Anticaries Agents and Fluoride Mechanism
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Questions and Answers

What primarily causes demineralization of tooth enamel?

  • Dietary calcium deficiency
  • Increased fluoride uptake
  • Fluoride interaction with saliva
  • Acids produced by bacteria metabolizing sugars (correct)

    • What compound is formed when fluoride interacts with hydroxyapatite?

  • Phosphate fluoride
  • Calcium fluorite
  • Carbonate
  • Fluorapatite (correct)

    • Which hypothesis suggests that fluoride reduces acid production in dental plaque?

  • Bacterial inhibition hypothesis (correct)
  • Enamel crystal stabilization hypothesis
  • Decreased acid solubility hypothesis
  • Fluorapatite formation hypothesis

    • How does fluoride primarily protect tooth enamel?

    <p>By decreasing enamel's solubility in acid</p> Signup and view all the answers

    What observation suggests that sodium fluoride’s effect diminishes quickly?

    <p>Its topical application effect reduces within a week.</p> Signup and view all the answers

    What role might fluoride have aside from forming fluorapatite?

    <p>Reducing defects in enamel crystals.</p> Signup and view all the answers

    Which condition leads to the higher fluoride uptake in enamel?

    <p>Compromised by carious lesions</p> Signup and view all the answers

    What is a potential consequence of fluoridated plaque?

    <p>Gum inflammation</p> Signup and view all the answers

    What is the primary component of the chemical reaction that produces calcium hydroxide from calcium oxide?

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

    Which substance is used in dental applications for polishing due to its abrasive properties?

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

    What is the main purpose of desensitizing agents in dentistry?

    <p>To reduce sensitivity to temperature</p> Signup and view all the answers

    How is strontium chloride prepared?

    <p>By adding strontium carbonate to hydrochloric acid</p> Signup and view all the answers

    Which of the following describes the appearance of zinc chloride?

    <p>White or practically white, crystalline powder</p> Signup and view all the answers

    What is a characteristic property of pumice that makes it suitable for dental polishing?

    <p>Light and porous structure</p> Signup and view all the answers

    What is the primary reason for higher incidence of dental caries in individuals consuming a high carbohydrate diet?

    <p>Increased acidity from bacterial metabolism</p> Signup and view all the answers

    What reaction occurs when carbon dioxide is passed through calcium hydroxide?

    <p>Precipitation of calcium carbonate</p> Signup and view all the answers

    How does fluoride contribute to the prevention of dental caries?

    <p>By replacing carbonate anions in hydroxyapatite</p> Signup and view all the answers

    What is a primary use of dental cements?

    <p>To temporarily protect areas after surgery</p> Signup and view all the answers

    What is the accepted mechanism of fluoride absorption when taken internally?

    <p>It is absorbed almost completely from the gastrointestinal tract</p> Signup and view all the answers

    Which of the following statements is true regarding the relationship between fluoride concentration and tooth enamel?

    <p>Fluoride concentration is greater in the surface layer of enamel</p> Signup and view all the answers

    What common dental hygiene practices are recommended for caries prevention?

    <p>Flossing and brushing with fluoride</p> Signup and view all the answers

    Which compound is primarily responsible for the mineral structure of teeth?

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

    What factor limits fluoride uptake from tissue fluids in teeth?

    <p>Contact loss with tissue fluids after calcification</p> Signup and view all the answers

    What role does plaque play in the development of dental caries?

    <p>Plaque creates crevices for food particle degradation</p> Signup and view all the answers

    What is the primary reason for concern over the loss of stannous ion activity?

    <p>It has been reported to be anticariogenic</p> Signup and view all the answers

    Which ingredient is currently used in toothpaste to maintain fluoride levels while preventing unwanted reactions?

    <p>Calcium pyrophosphate</p> Signup and view all the answers

    What is a characteristic property of stannous fluoride?

    <p>Melts at about 213° C</p> Signup and view all the answers

    What is the main advantage of the oral route of fluoride delivery?

    <p>It allows fluoride to be laid down in unerupted teeth.</p> Signup and view all the answers

    What is the usual fluoride concentration added to public water supply for fluoridation?

    <p>0.7 to 1 ppm</p> Signup and view all the answers

    Which of the following statements about calcium carbonate is accurate?

    <p>It is prepared by the reaction of calcium oxide with carbon dioxide.</p> Signup and view all the answers

    What is the main role of abrasive agents in dentifrices?

    <p>To polish and clean tooth surfaces</p> Signup and view all the answers

    Which reaction represents the preparation of sodium fluoride from hydrofluoric acid?

    <p>2HF + Na2CO3 → 2NaF + H2O + CO2</p> Signup and view all the answers

    What is a common characteristic of calcium salts when mixed with fluoride?

    <p>They form insoluble compounds that reduce available fluoride</p> Signup and view all the answers

    What is a characteristic of stannous fluoride solutions?

    <p>They deteriorate over time due to oxidation.</p> Signup and view all the answers

    Which of these compounds is known for being freely soluble in water?

    <p>Stannous fluoride</p> Signup and view all the answers

    How is stannous fluoride typically applied for topical use?

    <p>Using an 8% solution at 6- to 12-month intervals.</p> Signup and view all the answers

    What is converted when sodium fluoride is acidified?

    <p>Sodium fluoride to hydrofluoric acid.</p> Signup and view all the answers

    What reaction occurs when calcium carbonate is mixed with fluoride?

    <p>Forms calcium fluoride and carbonate ions</p> Signup and view all the answers

    What is the typical dose of sodium fluoride used to prevent dental caries?

    <p>2.2 mg per day</p> Signup and view all the answers

    Which statement about sodium fluoride is true?

    <p>It helps to prevent acid demineralization of teeth.</p> Signup and view all the answers

    Study Notes

    Anticaries Agents

    • Fluoride is commonly used to prevent tooth decay
    • Diet plays a role in caries formation, with high carbohydrate diets increasing the risk
    • Caries is caused by acids, primarily lactic acid, produced by bacteria metabolizing carbohydrates
    • Plaque buildup on tooth surfaces can trap food particles, providing a breeding ground for bacteria
    • Fluoride is absorbed from the gastrointestinal tract and deposited in bones and teeth
    • Fluoride replaces hydroxyl and carbonate anions in hydroxyapatite, forming fluorapatite
    • Fluoride concentration is higher in the surface layer of enamel, both erupted and unerupted
    • Fluoride uptake from tissue fluids is limited to the external surface of enamel

    The Mechanism of Fluoride Action

    • Two main hypotheses for fluoride's anticaries mechanism:
      • Decreased acid solubility of enamel: Fluoride converts hydroxyapatite to fluorapatite, which is less soluble in acidic environments.
      • Bacterial inhibition: Fluoride may inhibit bacterial enzymes, reducing acid production in dental plaque.
    • While fluorapatite formation is documented, it may not fully explain the observed decrease in acid solubility.
    • Other possibilities include fluoride's role in reducing enamel crystal defects or competing with carbonate during apatite formation.

    Administration of Fluoride

    • Fluoride can be administered orally or topically, both methods are effective
    • Oral administration allows fluoride to enter systemic circulation and be deposited in unerupted teeth
    • Fluoridation of public water supplies is a common and convenient method of fluoride delivery
    • The typical fluoride concentration in fluoridated water is 0.7 to 1 ppm, equivalent to 2.2 mg of sodium fluoride daily

    Specific Fluoride Compounds

    • Sodium Fluoride (NaF):

      • Used in dental products and drinking water
      • Protects teeth from acid demineralization
      • Strengthens tooth enamel
      • Prepared by neutralizing hydrofluoric acid with sodium carbonate or by double decomposition of calcium fluoride with sodium carbonate
      • Available as solutions, tablets, oral gels, and mouthwash

    • Stannous Fluoride (SnF₂):

      • Extensively used for topical fluoride applications
      • Solutions are unstable and require fresh preparation due to oxidation of stannous cation
      • Stannous cation itself is believed to have anticariogenic effects
      • Occurs as a white, crystalline powder, freely soluble in water, and topical use only.

    Cleaning Agents / Dentifrices

    • Dentifrices are used for cleaning tooth surfaces and polishing
    • They contain abrasive agents to remove plaque and debris
    • Calcium salts are commonly used as abrasive agents in dentifrices
    • Fluoride can react with calcium salts to form insoluble compounds like calcium fluoride, reducing fluoride availability
    • Calcium pyrophosphate and sodium polyphosphate are used to overcome this incompatibility and maintain fluoride efficacy

    Desensitizing Agents

    • Desensitizing agents reduce teeth sensitivity to heat and cold

    • They act as local anesthetics

    • Examples include strontium chloride and zinc chloride

    • Strontium Chloride (SrCl₂):

      • Prepared by adding strontium carbonate to hydrochloric acid
      • Used as a desensitizing agent in dental remedies

    • Zinc Chloride (ZnCl₂):

      • Occurs as a white crystalline powder or granules
      • Very deliquescent, acid to litmus
      • Highly soluble in water, alcohol, and glycerin
      • Used as an astringent and dentin desensitizer

    Dental Cements and Fillers

    • Dental cements are used to temporarily cover and protect areas that have undergone dental surgery.

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    Description

    This quiz explores the role of fluoride in preventing tooth decay and its mechanism of action against caries. Delve into how fluoride interacts with enamel and the factors influencing caries formation, including dietary impacts and bacterial activity.

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