Tissue Management and Impression Making
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Questions and Answers

What is a significant disadvantage of using polysulfide as an impression material?

  • Good flow and detail reproduction
  • Requires no special tray
  • Long working time
  • Poor dimensional stability (correct)

What type of polymerization does polysulfide undergo?

  • Condensation polymerization with by-products (correct)
  • Reversible hydrocolloid polymerization
  • Aqueous hydrocolloid polymerization
  • Addition polymerization with by-products

Which characteristic of polysulfide is considered an advantage?

  • High tear strength (correct)
  • High viscosity only
  • Instant setting time
  • Hydrophilic nature

How long should polysulfide be poured within to ensure accuracy?

<p>1 hour (A)</p> Signup and view all the answers

What is a primary characteristic of elastomeric impression materials?

<p>Include families like polysulfide and polyether (B)</p> Signup and view all the answers

Which type of impression material has the highest dimensional stability?

<p>Addition Silicon (A)</p> Signup and view all the answers

What is a disadvantage of using Polyether as an impression material?

<p>Highly rigid, causing difficulty with undercuts (B)</p> Signup and view all the answers

Which impression material is hydrophilic?

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

What by-product is generated during condensation polymerization of silicon?

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

Which type of impression material should be poured within 30 minutes of setting?

<p>Condensation Silicon (C)</p> Signup and view all the answers

Which impression material has no by-products during polymerization?

<p>Addition Silicon (A), Polyether (B)</p> Signup and view all the answers

What is a common challenge with hydrophobic impression materials?

<p>Poor wettability (D)</p> Signup and view all the answers

Which of the following materials is known for having the best elastic properties?

<p>Condensation Silicon (D)</p> Signup and view all the answers

Which impression material is considered irreversible and most widely used for study models?

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

What is a key advantage of using hydrocolloids in dental impressions?

<p>Hydrophilic properties (D)</p> Signup and view all the answers

What characteristic must impression materials have for easy manipulation?

<p>Adherence to the tray (C)</p> Signup and view all the answers

What is one major disadvantage of using irreversible hydrocolloid materials like alginate?

<p>Dimensionally unstable (A)</p> Signup and view all the answers

Which of the following materials is considered an elastomer in impression making?

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

Which method is NOT typically used for controlling hemorrhage during impression taking?

<p>Rubber dam (C)</p> Signup and view all the answers

What is a primary requirement for the immediate pouring of some impression materials?

<p>Hydrophilic nature (A)</p> Signup and view all the answers

Which type of impression material is known to exhibit excellent dimensional stability?

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

What is the primary purpose of an impression in dental practice?

<p>To create a negative likeness for fixed restorations (A)</p> Signup and view all the answers

Which of the following imperfections should be avoided in an impression?

<p>Air bubble voids (D)</p> Signup and view all the answers

What is a key requirement for impression trays?

<p>They should be dimensionally stable (D)</p> Signup and view all the answers

What is the function of the displacement cord during impression making?

<p>To displace gingival tissue for better access (C)</p> Signup and view all the answers

Which type of impression tray is more accurate?

<p>Special trays made of acrylic resin (A)</p> Signup and view all the answers

What thickness should be maintained for the impression material in special trays?

<p>2-3 mm (D)</p> Signup and view all the answers

Which method can be used to control hemorrhage during the impression making process?

<p>Using an infuser syringe (C)</p> Signup and view all the answers

Why is moisture control considered a challenge in taking impressions?

<p>Moisture can affect material setting (A)</p> Signup and view all the answers

Flashcards

Condensation Polymerization

A type of polymerization where a small molecule, like water, is released as a byproduct during the process of forming a larger polymer chain.

Additional Polymerization

A type of polymerization where no byproducts are released during the process of forming a larger polymer chain from monomers.

Polysulfide

The first type of elastomeric impression material commonly used in dentistry.

Advantages of Polysulfide

Polysulfide offers several advantages such as long working time, high tear strength, high flexibility, good flow, and excellent detail reproduction for impressions.

