Dentin Bonding in Dentistry
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Questions and Answers

What is the primary composition of the smear layer formed on dentin?

  • Salivary glycoproteins, chips, and enamel
  • Chips, hydroxyapatite crystals, collagen, saliva, and blood (correct)
  • Hydroxyapatite crystals, glycoproteins, and enamel
  • Enamel, collagen, and blood
  • Why might the smear layer be retained after dentin cutting?

  • To prevent micromechanical bonding with resin
  • To enhance bacterial penetration
  • To lower dentin permeability and minimize post-operative hypersensitivity (correct)
  • To increase dentin permeability significantly
  • What is the result of removing the smear layer from dentin?

  • Reduction in micromechanical bonding with restorative resin
  • Decrease in permeability of dentin
  • Formation of a strong bond between dentin and restorative material (correct)
  • Incorporation of microorganisms into the dentin
  • What is a characteristic of the smear layer formed on enamel?

    <p>It contains larger apatite crystals and salivary glycoproteins forming a crust</p> Signup and view all the answers

    What role does 'conditioning' play in the selective acid demineralizing and etching process?

    <p>Cleaning the surface and activating calcium ions</p> Signup and view all the answers

    What does 'etching' typically involve in the context of adhesive dentistry?

    <p>Using a strong acid to demineralize the calcium layer and increase surface reactivity</p> Signup and view all the answers

    Which of the following is NOT a benefit of keeping the smear layer?

    <p>Enhancing micromechanical bonding</p> Signup and view all the answers

    Which factor is associated with the increased permeability of dentin when the smear layer is removed?

    <p>Exposure of collagen</p> Signup and view all the answers

    Which requirement is essential for successful wetting of an adhesive on tooth tissues?

    <p>High surface energy of tooth tissues</p> Signup and view all the answers

    What should the surface tension of an adhesive be for sufficient wetting?

    <p>Less than the surface energy of the adherend</p> Signup and view all the answers

    Which of the following is NOT a requirement for successful wetting of adhesive?

    <p>High viscosity of the adhesive</p> Signup and view all the answers

    Which classification involves the use of primers and adhesives combined into one bottle?

    <p>Two-step etch &amp; rinse adhesive</p> Signup and view all the answers

    What characteristics should a successful adhesive joint possess?

    <p>Gap free and dimensionally stable</p> Signup and view all the answers

    What type of adhesives are glass ionomer adhesives considered as?

    <p>Smear layer modifying adhesives</p> Signup and view all the answers

    Which of the following is essential for a bonding process?

    <p>Displacing air and moisture</p> Signup and view all the answers

    What is the process of increasing energy per unit area of a surface called?

    <p>Surface tension</p> Signup and view all the answers

    What is a characteristic difference between two-step and all-in-one self-etch adhesives?

    <p>Two-step adhesives have separate acidic primer and adhesive applications.</p> Signup and view all the answers

    Which self-etch adhesive classification has a pH greater than 2.4?

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

    What makes bonding to dentin more difficult compared to bonding to enamel?

    <p>Dentin's heterogeneous composition and histological structure.</p> Signup and view all the answers

    What contributes to the inherent intrinsic wetness of dentin?

    <p>Continuous outward pressure of dentinal fluid</p> Signup and view all the answers

    What is a challenge presented by the complex histological structure of dentin?

    <p>Dentinal tubules increase in number and diameter toward the pulp.</p> Signup and view all the answers

    What is the pH range for mild self-etch adhesives?

    <p>pH ≥ 2</p> Signup and view all the answers

    Why does deep dentin present more difficulty in bonding compared to superficial dentin?

    <p>Deep dentin has higher intrinsic wetness and more dentinal tubules.</p> Signup and view all the answers

    What is the estimated intrapulpal fluid pressure in dentin?

    <p>25-30 mmHg</p> Signup and view all the answers

    What type of adhesion involves electrostatic interactions?

    <p>Physical adhesion</p> Signup and view all the answers

    Which type of adhesion is primarily used in dental applications?

    <p>Mechanical adhesion</p> Signup and view all the answers

    What type of adhesion occurs when there is bonding at the atomic or molecular level?

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

    What is the term for the degree of spreading of one drop of liquid on a solid surface?

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

    What is essential for an adhesive to produce good bonding?

    <p>Good wetting</p> Signup and view all the answers

    A contact angle of less than 90 degrees indicates what degree of adhesion?

    <p>Moderate adhesion</p> Signup and view all the answers

    What describes the mechanical retention used in dental applications?

    <p>Micro-mechanical retention</p> Signup and view all the answers

    What happens at a contact angle of 0 or 180 degrees?

    <p>Maximum adhesion</p> Signup and view all the answers

    What is considered the Gold standard for adhesives?

