Final Impression in Prosthodontics Lecture Quiz
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Questions and Answers

What is the primary purpose of using a light consistency impression material?

  • To inject over the prepared teeth and remaining dental arch (correct)
  • To act as a catalyst for the base material
  • To provide a heavy consistency for the final impression
  • To use as a tray material for seating the final impression

    • What is the main advantage of polysulfide impression materials?

  • Long working time for multiple preparations (correct)
  • Excellent dimensional stability after setting
  • Minimal shrinkage towards the tray
  • Short working time for single preparations

    • Which statement about polyether impression materials is true?

  • They are supplied as a single paste system
  • They have excellent dimensional stability upon polymerization (correct)
  • They have poor dimensional stability upon polymerization
  • They are recommended for use with a spacer-less tray

    • What is a disadvantage of polysulfide impression materials?

    <p>Objectionable odor and messiness</p> Signup and view all the answers

    Which impression material is recommended for use with a special tray with a 4 mm spacer?

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

    What is the recommended method for removing a polysulfide impression from the mouth?

    <p>Single swift pull</p> Signup and view all the answers

    Which statement about polysulfide impression materials is true?

    <p>They exhibit dimensional stability after setting</p> Signup and view all the answers

    What is the recommended viscosity of impression material to use as a tray material during the final impression procedure?

    <p>Putty or heavy body</p> Signup and view all the answers

    What is the main advantage of the Direct (intra oral) digital impression method?

    <p>It eliminates the need for taking a physical impression and fabricating a cast.</p> Signup and view all the answers

    What is the primary disadvantage of the Direct (intra oral) digital impression method?

    <p>Tongue and saliva may pose problems during scanning.</p> Signup and view all the answers

    What is the term used to describe the process of fabricating a restoration using digital impression data and CAD/CAM technology?

    <p>CAD-CAM</p> Signup and view all the answers

    In the context of digital impressions, what does the acronym 'CAD' stand for?

    <p>Computer Aided Designing</p> Signup and view all the answers

    Which system is mentioned in the text as being widely used for Direct (intra oral) digital impressions?

    <p>Cerec System</p> Signup and view all the answers

    What is the term used to describe the process of capturing a digital impression directly from the prepared tooth?

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

    Where can the digital impression data be transferred after capture?

    <p>Either to an in-office CAD/CAM system or an external lab CAD/CAM facility</p> Signup and view all the answers

    What is the term used to describe the method of taking a physical impression and fabricating a cast?

    <p>The text does not provide a term for this method</p> Signup and view all the answers

    What is the first step in the spaced putty-wash impression technique?

    <p>Take a putty impression of the dental arch before tooth preparation</p> Signup and view all the answers

    How is the space created inside the putty impression for the wash (light body) layer?

    <p>By using a polyethylene spacer placed over the putty</p> Signup and view all the answers

    What is the purpose of creating a space inside the putty impression?

    <p>To create a reservoir for the wash (light body) impression material</p> Signup and view all the answers

    What is the difference between an unspaced putty impression and a spaced putty impression?

    <p>An unspaced putty impression does not have a space for the wash layer, while a spaced putty impression does</p> Signup and view all the answers

    When should the putty impression be taken in relation to tooth preparation?

    <p>The putty impression can be taken either before or after tooth preparation</p> Signup and view all the answers

    What is the purpose of the wash (light body) impression material in this technique?

    <p>To provide a more accurate impression of the prepared tooth or teeth</p> Signup and view all the answers

    What is the purpose of using a polyethylene spacer in the spaced putty impression technique?

    <p>To create a space for the wash (light body) impression material</p> Signup and view all the answers

    What is the difference between the spaced putty impression technique and the unspaced putty impression technique?

    <p>The spaced technique involves creating a space for the wash layer, while the unspaced technique does not</p> Signup and view all the answers

    What does the image on the monitor show?

    <p>If all the needed details have been captured before sending to the lab</p> Signup and view all the answers

    What allows the laboratory technician to fabricate a restoration with excellent marginal fit and accurate occlusion?

    <p>The accuracy of mounting, bite registration, and die stability</p> Signup and view all the answers

    What advantage of digital impressions is mentioned in the text?

    <p>The ability to see if proper occlusal reduction has been achieved</p> Signup and view all the answers

    How are digital impressions stored according to the text?

    <p>On PCs</p> Signup and view all the answers

    What issue is eliminated with a digital impression system?

    <p>The need for disinfection of impressions</p> Signup and view all the answers

    What is a disadvantage of digital impression systems mentioned in the text?

    <p>The large size and weight of the camera head</p> Signup and view all the answers

    What is required to operate and maintain a digital impression system according to the text?

    <p>A trained operator</p> Signup and view all the answers

    What is mentioned as a disadvantage of digital impression systems in the text?

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

    What is the main purpose of a conventional impression in crown and bridge prosthodontics?

    <p>To provide an exact duplication of the prepared tooth and surrounding oral tissues</p> Signup and view all the answers

    Why is it important for an impression in crown and bridge prosthodontics to include uncut tooth surface beyond the preparation?

    <p>To allow for proper contouring of the restoration</p> Signup and view all the answers

    What role does the hydrophilicity of impression material play in crown and bridge prosthodontics?

    <p>It allows good surface wetting and high surface detail</p> Signup and view all the answers

    Why must the impression material used for crowns and bridges be elastic?

    <p>To allow for easy removal from undercut regions on the tooth</p> Signup and view all the answers

    The spacer is removed before taking the putty impression in the spaced putty-wash technique.

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

    In the unspaced putty-wash technique, a space is created after teeth preparation.

