Dental Anatomy: Loss of Enamel and Dentin
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Questions and Answers

What is a consequence of enamel or dentin loss due to lesions or cavities?

  • Enhancement of protective properties of the tooth
  • Exposure of the dentin-pulp system to various irritations (correct)
  • Increased resistance to thermal irritations
  • Reduced risk of dental caries
  • Which of the following is NOT a problem associated with the loss of enamel and dentin?

  • Pain from thermal or osmotic irritations
  • Dentin discoloration from food stains
  • Improved structural integrity of the tooth (correct)
  • Increased susceptibility to bacterial action
  • What is a characteristic of lesions involving dentin?

  • They often leave dentin with irregular shapes (correct)
  • They typically have a uniform shape
  • They do not affect the dentin's structure
  • They enhance the dentin's mechanical properties
  • Which property is NOT required for lining and cement materials?

    <p>Permanent adhesion to the tooth</p> Signup and view all the answers

    Why are lining materials used in cavity preparations?

    <p>To compensate for the lost aesthetics and protect the pulp</p> Signup and view all the answers

    What type of environmental exposures may patients experience due to loss of protective enamel?

    <p>Thermal and chemical irritations</p> Signup and view all the answers

    What could lead to mechanical failure in teeth with irregular dentin shapes?

    <p>Inconsistent loading patterns during chewing</p> Signup and view all the answers

    Which property ensures that lining materials do not react adversely with the tooth?

    <p>Chemical neutrality</p> Signup and view all the answers

    What is the primary purpose of calcium hydroxide being present in excess in the mix?

    <p>To act as a continuous source of calcium and hydroxide ions</p> Signup and view all the answers

    Which method is used to mix the cement to minimize air bubbles?

    <p>Uni-directional rotational motion</p> Signup and view all the answers

    What should be ensured about the cavity before inserting cement?

    <p>It should be dry without being desiccated.</p> Signup and view all the answers

    What happens to the cement when it comes into contact with the moist dentin surface?

    <p>It sets quickly.</p> Signup and view all the answers

    What must be maintained between the cement and the cavity margin after application?

    <p>At least a 1mm cement-free zone</p> Signup and view all the answers

    What is the primary component that causes light-cured calcium hydroxide cement to harden?

    <p>Light polymerization of the resin component</p> Signup and view all the answers

    Which instrument is NOT mentioned as a tool for applying the cement?

    <p>Syringe applicator</p> Signup and view all the answers

    What is the composition of light-cured calcium hydroxide cement?

    <p>One-paste system with resin and particles</p> Signup and view all the answers

    What is one advantage of using the resin component in dental liners?

    <p>It ensures reliable chemical bonding with resin composites.</p> Signup and view all the answers

    Which property does Mineral Trioxide Aggregate (MTA) NOT possess?

    <p>Insolubility in oral fluids</p> Signup and view all the answers

    What is a notable disadvantage of using MTA?

    <p>It can darken the tooth due to iron content.</p> Signup and view all the answers

    How does MTA compare to calcium hydroxide regarding the formation of a dentin bridge?

    <p>MTA promotes thicker dentin bridge formation.</p> Signup and view all the answers

    What is a significant property of MTA that improves its effectiveness?

    <p>Its ability to aid in the release of bioactive dentin matrix proteins.</p> Signup and view all the answers

    What disadvantage do resin liners have related to pharmacological effects?

    <p>They do not allow leaching of calcium hydroxide necessary for pulp medication.</p> Signup and view all the answers

    What is the approximate setting time for MTA?

    <p>2 hours and 45 minutes</p> Signup and view all the answers

    What is the primary characteristic of solution liners?

    <p>They rely on evaporation for hardening.</p> Signup and view all the answers

    Which thickness range defines thick liners?

    <p>200-1000 µm</p> Signup and view all the answers

    What advantage does MTA provide over conventional materials like calcium hydroxide?

    <p>Less necrosis of pulpal tissue.</p> Signup and view all the answers

    What percentage of dentin surface coverage can a single coat of varnish achieve?

    <p>50%</p> Signup and view all the answers

    Which component is primarily found in solution liners?

    <p>Copal resin</p> Signup and view all the answers

    What is a key indication for using cavity varnishes?

