Introduction to Amalgam Restorations
37 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is dental amalgam primarily composed of?

  • Gold and platinum
  • Tin and lead
  • Composite resin and glass ionomer
  • Silver-tin-copper alloy and mercury (correct)

    • What is a disadvantage of using dental amalgam for restorations?

  • Low long-term clinical success
  • Non-esthetic appearance (correct)
  • High wear resistance
  • Reduced strength

    • In which of the following scenarios is dental amalgam typically indicated?

  • Small cavities in lower incisors
  • Large cavities in posterior teeth (correct)
  • Restorations for mercury-sensitive patients
  • Esthetic restoration in anterior teeth

    • Which property of dental amalgam is characterized by its long-term clinical results?

    <p>Excellent wear resistance</p> Signup and view all the answers

    What classification of dental amalgam typically requires less condensation?

    <p>Spherical alloy</p> Signup and view all the answers

    Which of the following is NOT a contraindication for using dental amalgam?

    <p>Large cavities</p> Signup and view all the answers

    Which characteristic of dental amalgam is primarily related to its setting reaction?

    <p>Formation of a stable phase</p> Signup and view all the answers

    Which dental amalgam classification is known for easier carving but may lead to improper proximal contacts?

    <p>Lathe-cut alloy</p> Signup and view all the answers

    What is a significant consequence of excessive corrosion in dental amalgam?

    <p>Loss of strength</p> Signup and view all the answers

    How do high copper alloys compare to low copper alloys in terms of creep and flow?

    <p>Less creep and flow</p> Signup and view all the answers

    Which property of high copper alloys contributes to their dimensional stability?

    <p>Low dimensional changes</p> Signup and view all the answers

    Which of the following statements regarding tarnish and corrosion in amalgam is correct?

    <p>High copper alloys have better corrosion resistance.</p> Signup and view all the answers

    In terms of tensile strength, how do low copper alloys compare to high copper alloys?

    <p>Low copper alloys exhibit the lowest tensile strength.</p> Signup and view all the answers

    What effect does the presence of $ ext{γ}2$ in low copper amalgam have on creep?

    <p>Increases the creep</p> Signup and view all the answers

    Which dimensional change occurs first when mercury is combined with amalgam alloy?

    <p>Initial contraction</p> Signup and view all the answers

    How does under-trituration affect amalgam?

    <p>Leads to amalgam expansion</p> Signup and view all the answers

    What is the coefficient of thermal expansion for low copper amalgam at 37 ℃?

    <p>19.7 $ ext{μm/cm}$</p> Signup and view all the answers

    What can happen if zinc-containing alloy is contaminated with moisture during manipulation?

    <p>Gradual expansion of amalgam over time</p> Signup and view all the answers

    What is a common visual sign of tarnish on dental amalgam?

    <p>Surface appearing dull</p> Signup and view all the answers

    What is the primary consequence of high mercury content in amalgam?

    <p>Increases expansion of the restoration</p> Signup and view all the answers

    What can occur due to delayed expansion in zinc-containing amalgam?

    <p>Post operative sensitivity</p> Signup and view all the answers

    What is the range of compressive strength for amalgam after 7 days?

    <p>300-500 MPa</p> Signup and view all the answers

    Which type of amalgam has the lowest tensile strength?

    <p>Low copper amalgam</p> Signup and view all the answers

    How much strength does amalgam lose when the temperature rises to 60°C in the mouth?

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

    Which factor affects the strength of amalgam by altering the trituration process?

    <p>Amalgamator speed</p> Signup and view all the answers

    What is the modulus of elasticity range for amalgam?

    <p>20-50 GPa</p> Signup and view all the answers

    What can lead to amalgam flowing beyond the margin during setting?

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

    Which amalgam type exhibits the highest early tensile strength?

    <p>High copper amalgam</p> Signup and view all the answers

    Low mercury content in amalgam may result in which issue?

    <p>Rough and pitted surface</p> Signup and view all the answers

    What characterizes a low copper alloy?

    <p>Less than 6% Cu</p> Signup and view all the answers

    Which component in dental amalgam contributes to an increase in strength and tarnish resistance?

    <p>Copper (Cu)</p> Signup and view all the answers

    Which phase in the low copper amalgam setting reaction is the weakest?

    <p>Gamma 2</p> Signup and view all the answers

    What role does zinc play in dental amalgam?

    <p>Prevents oxidization of other metals</p> Signup and view all the answers

    In high copper amalgam, what is the product formed when Ag-Cu reacts with SnHg?

