Composite Restoration Chapter 8
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Questions and Answers

What is a characteristic of flowable composites compared to packable composites?

  • Higher strength and wear resistance
  • Lower viscosity and polymerization shrinkage
  • Easier adaptation to margins and contours
  • Lower filler content and increased polymerization shrinkage (correct)

    • Which property is primarily affected by the filler content in composite materials?

  • Color stability
  • Thermal resistance
  • Water sorption (correct)
  • Thermal conductivity

    • Why is the linear coefficient of thermal expansion important in composite materials?

  • It affects the strength of the material
  • It relates to dimensional changes with temperature (correct)
  • It influences the aesthetic appearance
  • It determines wear resistance

    • What is a common use for flowable composites?

    <p>Serving as pit-and-fissure sealants (B)</p> Signup and view all the answers

    How does increased viscosity in packable composites affect their performance?

    <p>Makes optimal marginal adaptation more difficult (D)</p> Signup and view all the answers

    What is a major disadvantage of flowable composites?

    <p>Increased polymerization shrinkage (A)</p> Signup and view all the answers

    What does wear resistance in composite materials refer to?

    <p>The capacity to withstand abrasive contact (B)</p> Signup and view all the answers

    Which property can be negatively affected if a composite is incompletely cured?

    <p>Water absorption levels (D)</p> Signup and view all the answers

    What is a characteristic of micro-fill composites?

    <p>They provide superior polishability and aesthetic qualities. (D)</p> Signup and view all the answers

    Which composite type is characterized by a combination of large and small filler particles?

    <p>Hybrid Composites (C)</p> Signup and view all the answers

    What is a main advantage of nanofill composites over other types?

    <p>They possess a significant reduction in wear and abrasion. (C)</p> Signup and view all the answers

    Which type of composite is primarily designed for minimal viscosity and can easily flow into cavities?

    <p>Flowable Composites (D)</p> Signup and view all the answers

    What is a notable disadvantage of macrofilled composites?

    <p>They are no longer used in clinical practice. (D)</p> Signup and view all the answers

    What is the primary component that distinguishes fillers in hybrid composites?

    <p>They are filled with both macro and micro-sized fillers. (B)</p> Signup and view all the answers

    Which property is particularly enhanced in nanofill composites compared to traditional composites?

    <p>Color stability over long term use. (B)</p> Signup and view all the answers

    What is a primary characteristic of flowable composites compared to traditional hybrids?

    <p>They are less resilient and not suitable for stress-bearing areas. (A)</p> Signup and view all the answers

    What is a primary characteristic of microfilled composite restorations?

    <p>Inferior physical and mechanical characteristics (B)</p> Signup and view all the answers

    What is the average particle size of microfiller particles in hybrid composites?

    <p>0.4–1 μm (D)</p> Signup and view all the answers

    Which of the following is NOT a property of nanofill composites?

    <p>Low filler levels (D)</p> Signup and view all the answers

    Which composite material has the highest filler content by weight?

    <p>Hybrid composite (A)</p> Signup and view all the answers

    What makes nanohybrid composites unique compared to traditional hybrid composites?

    <p>Inclusion of ultra-small nanofillers (A)</p> Signup and view all the answers

    Microfilled composites are particularly appropriate for restoring which type of lesions?

    <p>Class V cervical lesions (B)</p> Signup and view all the answers

    What type of texture do classic versions of hybrid materials exhibit?

    <p>Patina-like surface texture (D)</p> Signup and view all the answers

    Which characteristic is shared by both nanofill and nanohybrid composites?

    <p>Good polishability (D)</p> Signup and view all the answers

    Flashcards

    Packable composite

    A type of composite resin used in dental restorations that is designed for easier restoration of proximal contours and contacts.

    Flowable composite

    A composite resin with lower filler content, resulting in lower wear resistance, strength, and higher polymerization shrinkage.

    Linear Coefficient of Thermal Expansion

    The rate of change in a material's dimensions per unit change in temperature.

    Water sorption

    The amount of water a material absorbs over time per unit of surface area or volume.

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    Wear resistance

    A material's ability to resist surface loss from contact with other materials.

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    Polymerization shrinkage

    Reduces volume as it hardens after mixing.

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    Filler content

    The amount of filler particles in a composite material.

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    Composite LCTE

    The linear coefficient of thermal expansion of modern composites, approximately three times that of tooth structure.

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    Composite Material

    A material made from two or more components with different properties that, when combined, create a new material with unique characteristics.

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    Filler in Composite

    Inorganic particles in composite resin that contribute to strength, wear resistance, and other properties.

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    Matrix in Composite

    The organic resin that binds the filler particles together and allows the composite to be shaped.

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    Macrofilled Composite

    A type of composite with large filler particles. No longer widely used.

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    Microfilled Composite

    A type of composite with smaller filler particles, resulting in a smoother surface.

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    Hybrid Composite

    A type of composite that combines both large and small filler particles.

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    Nanofilled Composite

    A type of composite with extremely small filler particles, producing a very smooth surface.

