p> Signup and view all the answers

What is the typical setting time for polysulfide elastomer elastic impression material?

<p>8-12 minutes (D)</p> Signup and view all the answers

Which of the following elastomeric materials requires handling with consideration for rapid setting time?

<p>Polyether elastomer (C)</p> Signup and view all the answers

Which elastomeric impression material is known for being used with both stock and special trays?

<p>Silicone elastomer (A)</p> Signup and view all the answers

What is the primary benefit of using glutraldehyde in the disinfection of impressions?

<p>Effective disinfectant (C)</p> Signup and view all the answers

Which characteristic is common to both polysulfide and polyether elastomers?

<p>Long setting time (B)</p> Signup and view all the answers

Flashcards

Impression Material

A material used to create a mold of teeth and supporting tissues.

Impression Plaster

An early, rigid impression material for final impressions in edentulous patients (no teeth).

Impression Compound

A non-elastic, reversible impression material, good for preliminary impressions, especially in edentulous patients.

Impression Compound Type I

Brown cake impression material, primarily used for preliminary impressions in edentulous patients.

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Impression Compound Type II

Green stick impression material used for border molding custom trays.

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Impression Plaster Setting Time

Takes 3-5 minutes to set.

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Impression Compound Properties

Softened when heated, hardened when cooled. Thermoplastic, and reversible.

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Impression Compound Ingredients

Mostly wax, resin, fillers to give viscosity and coloring pigments.

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Zinc Oxide Eugenol (ZOE)

A non-elastic impression material used for secondary/final impressions in edentulous patients, possessing a sedative effect.

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Agar Reversible Hydrocolloid

A reusable, elastic impression material made from seaweed, used for final impressions.

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Alginate

An irreversible, elastic impression material used for primary impressions, often replacing agar.

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Powder/Water Ratio (Alginate)

More powder leads to a faster setting time in alginate; less powder leads to a slower setting time.

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Water Temperature (Alginate)

Warmer water speeds up the setting time of alginate; colder water slows it down.

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Alginate Setting

Alginate is set when it becomes rubbery, and this usually takes 2-5 minutes depending on the mix and type.

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Syneresis

The shrinking of an alginate impression due to drying out.

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Impression time limit

Alginate impressions need to be poured within 30 minutes of setting or they may lose accuracy/dimensions.

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Light Body Silicone

A type of silicone used for final impressions of crowns and bridges. It's usually mixed with another type of silicone, like heavy body.

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Medium Body Silicone

A versatile silicone that can be used alone or mixed with other types to take final impressions.

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Heavy Body Silicone

A thicker silicone that can be used alone or in combination with other types for impressions.

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Putty Silicone

A silicone used for primary impressions or combined with other silicones for final impressions. It's also used for border molding in denture patients.

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Latex & Silicone

Latex gloves should not be used when mixing or working with silicone impression materials.

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Iodophores

A disinfectant solution used for sterilizing impressions. It contains iodine and a carrier molecule, making it effective against bacteria and viruses.

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Sodium Hypochlorite

A common bleach solution used to disinfect impressions. It works by oxidizing and destroying microorganisms.

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Glutaraldehyde

A powerful disinfectant that is used to sterilize impressions and dental instruments. It's effective against bacteria, viruses, and fungi.

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Phenyl Phenol

A disinfectant used to clean impressions. It's known for its effectiveness against bacteria and fungi.

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Polysulfide Impression Material

A type of elastic impression material, often supplied as a base and accelerator paste mixture. It offers good flexibility, tear resistance, and detail capturing.

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Polyether Impression Material

A high-accuracy, elastic impression material, supplied as a base and accelerator paste mixture. It's known for ease of use, accurate details, dimensional stability, and undercuts.

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Silicone Impression Material

A versatile, elastic material used for taking both preliminary and final impressions. It comes in various consistencies to cater to different situations.

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Condensational Silicone Impression Material

A type of silicone impression material that sets via condensation reaction. It comes in different consistencies, including putty, and is known for its fast setting time.

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Study Notes

Impression Materials

  • Impression materials are used to create impressions of teeth and supportive tissues.
  • Ideal impression materials are non-toxic and non-irritating (biocompatible).
  • They have good flow, easy manipulation, dimensional stability after setting, acceptable price and availability, good shelf life, and pleasant taste, odor, and color.

Types of Impression Materials

  • Impression materials are categorized as elastic and non-elastic.

  • Non-elastic impression materials include plaster, impression compound, zinc oxide eugenol, and impression waxes.

    • Plaster: The earliest impression material used in dentistry, it has limited flow, used for edentulous patients' final impressions and in mild to no undercut conditions.
    • Impression compound: One of the oldest impression materials, it's rigid and reversible, thermoplastic. Used in preliminary impressions of edentulous patients, special trays, and border molding. It comes in types I (brown cake) and II (green stick).
      • Type I (brown cake): Used for primary impressions in edentulous patients with mild to no undercuts, requiring heat to soften and then cool.
      • Type II (green stick): Used for border molding of custom trays, softened by flame, changing from glossy when soft to matte when hard.
    • Zinc Oxide Eugenol (ZOE): Used for secondary/final impressions for edentulous patients, offers a sedative effect. It's thin and brittle, used in patients without undercuts, mixed on glass slabs, instead of plaster, and is used on bite registration material.
    • Impression Waxes: Thermoplastic materials flowing at mouth temperature, used for correcting small imperfections, typically in combination with other zinc oxide materials.

  • Elastic impression materials include hydrocolloids (reversible and irreversible), polysulfides, polyethers, and silicones (condensation and addition).

    • Hydrocolloids (reversible): Made from seaweed, reversible (reusable by heating), used to take final impressions.
      • Composition: Agar, Borax, Potassium sulfate, Benzoate, Additives.
    • Hydrocolloids (irreversible): Replaces agar in modern applications, used for primary impressions (poor detail) with undercut situations.
      • Composition: Potassium/sodium triethanolamine alginate, Calcium sulfate dihydrate, Zinc oxide, Potassium titanium fluoride, Diatomaceous earth, Trisodium phosphate, Coloring agents and flavoring agents.
    • Polysulfides: Synthetic elastomeric impression materials, supplied in two-paste systems (base/accelerator). Available in various viscosities (light, medium, heavy).
    • Polyethers: Elastic impression material suitable for secondary impressions, used in 3 viscosities (light, medium, heavy). Come as a base and accelerator.
    • Sillicones (condensation and addition): Used as final impressions using special trays. Available in various body types (light, medium, heavy, putty).

Impression Techniques

  • One-step Technique: Mix putty and catalyst, adapt to tray, immediately inject light body around prepared teeth, polymerize simultaneously.
  • Two-step Technique: mix putty, adapt to tray and place separator on top, take impression, remove from patient after it sets, remove separator, inject light body, retake impression, wait for setting, and remove.

Impression Materials: Advantages and Disadvantages

  • Summarized information about advantages and disadvantages of different materials is available in the text.

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Impression Materials Lab 6 PDF

Description

This quiz explores the different types of impression materials used in dentistry, focusing on their characteristics and classifications. Learn about elastic and non-elastic materials, including plaster and impression compounds, and their applications in creating dental impressions.

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