Second Impression: Techniques and Materials

1. Mucosal Impression:

• Purpose: To retain the shape of the supporting area, prevent deformation and compression, and accurately record the movement of the free mucosa.

2. Impression Tray Materials:

• Thermoplastic:

• Advantages:

• Easy to heat (50-55 degrees Celsius).

• Stable over time.

• Low cost.

• No deformation.

• Disadvantages:

• Can burn mucosa.

3. Second Impression Materials:

• Thermoplastic Compound:

• Advantages: Stable, no deformation.

• Polyether:

• Advantages: Stable, no deformation.

• Thiokol Rubber:

• Advantages:

• Highly accurate impression of the supporting surface.

• Long-term stability.

• Disadvantages:

• Hydrophobic (replace “hydrophilic”).

• Requires adhesive.

• Not repairable.

• Zinc Oxide Eugenol Paste:

• Advantages:

• Impression of the supporting surface.

• Stable, easy to handle.

• Suitable for areas with saliva.

• Flowable (replace “easy to handle”).

4. Impression Technique:

• Try-in: Check the aesthetics, border of the tray and compression relief areas.

• Tray Fabrication: Use thermoplastic or similar material.

• Impression Taking: Preferable to use Permlastic.