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Impression tray and impression technique. Dr. Nora Sheta. Steps of Complete Denture Construction. IMPRESSION TRAYS AND IMPRESSION TECHNIQUES. IMPRESSION. An impression is a negative record or imprint of the tissues of the oral cavity that forms the basal seat of the denture. - PowerPoint PPT Presentation
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Impression tray and Impression tray and impression technique impression technique
Dr. Nora Sheta
Clinical Laboratory
1. Examination & Diagnosis
2. Primary impression Study cast Special tray
3. Final impression Boxing and pouring master cast Occlusion blocks
4a. Jaw relation registration
4b. Selection of artificial teeth
Mounting on articulator Setting of artificial teeth and waxing up
5. Try in Processing
6. Insertion
7. Post insertion care
IMPRESSION TRAYS AND IMPRESSIONTECHNIQUES
IMPRESSION
An impression is a negative record or imprint of the tissues of the oral cavity that forms the basal seat of the denture.
Reproduce a positive form and shape of the same oral tissues (Cast) .
IMPRESSION TRAYS
“A tray is an instrument used to carry the impression material to the mouth , holding it in position against tissues until the material hardens ,it helps in removing the impression from the mouth “.
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
Types of TraysTypes of Trays
I- Stock trays
II- Custom trays (Special, Individual trays)
Impression trayImpression tray
is composed ofBody: The body
consists of a floor and flanges.
Handle.
The body and handle are designed The body and handle are designed to suit different mouths to suit different mouths
1-Dentulous mouth cases
.
2-Edentulous mouth cases
.
3-Partially edentulous mouth cases.
types Stock traytypes Stock tray
Perforated or non
perforated Metal or plastic
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 .
As a cast on which the final impression tray is fabricated.
SPECIAL OR INDIVIDUAL TRAYS
1. Shellac base plates .
2. Self & light curing acrylic resin .
3. Cast or swaged metal .
TYPES
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 .
Types of special 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 . 3- Cast or swaged metal tray 4- Vacuum formed plastic sheets It needs a pressure forming machine
Comparison between shellac Comparison between shellac and acrylic resin custom traysand acrylic resin custom trays
• Shellac base plate special tray
1. Low strength.2. Easily distorted by load
and temperature.3. Improper adaptation to
the cast4. Easily constructed
Self-cured acrylic resin special tray
1. Higher strength and rigidity.2. Not distorted by temperature.
3. Well adapted
4. Easily constructed
Tray can beTray can be
1- with a spacer
2- without a spacer
SHIM OR SPACER SHIM OR SPACER
“ One thickness of modeling wax or shellac base plate adapted on the study cast under the special tray “
Upper & Lower spacer (Shim) Upper & Lower spacer (Shim)
Custom (Special) trays with spacer Custom (Special) trays with spacer (Shim)(Shim)Steps for fabrication upper traySteps for fabrication upper tray
Custom Tray With SpacerCustom Tray With Spacer
Custom (Special) trays with spacer Custom (Special) trays with spacer (Shim)(Shim)Steps for fabrication lower traySteps for fabrication lower tray
1
2 3
4 5
6 7
8
9
FINAL IMPRESSION TECHNIQUES FINAL IMPRESSION TECHNIQUES OR THEORIES OR THEORIES
1 . Minimal Pressure Impression Technique (Mucostatic Impression Technique) .
2 . Definite Pressure Impression Technique or Mucocompression Impression or Functional Impression Technique .
3 . Selective Pressure Impression Technique .
(1) IMPRESSION TECHNIQUE
MINIMAL PRESSURE ( MUCOSTATIC)
FUNCTIONAL PRESSURE (MUCOCOMPRESSIVE) SELECTIVE PRESSURE
(2) PHILOSOPHY ALL THE TISSUES ARE UNDER THE LEAST PRESSURE.
ALL THE TISSUES ARE UNDER FUNCTIONAL PRESSURE.
TISSUES THAT CAN WITHSTAND PRESSURE ARE LOADED. AND TISSUES THAT CAN'T ARE RELIEVED.
(3) TRAY PERFORATED + ON SPACER + WITH TISSUE STOPS.
WELL ADAPTED + NO SPACER + WAXRIM.
STOCK TRAY WITH COMPOUND ,THEN IT IS RELIEVED AND WASHED WITH PLASTER IMPRESSION MATERIAL.
(4) PRESSURE FINGER PRESSURE PATIENTS BITING FORCE. FINGER PRESSURE.
(5) IMPRESSION MATERIAL PLASTER, FLOWY MATERIAL. ZnO/E , HEAVY MATERIAL IMPRESSION COMPOUND (HEAVY)+ PLASTER OR ZnO/E(FLOWY)
2NDRY IMPRESSION TECHNIQUES
CLINICAL
5 Final Impression .
Upper Impression
Lower Impression
Boxing the impressionBoxing the impression An impression is boxed to preserve
the borders of the impression so that it will be accurately reproduced in the cast.
Methods for boxingMethods for boxing
1- Wax method
2- Plaster and Pumice method
Beading wax for boxingBeading wax for boxing
1- Wax Method1- Wax Method
1-wax method1-wax method
1-wax method1-wax method Lower impressionLower impression
2-Plaster and Pumice method 2-Plaster and Pumice method Plaster and pumice for boxing Plaster and pumice for boxing
2-Plaster and Pumice method2-Plaster and Pumice methodUpper impressionUpper impression
BOXING
MASTER CASTS
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