Dental Caries and Cavity Classifications
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Questions and Answers

What is the importance of having the axial wall parallel to the tooth long axis in cavity preparation?

It allows for effective instrumentation up to the depth of the proximal portion.

Describe the recommended approach for beveling the enamel on the buccal wall in upper premolar cavities.

Beveling removes undermined enamel and achieves a 90° cross-sectional area.

What are two clinical considerations to protect the adjacent tooth during cavity preparation?

Using a matrix band and applying a rubber dam are effective protective measures.

Why is it preferable to complete the proximal outline before breaking the marginal ridge?

<p>It provides a guide for proximal design and protects the adjacent tooth from rotary instruments.</p> Signup and view all the answers

What changes should be made to the gingival floor for achieving a 90° cross-sectional area?

<p>The gingival floor should be slightly slanted gingivally.</p> Signup and view all the answers

What is the recommended distance of the gingival floor above the gingival crest in relation to the pulpal floor?

<p>The gingival floor should be 0.25 - 0.5 mm above the gingival crest and parallel to the pulpal floor.</p> Signup and view all the answers

How far should the axial wall be from the DEJ for adequate restoration bulk?

<p>The axial wall should be 1.5 - 2 mm away from the DEJ.</p> Signup and view all the answers

What is the minimum width of the cavity isthmus portion bucco-lingually recommended?

<p>The minimum width of the isthmus portion should be about ¼ the inter-cuspal distance.</p> Signup and view all the answers

What shape is suggested for the proximal portion of the cavity in the context of retention form?

<p>The proximal portion should have an inverted truncated cone shape.</p> Signup and view all the answers

What preparation technique is recommended for creating axial retention in cavity walls?

<p>Cavity walls should be prepared to be slightly converging occlusally to create mechanical undercuts.</p> Signup and view all the answers

Name a technique used to ensure retention along with a proximal dovetail in molars.

<p>The occlusal lock technique is used to provide retention along with a proximal dovetail.</p> Signup and view all the answers

What is the role of proximal axial grooves in cavity preparation?

<p>Proximal axial grooves are cut into the axio-buccal and axio-lingual line angles to enhance retention without risking pulp exposure.</p> Signup and view all the answers

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

<p>The convenience form is designed to provide accessibility to the proximal portion of the cavity.</p> Signup and view all the answers

What shape does caries typically spread in within enamel and dentin?

<p>Caries spreads in a conical pattern within both enamel and dentin.</p> Signup and view all the answers

What is the role of bite-wing x-ray films in the diagnosis of caries?

<p>Bite-wing x-ray films are necessary for the correct diagnosis of caries, as they help identify lesions that are difficult to detect visually.</p> Signup and view all the answers

Describe the occlusal portion of a Class II cavity preparation.

<p>The occlusal portion of a Class II cavity preparation is the same as that of a Class I cavity.</p> Signup and view all the answers

What characterizes the isthmus portion of a Class II cavity preparation?

<p>The isthmus portion is the narrowest connection between the occlusal and proximal portions of the cavity.</p> Signup and view all the answers

What considerations must be made for the proximal portion of a Class II cavity?

<p>The proximal portion must involve all carious enamel and dentin and ensure the cavity margins are in a self-cleansable area.</p> Signup and view all the answers

What effect does caries have on the marginal ridge and how does it spread?

<p>Caries tend to undermine the marginal ridge early and spread occlusally along the dento-enamel junction.</p> Signup and view all the answers

What is the importance of ensuring the cavity margins are in self-cleansable areas?

<p>Ensuring cavity margins are in self-cleansable areas helps to prevent caries recurrence.</p> Signup and view all the answers

What factors determine the outline form of the isthmus in Class II cavity preparation?

<p>The outline form of the isthmus is determined by the size of the contact area: straight for small, uniform for normal, and reverse curve for broad contact areas.</p> Signup and view all the answers

Flashcards

Class II Cavity

A smooth surface lesion found on the proximal surfaces of molars and bicuspids, typically in the middle-middle third of the tooth.