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    Why are Composites Used?

    Composite restorations are now the standard for filling cavities because they bond to the tooth, are strong, and look natural.

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    Microfill Composite Properties

    Microfill composites have some drawbacks in physical and mechanical characteristics but are highly wear-resistant. Their lower modulus of elasticity allows them to flex with the tooth, protecting the bonding interface. This makes them suitable for restoring cervical lesions or defects that experience significant flexing.

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    Hybrid Composite Properties

    Hybrid composites have better physical and mechanical characteristics than conventional composites due to their high filler content. Classic versions have a smooth, patina-like surface texture.

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    Nanohybrid Composite

    Newer versions of hybrid composites containing ultra-small nanofillers, resulting in superior characteristics.

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    Why are Nanofill and Nanohybrid Composites Popular?

    Nanofill and Nanohybrid composites are popular due to their versatile clinical applicability, offering good physical properties, excellent aesthetics, and high polishability.

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    Wear Comparison of Composites

    Hybrid composites exhibit a moderate wear rate, while Nanofill composites wear at a much slower rate due to their denser, more tightly packed structure.

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    Study Notes

    Composite Restoration (1)

    • The presentation is about composite restorations in operative dentistry.
    • The reference used is "Art and science of operative dentistry 6th edition, Introduction to Composite Restorations, Chapter 8, p:216".
    • Learning Objectives (ILOs) include defining composite materials, classifying composite resins by filler content and handling characteristics, and determining resin composite restoration properties.
    • Early acrylic resins were unsuccessful due to poor activator systems, high polymerization shrinkage, high coefficient of thermal expansion, and high wear.
    • These issues led to marginal leakage, pulp injury, recurrent caries, color changes, and loss of contour and contact.
    • Although use of acrylic resin is limited to making temporary restorations for operative procedures and fixed prosthodontics, it requires multiple appointments
    • In 1962, Bowen introduced filled resin restorative materials, which became the basis for composites.
    • A composite is a material made from two or more constituents that, when combined, produce a material with characteristics different from each individual component.
    • Components of composite materials are matrix, filler, coupling agent, initiators, accelerators and pigments.
    • Classification includes macrofilled, microfilled, hybrid and nanofilled, based on filler size.
    • Macrofilled, or conventional composites, contain approximately 75-80% inorganic filler by weight, with an average particle size of 8 µm.
    • Their rough surface texture makes them more prone to discoloration.
    • Microfilled composites were introduced in the late 1970s to address the drawbacks of macrofilled composites.
    • They have smooth, lustrous surfaces resembling tooth enamel and are less susceptible to plaque retention and discoloration.
    • Microfilled filler particle size is 0.01 - 0.04 µm and filler content approximately 35-60% by weight.
    • Hybrid composites combine the advantages of both macrofill and microfill composites, resulting in smaller particle sizes (0.4–1 µm).
    • Their filler content ranges from 75-85% by weight.
    • Nanohybrid and nanofilled composites contain ultra-small nanofillers which provide good physical properties and improved aesthetics, making them highly polishable.
    • Nanofill particle size is extremely small (0.005–0.01 µm).
    • Nanofilled and nanohybrid composites are the most popular restorative materials due to their wide clinical applicability.

    Classification (continued)

    • Classification of composite materials can be based on handling characteristics: flowable and packable.
    • Packable composites are more viscous and attempt to restore contours and contacts but can be difficult to achieve optimal marginal adaptation.
    • Flowable composites have lower filler content, which results in inferior physical properties like low wear resistance and lower strength but higher polymerization shrinkage.
    • The decrease in filler loading decreases viscosity, and mechanical properties as well as increasing polymerization shrinkage.

    Properties

    • Properties of composite restorations include linear coefficient of thermal expansion, water sorption, wear resistance, surface texture, radiopacity, modulus of elasticity, and polymerization.
    • The linear coefficient of thermal expansion of composite materials is approximately three times that of tooth structure.
    • Water sorption is the amount of water a material absorbs. Higher filler content leads to lower water absorption.
    • Wear resistance is the material's ability to resist surface loss from abrasive contact.
    • Surface texture is the smoothness of the material, with nanohybrid and nanofilled composites being polishable and compatible with soft tissues.
    • Radiopacity is the material's ability to allow the radiolucency of recurrent caries to be seen in radiographs. Most contain radiopaque fillers.
    • The modulus of elasticity is the stiffness of a material. Flexibly is beneficial for class V restorations in teeth undergoing high occlusal forces.
    • Polymerization is the process by which the composite material sets.
    • Nanofilled/Nanohybrid composites are a good choice for small cervical caries.

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    Lecture 4 Composite Restoration Part 1 PDF

    Description

    This quiz focuses on composite restorations in operative dentistry, based on Chapter 8 of the book 'Art and Science of Operative Dentistry'. You will learn about the definition of composite materials, classification of composite resins, and the properties of resin composite restorations. It covers historical developments and challenges faced with acrylic resins and how filled resin restorative materials revolutionized dental practice.

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