Taking the Initial Impression in Full Mouth Rehabilitation

Taking the Initial Impression in Full Mouth Rehabilitation

# 1. Initial Impression

The initial impression serves as the “foundation” for the prosthesis, used to create a custom tray for the next impression.

• Functional Mucosal Impression: Used when it is necessary to record the movement of the mucosa.

• Static Mucosal Impression: Used when it is necessary to record the static position of the mucosa.

# 2. Factors Ensuring Good Impression Results

To achieve good results in the impression process, attention should be paid to these factors:

• Material: Impression material should be suitable for the purpose and requirements of each case.

• Tray: The impression tray should be appropriately sized to cover the entire area needing to be impressed.

• Technique: Impression technique should be performed accurately to ensure the accuracy of the impression.

# 3. Impression Materials

• Alginate: This is the most commonly used material, with advantages such as:

• Fast setting time.

• Doesn’t deform soft tissue.

• Easy to control.

• Rubber: Less commonly used due to higher cost.

• Plaster: Plaster doesn’t deform the position of the flabby ridge.

# 4. Techniques for Using Impression Materials

• Alginate: Use a perforated spoon to create airflow.

• Silicon: Use adhesive to secure the material to the tray.

# 5. Requirements to Provide to the Technician When Making a Custom Spoon

The dentist needs to provide information to the technician to create a suitable custom spoon:

• Spoon Border: Outline the floor of the vestibule in pencil, the tray border in red pen.

• Compression Areas: The area where the alveolar ridge, bony spines, the midline of the palate with thin mucosa, hard prominences, and the buccal frenum are located.

• Bite Rim Height: Upper jaw: HT 22mm, HD 18mm. Lower jaw: HT 18mm, HD 18mm.

# 6. Drawing the Borders of the Custom Impression Tray

• Upper Jaw:

• Anterior Border: 1-1.5mm away from the floor of the vestibule, Eisenring area 0.5mm away.

• Posterior Border:

• If the soft palate is perpendicular to the hard palate: The border stops at the junction of the soft palate and hard palate.

• If the soft palate is slanted towards the hard palate: The border lies 1mm posterior to the junction.

• If the soft palate is horizontal to the hard palate: The border lies 2mm posterior to the two palatine fossae.

• Lower Jaw:

• External Border: 1.5-2mm away from the floor of the vestibule, fish pouch extending beyond the outer diagonal line by 1-2mm, covering the entire posterior mandibular triangle.

• Tongue Border: Anterior to r34-44, 1mm away from the floor of the mouth, middle extending through the inner diagonal line by 4-6mm, posterior covering the entire posterior mandibular triangle.

Note: The bite rim height needs to be adjusted according to each specific case.