Temporary Crowns Overview and Manufacturing Process

Temporary Crowns: Overview

  • Definition: Temporary crowns are provisional restorations placed on prepared teeth until a permanent crown is ready.
  • Importance:
    • Restore Aesthetics and Function: Ensures the appearance and functionality of teeth until the final restoration can be completed.
    • Prevent Dentinal Sensitivity: Protects exposed dentin from sensitivity issues.
    • Protection from Re-infection: Shields root-filled molars from bacterial contamination.
    • Prevention of Tooth Movements: Maintains the alignment and position of the prepared tooth.

Ideal Properties of a Temporary Crown

  1. Aesthetic Quality: Should look similar to natural teeth.
  2. Sufficient Strength: Must withstand functional forces.
  3. Restore Contact Points: Important for maintaining occlusion with adjacent teeth.
  4. Accurate Margins: Prevents plaque accumulation and ensures a proper fit.
  5. Retentive: Should be secure yet easy to remove.
  6. Biocompatibility: Materials should not cause any adverse reactions in the oral environment.

Methods of Manufacturing Temporary Crowns

  1. Direct Custom Made:
    • Procedure: A mold of the prepared tooth is made chairside, and a temporary crown is fabricated directly.
    • Material Used: Typically, Bis-acryl composites (e.g., Integrity) which are injected into the custom mold.
  2. Prefabricated:
    • Usage: Ready-made crowns that require adjustments to fit individual teeth.
    • Materials: Polycarbonate for anterior crowns, aluminum, and stainless steel for posterior crowns.
  3. Indirect Laboratory Made:
    • When Used: For longer-lasting temporary crowns (more than 3-4 weeks).
    • Process: Made by a lab technician using acrylic materials (heat-cured PMMA) on a plaster model of the prepared tooth.

Cementation of Temporary Crowns

  • Requirements:
    • Strong enough to maintain the crown during the period of temporization.
    • Allows easy removal when necessary.
    • Should not bond to the tooth.
  • Types of Cement:
    • Fine particle zinc oxide eugenol cement.
    • Tempbond (Kerr USA): Commonly used temporary cement.
    • Non-eugenol Cements: Used for resin cements in permanent crown procedures.

Challenges and Solutions

  • Tooth in Poor Condition: If the tooth needing a crown is damaged, a diagnostic wax-up can be created to fabricate a mold for an ideal tooth shape.
  • Adjustments in Aesthetics/Occlusion: Temporary crowns allow for aesthetic adjustments before a final crown is placed.