Dental Materials: Impression Materials
40 Questions
0 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 is the primary function of the special water cooled perforated tray?

  • To store the material for up to 24 hours
  • To cool the gel to 43°C
  • To circulate cold water at 20°C (correct)
  • To heat the gel to 100°C

    • What is the advantage of using this material in terms of dimensional stability?

  • It is dimensionally stable during storage
  • It is dimensionally unstable due to syneresis and imbibition (correct)
  • It is stable for up to 24 hours
  • It can be electroplated

    • What is the purpose of heating the gel to 100°C?

  • To melt the agar
  • To create a reversible hydrocolloid (correct)
  • To temper the gel
  • To cool the gel

    • What is the composition of the gel?

    <p>85% water and 15% agar</p> Signup and view all the answers

    What is the elasticity of the material?

    <p>It is viscoelastic with 98.8% elastic recovery</p> Signup and view all the answers

    What is the purpose of the syringe and tray?

    <p>To manipulate and set the reaction</p> Signup and view all the answers

    What type of impression is Plaster of Paris classified as?

    <p>Non-elastic impression</p> Signup and view all the answers

    What is the disadvantage of the material in terms of storage?

    <p>It is dimensionally unstable due to syneresis and imbibition</p> Signup and view all the answers

    What is the application of alginate impression material?

    <p>Primary impression</p> Signup and view all the answers

    Which impression material is hydrophobic?

    <p>Polysulfide and addition silicone</p> Signup and view all the answers

    What type of impression is classified according to the mode of setting?

    <p>Thermoset and Thermoplastic</p> Signup and view all the answers

    What is the main characteristic of Non-elastic impressions?

    <p>They fracture or are permanently deformed on removal</p> Signup and view all the answers

    Which impression material is used for edentulous patients without bony undercut?

    <p>Plaster of Paris</p> Signup and view all the answers

    What is the primary application of impression plaster?

    <p>To make secondary impressions for edentulous patients without bony undercut</p> Signup and view all the answers

    What type of impression is classified according to the interaction of the material with water and moisture?

    <p>Hydrophobic and Hydrophilic</p> Signup and view all the answers

    Which impression material is an example of Thermoplastic impression?

    <p>Impression compound</p> Signup and view all the answers

    What is the composition of impression plaster?

    <p>β Ca SO₄.½ H₂O and water</p> Signup and view all the answers

    What is the main characteristic of Elastic impressions?

    <p>They recover their original shape after removal</p> Signup and view all the answers

    What is the setting time for impression plaster?

    <p>5 minutes</p> Signup and view all the answers

    What is a disadvantage of using impression plaster?

    <p>It absorbs water, causing dry mouth sensation</p> Signup and view all the answers

    Why is a separating medium required when using impression plaster?

    <p>To separate the plaster from the stone cast</p> Signup and view all the answers

    What is the dimensional stability of impression plaster?

    <p>0.06% change on setting</p> Signup and view all the answers

    What type of impression material is impression compound?

    <p>Rigid, reversible impression material</p> Signup and view all the answers

    What is a characteristic of impression compound?

    <p>It has thermoplastic properties</p> Signup and view all the answers

    What is the process that occurs when a low Mw polymer is mixed with a suitable reactor at room temperature?

    <p>Polymerization</p> Signup and view all the answers

    What is the main difference between hydrophilic and hydrophobic impressions?

    <p>Their wetting properties to soft tissues and gypsum material</p> Signup and view all the answers

    Which type of elastomer can be electroplated?

    <p>All of the above except polyether</p> Signup and view all the answers

    What is an advantage of elastomers over hydrocolloids?

    <p>Higher dimensional stability in storage</p> Signup and view all the answers

    What is the application of polysulfide impression materials?

    <p>Secondary full mouth, quadrant, or single impressions</p> Signup and view all the answers

    What is the result of polymerization of a low Mw polymer?

    <p>Increase in molecular weight</p> Signup and view all the answers

    What is a characteristic of hydrophobic impressions?

    <p>Decreased wetting to soft tissues and gypsum material</p> Signup and view all the answers

    What is a type of elastomer?

    <p>Polysulfide</p> Signup and view all the answers

    What is the primary function of an impression material?

    <p>To create a replica of the oral tissues</p> Signup and view all the answers

    What is the purpose of using an impression tray?

    <p>To carry the impression in its plastic form</p> Signup and view all the answers

    What is the ideal property of an impression material in terms of its setting time?

    <p>It should have a suitable setting time</p> Signup and view all the answers

    What is the purpose of step 7 in the impression process?

    <p>To disinfect the impression</p> Signup and view all the answers

    What is the term for the areas under the inclined planes?