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Disadvantages of Polysulfide

Polysulfide also presents some drawbacks including poor dimensional stability, water by-product, limited pour time, messy handling, bad odor and taste, staining, long setting time, and sensitivity to temperature variations.

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Hydrocolloid Impression Material

A type of impression material that is water-based and uses a gelatin-like substance.

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Irreversible Hydrocolloid

A type of hydrocolloid impression material that permanently sets and cannot be reversed back to its original state.

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Reversible Hydrocolloid

A type of hydrocolloid impression material that can be repeatedly softened and set by changing its temperature.

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Alginate Impression Material

A widely used irreversible hydrocolloid impression material that sets quickly and is commonly used for study models or opposing dentition.

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Advantages of Hydrocolloids

Hydrocolloid impression materials are hydrophilic (displace moisture), inexpensive, and easy to use.

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Disadvantages of Hydrocolloids

Hydrocolloids are dimensionally unstable, meaning they can shrink or absorb water, and require immediate pouring.

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Syneresis

A shrinking of hydrocolloid impression material due to loss of water.

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Imbibition

An expansion of hydrocolloid impression material due to absorption of water.

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What is an impression?

A negative likeness of the teeth and surrounding structures used to create a fixed restoration in the lab.

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Components of an acceptable impression

An acceptable impression must include well-defined prepared and unprepared tooth surfaces, accurate margins, and clear surrounding tissue details.

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Common impression imperfections

Impressions should be free from air bubbles, tears, or other imperfections that can compromise the accuracy of the final restoration.

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Challenges of taking impressions

Taking an impression can be challenging due to patient communication, ensuring moisture control, preserving surrounding tissues, and working in delicate spaces.

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Why impression trays are important

Impression trays are essential because they provide a rigid and stable framework for holding the impression material, allowing uniform thickness and proper extension for capturing the details of the teeth.

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Types of impression trays

There are different types of impression trays: stock trays, special trays, and water-cooled stock trays for specific impression materials.

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Stock trays

Stock trays are pre-fabricated trays, usually made of metal or plastic, that are readily available and offer time savings. However, they require sterilization.

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Special trays

Special trays are customized to the patient's mouth, usually made of acrylic resin, and offer greater accuracy. They are fabricated for each impression.

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Polyether Impression Material

A type of elastomeric impression material known for its high accuracy and dimensional stability. It is hydrophilic, can be mixed manually or automatically, and is used in various viscosities.

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Polyether Advantages

Offers high accuracy, excellent dimensional stability, good surface details, and wettability. Can be stored for a week and allows for multiple pouring.

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Polyether Disadvantages

Has a short working time, is highly rigid, has low tear strength, and absorbs water. Can be challenging with undercuts.

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Condensation Silicon Impression Material

A type of elastomeric impression material known for its better elastic properties and longer working time. It is hydrophobic and undergoes condensation polymerization, releasing ethyl alcohol as a byproduct.

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Condensation Silicon Advantages

Offers better elastic properties, good working and setting time, and can be used with stock or special trays.

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Condensation Silicon Disadvantages

Has poor dimensional stability, high shrinkage due to ethanol evaporation, and needs to be poured within 30 minutes. It's hydrophobic, has low tear strength, and has poor wettability.

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Addition Silicon Impression Material

A type of elastomeric impression material known for its high accuracy and high dimensional stability. It is hydrophobic and undergoes addition polymerization without byproducts.

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Addition Silicon Advantages

Offers high accuracy, high dimensional stability (can be poured within a week), good surface details, and allows for multiple pouring. Easy to mix.

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What is an elastomer?

A rubber-like material used for dental impressions, known for its flexibility and ability to capture details.

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How are elastomers classified?

Elastomers are categorized based on their chemical composition (condensation or addition polymerization) and viscosity (very high, high, medium, low).

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What is polysulfide?

The first elastomeric impression material developed for dentistry, consisting of two pastes (base and catalyst), and available in three viscosities (heavy, medium, light).

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What is a notable advantage of polysulfide?

One key benefit of polysulfide is its long working time, allowing for ample time to manipulate the material and achieve accurate impressions.

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What is a disadvantage of polysulfide?

Polysulfide has the drawback of poor dimensional stability, meaning it can change in size over time, affecting the accuracy of the impression.

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Study Notes

Tissue Management and Impression Making

  • Impressions are negative likenesses of teeth and surrounding structures. They are essential for creating fixed restorations in the lab.

  • An acceptable impression should have:

    • Prepared/unprepared tooth surfaces
    • Accurate margins
    • Accurate surrounding structures

  • Impressions should be free from:

    • Air bubbles
    • Tears
    • Other imperfections

Impression Trays

  • Requirements:

    • Rigid
    • Dimensionally stable
    • Provide even space for impression material
    • Proper extension
    • Retentive for impression material

  • Types:

    • Stock trays:
      • Metallic/plastic
      • Time-saving
      • Material usage
      • Require sterilization
    • Special trays:
      • Acrylic resin
      • More accurate
      • Material usage

  • Thickness: Typically 2-3mm

  • Separation: 2mm separation that extends 3-5 mm apically to the gingival margin and 3mm beyond the most distal tooth.

  • Tissue Stops: Usually on non-functioning cusps of unprepared teeth

Impression Materials

  • Properties:
    • Easy to mix and handle
    • Fluid
    • Reasonable working and setting time
    • Non-harmful
    • Elastic
    • Adhere to the tray
    • Stable
    • Easy to pour
    • Acceptable to the patient
    • Multiple pouring

Classification of Impression Materials

  • Elastic Impression Materials:
    • Aqueous Hydrocolloids:
      • Irreversible (Alginate): Widely used, suitable for study models or opposing non-prepped dentition.
      • Reversible (Agar): Excellent dimensional stability and hydrophilic, requires immediate pouring.
    • Elastomers:
      • Polysulfide: First dental elastomeric material, 2 pastes with 3 viscosities. Hydrophobic and uses condensation polymerization.
        • Advantages: Long working time, high tear strength, high flexibility, good flow and detail.
        • Disadvantages: Poor dimensional stability, water byproduct, pour within 1 hour, single pour, requires special tray, smelly, stains, long setting time, impacted by temperature and humidity
      • Polyether: 2 pastes with 3 viscosities, no by-products, hydrophilic. Can be hand mixed or automated. Additional polymerization.
        • Advantages: High accuracy, high dimensional stability, stock or special trays, good surface details, pour within 1 week (saved dry).
        • Disadvantages: Short working time, highly rigid, low tear strength, absorbs water
      • Condensation Silicons: Base and catalyst in 4 viscosities, Hydrophobic and Condensation polymerization.
        • Advantages: Better elastic properties, good working and setting time, stock or special trays.
        • Disadvantages: Poor dimensional stability, high shrinkage, needs to be poured within 30 minutes, hydrophobic, low tear strength .
      • Addition Silicons: Base and catalyst with 4 viscosities, Addition polymerization, no by-products, hydrophobic.
        • Advantages: Highly accurate, high dimensional stability (pour within 1 week), stock or special tray, multiple pouring, easy to mix.
        • Disadvantages: Surfer inhibit polymerization, Latex gloves contain sulfur, Short working time, lower tear strength, absorbs water, hydrophobic

Comparisons of Impression Materials

  • Working time: Alginate < Polyether < Silicons < Polysulfide < Agar
  • Setting time: Alginate < Polyether < Agar < Silicons < Polysulfide
  • Stiffness: Polyether > Silicons > Polysulfide > Hydrocolloids
  • Tear Strength: Polysulfide > Silicons > Polyether > Silicons > Hydrocolloid
  • Cost: Alginate < Agar < Polysulfide < Silicons < Polyether
  • Dimensional Stability: Silicons > Polyether > Polysulfide > Silicons > Hydrocolloid
  • Wettability: Hydrocolloids > Polyether > Silicons > Polysulfide > Silicons

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Tissue Management and Impression Making PDF

Description

This quiz delves into the essential techniques of tissue management and impression making in dental restorations. You'll explore the characteristics of acceptable impressions and the requirements for different types of impression trays. Test your knowledge to ensure accuracy and efficiency in creating dental impressions.

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