Isthmus

The narrowest connection between the occlusal and proximal portions of a Class II cavity.

Isthmus Outline Forms

The shape of the isthmus can be straight, uniform, or reverse curve.

Proximal Preparation

The proximal portion of a Class II cavity should be extended enough to remove all caries and allow for adequate cleaning.

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Dento-enamel Junction (DEJ)

The portion of the tooth where the enamel and dentin meet.

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Conical Pattern of Caries

Caries in enamel and dentin spread in a cone shape, with the base at the DEJ.

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Occlusal Spread of Caries

Caries often extends occlusally along the DEJ, undermining the marginal ridge.

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Bucco-lingual Spread of Caries

Caries can extend buccally and lingually towards the axial angles.

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Axial Wall Parallelism in Class II Cavities

The occlusal wall should be parallel to the tooth's long axis from the occlusal to the gingival surfaces. This allows instruments access to the deepest part of the proximal cavity.

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Flared Walls in Class II Proximal Cavities

The buccal and lingual walls of the proximal portion of the cavity are gently curved outwards to ensure a 90-degree angle with the instruments.

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Beveling the Buccal Wall in Upper Premolars

Beveling the buccal wall of the proximal portion of upper premolars removes undermined enamel and ensures a 90-degree angle for proper instrumentation.

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Proximal Preparation Sequence in Class II Cavities

Completing the proximal outline before breaking the marginal ridge and proximal enamel plate provides a guide for cavity preparation, protects the adjacent tooth, saves time and effort, and reduces heat generation.

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Matrix Band in Class II Cavity Preparation

A matrix band placed around the neighboring tooth during cavity preparation helps protect the adjacent tooth structure.

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Reverse Curve Approach

A curved preparation line on the buccal wall of upper premolars designed to remove all undermined enamel and ensure proper contact with the adjacent tooth.

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Resistance Form

A specific type of preparation that focuses on creating smooth, parallel walls to maintain the structural integrity of the tooth while also providing space for the restoration. It is a key feature of Class II preparations.

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Retention Form

The part of the preparation that focuses on preventing the restoration from being dislodged, ensuring it stays securely in place.

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Gingival Floor

A specific preparation technique used in Class II restorations. It is characterized by a smooth, flat surface that is parallel to the occlusal plane and pulpal floor, facilitating a precise and well-supported restoration.

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Axial Wall Distance

The distance between the external tooth surface and the prepared axial wall. It is typically maintained at 1.5-2mm to ensure adequate restoration thickness providing good resistance.

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Proximal Axial Grooves

A key aspect of retention form. It is typically achieved by using a small tapered fissure bur to create grooves in the axio-buccal and axio-lingual line angles. These grooves help anchor the restoration.

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Proximal Dovetail

An extension of the proximal dovetail used in premolars and molars to provide additional retention for the restoration. It also helps prevent the restoration from being dislodged by occlusal forces.

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Rounding, Beveling, Saucerization

A critical feature of Class II restorations which creates a smooth, rounded angle in the preparation to reduce stress concentration areas and ensure a well-integrated restoration.

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Study Notes

Caries Characteristics

  • Two cones with bases at the DEJ (dentino-enamel junction)
  • Cone-shaped spread in enamel, base at DEJ, small opening
  • Cone-shaped spread in dentin, base at DEJ
  • Rapid lateral spread at DEJ

Tooth Classes

  • Class 1:
    • Maxillary first molar: Kidney shape (mesial cavity)
    • Mandibular first molar: Bat shape
    • Mandibular first premolar: Snake eye or butterfly shape
    • Mandibular second molar: Plus shape
    • Mandibular second premolar: Y shape
    • Maxillary premolars: Butterfly shape

Class VI Lesions

  • Images depicting Class VI lesions are shown

Class II Cavity Preparation for Amalgam Restoration

  • Information provided in a slide header format

Class II Cavities

  • Definition: Smooth surface lesion on proximal surfaces of molars and bicuspids in the middle third of the tooth
  • Types: Simple, Compound, Complex (illustrated with images)

Caries Characterstics

  • Difficult to detect until a considerable size
  • Bite-wing x-ray film necessary for correct diagnosis
  • Spreads in enamel and dentin in a conical pattern
  • Spreads occlusally along the dento-enamel junction and under the marginal ridge early
  • Extends bucco-lingually and gingivally
  • Recurrence at buccal, gingival and lingual gingival line angles of the cavity margin is likely.

