Principles of Cavity Preparation I: Aims, Classification and Terminology

Aims of Tooth Preparation

  1. Remove defects and provide protection to pulp.
  2. Extend restoration conservatively.
  3. Increase resistance to fracture.
  4. Allow esthetic and functional placement of material.

Stages of Tooth Preparation

  1. Initial tooth preparation
  2. Final tooth preparation

Factors Affecting Tooth Preparation

  1. Diagnosis: pulpal and periodontal status, occlusal relationships, esthetics, relationship of restorative procedure to other treatment, risk potential.
  2. Knowledge of Dental Anatomy: knowledge of the external and internal structures of the tooth, and the relationship with surrounding tissues.
  3. Patient: patient’s knowledge, economic status, age.
  4. Conservation of tooth structure.
  5. Restorative material factors.

Tooth Prep Terminology

  1. Simple tooth prep: 1 surface involved.
  2. Compound tooth prep: 2 surfaces involved.
  3. Complex tooth prep: 3 surfaces involved.
  4. Internal wall: Prepared (cut) surface that does not extend to external tooth surface.
  5. Axial wall: Internal wall parallel to long axis of the tooth.
  6. Pulpal wall: Internal wall perpendicular to long axis of the tooth, occlusal to pulp.
  7. External wall: Prepared surface that extends to the external tooth surface.
  8. Floor/seat: Flat prepared wall perpendicular to occlusogingival occlusal force.
  9. Line angle: Junction of 2 planar surfaces.
  10. Point angle: Junction of 3 planar surfaces.
  11. Cavosurface angle: Angle of tooth structure formed by the junction of prepared wall and the external surface.
  12. Cavosurface margin: Junction of prepared wall and the external surface.

    Cavity Walls and Angles

    A visualization of cavity walls and angles. (Source: “Practical Handout, Operative Dentistry” by Dr.Shawfekar)

Classification of Tooth Prep

  1. Class 1:All pits and fissures restorations.
  2. Class 2: Proximal surfaces of posterior teeth.
  3. Class 3: Proximal surfaces of anterior teeth.
  4. Class 4: Proximal surfaces of anterior teeth involving incisal angle.
  5. Class 5: Gingival third of facial or lingual surfaces of all teeth.
  6. Class 6: Cusps of posterior teeth.
G.V. Black's Classification

G.V. Black proposed a classification of carious lesions. Practically, because tooth cavity preparation follows the course of the carious lesion, it has been adopted as G.V. Black’s Classification of Tooth Prep/Cavities as well.

This is a topic summary based on Varun Pandula’s blog post and Sturdevant’s Art and Science of Operative Dentistry, 5th edition.

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