Dental Impression Materials Chapter 46
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Questions and Answers

What is a colloid?

  • A gelatinous material used to obtain impressions (correct)
  • A solid material used to create molds
  • A type of metal used in dental tools
  • A liquid with no viscosity

    • What is the process of border molding?

    The process of using your fingers to achieve a closer adaption of the edges of an impression.

    What are elastomeric materials?

    Materials with elastic properties and are made from rubber.

    What is the base in relation to impression materials?

    <p>The foundation or basic ingredient of a material.</p> Signup and view all the answers

    What does 'centric' mean in dental terms?

    <p>To have something centered, such as your maxillary teeth centered over your mandibular teeth.</p> Signup and view all the answers

    What is agar?

    <p>A gelatin type material derived from seaweed.</p> Signup and view all the answers

    What is syneresis?

    <p>The loss of water causing shrinkage.</p> Signup and view all the answers

    What does tempering refer to?

    <p>To bring a material to a desired temperature and consistency.</p> Signup and view all the answers

    What does viscosity describe?

    <p>A property of fluids with a high resistance to flow.</p> Signup and view all the answers

    What is alginate known for in dentistry?

    <p>The material of choice in dentistry for preliminary impressions.</p> Signup and view all the answers

    What is hysteresis in the context of materials?

    <p>To transform a material from one physical state to another.</p> Signup and view all the answers

    What does 'hydro' refer to?

    <p>Water.</p> Signup and view all the answers

    What is occlusal registration?

    <p>A reproduction of someone's bite with the use of wax to elastomeric material.</p> Signup and view all the answers

    What is a catalyst?

    <p>A substance that modifies or increases the rate of a chemical reaction.</p> Signup and view all the answers

    What is imbibition?

    <p>The absorption of water, causing an object to swell.</p> Signup and view all the answers

    What is a negative reproduction?

    <p>An impression is considered a negative reproduction.</p> Signup and view all the answers

    What is bite registration?

    <p>Type of impression used by a dental lab tech for occlusal relationship.</p> Signup and view all the answers

    What is a quadrant in dental impressions?

    <p>A type of stock tray that covers half the arch.</p> Signup and view all the answers

    What does perforated refer to in impression trays?

    <p>Type of tray which allows impression material to mechanically lock on.</p> Signup and view all the answers

    What is a custom tray?

    <p>Constructed to fit the mouth of a specific patient.</p> Signup and view all the answers

    What is rope wax used for?

    <p>Used to extend the length of a tray to accommodate third molars.</p> Signup and view all the answers

    What is seaweed in the context of dental materials?

    <p>Organic substance of hydro colloid material.</p> Signup and view all the answers

    What is a strong gag reflexive?

    <p>Reason for using a fast set alginate for preliminary impression.</p> Signup and view all the answers

    What is the ratio for a maxillary impression?

    <p>3 scoops of water to 3 scoops of powder.</p> Signup and view all the answers

    What is alginate also known as?

    <p>Irreversible hydrocolloid.</p> Signup and view all the answers

    What is a mixing bowl used for?

    <p>Used to mix irreversible hydrocolloid.</p> Signup and view all the answers

    What is a conditioning bath?

    <p>Reversible hydrocolloid material is placed in what before the impression is taken.</p> Signup and view all the answers

    What type of impression do elastomeric materials create?

    <p>Final impression.</p> Signup and view all the answers

    What are the ways elastomeric materials are supplied?

    <p>Paste, cartridge, putty.</p> Signup and view all the answers

    What is light body material?

    <p>Type of viscosity of a final impression material that is applied first to the prepared tooth or teeth.</p> Signup and view all the answers

    What is a rubber base also known as?

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

    What does an extruder with tip or COE syringe do?

    <p>Dentist uses these to express the light body impression material around a prepared tooth.</p> Signup and view all the answers

    What is an automix system?

    <p>System which accomplishes the mixing of final impression material for the assistant.</p> Signup and view all the answers

    What is baseplate wax?

    <p>The material universally used for taking a bite registration.</p> Signup and view all the answers

    What tray type is most commonly selected when polysiloxane bite registration material is used?

    <p>Gauze tray.</p> Signup and view all the answers

    What should baseplate wax be done before placement in the patient's mouth?

    <p>Warmed.</p> Signup and view all the answers

    What should a dental assistant be doing while the dentist is dispensing the syringe material around the prepared tooth?

    <p>Readying the tray with heavy body material.</p> Signup and view all the answers

    What should be done to a preliminary impression before transport to the lab?

    <p>Rinsed, disinfected, wrapped in a moist paper towel, and placed in a precautionary bag.</p> Signup and view all the answers

    What are the three classifications of impressions?

    <p>Preliminary, final, occlusal aka bite registrations.</p> Signup and view all the answers

    Who takes preliminary impressions?

    <p>Dentist or EFDA/RDA.</p> Signup and view all the answers

    What are preliminary impressions used for?

    <p>Diagnostic models, custom trays, provisional coverage, orthodontic appliances, pretreatment and post-treatment records.</p> Signup and view all the answers

    Who takes bite registrations?

    <p>Dentist or EFDA/RDA.</p> Signup and view all the answers

    What do bite registrations provide?

    <p>The dentist or lab technician with an accurate registration of the patient's centric relationship between the maxillary and mandibular arches.</p> Signup and view all the answers

    What is the purpose of impression trays?

    <p>Used to hold impression materials within the mouth.</p> Signup and view all the answers

    Why are impression trays sufficiently rigid?

    <p>Carry material into oral cavity, hold the material close to the teeth, avoid reading during removal, prevents warping the completed impression.</p> Signup and view all the answers

    What are the basic types of impression trays?

    <p>Stock, custom.</p> Signup and view all the answers

    What is utility wax used for?

    <p>Depth or length of the tray can be extended by adding wax to the border of the tray.</p> Signup and view all the answers

    When should utility wax be added to trays?

    <p>When the tray does not completely cover the posterior teeth or when a patient has an unusually hard palate.</p> Signup and view all the answers

    What is alginate also known as?

    <p>Irreversible hydrocolloid.</p> Signup and view all the answers

    What is the most common way alginate is purchased?

    <p>Containers about the size of coffee cans.</p> Signup and view all the answers

    What are premeasured, individual packages of alginate?

    <p>More expensive but save time by eliminating the need for measurement of the powder.</p> Signup and view all the answers

    What changes can alginate have?

    <p>Flavoring and color changes when set.</p> Signup and view all the answers

    What is the shelf life of alginate?

    <p>1 year.</p> Signup and view all the answers

    What conditions can cause alginate to deteriorate quickly?

    <p>Exposed to elevated temperatures and moisture.</p> Signup and view all the answers

    What are the types of alginate setting?

    <p>Normal, fast.</p> Signup and view all the answers

    What is the best temperature of water used for mixing alginate?

    <p>Room temperature (21°C or 70°F).</p> Signup and view all the answers

    What happens when using cooler water for mixing alginate?

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

    What happens when using warmer water for mixing alginate?

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

    How should alginate impressions be explained to patients?

    <p>The material will feel cool, there is no unpleasant taste, and it will set quickly.</p> Signup and view all the answers

    What can help the patient relax and be more comfortable during the procedure?

    <p>Breathing deeply through the nose.</p> Signup and view all the answers

    Where should the impression tray be centered?

    <p>Over the central and lateral incisors.</p> Signup and view all the answers

    What are specific criteria for evaluating an alginate impression?

    <p>Should be centered over incisors, complete peripheral roll, not overseated, free from tears or voids, and sharp anatomical detail is provided.</p> Signup and view all the answers

    What does overseating result in?

    <p>Overexposure of areas to the impression trays.</p> Signup and view all the answers

    What is reversible hydro colloid made of?

    <p>Approximately 85% water and 13% agar.</p> Signup and view all the answers

    What are specialized conditioning baths used for?

    <p>To change reversible hydro colloid material from one consistency to another.</p> Signup and view all the answers

    What is the first bath used for?

    <p>For liquefying the semi-solid material.</p> Signup and view all the answers

    What is the second bath for in reversible hydro colloid?

    <p>Becomes a storage bath that cools the material readying it for the impression.</p> Signup and view all the answers

    What is the third temperature kept at in separate bath?

    <p>110°F for tempering the material after it has been placed in the tray.</p> Signup and view all the answers

    When are elastomeric materials used?

    <p>When an accurate impression is essential.</p> Signup and view all the answers

    What does 'elastomeric' mean?

    <p>Having elastic or rubber-like qualities.</p> Signup and view all the answers

    What is polymerization?

    <p>Curing reaction that begins as soon as the base and catalyst are brought together.</p> Signup and view all the answers

    What happens during the first set in the curing reaction?

    <p>Results in the stiffening of the paste without appearance of elastic properties.</p> Signup and view all the answers

    What occurs during the final set of the curing reaction?

    <p>Begins with the appearance of elasticity and proceeds through a gradual change to a solid, rubbery mass.</p> Signup and view all the answers

    What is the final cure in the context of curing reactions?

    <p>Occurs within 1 to 24 hours with only a slight dimensional change noted.</p> Signup and view all the answers

    What are some mixing techniques used for impression materials?

    <p>There are many different mixing techniques used for use with impression material.</p> Signup and view all the answers

    What is the most common mixing sequence?

    <p>Preparing the light bodied material first followed by the heavy bodied material.</p> Signup and view all the answers

    What is the mixing unit system?

    <p>Controlled dispensing that ensures no excess material remains and aids in infection control.</p> Signup and view all the answers

    What is polysiloxane bite registration paste?

    <p>One of the most popular materials used for bite registrations supplied as a paste system in cartridges.</p> Signup and view all the answers

    What is zinc oxide eugenol bite registration paste?

    <p>Aka ZOE, used when a more durable material is needed for bite registrations.</p> Signup and view all the answers

    Study Notes

    Impression Materials Overview

    • Colloid refers to a gelatinous material specifically utilized for obtaining impressions in dental practice.
    • Border molding is the technique of manipulating the edges of an impression for better adaptation using fingers.
    • Elastomeric materials have rubber-like elastic properties and are crucial for accurate dental impressions.
    • The term "base" indicates the foundational component or primary ingredient of a material used in impressions.

    Dental Terminology

    • Centric describes the positioning where maxillary teeth align over mandibular teeth.
    • Agar is a type of hydrocolloid material derived from seaweed, often used in impressions.
    • Syneresis is the phenomenon where a material loses water, leading to shrinkage.
    • Tempering is the process of adjusting a material to a specific temperature and consistency.
    • Viscosity characterizes the resistance of fluids to flow, impacting how impressions behave.

    Types of Materials and Impressions

    • Alginate is the preferred material for preliminary impressions in dental settings, categorized as irreversible hydrocolloid.
    • Hysteresis refers to the phase change of a material from one physical state to another.
    • Occlusal registration captures the bite with wax or elastomeric materials and is essential for dental technicians.

    Processing and Usage

    • Catalyst speeds up the chemical reaction in materials used for impressions.
    • Imbibition indicates the absorption of water leading to swelling in materials.
    • A negative reproduction occurs when an impression captures the shape of the oral structures.
    • Impression trays hold impression materials in place and come in stock or custom types.

    Types of Trays

    • Quadrant trays cover half of the dental arch and can be perforated for better material adherence.
    • Custom trays are tailored to fit individual patients, enhancing the quality of the impression.
    • Utility wax extends the length of trays for accommodating dental structures like third molars.
    • Impression trays must be sufficiently rigid to carry materials into the oral cavity without distortion.

    Guidelines for Alginate Use

    • Alginate can be premeasured and packaged to save preparation time and ensure accuracy.
    • The optimal mixing ratio for a maxillary impression is three scoops of water to three scoops of powder.
    • Refrigeration and exposure to moisture can quickly deteriorate alginate, leading to improper setting.
    • Alginate typically maintains a shelf life of around one year.

    Temperature Influence on Setting

    • Mixing alginate with water at room temperature (21°C or 70°F) is ideal.
    • Cooler water increases setting time, whereas warmer water reduces it, impacting the impression process.
    • Patients may experience the cooling sensation of alginate during the impression process, which is generally non-offensive.

    Evaluation of Impressions

    • Key criteria for evaluating alginate impressions include:
      • Proper centering over incisors.
      • Complete peripheral roll capturing vestibular areas.
      • Absence of overseating, tears, or voids.
      • Accurate reproduction of anatomical details like frenums and ridges.

    Reversible Hydrocolloid Materials

    • Composed primarily of water and agar (~85% water, 13% agar).
    • Specialized conditioning baths transition reversible hydrocolloid from one consistency to another for accurate impressions.

    Elastomeric Materials and Their Properties

    • Elastomeric materials are key for cases where precise impressions are required; they exemplify rubber-like elasticity.
    • Polymerization is the curing reaction that changes the material from paste to a rubbery state, involving multiple steps.

    Bite Registration Materials

    • Polysiloxane bite registration paste is widely used for capturing occlusal relationships and is available in cartridge systems.
    • Zinc oxide eugenol (ZOE) paste offers durability for bite registrations when necessary.

    Final Notes on Impression Procedures

    • Mixing techniques for impression materials may vary, but commonly involve preparing light-bodied material first, followed by heavy-bodied material.
    • Proper infection control and disposal of materials are essential for maintaining a hygienic dental practice.

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    Description

    Test your knowledge on chapter 46 related to impression materials used in dentistry. This quiz covers important terms like colloid, border molding, and elastomeric materials. Perfect for dental students or professionals looking to refresh their understanding.

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