Principles of Cavity Preparation in Dentistry
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Questions and Answers

What is the primary purpose of resistance form in cavity preparation?

  • To remove unsupported enamel to prevent fracture
  • To restrict the extension of the walls for strong cusp and ridge support
  • To shape the cavity walls to withstand the force of mastication without fracture (correct)
  • To create a smooth pulpal floor to resist restoration movement

    • Why should the pulpal floor be flat and perpendicular to the long axis in cavity preparation?

  • To allow for easy removal of unsupported enamel
  • To reduce stress concentration at internal line angles
  • To resist restoration movement and prevent wedging action on the tooth (correct)
  • To prevent the spread of caries in dentin

    • What is the significance of slightly curved (rounded) internal line angles in cavity preparation?

  • To restrict the extension of the walls for strong cusp and ridge support
  • To reduce the spread of caries in dentin
  • To allow for easy removal of unsupported enamel
  • To prevent stress concentration and fracture of tooth structure (correct)

    • Why should unsupported enamel be removed during cavity preparation?

    <p>Enamel is brittle and will fracture easily when subjected to force</p> Signup and view all the answers

    What should be restricted by controlling the width of the cavity in cavity preparation?

    <p>The extension of the walls to allow strong cusp and ridge with sufficient dentin support</p> Signup and view all the answers

    What is the typical depth of the cavity when caries is present in the pulpal floor or axial wall or both?

    <p>1.5 mm</p> Signup and view all the answers

    What instrument should be used to remove caries when present in the pulpal floor or axial wall or both?

    <p>Spoon excavator</p> Signup and view all the answers

    How can caries dentin be detected?

    <p>By tapping on it with a metal instrument</p> Signup and view all the answers

    What can result from removing all of the pulpal floor due to caries?

    <p>Both A and B</p> Signup and view all the answers

    What are the objectives of finishing the cavity walls?

    <p>To provide maximum strength of both the tooth and restorative material at and near the margin</p> Signup and view all the answers

    What factors must be considered in the finishing of enamel walls and margins?

    <p>Direction of enamel rods, support of enamel rods, type of restorative material, location of margins, and desired smoothness</p> Signup and view all the answers

    What is the purpose of toilet of the cavity?

    <p>To clean the cavity from small chips of cutting tooth structure and remove carious lesion</p> Signup and view all the answers

    How should toilet of the cavity be performed?

    <p>Using a dry cotton pellet followed by oil-free air spray for drying</p> Signup and view all the answers

    What should be used to detect caries dentin?

    <p>Sharp probe or metal instrument</p> Signup and view all the answers

    What is the result of removing all pulpal floor?

    <p>Unnecessary cutting of tooth structure and increased possibility of hitting the pulp</p> Signup and view all the answers

    What should be used to remove caries when present in pulpal floor or axial wall?

    <p>Spoon excavator</p> Signup and view all the answers

    What must be considered in finishing enamel walls and margins?

    <p>Direction of enamel rods, support of enamel rods, type of restorative material, location of margins, and desired smoothness</p> Signup and view all the answers

    What is the aim of the retention form in restorative dentistry?

    <p>To resist displacement or removal of the restoration against tipping or lifting forces</p> Signup and view all the answers

    Why should the width of the cavity be 1/4 of the intercuspal distance?

    <p>To preserve sound tooth structure and prevent weak remaining tooth structure</p> Signup and view all the answers

    What is the purpose of a smooth pulpal floor in cavity preparation?

    <p>To avoid concentrating occlusal force on irregular areas and causing fracture</p> Signup and view all the answers

    Why should the mesial and distal walls of the cavity be made parallel or slightly diverge?

    <p>To prevent unsupported enamel and fracture under occlusal load</p> Signup and view all the answers

    What is the minimum thickness of amalgam required to withstand the load applied without being fractured?

    <p>1-1.5 mm</p> Signup and view all the answers

    What is the purpose of box form in cavity preparation?

    <p>To provide flat, smooth, and plane walls and floors for the restoration</p> Signup and view all the answers

    What is the aim of convenience form in restorative dentistry?

    <p>To allow adequate observation, accessibility, and ease of operation in preparing and restoring the cavity</p> Signup and view all the answers

    What is the recent trend in conservative restorative dentistry regarding retention?

    <p>Depend on adhesive materials capable of bonding all restorative materials to tooth structure</p> Signup and view all the answers

    What is the function of an axial groove in restorative dentistry?

    <p>To provide secondary or auxiliary retention</p> Signup and view all the answers

    What is the purpose of reverse bevel in gold inlays?

    <p>To resist displacement or removal of the restoration against tipping or lifting forces</p> Signup and view all the answers

    Why should convergence of buccal and lingual (palatal) walls be about 50 degrees?

    <p>To prevent unsupported enamel and fracture under occlusal load</p> Signup and view all the answers

    What is the advantage of reducing dependence on mechanical interlocking for retention?

    <p>Reduces unnecessary tooth cutting and destruction for creating dove tails and undercuts</p> Signup and view all the answers

    Study Notes

    Cavity Preparation

    • Primary purpose of resistance form is to prevent fracture of tooth structure.
    • Pulpal floor should be flat and perpendicular to the long axis to allow for even distribution of stress and reduce the risk of fracture.

    Cavity Design

    • Slightly curved (rounded) internal line angles help to reduce stress concentrations and prevent fracture.
    • Unsupported enamel should be removed to prevent fracture and ensure structural integrity.

    Width and Depth of Cavity

    • Width of cavity should be restricted to 1/4 of the intercuspal distance to prevent excessive removal of tooth structure.
    • Typical depth of cavity when caries is present in pulpal floor or axial wall is 0.5-1.5 mm.

    Caries Removal

    • Caries dentin can be detected using a caries detector dye.
    • Excavators or round burs should be used to remove caries when present in pulpal floor or axial wall.

    Finishing the Cavity

    • Objectives of finishing the cavity walls are to provide a smooth surface, remove any sharp edges, and ensure a tight seal.
    • Factors to consider when finishing enamel walls and margins include beveling, smoothing, and polishing.

    Toilet of the Cavity

    • Purpose of toilet of the cavity is to remove any debris or residue, ensuring a clean surface for restoration.
    • Toilet of the cavity should be performed using a soap and water followed by an alcohol rinse.

    Retention Form

    • Aim of retention form is to provide mechanical interlocking between the tooth and the restoration.
    • Width of the cavity is restricted to allow for adequate retention without excessive removal of tooth structure.

    Other Considerations

    • Smooth pulpal floor helps to reduce stress concentrations and prevent fracture.
    • Mesial and distal walls of the cavity should be made parallel or slightly divergent to allow for even distribution of stress.
    • Minimum thickness of amalgam required to withstand the load applied without being fractured is 1.5 mm.
    • Box form provides additional retention through mechanical interlocking.
    • Convenience form provides easy access for restoration placement and removal.
    • Recent trend in conservative restorative dentistry is to reduce dependence on mechanical interlocking for retention.
    • Axial groove serves as a guide for the placement and removal of the restoration.
    • Reverse bevel in gold inlays helps to increase the strength of the restoration.
    • Convergence of buccal and lingual (palatal) walls should be about 50 degrees to allow for easy removal of the restoration.

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    Related Documents

    Principles of Cavity Preparation PDF

    Description

    Learn about the resistance form and the shaping and placement of cavity walls to withstand mastication force. Understand the importance of a flat pulpal floor in preventing restoration movement and tooth fracture.

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