Denture Base Polymers Overview
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Questions and Answers

What is the primary cause of irritation to the soft tissues of the mouth associated with polymerization?

  • Exothermic reaction
  • Residual monomer (correct)
  • Thermal behavior
  • Crosslinking

    • Which stage of free radical polymerization follows initiation and is characterized by the continuous chemical reaction?

  • Inhibition
  • Propagation (correct)
  • Condensation
  • Termination

    • What distinguishes condensation polymerization from addition polymerization?

  • Production of a by-product (correct)
  • Formation of linear structures
  • The use of free radicals
  • Presence of a volatile solvent

    • What role does hydroquinone play in polymerization?

    <p>Retards the polymerization reaction</p> Signup and view all the answers

    Which property is characteristic of thermosetting polymers compared to thermoplastic polymers?

    <p>They form a three-dimensional network</p> Signup and view all the answers

    What happens to thermoplastic polymers when they are reheated?

    <p>They can be reshaped and will harden in the new form.</p> Signup and view all the answers

    Which of the following factors is NOT associated with polymerization?

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

    Which type of polymerization is characterized by an irreversible process when heated?

    <p>Thermosetting polymerization</p> Signup and view all the answers

    Which of the following is NOT a requirement of denture bases?

    <p>Good electrical conductivity</p> Signup and view all the answers

    What is a disadvantage of metallic denture bases?

    <p>Heavy weight</p> Signup and view all the answers

    Which of the following non-metallic denture bases can transmit heat?

    <p>None of the above</p> Signup and view all the answers

    Which feature is most beneficial for achieving a natural appearance in denture bases?

    <p>Color stability</p> Signup and view all the answers

    What could be a potential issue with non-metallic denture bases?

    <p>Crazing and bleaching</p> Signup and view all the answers

    Which of the following materials is used in metallic denture bases?

    <p>Cast titanium</p> Signup and view all the answers

    What is a common property of acrylic resin used in denture bases?

    <p>It can be pigmented</p> Signup and view all the answers

    What is a potential advantage of using metallic denture bases?

    <p>They provide minimal bacterial colonization</p> Signup and view all the answers

    What is the typical monomer to polymer ratio by volume for heat cured acrylics?

    <p>3:1</p> Signup and view all the answers

    Which ingredient acts as an inhibitor in the liquid portion of the heat cured acrylic mix?

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

    What is the purpose of barium salts in the heat cured acrylic composition?

    <p>To provide radiopacity</p> Signup and view all the answers

    What stage follows the stringy or sticky stage in the curing process of heat cured acrylic?

    <p>Sandy stage</p> Signup and view all the answers

    What is the main risk associated with a high powder to liquid ratio in heat cured acrylic mixing?

    <p>Incomplete wetting of powder</p> Signup and view all the answers

    What is one of the key benefits of using prepolymerized polymethyl methacrylate in heat cured acrylic?

    <p>Reduces polymerization shrinkage</p> Signup and view all the answers

    During which step of denture construction does wax elimination occur?

    <p>Flasking procedure</p> Signup and view all the answers

    What is the role of acrylic fibers in heat cured acrylics?

    <p>To mimic blood vessels</p> Signup and view all the answers

    What describes a copolymer formed by two monomers entering the chain in a random manner?

    <p>Random copolymer</p> Signup and view all the answers

    Which type of polymer structure is characterized by a network of interconnected molecules?

    <p>Cross-linked structure</p> Signup and view all the answers

    What is the primary function of the polymerization process?

    <p>To transform low molecular weight monomers into high molecular weight polymers</p> Signup and view all the answers

    Which of the following correctly describes a block copolymer?

    <p>A linear copolymer with long uninterrupted sequences of each polymeric species</p> Signup and view all the answers

    What property is generally associated with polymers of higher molecular weight?

    <p>Higher softening and melting points</p> Signup and view all the answers

    Which statement best describes linear and branched polymer structures?

    <p>They are separate and distinct entities with flexible configurations.</p> Signup and view all the answers

    In the context of denture base polymers, what is polymethyl methacrylate primarily used for?

    <p>As the main component of denture bases</p> Signup and view all the answers

    What effect does a cross-linked polymer have on its ability to absorb liquids?

    <p>It does not absorb liquids as readily as linear or branched polymers.</p> Signup and view all the answers

    What is a potential downside of using higher residual monomer in dental materials?

    <p>Possibility of irritation to soft tissues</p> Signup and view all the answers

    Which of the following components is NOT found in light-cured acrylics?

    <p>Carbon fibers</p> Signup and view all the answers

    What is a key advantage of light-cured acrylic compared to conventional acrylic systems?

    <p>No presence of MMA monomer</p> Signup and view all the answers

    How does acrylic resin's poor thermal conductivity benefit its use in dental applications?

    <p>Prevents heat transfer to oral tissues</p> Signup and view all the answers

    What type of reaction is more likely with cold-cure resin due to residual monomers?

    <p>Immediate allergic reactions</p> Signup and view all the answers

    Which of the following is a characteristic that may result from water sorption in acrylic resin?

    <p>Expansion after immersion</p> Signup and view all the answers

    What effect does the high coefficient of thermal expansion have on denture bases?

    <p>Potential loosening of porcelain teeth</p> Signup and view all the answers

    Which material property is NOT typically associated with conventional heat-accelerated acrylic resins?

    <p>High tensile strength</p> Signup and view all the answers

    What is the significance of the density difference between methyl methacrylate monomer and poly-methyl methacrylate?

    <p>It reveals a decrease in the volume of monomer by approximately 21% during polymerization.</p> Signup and view all the answers

    Why are denture teeth typically chosen to match the patient's natural teeth?

    <p>To maintain aesthetic appearance and avoid looking artificial.</p> Signup and view all the answers

    What is a quality that artificial teeth should not possess according to denture requirements?

    <p>High density to ensure stability.</p> Signup and view all the answers

    What is a key advantage of acrylic resin teeth compared to those made from other materials?

    <p>They bond chemically with the denture base during processing.</p> Signup and view all the answers

    What processing method is employed for improved denture production?

    <p>Water bath processing followed by boiling.</p> Signup and view all the answers

    What characteristic is essential for denture teeth to allow adjustments by a dentist?

    <p>Hard enough to resist abrasiveness.</p> Signup and view all the answers

    Why might a patient be advised against choosing bright white denture teeth?

    <p>Because they may appear artificial compared to natural teeth.</p> Signup and view all the answers

    What tends to increase the strength of acrylic denture teeth during manufacturing?

    <p>Increased cross-linking agent.</p> Signup and view all the answers

    Study Notes

    Denture Base Polymers

    • Denture bases are the parts of dentures that support and hold artificial teeth.
    • They rest on the tissues.
    • Functions include supporting and retaining teeth, stress distribution, and improving aesthetics.
    • Requirements of denture bases include having strength and durability, satisfactory thermal properties (thermal conductivity and CTE), accuracy and dimensional stability, chemical stability, insolubility and low sorption of oral fluids, absence of taste and odor, biocompatibility, natural appearance and color stability, adhesion to other materials, ease of fabrication, and a moderate cost.
    • Denture bases can be classified as metallic or non-metallic. Metallic include cast gold alloys, cast cobalt-chromium, cast titanium and titanium alloys, and swaged stainless steel.
    • Advantages of metallic denture bases include high mechanical properties, resistance to scratching, minimal allergy and bacterial/fungal colonization.
    • Disadvantages of metallic denture bases include not matching gingival tissues, difficulty in construction/repairs, finishing/polishing, relining, weight, and cost.
    • Non-metallic denture bases include heat-cured PMMA, self-cured PMMA and light-cured PMMA.
    • Advantages of non-metallic bases include a color that matches gingival tissues, ease of construction, repair, finishing, polishing, relining, lightweight, and cost.
    • Disadvantages of non-metallic bases include moderate mechanical properties, susceptibility to scratching, lack of heat transmission, possible allergies, potential for crazing or bleaching, more colonization likelihood.
    • Acrylic resins are polymers of methyl methacrylate.
    • Types of acrylic resin used in denture bases include heat-cured, self-cured, and light-cured.
      • Heat-cured acrylic is common with low monomer content, and usually supplied in powder and liquid form.
      • Self-cured acrylic uses a chemical activator to initiate polymerization.
      • Light-cured acrylic uses visible blue light as an activator, is supplied in sheets, and is adapted to the cast dentures.
    • Acrylic resin teeth are similar to the base resins but are strengthened with cross-linking agents.
    • Porcelain teeth are harder, more stain-resistant, and held to the denture by mechanical undercuts.
    • Porcelain teeth are rarely used because they wear on opposing teeth and cause bone loss in supporting and opposing alveolar ridges.
    • Polymerization is a chemical reaction that forms polymer chains from monomers.
      • Addition polymerization occurs without loss of mass.
      • Condensation polymerization involves the loss of a small molecule like water.
      • Free radical polymerization stages: Initiation, Propagation, and Termination.
    • Inhibitiors in polymerization process can prevent monomers from becoming polymers.
    • Polymer structure can be linear, branched, or cross-linked; cross-linked polymers are more rigid.
    • Polymerization is affected by different chemical factors.

    Denture teeth

    • Denture teeth come in various shapes, sizes, and shades.
    • Teeth shape is chosen to match the patient's natural teeth, often based on previous photos.
    • Tooth sizes are determined by the patient's arch size.
    • Patients sometimes desire overly bright white teeth and need appropriate color guidance.
    • Teeth should have good appearance (similar to natural teeth in shape, color and translucency).
    • Teeth should have compatible attachment to denture bases.
    • Teeth need to have low density to not increase the overall weight.
    • Teeth should be strong and tough to resist fracture.
    • Teeth need to withstand mouth abrasions during cleaning.
    • Teeth should allow dental grinding for occlusion adjustments.

    Denture construction steps

    • Flasking: Molding denture
    • Wax elimination: Removal of wax used in the mold
    • Proportioning, mixing and packing: Mixing resins for base
    • Trial closure: Checking fit with the mouth
    • Curing: Polymerization process
    • Deflasking, finishing & polishing: Final shaping and polishing
    • Mixing ratio is typically 3:1 by volume, 2:1 by weight.
    • Initial mixing is done in a sealed glass jar to prevent loss of monomer by evaporation.
    • Mixing ratio that is too high or too low can result in poor quality dentures.
    • Polymerization stages: Sandy, Stringy/sticky, Dough, Rubbery, and Stiff stages
    • Curing stages for heat-cured resin involves gradually increasing temperatures above 70 degrees C., where exothermic reaction may result in undesirable boiling.
    • Curing times and temperatures can vary based on denture complexity

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    Denture Base Polymers PDF

    Description

    This quiz covers essential knowledge about denture base polymers, including their functions, requirements, and classifications. Explore the advantages and disadvantages of metallic and non-metallic denture bases, and understand their importance in dental applications.

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