    <p>AgHg + CuSn</p> Signup and view all the answers

    What is the primary property measured by compressive strength in dental amalgam?

    <p>Ability to withstand force toward an object</p> Signup and view all the answers

    Which of the following is true regarding high copper amalgam versus low copper amalgam?

    <p>High copper amalgam has additional phases such as Ag-Cu.</p> Signup and view all the answers

    What effect does tin (Sn) have on the properties of dental amalgam?

    <p>Increases flow and creep, decreases strength</p> Signup and view all the answers

    Study Notes

    Introduction to Amalgam Restorations

    • Amalgam is a metallic restorative material composed of silver-tin-copper alloy and mercury
    • The unset mixture is pressed (condensed) into a cavity and contoured to restore tooth form and function
    • It's used as a direct filling material due to its mechanical properties, low cost, and easy placement

    Lecture Objectives

    • Define dental amalgam restoration
    • List advantages, disadvantages, indications, and contraindications of amalgam restoration
    • Identify amalgam classifications
    • Identify amalgam composition
    • Explain the amalgam setting reaction
    • Describe amalgam properties

    Advantages

    • Ease of use
    • High strength
    • Excellent wear resistance
    • Favorable long-term clinical research results
    • Low cost

    Disadvantages

    • Non-esthetic
    • Less conservative (more tooth structure removal)
    • Non-insulating
    • More difficult tooth preparation
    • Environmental concern

    Indications

    • Posterior teeth restorations
    • Large cavities
    • Areas with limited moisture control
    • Core build-ups for crowns

    Contraindications

    • Esthetic areas (anterior teeth)
    • Mercury-sensitive patients
    • Small cavities
    • If composite restoration offers a better, more conservative restoration

    Amalgam Classification

    • Classification based on particle shape (spherical, lathe-cut, admix)
    • Classification based on copper content (low copper, high copper)
    • Classification based on zinc content (zinc-containing, zinc-free)

    Amalgam Composition

    • Silver (Ag): Increases strength, resists tarnish and corrosion
    • Tin (Sn): Decreases strength, increases flow and creep
    • Copper (Cu): Increases strength, resists tarnish and corrosion
    • Zinc (Zn): Prevents oxidization of other metals, increases strength and creep resistance

    Amalgam Setting Reaction

    • Low copper amalgam (conventional): AgSn + Hg → AgSn + AgHg + SnHg
    • High copper amalgam: AgSn + Ag-Cu + Hg → AgSg + AgHg + SnHg + Ag-Cu

    Amalgam Properties

    • Compressive strength: The ability to withstand force toward an object; higher in high-copper amalgam. (300 - 500 MPa)
    • Tensile strength: The ability to withstand force lateral to an object; lower in low-copper amalgam compared to high-copper (48-60 MPa)
    • Modulus of elasticity: Measurement of material stiffness. (20-50 GPa)
    • Creep & Flow: Time-dependent plastic deformation under static load; higher in low-copper amalgam
    • Dimensional changes: Changes in shape and dimensions under heat or chemical reaction; greatest in low-copper amalgam (19.7 µm/cm)
    • Tarnish & Corrosion: Discoloration or chemical/electrochemical process of metal dissolution due to environmental attack; can lead to porosity, loss of strength, and releasing metal products.

    Factors Affecting Amalgam Strength

    • Temperature: Significant strength loss with increased temperature
    • Mercury content: Higher mercury content leads to decreased strength; lower mercury levels can produce a rough surface
    • Trituration: Under- or over-trituration affects strength regardless of copper content
    • Condensation: Type of alloy determines condensation pressure requirements for optimal compressive strength

    Factors Affecting Amalgam Creep

    • Amalgam composition: Presence of zinc in low-copper amalgam increases creep
    • Amalgam manipulation: Proper condensation and trituration time reduces creep in high-copper amalgam

    Factors Affecting Amalgam Dimensional Changes

    • Mercury content: High mercury content leads to high expansion
    • Trituration: Under-trituration causes expansion, while over-trituration causes contraction
    • Condensation: Lower condensation pressure leads to expansion

    Additional Information

    • Amalgam may have self-sealing ability; filling the gap between tooth/restoration over time—likely due to creep and corrosion products
    • Amalgam restorations can corrode in the oral environment. This corrosion can trigger galvanic action, leading to ion release.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Amalgam Part 1 PDF

    Description

    This quiz covers the essential aspects of dental amalgam restorations, including their composition, properties, advantages, and disadvantages. Learners will explore indications for use and the setting reaction involved in the restoration process. Understand the critical balance between practicality and aesthetics in dental care with amalgam.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser