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Questions and Answers
Which type of margin is considered more conservative in tooth preparation?
Which type of margin is considered more conservative in tooth preparation?
Placing the margin of a dental restoration subgingivally is widely accepted due to its absence of adverse effects on dental health.
Placing the margin of a dental restoration subgingivally is widely accepted due to its absence of adverse effects on dental health.
False
What is one of the primary reasons for sufficient axial reduction in tooth preparation?
What is one of the primary reasons for sufficient axial reduction in tooth preparation?
To secure space for adequate thickness of restorative material.
The placement of the finish line should ideally be _____ to facilitate cleaning by the patient.
The placement of the finish line should ideally be _____ to facilitate cleaning by the patient.
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Match the following advantages with supragingival margin placement:
Match the following advantages with supragingival margin placement:
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What is the minimum distance a crown margin should be placed from the alveolar crest to avoid bone resorption?
What is the minimum distance a crown margin should be placed from the alveolar crest to avoid bone resorption?
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The adaptation of the restoration margin to the tooth is crucial in reducing the chances of recurrent caries.
The adaptation of the restoration margin to the tooth is crucial in reducing the chances of recurrent caries.
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What happens if the crown margin intrudes into the biologic width?
What happens if the crown margin intrudes into the biologic width?
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A well-designed preparation has a margin that is _____ and even.
A well-designed preparation has a margin that is _____ and even.
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Match the following scenarios with their implications:
Match the following scenarios with their implications:
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Study Notes
Bio-Mechanical Principles and Tooth Preparation
- Improper tooth preparation can negatively affect long-term dental health
- Axial reduction is crucial for creating space for restorative materials with proper thickness
- Margin placement significantly impacts restoration fabrication and cleanliness
- Supragingival margins are generally preferred for ease of preparation, finishing, and impression taking, as well as for easy restoration evaluation
- Subgingival margins are necessary in certain cases, such as when caries, erosion, or previous restorations extend subgingivally, or when additional retention is needed
- Crown margins should be placed at least 2.0 mm away from the alveolar crest to avoid bone resorption
Marginal Integrity
- Marginal adaptation is crucial for preventing recurrent caries and periodontal disease
- Smooth and even margins minimize chances of recurrent caries and periodontal disease
- A well-designed preparation ensures a smooth and even margin
- Featheredge margins (shoulderless) should be avoided due to lack of bulk at the margin, which can lead to over contoured restorations
- Chisel-edge margins are associated with excessively tapered preparations and can be difficult to control
- Chamfer margins are ideal for cast metal crowns and metal portions of metal-ceramic crowns, providing adequate bulk and a distinct finish line
- Beveled margins are suitable for cast restorations when a ledge or shoulder exists, providing a smooth transition between the restoration and unprepared tooth structure
- Shoulder margins are recommended for all-ceramic crowns and facial portions of metal-ceramic crowns, providing adequate bulk for porcelain
- Radial shoulder margins offer a modified shoulder design with a rounded internal angle, reducing stress concentration in the tooth structure
- Sloped shoulder margins are a modification of the classic shoulder design, reducing the possibility of leaving unsupported enamel
- Shoulder with bevel margins are used for proximal boxes of inlays and onlays, occlusal shoulder of onlays and mandibular three-quarter crowns, and facial finish line of metal-ceramic restorations where gingival esthetics are not critical
Finish Line Types, Advantages, and Disadvantages
- Feather Edge: Conservation of tooth structure, Can lead to over-contoured restorations
- Chisel Edge: Conservation of tooth structure, Can lead to over-contoured restorations, Difficult to control margin location
- Chamfer: Distinct, well-defined finish line, Care during preparation to avoid unsupported enamel, Suitable for cast metal restorations, lingual margins of labial veneer metal-ceramic restorations
- Shoulder: Adequate bulk of restorative material, Less conservative than chamfer finish line, Sharp internal line angle, Suitable for full veneer metal-ceramic restorations, all-ceramic crowns
- Shoulder with Bevel: Adequate bulk of restorative material, Less conservative to tooth structure, Bevel removes unsupported enamel, Bevel needs to be placed apically, Suitable for metal-ceramic restorations, previous caries or restorations at finish line area
- Beveled: Removes unsupported enamel, Less conservative, Requires subgingival extension for optimal esthetics, Suitable for ledges due to previous caries or erosion at the cervical margin
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Description
Explore the critical concepts of tooth preparation and marginal integrity in dental practice. Understand the importance of axial reduction, margin placement, and their effects on restoration success and oral health. This quiz will deepen your knowledge of best practices for effective tooth preparation.