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

    The light body impression material is injected before the heavy body impression material in the putty-wash technique.

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

    A spacer is used when taking impressions for post crowns to facilitate insertion into tiny canals.

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

    The light body impression material is removed from the patient's mouth before it is completely set.

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

    Impression materials for crowns and bridges need to be rigid to prevent distortion during removal.

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

    The putty impression should not include uncut tooth surfaces beyond the preparation.

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

    Digital impressions are typically stored in physical storage units according to the text.

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

    In crown and bridge prosthodontics, a good impression should only include the prepared tooth without considering the surrounding teeth and tissues.

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

    Bubble-free impressions are crucial in crown and bridge work to ensure accuracy, especially at the area of the finish line.

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

    The material used for final impressions in crown and bridges should not be elastic after placement in the mouth.

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

    Hydrophilic impression materials have a low affinity for moisture and do not provide good surface wetting.

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

    Digital impressions are stored in physical trays according to the text.

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

    Polysulfide impression materials are not suitable for crown and bridge prosthodontics.

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

    A light body impression material is primarily used for creating the main body of the impression in crown and bridge work.

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

    Accurate articulation of the cast is not important when taking impressions for crown and bridge prosthetics.

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

    A plastic post can be used as reinforcement for the impression material.

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

    Air bubble presence in the area of preparation is not a concern when inspecting the impression.

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

    To obtain a good final impression, a wet field of operation is recommended.

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

    Digital impressions represent an outdated development in Dentistry.

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

    Digital impressions convert the shape of prepared teeth into two-dimensional images.

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

    Hydrocolloids are hydrophobic and displace moisture.

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

    The main purpose of using a light consistency impression material is to create voids in the impression.

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

    A special tray is not required when obtaining a good final impression.

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

    Polyether and hydrophilic addition silicon impression materials should be submerged in a glutaraldehyde solution for disinfection.

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

    Impression material should be immediately rinsed with tap water after removal from the patient's mouth.

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

    It is necessary to follow the manufacturer's recommendations when using disinfecting solutions or sprays on impression material.

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

    All impression materials come in contact with body fluid when removed from the patient's mouth.

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

    Glutaraldehyde Solution 10 should not be used for disinfection of impression materials.

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

    Disinfecting impression materials for too long can lead to dimensional and surface changes, affecting accuracy in dies and models.

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

    Polyether and hydrophilic addition silicon impression materials are not suitable for being sprayed and stored in a plastic bag for disinfection.

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

    The impression material used for crowns and bridges should not be elastic.

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

    CAD-CAM stands for Computer Aided Designing - Computer Aided Milling.

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

    CAD/CAM systems consist of scanning, designing, and casting phases.

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

    Digital scanning can be divided into Direct (intra oral) and Indirect (extra oral) digital impressions.

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

    The introduction of CAD/CAM systems to dental field was in the 1990s.

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

    Indirect digital impression systems scan a stone cast or die of the prepared tooth in the patient's mouth.

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

    Direct digital impression systems require the dental technician to add porcelain for individualization of restorations.

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

    Master cast fabrication is a quick and error-free method in digital scanning.

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

    CAD CAM systems eliminate the need for preparation of abutment teeth in traditional impression techniques.

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

    Study Notes

    Impression Materials and Techniques

    • Shadowing effect limits the use of extra-oral digitization methods.
    • Direct (intra-oral) digital impression:
      • Uses an intra-oral camera (scanner) to capture the desired image (optical impression).
      • Transfers the image electronically to CAD/CAM for fabrication.
      • Advantages: takes data directly from prepared tooth, eliminates need for impression and cast fabrication.
      • Disadvantage: tongue and saliva may pose problems.
    • Polysulfide impression material:
      • Supplied as a two-paste system (base and catalyst).
      • Available in various viscosities (light, medium, heavy).
      • Advantages: accurate, long working time, excellent tear resistance.
      • Disadvantages: messy, objectionable odor, long setting time, shrinkage towards tray.
    • Polyether impression material:
      • Excellent dimensional stability.
      • Techniques: spaced putty impression, un-spaced putty impression.
      • Advantages: high accuracy, minimal distortion.
      • Disadvantages: complex procedure, operator skill required.

    Digital Impression

    • Advantages:
      • Allows for single-appointment restoration fabrication.
      • Eliminates impression fabrication and disinfection steps.
      • Enables digital record-keeping and storage.
      • Reduces chairside time.
    • Disadvantages:
      • Large camera size and weight.
      • Complex equipment requires trained operator.
      • High cost.

    Conventional Impression

    • Requirements for a good impression in crown and bridge prosthodontics:
      • Accurate duplication of prepared tooth and surrounding tissues.
      • Bubble-free impression.
      • Registration of undercut surfaces without distortion or fracture.
    • Properties of material used for final impression in crowns and bridges:
      • Elastic after placement in the mouth.
      • Hydrophilicity for good surface wetting and detail.

    Impression Procedure

    • Spaced putty wash technique:
      • Record putty impression of dental arch, including prepared tooth.
      • Create space inside impression using a spacer or scalpel.
      • Mix light body impression material and inject around preparation and dental arch.
    • Un-spaced putty wash technique:
      • Record putty impression after teeth preparation.
      • No space creation, direct injection of light body material.

    Post-Crown Impression

    • Requires impression for root canal space.
    • Difficulty in inserting and removing impression material from canal.
    • Use of reinforcement (plastic post or stainless wire) to support impression material.

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    Description

    Test your knowledge on final impressions in prosthodontics, focusing on conventional and digital impression techniques. Learn about the requirements for a good impression in crown and bridge prosthodontics.

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