    <p>Three-step water/ethanol based adhesives</p> Signup and view all the answers

    Which type of etch-and-rinse adhesive has low technique sensitivity?

    <p>Three-step adhesives</p> Signup and view all the answers

    What is a disadvantage of etch-and-rinse adhesives related to the smear layer?

    <p>They totally remove the smear layer, causing post-operative sensitivity.</p> Signup and view all the answers

    What is the main advantage of a particle-filled adhesive in etch-and-rinse systems?

    <p>Acts as a shock absorber and increases bond strength</p> Signup and view all the answers

    What happens if dentin is over-dried during the use of etch-and-rinse adhesives?

    <p>It leads to the collapse of collagen fibers.</p> Signup and view all the answers

    Which step is NOT required in self-etch adhesives?

    <p>Separate etching step</p> Signup and view all the answers

    What is a primary disadvantage of multi-step etch-and-rinse adhesives?

    <p>They require a separate rinsing step</p> Signup and view all the answers

    What is the risk associated with aggressive etching using phosphoric acid in etch-and-rinse adhesives?

    <p>It leads to demineralization to an inaccessible depth.</p> Signup and view all the answers

    What primary nature does the hybrid layer possess?

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

    What happens to the dentin surface's bond strength if it is made too dry?

    <p>It decreases due to ineffective penetration of the adhesive</p> Signup and view all the answers

    In the two-step etch & rinse adhesives, what components are combined into one solution?

    <p>Primer and adhesive bonding components</p> Signup and view all the answers

    Which technique involves applying a water-based primer capable of re-expanding the collapsed collagen network?

    <p>Dry bonding technique</p> Signup and view all the answers

    What is a characteristic of the hybrid layer related to its mechanical properties compared to dentin?

    <p>More tough and less hard</p> Signup and view all the answers

    What scenario leads to a reduction in bond strength due to water droplets diluting the resin primer?

    <p>Dentin surface is too wet</p> Signup and view all the answers

    Why is a solvent-containing primer used in the wet bonding technique?

    <p>To displace dentinal water and carry monomers into dentinal tubules</p> Signup and view all the answers

    What does too much moisture on the dentin surface prevent?

    <p>Frosted etch appearance of enamel</p> Signup and view all the answers

    Which process is simplified by using self-etch adhesives?

    <p>Clinical application procedure</p> Signup and view all the answers

    What occurs simultaneously with self-etch adhesives?

    <p>Demineralization and resin infiltration</p> Signup and view all the answers

    What is a disadvantage of one-step self-etch adhesives?

    <p>Relatively low bond strength</p> Signup and view all the answers

    Why might mild self-etch adhesives require additional pre-etching on enamel?

    <p>To achieve proper enamel etching</p> Signup and view all the answers

    What is an advantage of polyacrylic acid conditioning?

    <p>Exposure of a clean dentin surface and smear plugs</p> Signup and view all the answers

    How long should polyacrylic acid be used to condition enamel and dentin?

    <p>10 seconds</p> Signup and view all the answers

    What is a characteristic of self-etch adhesives?

    <p>They do not require a rinsing step</p> Signup and view all the answers

    What is the main difference between mild and strong self-etch adhesives?

    <p>The depth of demineralization</p> Signup and view all the answers

    What do two-step self-etch adhesives consist of?

    <p>A hydrophilic primer solution and a hydrophobic adhesive resin</p> Signup and view all the answers

    How do one-step self-etch adhesives differ from two-step self-etch adhesives?

    <p>They are complex mixtures of both hydrophilic and hydrophobic monomers</p> Signup and view all the answers

    What enables mild self-etch adhesives to still achieve satisfactory bond strength despite shallow hybridization?

    <p>Chemical interaction with hydroxyapatite crystals</p> Signup and view all the answers

    Which self-etch adhesive type creates the thickest hybrid layer?

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

    What is the primary difference between adhesion and cohesion?

    <p>Adhesion involves attraction between different substances, while cohesion involves attraction within similar substances.</p> Signup and view all the answers

    Which property is significant for reducing microleakage in dental restorations?

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

    In an adhesive joint, what is the role of the adhesive?

    <p>It interacts with two surfaces to form adhesive interfaces.</p> Signup and view all the answers

    Which material has intrinsic self-adhesive capacity in dental applications?

    <p>Glass ionomer cement</p> Signup and view all the answers

    What is considered an adherent in the context of dental adhesion?

    <p>The material or surface to which the adhesive is applied</p> Signup and view all the answers

    Which advantage is NOT associated with adhesion in dental restorations?

    <p>Increase in susceptibility to breakage</p> Signup and view all the answers

    Which term refers to the forces between atoms or molecules at an interface that hold two phases together?