Class II Cavity Preparation: Design

  • Composed of three parts: Occlusal, Isthmus, and Proximal.

Isthmus Outline Form

  • Straight: small contact area
  • Uniform: normal contact area
  • Reverse curve: broad/wide contact area

Proximal Portion

  • Involvement of all carious enamel and dentin
  • Freeing the proximal surface lingually, buccally, and gingivally
  • Placing cavity margins in embrasures, self-cleansable
  • Buccal wall midway between contact and axial line angle, parallel to buccal surface of tooth
  • Lingual wall midway between contact and lingual axial line angle, parallel to lingual surface of tooth
  • Gingival floor between 0.25 - 0.5mm above gingival crest, parallel to pulpal floor and occlusal plane
  • Axial wall 1.5-2mm from DEJ for enough bulk

Resistance Form

  • Occlusal portion: Same as class I cavity
  • Isthmus portion: Minimal width (¼ intercuspal distance), roundation/beveling of axio-pulpal line angle, increase bulk at isthmus
  • Reverse Curve: Wide proximal contact area, conserve sound tooth structure, freeing undermined enamel with correct CSA 90°
  • Proximal Portion: Reverse curve approach, smooth, flat, parallel pulpal floor and occlusal plane, axial walls parallel, 1.5-2 mm from DEJ, uniform bulk

Retention Form

  • Axial Retention: Mechanical undercuts, cavity walls converging occlusally, inverted truncated cone shape of the proximal portion

Lateral Retention

  • Proximal dove tail (premolars and molars, prevention and retention also)
  • Occlusal lock
  • Proximal axial grooves (cut into axo-buccal and axolingual line angles-extended to gingival floor, wider internally and gingivally)
  • Pin retention in extensive cavities

Convenience Form

  • Cutting an occlusal cavity for accessibility to the proximal portion
  • Accentuation of cavity walls and margins
  • Roundation of line angles
  • Axial wall parallel to tooth long axis in occluso-gingival direction
  • Selection of suitable sized instruments

Finishing of Enamel Wall

  • Occlusal portion: Same as class I cavity
  • Isthmus portion: Enamel wall in direction of enamel rods (CSA 90°), Free from any loose, undermined, or friable enamel
  • Proximal portion: Buccal and lingual walls flared slightly outward to obtain 90° CSA, Gingival floor slanted slightly gingivally to obtain 90°; Reverse curve approach in buccal wall, undermining buccal wall enamel.
  •  Beveling of undermined buccal enamel (CSA 90°)

Clinical Considerations

  • Complete proximal outline before breaking marginal ridge and proximal enamel plate
  • Guides for proximal design
  • Protects proximal surface of adjacent tooth from rotary instruments
  • Saves time and effort
  • Reduces heat generation

Protecting Neighboring Teeth and Ginigva

  • Using a matrix band around the neighboring tooth during cavity preparation
  • Using rubber dam to protect gingival tissues
  • Using a circular wedge during gingival floor preparation to protect gingiva

Class II Simple Proximal Cavity

  • Enough proximal access due to: missing adjacent tooth, wide embrasure due to senile gum recession, ridge intact and not undermined by caries

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Related Documents

Class II Cavity Preparation PDF

Description

Test your knowledge on the characteristics of caries and different tooth classes. The quiz covers Class II cavity preparations for amalgam restoration and Class VI lesions. Enhance your understanding of dental anatomy and cavity classifications through this engaging assessment.

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