    <p>To insulate against galvanic currents</p> Signup and view all the answers

    Which of the following is NOT a type of thick liner?

    <p>Solution Varnish</p> Signup and view all the answers

    What is a common clinical application of thin liners?

    <p>To seal cavity margins under amalgam restorations</p> Signup and view all the answers

    What happens to the resin in solution liners shortly after application?

    <p>It evaporates to leave a film.</p> Signup and view all the answers

    What is the preferred method for mixing cement to manage heat dissipation?

    <p>Using a large area with a long bladed spatula</p> Signup and view all the answers

    Why should a cavity varnish be used under the cement?

    <p>For chemical pulp protection</p> Signup and view all the answers

    What is one of the main benefits of resin-reinforced ZOE cement?

    <p>It has a reduced mixing time</p> Signup and view all the answers

    What is the consistency of the base created with the cement?

    <p>Heavy and putty-like</p> Signup and view all the answers

    What is the primary indication for using polycarboxylate cement?

    <p>Under metallic restorations for protection</p> Signup and view all the answers

    How should the cement powder be measured before mixing?

    <p>Divided systematically into halves and quarters</p> Signup and view all the answers

    What type of cement is modified by the incorporation of smaller powder particles?

    <p>Resin-reinforced ZOE cement</p> Signup and view all the answers

    What is a recommended action before the application of cement in the cavity?

    <p>Clean and dry the cavity without desiccation</p> Signup and view all the answers

    Study Notes

    Loss of Enamel and Dentin

    • Loss of enamel or dentin reduces tooth protection and increases vulnerability to irritations.
    • Dentin-pulp system exposure can lead to pain and conditions like dental caries or pulpitis.
    • Enamel loss allows chromogenic bacteria and food stains to discolor dentin, affecting aesthetics.
    • Irregular-shaped lesions may cause stress concentrations, leading to mechanical failure of the tooth.

    Restoration and Protection

    • Permanent restoration materials often fail to fully restore lost protective functions of enamel and dentin.
    • Lining materials are essential for:
      • Providing thermal, chemical, electrical, and biological protection.
      • Medicated pulp protection and aesthetic compensation.

    Required Properties for Lining Materials

    • Compatibility with tooth structure and restorative materials.
    • Ease of application and sealing ability for dentinal tubules.
    • Sufficient working time and appropriate thickness (thin films: 1-50 µm; thick liners: 200-1000 µm).

    Thin Liners

    • Solution liners (varnishes, 2-5 µm) rely on non-aqueous solvents for evaporation-based hardening.
    • Example composition includes copal resin dissolved in volatile solvents.
    • Clinical application involves a thin coat, often requiring a second layer for better coverage (80-85%).

    Indications for Thin Liners

    • Applied under amalgam restorations for initial cavity sealing and electric insulation from currents.
    • Prevents cement acidity from damaging the pulp when using zinc phosphate cement.

    Calcium Hydroxide Cements

    • Two types: Hard setting and Light-Cured.
    • Light-Cured variants enhance working time and bonding reliability but lack leachable calcium hydroxide effects.

    Mineral Trioxide Aggregate (MTA)

    • MTA is a hydraulic Portland cement with calcium oxides, known for:
      • Antibacterial properties and high pH.
      • Superior dentin bridge formation compared to calcium hydroxide.
    • Limitations include prolonged setting time (approximately 2 hours and 45 minutes) and high cost.

    Handling and Use of MTA

    • Cavity must be clean and properly isolated; a cavity varnish is recommended for chemical protection.
    • Mixing MTA involves careful portioning and methodical combining to manage exothermic reactions.
    • Placement with a condenser is crucial to ensure effective application; excess cement should be removed before setting.

    Resin-Reinforced ZOE Cement

    • Modified with resins and smaller powder particles to enhance strength and speed of setting.
    • Commonly used as a base under metallic restorations and as a long-term temporary filling.

    Polycarboxylate Cement

    • Composed of zinc oxide powder and polyacrylic acid liquid, providing chemical adhesion properties beneficial in dental applications.

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    Description

    Explore the impact of enamel and dentin loss on tooth protection and the subsequent risks posed to the dentin-pulp system. This quiz discusses various problems associated with enamel and dentin loss, including exposure to thermal and osmotic stimuli.

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