Dental Preparation Considerations

Biologic Consideration

• Adjacent teeth: Protecting adjacent teeth from damage is critical during tooth preparation.
  • Using a tapered diamond instrument to carefully remove interproximal contact areas can minimize damage.
  • A metal matrix band can be used as protection, but care should be taken as it is thin and can be perforated.
• Soft tissue: Careful retraction with instruments is necessary to prevent damage to the tongue, lips, and cheeks.
• Pulp: Protecting the pulp during preparation is crucial to prevent pulpal injuries.
  • Causes of pulpal injury include extreme temperatures, chemicals, and bacteria.
  • Use water coolant during preparation to help prevent heat buildup.
  • Use cavity varnish to create a barrier between dentin and restorative materials.
  • Bacterial action: Properly removing all carious dentin is important to prevent bacteria from causing further damage.

Preservation of Tooth Structure

• Basic tenets: Conserving as much tooth structure as possible is a fundamental principle in restorative dentistry.
• Thickness of Remaining Dentin: Remaining dentin thickness is important for pulpal health. Thicker dentin results in less pulpal response to treatments.
• Guidelines for Conservation of Tooth Structure:
  • Employ partial coverage restorations when appropriate.
  • Minimize convergence angle (taper) between axial walls.
  • Ensure even occlusal reduction for uniform thickness in the restoration.
  • Ensure sufficient axial tooth reduction to facilitate proper contouring.
  • Choose margins compatible with the principles of tooth preparation.
  • Avoid unnecessary apical extension of the preparation.

Considerations Affecting Future Dental Health

• Axial Reduction: Appropriate axial reduction is needed for sufficient restorative material thickness.
• Margin Placement: Margin placement influences restoration fabrication and long-term durability.
  • Smooth, exposed margins can be easily finished and kept clean.
  • Margins should be placed in accessible areas for the dentist and patient.
  • Subgingival margins: Avoid subgingival margins because they are associated with periodontal issues.
• Supragingival Margins: Placing margins supragingivally is recommended for several reasons:
  • Easier to prepare without soft tissue trauma.
  • Easier to finish and keep clean.

Margin Types

• Feather Edge: Conserves tooth structure but can lead to over-contoured restorations.
• Chisel: Conserves tooth structure, but prone to over-contouring.
• Chamfer:
  • Distinct, well-defined finish line.
  • Provides adequate material bulk.
  • Suitable for cast metal crowns and metal portions of metal-ceramic crowns.
• Shoulder:
  • Provides adequate bulk for restoration.
  • Less conservative than chamfer.
  • Suitable for full veneered metal-ceramic restorations and all-ceramic crowns.
• Shoulder with Bevel:
  • Provides adequate bulk.
  • Less conservative than other types.
  • Bevel helps remove unsupported enamel.
  • Suitable for metal-ceramic restorations, and in situations with previous caries or restorations at the margin.
• Beveled:
  • Removes unsupported enamel.
  • Ideal for ledges due to caries or erosion.

Finish Line Designs

• Feather Edge:
  • Conserves tooth structure.
  • Can easily lead to over-contouring.
• Chisel:
  • Conserves tooth structure.
  • Can lead to over-contouring and is difficult to control.
• Chamfer:
  • Distinct, well-defined finish line.
  • Provides adequate bulk.
  • Suitable for cast metal crowns and metal portions of metal-ceramic crowns.
• Shoulder:
  • Provides adequate bulk.
  • Less conservative than chamfer.
  • Suitable for full veneered metal-ceramic crown and all-ceramic crown restorations.
• Shoulder with Bevel:
  • Provides adequate bulk.
  • Less conservative.
  • Bevel removes unsupported enamel.
  • Suitable for metal-ceramic restorations and in situations with previous caries or restorations at the margin.
• Beveled:
  • Removes unsupported enamel.
  • Less conservative.
  • Ideal for ledges due to caries or erosion.

This quiz explores the biological considerations and methods for preserving tooth structure during dental procedures. Key topics include protecting adjacent teeth, soft tissue management, and pulp protection during tooth preparation. Learn how to effectively minimize damage and ensure patient safety.