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

    What is considered an adherend in resin composite bonding to tooth structure?

    <p>The composite and tooth substrates</p> Signup and view all the answers

    Study Notes

    Dentin Bonding

    Self-Etch Adhesives

    • Do not use a separate etching step
    • Two options:
      • Two-step: acidic primer and adhesive are applied individually
      • All-in-one adhesive: primer and adhesive agent are combined in one bottle

    Classification of Self-Etch Adhesives

    • Classified according to their aggressiveness or acidity:
      • Ultramild (pH > 2.4)
      • Mild (pH ≥ 2)
      • Intermediate (pH = 1.5)
      • Strong (pH ≤ 1)

    Bonding to Enamel vs. Dentin

    • Bonding to enamel is easier than bonding to dentin

    Problems in Bonding to Dentin

    • Heterogenous composition:
      • High water and organic content (collagen)
      • Only 70% inorganic hydroxyapatite
      • Uneven distribution of constituents in intertubular and peritubular dentin
    • Complex histological structure:
      • Dentin composed of numerous dentinal tubules
      • Each tubule surrounded by a collar of hypermineralized peritubular dentin
      • Intertubular dentin less mineralized and contains more organic collagen
      • Dentinal tubules diverge from the dentino-enamel junction to the pulp
    • Inherent intrinsic wetness:
      • Dentinal tubules filled with dentinal fluid
      • Dentin under constant wetness
      • Deep dentin has more intrinsic wetness than superficial dentin
    • Dynamic tissue:
      • Dentin subject to continuous physiologic and pathologic changes
      • Presence of more than one type of dentin presents challenges in dentin bonding
    • Presence of smear layer:
      • A layer of cutting debris formed on the surface of dentin after cutting

    Advantages of Etch-and-rinse Adhesives

    • Proven effective bonding with enamel and dentin
    • Three-step water/ethanol based adhesives are considered the Gold standard for adhesives
    • Low technique sensitivity
    • Possibility for particle-filled adhesive

    Disadvantages of Etch-and-rinse Adhesives

    • Time consuming due to multi-steps required
    • Separate post-etching rinsing step is required
    • Risk of over-etching dentin
    • Total removal of smear layer can cause post-operative sensitivity
    • Sensitive to over-wet or over-dry dentin condition

    Properties of Hybrid Layer

    • Primarily organic in nature
    • Resistant to acids and proteolysis
    • Lower modulus of elasticity than dentin
    • Acts as an elastic buffering layer
    • More tough and less hard than dentin

    Wet versus Dry Bonding

    • Conventionally, acid etched enamel was dried with short intermittent blasts of air
    • However, this causes collapse of dentinal unsupported collagen network
    • Two approaches to overcome this problem:
      • Dry bonding technique:
        • Air drying of enamel and dentin
        • Applying a water-based primer
      • Wet bonding technique:
        • Leaving dentin moist
        • Using a solvent-containing primer with water-chasing capacity

    If the Dentin Surface is Made Too Dry

    • Collapse of the collagen fibers and demineralized dentin occurs
    • Results in low bond strength

    If the Dentin Surface is Too Wet

    • Cannot check for the "frosted" etch appearance of the enamel
    • Reduction in bond strength due to dilution of resin primer

    The Smear Layer

    • Formed on the surface of dentin after cutting
    • Composed of chips, hydroxyapatite crystals, collagen, saliva, and blood
    • Incorporates microorganisms
    • Becomes packed inside the dentinal tubule forming a smear plug

    To Remove or Keep the Smear Layer?

    • Retain the smear layer because:
      • Lowers dentin permeability
      • Provides barrier to bacterial penetration
      • Provides a drier surface for adhesion
      • Minimizes post-operative hypersensitivity
      • Prevents the ingress of irritants
    • Remove the smear layer because:
      • Incorporates microorganisms
      • Loosely attached to the underlying dentin
      • Exposed collagen enhances micromechanical bonding to resin

    Steps of Bonding to Enamel & Dentin

    • Etch & rinse adhesives:
      • Selective acid demineralizing & etching
      • Conditioning
      • Etching
      • Intimate molecular contact between adhesive and tooth tissues

    Requirements for Successful Wetting of Adhesive

    • Intimate molecular contact between adhesive and tooth tissues
    • Cleanliness of the tooth tissues
    • High surface energy of the tooth tissues
    • Low-surface tension of the adhesive material
    • Low viscosity of the adhesive
    • Ability to displace air and moisture during the bonding process

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    Description

    Learn about self-etch adhesives in dentin bonding, their classification, and bonding to enamel vs. dentin. Understand the differences in acidity and application processes.

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