Questions and Answers
What are pits and fissures cavities?
All the cavities on the occlusal surfaces and the occlusal 2/3rds of the facial and lingual surfaces of the posterior teeth and the lingual surfaces of maxillary incisors.
What is enamel composed of?
Millions of enamel rods or prisms.
Where do the enamel rods exist?
Extend from the DEJ to the external surface of the tooth.
What is the direction of the enamel rods?
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How does the direction of the enamel rods differ in the cervical region?
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What are the US public health criteria for describing a carious lesion?
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What are cavities that extend beyond frank cavity into the dentin?
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What is a prepared cavity?
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What does the external outline principle: CSM state?
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What is meant by extension for prevention?
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What are the external outline characteristics?
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How do you decide on the extent of external outline in the clinic?
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What is enameloplasty?
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Describe pulpal line angles.
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Describe mesial and distal walls.
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What are the pros and cons of Dr. Sturdevant preparation?
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What are the pros and cons of Dr. Charbeneau preparation?
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What are the pros and cons of Dr. Hadavi preparation?
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What is Dr. Sturdevant amalgam margin?
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What is Dr. Charbeneau amalgam margin?
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What is Dr. Hadavi amalgam margin?
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Why do mesial and distal walls diverge pulpo-occlusally?
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What are the general principles in establishing outline form?
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What is the desired degree of smoothness or roughness for enamel walls based on the restorative materials used?
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What is convenience form?
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What are the tooth preparation principles for amalgam?
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What are the tooth preparation principles for modified preparation, composite and bonding?
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What should an examination kit contain?
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What are cavity preparation instruments?
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What are the steps in cavity preparation?
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What is the proper bur direction for preparing an occlusal cavity?
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What should the cavity outline and walls have?
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What does the design of the cavo-surface angle depend upon?
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How should internal outline be defined?
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What are some popular mistakes in cavity preparation?
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Study Notes
Cavity Preparation Overview
- Pits and fissures cavities are located on occlusal surfaces and occlusal 2/3rds of facial and lingual surfaces of posterior teeth, as well as the lingual surfaces of maxillary incisors.
- Enamel comprises millions of enamel rods or prisms that extend from the dentino-enamel junction (DEJ) to the tooth's external surface.
- Enamel rods are oriented perpendicularly to both the DEJ and the tooth surface, with a deviation to an apical direction in the cervical region.
Carious Lesion Identification
- US public health criteria for carious lesions include opacity around pits and fissures, a soft base, softened enamel that flakes, stickiness, and loss of translucency.
- Extensive cavities are those that extend beyond frank cavities into dentin, indicating deeper carious involvement.
Cavity Preparation Definitions
- A prepared cavity is one that has been readied for the insertion of restorative materials after a carious lesion has been addressed.
- The external outline principle requires that all cavosurface margins extend 0.5 mm beyond any defective tissue into sound tooth structure.
External Outline Considerations
- Characteristics of the external outline include the extent of caries, removal of surrounding enamel defects, convenience of access and visibility, and considerations of soft tissue and aesthetics.
- To determine external outline extent, begin cavity preparation with an explorer to locate starting points, and remove fissures or caries contributing to microleakage.
Enamel Reshaping and Angles
- Enameloplasty reshapes the enamel surface and may be performed if only 1/3 or less of the enamel depth is affected.
- Pulpal line angles should be rounded and well-defined, while mesial and distal walls must create obtuse angles with the pulpal floor.
Restoration Techniques Overview
- Dr. Sturdevant's preparation encourages a retentive restoration but may leave unsupported enamel rods.
- Dr. Charbeneau's method avoids unsupported rods but results in weaker margins needing additional dentinal retention.
- Dr. Hadavi’s approach also avoids unsupported rods but maintains moderate restoration strength.
Amalgam Margins
- Sturdevant's amalgam margins are characterized by a 90-degree angle, while Charbeneau's typically form an acute angle, and Hadavi's are larger but still acute.
Cavity Wall Characteristics
- Mesial and distal walls diverge pulpo-occlusally to align with enamel rods, preserve intact dentin, and strengthen marginal ridges.
- General principles for establishing outline form include complete removal of carious lesions, placement of margins in sound enamel, and elimination of undermined enamel rods.
Wall Smoothness and Roughness
- For smooth walls, cast gold restorations permit undistorted impressions and close adaptation.
- Rough walls, often found in composite restorations, enhance bonding surface area.
- Acceptable walls in amalgam restorations aid in reducing marginal leakage.
Tooth Preparation Principles
- For amalgam, all carious and weakened structures are removed, leaving strong tooth structure, while protecting underlying pulpal tissue.
- Modified preparation for composite emphasizes non-uniform depth, varying wall heights, and bevels.
Examination and Instrumentation
- An examination kit for cavity preparation should include a mouth mirror, explorer, calibrated condenser, and cotton pliers.
- Cavity preparation instruments encompass rotary cutting tools (256, high and low speed) and hand cutting tools (chisels, hatchets, hoes).
Preparation Steps and Guidelines
- The steps in cavity preparation are penetration, extension, and finishing.
- A bur for occlusal cavity preparation should be placed at 90 degrees to the plane over the cusps and marginal ridges.
- Cavity outlines should feature smooth curves and straight lines, adhering to specific angles based on restorative materials.
Internal Outline Qualities
- The internal outline of a cavity should be defined and rounded but not sharp.
- Common preparation mistakes include unsupported enamel rods, under/over-extension, and non-conformity to tooth anatomy.
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Description
Test your knowledge on cavity preparation with these flashcards designed for Class 1 students. Learn about pits and fissures, the composition of enamel, and the structure of enamel rods. Perfect for reinforcing dental terminology and concepts essential for future practice.