Bio-Mechanical Principles in Dentistry
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Questions and Answers

What is a potential result of applying a featheredge margin?

  • Increased strength of the restoration
  • Over contoured restorations (correct)
  • Adequate bulk at the margin
  • Reduced conservation of tooth structure
  • A chamfer margin is particularly suitable for all-ceramic crowns.

    False

    What is the angle that a shoulder margin should form with unprepared tooth structure?

    90 degrees

    An excessively tapered preparation can lead to a __________ margin.

    <p>chisel edge</p> Signup and view all the answers

    Match the margin type with its suitability:

    <p>Chamfer margin = Suitable for cast metal crowns Beveled margin = Suitable for cast restorations with ledges Featheredge margin = Often leads to over contoured restorations Shoulder margin = Recommended for all-ceramic crowns</p> Signup and view all the answers

    What should the angle of the diamond be held at while preparing the gingival margin?

    <p>Aiming away from the tooth</p> Signup and view all the answers

    Over reduction of the tooth structure can enhance retention.

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

    What is the primary objective of beveling a margin?

    <p>To minimize marginal discrepancy and protect unprepared tooth structure.</p> Signup and view all the answers

    What is the recommended method to prevent heat buildup when preparing retentive features?

    <p>Prepare at low rotational speed</p> Signup and view all the answers

    Chemical agents used for cleaning tooth preparation are safe and do not irritate the pulp.

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

    What is one of the basic tenets of restorative dentistry regarding tooth structure?

    <p>To conserve as much tooth structure as possible.</p> Signup and view all the answers

    The thickness of the remaining dentin is inversely proportional to the ________ response.

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

    Match the following guidelines for conservation of tooth structure with their descriptions:

    <p>Partial coverage restoration = Preserves more tooth structure Minimal convergence angle = Reduces stress on the restoration Even occlusal reduction = Ensures uniform thickness Conservative margin selection = Compatible with tooth preparation principles</p> Signup and view all the answers

    What can contribute to pulpal damage during restorative procedures?

    <p>Chemical action of dental materials</p> Signup and view all the answers

    Microleakage can lead to bacterial action contributing to pulpal damage.

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

    What should be done to ensure adequate tooth structure for fixed prosthesis placement?

    <p>Remove all carious dentin.</p> Signup and view all the answers

    What is a consequence of excessive taper in tooth preparation?

    <p>Considerable loss of tooth structure</p> Signup and view all the answers

    Traditionally, subgingival margins are considered better for dental restorations than supragingival margins.

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

    What is the primary reason for axial reduction in tooth preparation?

    <p>To secure space for adequate thickness of restorative material.</p> Signup and view all the answers

    The practice of routinely placing margins subgingivally has been linked to ______.

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

    Match the margin placement types with their advantages:

    <p>Supragingival = Easily finished and kept clean Subgingival = Difficult to keep clean and maintain</p> Signup and view all the answers

    Which of the following is NOT a disadvantage of subgingival restoration margins?

    <p>Easier preparation</p> Signup and view all the answers

    The placement of the finish line has no impact on the structure of the final restoration.

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

    What kind of margins should be used whenever possible in dental restorations?

    <p>Supragingival margins</p> Signup and view all the answers

    Study Notes

    Bio-Mechanical Principles

    • Improper tooth preparation can negatively impact long term dental health.
    • Axial reduction is necessary for sufficient restorative material thickness and to avoid over contouring.
    • Margin placement is vital for restoration fabrication and ease of cleaning.
    • Margins should be as smooth as possible and fully exposed for cleaning.
    • Margins should be placed where they can be finished by the dentist and kept clean by the patient.
    • Margins should be placed where they can be duplicated by the impression without tearing or deforming the impression.
    • Supragingival margins are preferred over subgingival margins as they are easier to prepare, finish, and keep clean.

    Margin Types

    • Featheredge margins are not recommended due to a lack of bulk at the margin and potential for over contouring.
    • Chisel-edge margins are associated with excessively tapered preparations or incorrect axial reduction.
    • Chamfer margins are ideal for cast metal crowns and metal portions of metal-ceramic crowns as they provide good bulk and are easily identified.
    • Beveled margins are suitable for cast restorations when a ledge or shoulder already exists. They allow for bending or burnishing of the cast metal margin and minimize marginal discrepancies, protecting unprepared tooth structure.
    • Shoulder margins are preferred for all-ceramic crowns and facial parts of metal-ceramic crowns.

    Considerations For Tooth Preparation

    • Avoid excessive pressure, high rotational speeds, and inappropriate bur types and shapes during preparation to minimize heat generation.
    • Use water spray strategically to cool the cutting area, especially when preparing grooves or pinholes.
    • Chemical agents used for cleaning and degreasing should be avoided as they can irritate the pulp.
    • Remove all carious dentin to prevent bacterial action leading to pulpal damage under restorations.
    • Minimize pulpal effects by preserving as much tooth structure as possible.
    • The thickness of remaining dentin is inversely proportional to the pulpal response.

    Guidelines For Conserving Tooth Structure

    • Use partial coverage restorations over full coverage restorations.
    • Prepare teeth with minimal convergence angle (taper) between the axial walls.
    • Reduce the occlusal surface evenly and anatomically for uniform restoration thickness.
    • Ensure even and adequate reduction of the axial tooth surfaces for proper axial contour.
    • Choose a conservative margin compatible with other tooth preparation principles.
    • Avoid unnecessary apical extension of the preparation.

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    Description

    This quiz explores essential bio-mechanical principles critical for effective dental restorative practices. It covers topics such as tooth preparation, margin placement, and the significance of maintaining clean margins for long-term dental health. Understand the implications of different margin types and their impact on restorative procedures.

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