Dental Occlusal Reduction Quiz
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Questions and Answers

What is the correct depth for reducing the central groove in occlusal reduction?

  • 1.5 mm
  • 0.5 mm
  • 0.8 mm (correct)
  • 1.0 mm

How should the functional cusp bevel be oriented in relation to the opposing triangular ridge?

  • Parallel to the ridge (correct)
  • Perpendicular to the ridge
  • At a 45-degree angle to the ridge
  • 1.5 mm away from the ridge

Which instrument is recommended for placing guiding grooves during occlusal reduction?

  • Flat-end diamond.
  • Round-end tapered diamond
  • Straight diamond bur
  • Tapered carbide (correct)

What is the minimum clearance required on functional cusps during occlusal reduction?

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

Which method can be utilized to assess occlusal clearance?

<p>Utility wax and wax caliper (A)</p> Signup and view all the answers

What is the ideal margin configuration recommended in the axial reduction aiming for a supragingival position?

<p>0.5 mm chamfer finish line (A)</p> Signup and view all the answers

What is the correct total convergence angle between opposing axial walls during axial reduction?

<p>6 degrees (C)</p> Signup and view all the answers

What is a primary requirement for the preparation of a full metal crown?

<p>Preservation of remaining tooth structure (B)</p> Signup and view all the answers

How should the alignment grooves be placed on the buccal and lingual walls?

<p>One in the center and one in each transitional line angle (A)</p> Signup and view all the answers

Which of the following advantages is specifically associated with full metal crowns?

<p>Greater retention due to the inclusion of all axial surfaces (C)</p> Signup and view all the answers

What is a disadvantage of using a complete metal cast crown?

<p>It does not allow for electric vitality testing due to metal interference (C)</p> Signup and view all the answers

What must be avoided during the axial reduction to prevent unsupported enamel?

<p>Cutting too deeply with the diamond (D)</p> Signup and view all the answers

In which scenario is a full metal crown particularly beneficial?

<p>For managing furcation involvement to improve oral hygiene (A)</p> Signup and view all the answers

What is the appropriate width of the cervical chamfer during preparation?

<p>0.5 mm (B)</p> Signup and view all the answers

What instrument is primarily used for axial reduction?

<p>A narrow, round-tipped diamond (A)</p> Signup and view all the answers

How does the strength of a complete metal crown compare to other types of restorations?

<p>It has superior strength compared to other restorations (A)</p> Signup and view all the answers

What is the purpose of placing additional retentive features during finishing?

<p>To secure the restoration in place (D)</p> Signup and view all the answers

What might be a concern for patients regarding the aesthetic aspect of full metal crowns?

<p>They may display metal, especially in visible areas (C)</p> Signup and view all the answers

Why is it important to maintain one half of the tooth intact during preparation?

<p>To serve as a reference for adequacy of preparation (C)</p> Signup and view all the answers

Which of the following is NOT a function or feature of a complete metal cast crown?

<p>Performs effective electric vitality testing (B)</p> Signup and view all the answers

What specific modification can a full metal crown aid in regarding tooth contour?

<p>Management of malaligned teeth (A)</p> Signup and view all the answers

What is the preferred instrument for finishing the chamfer margin?

<p>A fine-grit diamond or carbide bur (C)</p> Signup and view all the answers

What is the advantage of having smooth transitions from occlusal to axial surfaces?

<p>It reduces bubble formation during restoration fabrication (D)</p> Signup and view all the answers

What is the minimum recommended occlusal clearance for non-centric cusps during cast crown preparation?

<p>1 mm (A)</p> Signup and view all the answers

What is the role of the periodontal probe during the preparation process?

<p>To check the relative parallelism of alignment grooves (D)</p> Signup and view all the answers

What is the recommended taper or convergence between opposing axial surfaces?

<p>6 degrees (B)</p> Signup and view all the answers

What is the primary indication for using a complete cast crown?

<p>To provide maximum retention and resistance (A)</p> Signup and view all the answers

Which of the following statements about undercuts during crown preparation is correct?

<p>Undercuts should not exist between any opposing axial walls. (A)</p> Signup and view all the answers

What angle should the functional cusp bevel be placed at relative to the long axis of the tooth?

<p>45 degrees (D)</p> Signup and view all the answers

In what situation is a complete cast crown contraindicated?

<p>When treatment can be met with a conservative restoration (D)</p> Signup and view all the answers

Which part of the preparation process involves determining the occluso-gingival length of the crown?

<p>Occlusal reduction (C)</p> Signup and view all the answers

How much clearance should be provided for the non-functional (non-centric) cusp?

<p>0.6 mm (D)</p> Signup and view all the answers

What configuration should the margin of the prepared tooth have for crown placement?

<p>Chamfer (B)</p> Signup and view all the answers

What is the minimum occlusal clearance required for non-functional cusps in a complete cast crown preparation?

<p>1 mm (B)</p> Signup and view all the answers

Which of the following describes over-tapering in tooth preparation?

<p>Reduces retention of the completed restoration (B)</p> Signup and view all the answers

What is one of the main reasons for using a complete cast crown on endodontically treated teeth?

<p>To compensate for lost tooth structure (A)</p> Signup and view all the answers

What is the recommended metal thickness at the margin of the crown preparation?

<p>0.5 mm (C)</p> Signup and view all the answers

When are axial contours typically corrected in the preparation for a complete cast crown?

<p>When correction is not feasible with conservative techniques (D)</p> Signup and view all the answers

What type of teeth are complete cast crowns particularly indicated for?

<p>Teeth under heavy occlusal stress (B)</p> Signup and view all the answers

What is the goal of occlusal reduction in the preparation of a complete cast crown?

<p>To create sufficient space for the restorative material (C)</p> Signup and view all the answers

Flashcards

What is a full metal crown?

A dental restoration that replaces the entire crown of a tooth, made entirely of metal.

What is the preparation for a full metal crown?

The process of preparing a tooth for a full metal crown involves removing a significant amount of tooth structure.

What are the key requirements for preparing a full metal crown?

  1. Ensuring enough tooth structure is removed for a strong crown. 2) Preserving as much remaining tooth as possible. 3) Creating a crown that is strong enough to withstand chewing forces.

What is the advantage of full metal crowns in terms of retention?

Full metal crowns provide superior retention compared to crowns that cover only part of a tooth. The entire surface of the crown is enclosed in the preparation, making it very secure.

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What is the advantage of full metal crowns in terms of resistance form?

Full metal crowns offer greater resistance against chewing forces compared to crowns that only cover part of a tooth. This is due to the full coverage and the strong metal material.

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What is the advantage of full metal crowns in terms of strength?

Full metal crowns are very strong, making them ideal for situations where maximum strength is needed. They can withstand the forces of chewing better than other types of crowns.

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What is the advantage of full metal crowns in terms of modifying the tooth's shape?

Full metal crowns allow for modification of the tooth's shape, which is beneficial in cases of misaligned teeth, furcation involvement (where roots are exposed), and as retainers for removable dentures.

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What is the advantage of full metal crowns in terms of occlusion?

Metal crowns can be easily modified to adjust the bite, especially useful in cases of teeth that have erupted too far or when the bite needs to be corrected.

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What is a Full Cast Crown?

A full crown covers the entire tooth, restoring it to its original shape, size, and function.

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When is a Full Cast Crown Preferred?

Provides optimal retention and resistance, ideal when strong forces are anticipated, such as for long-span bridges.

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What are the Indications of a Full Cast Crown?

Full crowns are indicated to restore teeth significantly damaged by decay, trauma, or previous restorations.

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What are the Contraindications of a Full Cast Crown?

Full crowns are not recommended if less invasive treatments like partial crowns are sufficient to achieve the desired outcome.

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What is Occlusal Reduction?

It is the first step of preparing a tooth for a full crown. It creates space for the crown material and shapes the crown for optimal fit.

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What is the Purpose of Axial Grooves?

It involves using a fine-grit bur to create grooves around the tooth, to help with the retention of the crown.

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What is the Importance of Axial Reduction?

It is a critical stage in preparation that ensures the final crown fits well and is properly aligned with opposing teeth.

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What is Finishing and Evaluation in Full Crown Preparation?

This final step involves smoothing the preparation, ensuring a smooth transition between the prepared tooth and the new crown.

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What instruments are used in occlusal reduction?

Specialized instruments like tapered carbide burs or diamonds are used to create grooves and bevels on the tooth surface for a crown.

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What are guiding grooves and their purpose?

These are strategically placed indentations in the chewing surface of a tooth to ensure the crown fits properly.

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What is the functional cusp bevel and why is it important?

This bevel is a slight angle created on the functional cusp, essential for maintaining enough tooth structure for strength and stability.

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What are the depths of the cuts in occlusal reduction?

The depth of the cuts depends on the location and required clearance. Central grooves and nonfunctional cusps are 0.8mm deep, while functional cusps are 1.3mm.

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Why is half of the occlusal surface reduced first?

To reduce the crown preparation in stages. It helps to maintain reference points and ensure the tooth is properly shaped.

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What is the minimum clearance required for occlusal reduction?

A minimum clearance is necessary to avoid interference during chewing. Functional cusps require 1.5mm clearance and nonfunctional cusps need 1.0mm.

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What are methods to evaluate occlusal clearance?

These are different methods used to check for proper clearance during occlusal reduction.

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Crown Preparation

The process of shaping the tooth to create a smooth, contoured surface for the crown to fit on.

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Diamond Depth

When placing the crown, make sure the diamond does not cut into the tooth beyond the midpoint of the tooth structure, as this can create a weak spot.

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Axial Reduction Instrument

A small, narrow diamond used to shape the tooth for the crown, resembling a round-tipped instrument.

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Cervical Chamfer

A narrow groove or line created around the base of the tooth to provide a stronger bond for the crown, usually around 0.5 mm wide.

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Crown Finishing

The process of removing excess tooth structure and ensuring the crown preparation is smooth and regular, preventing bubbles during the crown creation process.

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Metal Matrix Band

A small, round piece of metal used to protect the neighboring teeth during tooth preparation.

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Crown Evaluation

A final check after crown preparation to confirm that all aspects of the preparation are correct and complete.

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Remaining Islands

Areas of tooth removed during crown preparation that leave small islands of tooth structure remaining.

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Occlusal Reduction

The amount of tooth structure removed to accommodate the crown material. It should be sufficient for proper fit and strength.

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Non-Centric Cusp Bevel

The minimum clearance needed for non-centric cusps during crown preparation. This ensures sufficient space for the crown material and prevents interference with other teeth.

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Axial Reduction

This refers to the angle or taper created on the walls of the preparation. It should be approximately 6 degrees to ensure proper retention of the crown.

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Finishing and Evaluation

The process of smoothing and finishing the prepared tooth surface to create a smooth transition for the crown. This ensures a tight fit and prevents irritation to the gums.

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Chamfer Margin

A margin configuration that creates a smooth, gradual transition between the prepared tooth and the crown. This helps prevent food trapping and gum irritation.

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Centric Cusp Bevel

The minimum clearance needed for centric cusps during crown preparation. This ensures proper contact and prevents excessive wear on the opposing teeth.

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No Undercuts

Removing undercuts or irregularities on the prepared tooth surface to allow for smooth placement and removal of the crown.

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Supragingival Margin

The location of the crown margin should be above the gum line to prevent irritation and promote better hygiene.

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Study Notes

Complete Cast Crown Preparation

  • Definition: A full metal restoration that restores a tooth's function.

  • Requirements:

    • Removal of adequate tooth structure.
    • Preservation of remaining tooth structure.
    • Reduction to create a crown with acceptable strength.

Advantages

  • Greater Retention: Includes all axial surfaces in the preparation, providing superior retention compared to less extensive restorations like three-quarter crowns.
  • Resistance Form: The preparation has greater resistance form than partial-coverage restorations.
  • Superior Strength: Stronger material compared to other restoration types.

Additional Benefits

  • Modifying Axial Contour: Enables modification of the axial tooth contour for malaligned teeth or furcation involvements. Improved oral hygiene is also possible through re-contouring of buccal and lingual walls.
  • Removable Partial Denture Retainers: Often the only option that allows creation of properly shaped survey lines, guide planes, and occlusal rests.
  • Occlusion Modification: Easier modification of the occlusion, which can be difficult with more conservative restorations, such as with supra-erupted teeth or if the occlusal plane needs re-establishment.

Disadvantages

  • Less Conservative: Involves all tooth surfaces, which potentially carries risk for the pulp and periodontium.
  • Vitality Testing Restrictions: The conductive metal prevents electric vitality testing.
  • Aesthetic Concerns: Patients may object to the display of metal, particularly in those with a normal smile line, which might limit use to posterior teeth.

Indications

  • Single Crowns and Fixed Partial Dentures (FPDs): Suitable for posterior maxillary/mandibular molars and premolars.
  • Extensive Coronal Destruction: Used for teeth with significant loss of tooth structure.
  • Posterior Short Clinical Crowns: Ideal solution when the clinical crown is short.
  • High Displacement Forces: Useful for long-span fixed partial dentures where high displacement forces are likely.
  • Correction of Axial Contours (when necessary): Used when creating a more conservative preparation isn't possible.
  • Removable Partial Denture Support: Can act as a support for removable partial dentures.
  • Endodontically Treated Teeth: High strength compensates for loss of tooth structure in endodontically treated teeth.

Contraindications

  • Conservative Restoration Options: If a conservative restoration is sufficient.
  • Limited Retention/Resistance Needs: If less than maximum retention and resistance are required.
  • High Esthetic Needs: Not ideal for anterior teeth requiring high aesthetics.

Preparation Armamentarium

  • High-Speed Contra-Angle Hand Pieces— Instruments for various reductions.
  • Round-Ended Tapered Diamonds: Various grit sizes for different reduction types.
  • Occlusal Guiding Grooves: Prepare the occlusal surface.
  • Occlusal Reduction: Reduce the occlusal surface of the tooth.
  • Axial Alignment Grooves: Create grooves for appropriate axial reduction.
  • Axial Reduction: Reduce the axial surface to a specific shape and margin.
  • Finishing and Verification of Occlusal Clearance: The final process to check the preparation and confirm the desired occlusal clearance.

Occlusal Reduction

  • Initial Reduction: Perform half the occlusal reduction at first and maintain the other half as a reference.
  • Functional Cusp Bevel: A 1.5 mm bevel placed parallel to the opposing triangular ridge.
  • Correct Depth: 0.8 mm for non-functional cusps and 1.3 mm for functional cusps.
  • Instruments: Round-ended, tapered diamond instruments for optimal results.

Evaluation Methods

  • Utility Wax and Wax Calipers
  • Occlusal Reduction Gauges
  • Occlusal Clearance Tabs
  • Occlusal Reduction Rings
  • Rubber Base

Axial Reduction

  • Aim: Achieving a 6-degree taper or convergence angle between opposing axial walls and a minimum wall height of 3mm.
  • Margin Configuration: Chamfer finish line 0.5 mm following the gingival contour.
  • Alignment Grooves: Placing grooves in the buccal and lingual walls, one centered and one in each mesial/distal transitional line angles.

Finishing

  • Smooth surface finish for all prepared tooth surfaces.
  • Smooth transitions from the occlusal to the axial surfaces.
  • Use fine-grit diamond or carbide for finishing the chamfer margin.

Criteria for Complete Cast Crown Preparation

  • Occlusal Room: Adequate space for the restoration material.
  • Minimum Occlusal Clearance: 1 mm for non-centric cusps and 1.5 mm for centric cusps.
  • Conservative Reduction: Following normal anatomic contours.
  • Axial Reduction: Parallel to the tooth's long axis with a 6-degree taper.
  • No Over-Tapering: Maintaining adequate retention for the finished restoration.
  • No Undercuts: Ensuring smooth movement of the restoration across the opposing axial walls.
  • Functional (Centric) Cusp Bevel: A 1.5 mm bevel, angled flatter than the external surface at approximately 45 degrees.
  • Non-Functional Cusp Bevel: Minimum of 0.6 mm clearance for adequate strength.

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Test your knowledge on occlusal reduction techniques in dentistry. This quiz covers essential concepts such as depth of groove reduction, orientation of functional cusp bevels, and the requirements for full metal crowns. Perfect for dental students and professionals looking to sharpen their skills.

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