    <p>Under cut</p> Signup and view all the answers

    What is the purpose of using a vibrator during impression mixing?

    <p>To remove air bubbles from the mixture</p> Signup and view all the answers

    What is the ideal property of an impression material in terms of its mechanical properties?

    <p>It should have acceptable strength to withstand forces</p> Signup and view all the answers

    What is the step that follows impression disinfection in the impression process?

    <p>Mixing gypsum materials</p> Signup and view all the answers

    Study Notes

    Impression Materials

    • Impression material is used to record the shape and dimensions of oral tissues.

    Impression Trays

    • Impression trays are used to carry the impression material in its plastic form to be inserted into the patient's mouth and removed after setting.

    Steps of Impression Taking

      1. Tray selection
      1. Impression mixing
      1. Hand mixing and vibrating
      1. Loading the impression into the tray
      1. Insertion of the impression into the patient's mouth
      1. Removal of the impression from the patient's mouth after setting
      1. Impression disinfection

    Ideal Properties of Impression Materials

      1. Non-toxic, non-irritant, and insoluble in oral fluids
      1. Pleasant odor, taste, and color
      1. Suitable setting time
      1. Good reproduction of fine details (good wetting of oral tissues)
      1. Minimal dimensional changes on setting
      1. Dimensional stability after setting
      1. Compatibility with model and die materials
      1. Adequate mechanical properties
      1. Adequate shelf life
      1. Reasonable cost

    Classifications of Dental Impressions

    • I. According to the mode of setting:
    • Thermoset impressions (hardening by irreversible chemical reaction)
    • Thermoplastic impressions (softening and hardening by reversible physical reaction)
    • II. According to behavior after setting:
    • Non-elastic (rigid) impressions
    • Elastic impressions
    • III. According to the interaction of the material with water and moisture:
    • Hydrophobic impressions
    • Hydrophilic impressions

    Impression Materials

    • Rigid impressions:
      • Impression Plaster
      • Impression Compound
      • Zinc Oxide and Eugenol (ZnO/E)
    • Elastic impressions:
    • Hydrocolloids
    • Elastomers + Polysulfide + Condensation silicone + Addition silicone + Polyether

    Rigid Impression Materials

    • Definition: Materials that cannot record undercut areas
      1. Impression Plaster
    • Used for edentulous patients without bony undercuts
    • Used for occlusal bite registration
    • Has good dimensional stability (0.06% change on setting)
    • Requires a separating medium
      1. Impression Compound
    • Definition: Rigid impression material that sets by a physical reaction
    • Composition: Natural resin and waxes
    • Presentation: Gel in sealed tubes or jar
    • Manipulation and setting reaction: Reversible hydrocolloid, physical reaction
    • Has thermoplastic properties

    Hydrocolloids

    • Definition: Impression material that sets by a physical reaction
      1. Agar
    • Composition: Natural polymer extract from seaweeds
    • Presentation: Powder to be mixed with water
    • Manipulation and setting reaction: Reversible hydrocolloid, physical reaction
      1. Alginate
    • Application: Primary impression
    • Presentation: Powder to be mixed with water
    • Composition: Natural marine plant
    • Polymerization: Low Mw polymer + reactor → high Mw

    Elastomers

    • Definition: Rigid impression material that sets by a chemical reaction
      1. Polysulfide
    • Consistency: Light, Medium, Heavy, Putty
    • Chemistry: Low Mw polymer + reactor → high Mw
      1. Condensation silicone
    • Consistency: Light, Medium, Heavy, Putty
      1. Addition silicone
    • Consistency: Light, Medium, Heavy, Putty
    • Hydrophilic properties
      1. Polyether
    • Consistency: Light, Medium, Heavy

    Advantages of Elastomers over Hydrocolloids

    • Higher tear strength
    • More dimensionally stable in storage
    • Ability to be electroplated (except polyether)
    • Compatible with model and die materials

    Hydrophilic and Hydrophobic Impression Materials

    • Hydrophilic: Proper wetting to the soft tissues and gypsum material
    • Hydrophobic: Decreased wetting to the soft tissues and gypsum material, can be electroplated

    Studying That Suits You

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

    Quiz Team

    Description

    Learn about impression materials used in dentistry to record the shape and dimensions of oral tissues. Understand the different types of impression trays and their uses.

    More Like This

    Dental Impression Materials
    91 questions

    Dental Impression Materials

    FortuitousMagnesium avatar
    FortuitousMagnesium
    Dental Impression Materials
    8 questions

    Dental Impression Materials

    SereneTransformation avatar
    SereneTransformation
    Dental Impression Materials Quiz
    10 questions

    Dental Impression Materials Quiz

    MesmerizingMeteor avatar
    MesmerizingMeteor
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser