Dental Impression Techniques
30 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What should be done first when preparing the mixture?

  • Mix water with the powder until creamy
  • Place water into the rubber bowl (correct)
  • Allow the mixture to set immediately
  • Add the powder directly into the patient's mouth

What is the purpose of mixing the powder with water?

  • To ensure the mixture is fluffy
  • To form a creamy mixture (correct)
  • To increase the volume of the powder
  • To create a solid form

What tool is used to mix the water and powder?

  • A blender
  • A whisk
  • A spoon
  • A spatula (correct)

How should the mixture be applied after it is prepared?

<p>Filled into a tray and seated into the mouth (B)</p> Signup and view all the answers

What happens after the tray is placed in the patient's mouth?

<p>It is allowed to set (A)</p> Signup and view all the answers

What is a consequence of storing substances in hot water for an extended period?

<p>It can lead to leaching of important constituents. (D)</p> Signup and view all the answers

What materials are commonly used for final impressions in complete denture work?

<p>Zinc-oxide eugenol and impression plaster (D)</p> Signup and view all the answers

What is the recommended thickness for the acrylic tray used with the material?

<p>1.5 mm (A)</p> Signup and view all the answers

What happens when a compound is overheated in hot water?

<p>It becomes sticky and difficult to handle. (B)</p> Signup and view all the answers

Which type of tray is utilized for taking impressions of partially edentulous ridges?

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

Which impression materials are mentioned for use in stock trays?

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

Which important constituent is mentioned as being affected by leaching in hot water?

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

What is the percentage of dimensional changes during the setting of the material?

<p>0.06% (A)</p> Signup and view all the answers

What characteristic is NOT applicable to the type of stock tray used for taking impressions?

<p>Custom-fit for individual mouths (D)</p> Signup and view all the answers

What practice can help maintain the quality of a compound when using hot water?

<p>Minimizing the time the compound spends in hot water. (A)</p> Signup and view all the answers

Which of the following statements about the dimensional stability of the material is true?

<p>It maintains minimal dimensional changes during setting. (D)</p> Signup and view all the answers

When taking a final impression for complete dentures, which of the following is typically used?

<p>Zinc-oxide eugenol or impression plaster (C)</p> Signup and view all the answers

What type of tray is recommended for optimal use of the material?

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

To prevent the compound from becoming difficult to handle, what should be avoided?

<p>Overheating it during storage. (D)</p> Signup and view all the answers

How is the dimensional stability of the material quantitatively expressed during setting?

<p>0.06% (D)</p> Signup and view all the answers

How long is the mixing process supposed to last?

<p>60 seconds (A)</p> Signup and view all the answers

What tool is used to combine the strips during the mixing process?

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

At what point are the strips combined together?

<p>From the 1st sweep of spatula (A)</p> Signup and view all the answers

What is the next step after mixing the strips for about 60 seconds?

<p>Fill the mixture into a special tray (C)</p> Signup and view all the answers

How many strips are mentioned to be combined during the mixing process?

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

What is the primary role of resinous balsam in the mentioned mixture?

<p>To improve flow and mixing properties (C)</p> Signup and view all the answers

What does the chemical reaction of ZnO and eugenol produce?

<p>Zinc eugenolate and unreacted ZnO (C)</p> Signup and view all the answers

What is included in the set material after the reaction?

<p>An amorphous zinc eugenolate matrix (C)</p> Signup and view all the answers

What is the percentage of the coloring agent used in the mixture?

<p>5% (B)</p> Signup and view all the answers

What does the unreacted ZnO represent in the set material?

<p>A byproduct with no functional role (B)</p> Signup and view all the answers

Flashcards

Final Impression Technique (Full Dentures)

A final impression technique for full dentures using zinc oxide eugenol (ZOE) or impression plaster.

Stock Tray (Partially Edentulous)

A type of tray used to take impressions for partially edentulous arches.

Heavy Body Impression Material

A type of impression material used with stock trays for partially edentulous arches, known for its thick consistency.

Hydrocolloids or Elastomers (Light Body)

A type of impression material known for its fluidity, often used in custom trays for partially edentulous arches.

Signup and view all the flashcards

Hydrocolloids or Elastomers (Custom Tray)

Used in custom trays for partially edentulous arches, these materials are precise and can capture fine details.

Signup and view all the flashcards

Final Impression Technique

A process of creating a dental impression material by mixing water with powder, using a spatula to achieve a creamy consistency.

Signup and view all the flashcards

Rubber Bowl

A flexible, bowl-shaped container used to hold the impression material while it's mixed and prepared.

Signup and view all the flashcards

Trey

A flat, generally rigid tray used to carry the impression material into the patient's mouth.

Signup and view all the flashcards

Seating the Impression

The final step where the prepared impression material is placed within the patient's mouth, where it sets and captures a detailed impression.

Signup and view all the flashcards

Dental Impression Material

A type of dental material that becomes hard and rigid after mixing with water, allowing it to capture a precise replica of teeth and surrounding gum tissues.

Signup and view all the flashcards

Acrylic Tray

A tray made of acrylic with a spacer, typically 1-1.5 mm thick, used to hold impression material.

Signup and view all the flashcards

Dimensional Stability

The ability of a material to resist changes in its shape or size, especially due to temperature or moisture.

Signup and view all the flashcards

Dimensional Change

The amount of change in size or shape that a material experiences when it sets or hardens.

Signup and view all the flashcards

Low Dimensional Change

A very small percentage of change in size or shape during the setting process. For example, 0.06% means that for every 100 units, the material only changes by 0.06 units.

Signup and view all the flashcards

Why Low Dimensional Change is Important

A material that has a low dimensional change is preferred because it produces a more accurate impression, ultimately leading to a better fitting restoration.

Signup and view all the flashcards

Hot Water Storage

Storing dental materials in hot water for extended periods can lead to the loss of important components.

Signup and view all the flashcards

Stearic Acid

Stearic acid is an important ingredient in some dental materials.

Signup and view all the flashcards

Overheating Dental Materials

Excessive heat can cause dental materials to become sticky and difficult to work with.

Signup and view all the flashcards

Storage Conditions for Dental Materials

Dental materials should be stored in a cool and dry place to maintain their quality.

Signup and view all the flashcards

Leaching

The removal of valuable components from a material, often due to exposure to a solvent or heat.

Signup and view all the flashcards

Mixing Dental Impression Material

The process of combining two materials, usually a powder and a liquid, to create a usable dental impression material.

Signup and view all the flashcards

Mixing Time

A specific length of time, typically around 60 seconds, during which two components of a dental impression material are mixed together.

Signup and view all the flashcards

Special Tray

A flat, rigid tray used to hold and deliver the dental impression material into the patient's mouth.

Signup and view all the flashcards

First Sweep of Spatula

The initial step in creating a dental impression, where the two components of the impression material are combined using a spatula.

Signup and view all the flashcards

Combined Strips of Impression Material

The combination of two strips of dental impression material, likely a powder and a liquid, that are mixed to form a usable consistency.

Signup and view all the flashcards

What is Zinc Oxide Eugenol (ZOE)?

Zinc oxide eugenol (ZOE) is a type of dental impression material used for making final impressions. It sets to form a rigid replica of the teeth and gum tissues.

Signup and view all the flashcards

How does ZOE react?

The chemical reaction of ZOE involves zinc oxide (ZnO) and eugenol. When these two components mix with water, they form zinc eugenolate. This is a gelatinous substance that sets into a hard, stable impression.

Signup and view all the flashcards

What's the final structure of a ZOE impression?

In ZOE impressions, the final material consists of a mixture of zinc eugenolate, which holds unreacted zinc oxide particles together.

Signup and view all the flashcards

What does Resinous Balsam do?

Resinous balsam is an ingredient added to the mixture to improve the flow and mixing properties of ZOE, making it easier to work with.

Signup and view all the flashcards

Why are Coloring Agents added to ZOE?

Coloring agents are added to ZOE, typically in small amounts (5%), to provide a visual contrast for better visibility during the impression process.

Signup and view all the flashcards

Study Notes

Impression Materials

  • A dental impression is a negative record of the tissues in the mouth. It is used to create a positive reproduction of the teeth and surrounding structures.
  • A positive reproduction is made by pouring a suitable material (like dental stone) into the impression, allowing it to harden.
  • A single tooth reproduction is called a die, while several teeth or a whole arch is called a cast or model.
  • Impression material is placed in a tray, which can be a stock tray or a special tray.

Classification of Impressions

  • Preliminary impressions
  • Final impressions
  • Bite registrations

Impression Trays

  • Quadrant tray: Covers half of the arch.
  • Section tray: Covers the anterior portion of the arch.
  • Full arch tray: Covers the entire arch.
  • Perforated tray: Has holes to hold the impression material in place.
  • Smooth tray: The interior is coated with adhesive to hold the impression material.

Requirements of an Ideal Impression Material

  • Accurate reproduction of surface details, depending on low viscosity for soft tissue prevention of displacement.
  • Compatibility with moisture and saliva (hydrophilic).
  • Dimensional accuracy and stability, depending on the type of tray and material shrinkage.
  • Permanent set and storage stability.
  • Freedom from toxic or irritant constituents.
  • Easy manipulation, appropriate setting time, and adequate strength.
  • Compatibility with cast and die material.
  • Easy disinfection.

Key Properties

  • Accuracy: Ability to replicate intraoral surface details.
  • Dimensional stability: Ability to maintain its size over time.
  • Tear resistance: Ability to resist tearing.

Classification of Impression Materials (According to Elasticity)

  • Elastic materials: Return to their original shape after removal from the mouth. They can engage undercuts and are used in partially and fully edentulous patients.
  • Rigid materials: Do not return to their original shape. They cannot engage undercuts and are used for edentulous patients only.

Classification of Impression Materials (According to Setting Reaction)

  • Physical reaction (reversible, thermoplastic): Softens when heated and hardens when cooled (e.g., impression compound, agar, wax).
  • Chemical reaction (irreversible): Chemical changes occur during setting (e.g., impression plaster, zinc oxide eugenol, alginate, polysulfide, silicones, polyether).

Classification of Impression Materials (According to Reaction with Saliva)

  • Hydrophilic: Compatible with moisture and saliva, completely absorbing it.
  • Hydrophobic: Does not absorb saliva; saliva will repel off the surface.

Classification of Impression Materials (According to Viscosity Before Setting)

  • Mucostatic: Does not compress tissue during setting.
  • Mucocompressive: Compresses tissue during setting (more viscous).
  • Pseudo-plastic: Viscous materials that become fluid under low stress.

Methods of Making Impressions

  • Stock tray with pressure: Primary impressions for complete dentures using impression compound.
  • Resin custom tray without pressure: Final impressions for complete dentures using Zinc oxide-eugenol or impression plaster.
  • Stock tray (rim-lock, perforated or adhesive): Partially edentulous impressions using hydrocolloids or elastomers.
  • Custom Resin trays: Crown and bridge impressions or partial dentures, using regular or heavy/light body elastomers.

Impression Plaster

  • Presentation: Powder mixed with water (w/p=0.6).
  • Composition:Calcium sulfate beta hemihydrate, potassium sulfate, borax, pigments (like alizarin).

Starch in Impression Plaster

  • Added for easier separation of the cast from the impression.
  • Hot water softens the starch grains for easy separation.

Zinc Oxide-Eugenol

  • Reaction of zinc oxide and eugenol creates a hard mass, with mechanical and medical properties (used in certain dental fields).
  • Various types (I and II), with different setting times.

Impression Materials: Advantages and Disadvantages

  • Advantages:*
  • High accuracy for soft tissue impressions
  • Good surface detail reproduction
  • Inexpensive
  • Disadvantages:*
  • Messy material
  • Variable setting time (dependent on temperature and humidity)
  • Non-elastic, susceptible to fracture in undercuts
  • Eugenol is irritating to soft tissues.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Dental Materials Lecture 3 PDF

Description

This quiz covers essential techniques in dental impression making, focusing on the preparation and application of mixtures for final impressions in complete denture work. It addresses materials, tools used, and the effects of temperature on dental compounds. Test your knowledge on the important steps and considerations in this crucial dental procedure.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser