impression

Dr. Salah Kh. Al-Rawi

BDS, MSc. PhD
Dental Science, Prosthodontist, Maxillo-Facial Prostheses
Complete denture Impressions

Impression

A complete denture impression is a negative registration of the entire denture bearing, stabilizing, and border seal areas present in the edentulous mouth.
A preliminary impression is an impression made for the purpose of diagnosis or for the construction of a special or custom tray.
A final impression is an impression for making the master casts. The master casts are used in constructing the dentures.

Impression tray

is composed of
Body: The body consists of a floor and flanges.
Handle.

IMPRESSION TRAYS

Parts

1 . Body
2 . Handle
Body
Body
Handle
Handle

DENTULOUS TRAY

EDENTULOUS TRAY
Dentulous Tray
Edentulous Tray
Body
Handle
Body
Handle
Floor
Flange
Floor
Flange


Straight
L - Shape

Flat

Long
Round
Short

It is a device used to carry & control impression material while making an impression

• 1-stock tray
The tray we use in the primary impression
• 2-custom tray
The tray we use in the final impression ,and constructed on diagnostic cast
Types of Impression tray

(Special, Individual trays)

Types of stock trays
• Metallic it can be aluminum or stainless steel.
• Non metallic:-
• Plastic tray which can be sterilized.
• Disposable plastic trays.

• 1. Perforated trays (used with alginate)

• Non perforated or plain trays
(used with impression compound)

Types of stock trays

Impression materials for complete denture:
• Primary impression :
• a) impression compound
• b) Alginate
• Secondary impression :
• Rubber base
• Zinc oxide Eugenol
• plaster of paris

• Preliminary Impression

• Study cast
• USES
• As a study cast to study :
• 1. Ridge shape .
• 2. Palatal Vault shape .
• 3. Denture bearing areas .
• 4. Areas of undercut .
• 5. Relief areas .
• 6. Posterior palatal seal area .
• 7. Sharp bony edges .
• 8. Depth of the sulcus .
• 9. Inter-ridge space
• 10. Inter-ridge relations .



•

SPECIAL OR INDIVIDUAL TRAYS

1- Shellac base plate special tray
2- Acrylic resin custom (special) trays:
a- cold cured
b- heat cured
c- light cured

Both heat and cold cured are used widely now.

It is rigid and light in weight, not wrap in the mouth .
Types according to materials fabrication
Advantages of Special Trays
1 . Fit more accurately the individual arch of the patient.
2 . Bulk of the impression material is reduced .
4 . More accurate border contour
5 . Less impression material is used .
6. More comfortable to the patient .

Final impression Techniques

Mucostatic technique

Also referred as open mouth technique.
Record the tissues in there undisplaced position.
dentist exerts pressure.

• MAXILLARY IMPRESSION

MANDIBULAR IMPRESSION

• 3- Boxing the impression

• An impression is boxed to preserve the borders of the impression so that it will be accurately reproduced in the cast.
ADVANTAGES OF BOXING
1 . The borders of the impression are preserved
2 . The thickness of the base of the cast can be controlled
3 . Permits vibrating the stone material into the impression
4 . Time is conserved
5 . Material are conserved

THANK YOU