Dental Biomaterials II - Impression Materials Definitions
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Questions and Answers

What is the primary purpose of a dental impression?

  • To construct a custom tray for impression materials
  • To accurately record the dimensions of oral tissues (correct)
  • To record the fine details of the oral structures
  • To create a positive replica of the oral tissues

    • Which type of impression does not register fine details?

  • Special tray impression
  • Primary impression (correct)
  • Stock tray impression
  • Secondary impression

    • What is the main function of a dental tray in the context of impressions?

  • To carry the impression materials into the patient’s mouth (correct)
  • To record the fine details of oral structures
  • To provide support to oral tissues
  • To create a negative replica of teeth

    • Which material is predominantly used to make stock trays for primary impressions?

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

    What is a characteristic requirement of ideal impression materials?

    <p>Compatibility with die materials</p> Signup and view all the answers

    Among the properties listed, which is NOT a requirement for ideal impression materials?

    <p>High flow properties</p> Signup and view all the answers

    What is the purpose of Type II tray compound in dentistry?

    <p>Act as a support for other impression materials</p> Signup and view all the answers

    What is the composition of Type II tray compound mainly made of in terms of percentage?

    <p>40% resin and 7% waxes</p> Signup and view all the answers

    Which statement best describes the reaction of Type II tray compound upon heating and cooling?

    <p>Softens upon heating and hardens upon cooling</p> Signup and view all the answers

    How is Type II tray compound manipulated for use?

    <p>Softening, loading into the stock tray, followed by insertion, cooling, and impression removal</p> Signup and view all the answers

    What is the role of filler in Type II tray compound?

    <p>To provide body and suitable working consistency</p> Signup and view all the answers

    How does Type II tray compound differ from acrylic special tray?

    <p>Type II tray compound is a modeling or tracing material, while acrylic special tray is a support material</p> Signup and view all the answers

    Which statement about the thermal properties of impression compounds is correct?

    <p>They have low thermal conductivity and a high coefficient of thermal expansion.</p> Signup and view all the answers

    Which of the following is NOT a cause of warpage in impression compounds?

    <p>Pouring the impression immediately after removal from the mouth</p> Signup and view all the answers

    Which property of impression compounds is desirable for their manipulation?

    <p>Thermoplastic behavior and sufficient flow at elevated temperatures</p> Signup and view all the answers

    What is the recommended technique for softening impression compound sticks?

    <p>Holding them above a flame and then tempering in air or warm water</p> Signup and view all the answers

    Which of the following is NOT an advantage of impression compounds?

    <p>Can reproduce undercuts</p> Signup and view all the answers

    What is a potential hygiene concern with the use of impression compounds?

    <p>Reusing them without proper disinfection can lead to cross-contamination.</p> Signup and view all the answers

    What is the primary function of the inert oil in the base paste of zinc oxide eugenol (ZOE) impression material?

    <p>To act as a plasticizer and mask the action of eugenol</p> Signup and view all the answers

    What is the role of the catalyst paste (accelerator or reactor) in the setting reaction of ZOE impression material?

    <p>It facilitates the formation of the zinc eugenolate chelate</p> Signup and view all the answers

    What is the primary chemical reaction involved in the setting of ZOE impression material?

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

    Which statement about the manipulation of ZOE impression material is correct?

    <p>Mixing can be accomplished in 30-45 seconds until a homogenous mix is formed</p> Signup and view all the answers

    What is the primary function of zinc acetate, $MgCl_2$, or $CaCl_2$ in the catalyst paste of ZOE impression material?

    <p>To act as a catalyst (accelerator) for the setting reaction</p> Signup and view all the answers

    Which statement about the working time of ZOE impression material is correct?

    <p>The working time is shortened by the presence of water</p> Signup and view all the answers

    What is the initial setting time for Zinc Oxide Eugenol (ZOE) impression paste?

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

    How does water, high humidity, and high temperature affect the setting time of ZOE impression material?

    <p>Shorten the setting time</p> Signup and view all the answers

    What is a factor that accelerates the reaction and setting time of ZOE impression paste?

    <p>Adding a drop of water</p> Signup and view all the answers

    What is a correct statement about the dimensional changes of ZOE impression material?

    <p>Dimensional changes during setting are 0.1%</p> Signup and view all the answers

    What is a common use of ZOE impression paste?

    <p>Final impression for edentulous patients using border molded acrylic special tray</p> Signup and view all the answers

    What material is often used as the model material for ZOE impressions?

    <p>Gypsum products</p> Signup and view all the answers

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