TRAYS

Definitions

Tray

Device Used To Carry The Impression Material To The Mouth, Confine The Material In Apposition To The Surfaces To Be Recorded And Control The Impression Material While It Sets .

Impression

Is A Negative Replica Or Imprint Of The Teeth And Adjacent Tissues For Use In Dentistry

Impression Material Is A Substance Used For Making A Negative replica For The Required Tissues

Cast (Model)

Is A Positive Replica (Imprint) Of A Part

Or Parts Of The Oral Cavity

Types Of Impression Trays

Stock Trays (Various Size & Made By Manufactures)

Custom (Individual Or Special) Trays Made For One Patient And Discarded Later

Requirements Of An Ideal Impression Tray

Rigid

Retain Shape

Easily To Be Trimmed And Modified

Smooth Edges

Control Material During Seating, Set &Removal

Classification Of Dental STOCK Trays

Metal trays are made of

Aluminum or stainless steel

Non metallic trays are made of

*Plastic (disposable)

**Plastic can be sterilized (xantalgin trays)

According to the nature of impression materials

*Plain tray

*Perforated tray

*Rim lock tray

*Water cooled tray

Water Cooled Tray

# PARTS OF STOCK TRAY

BODY & HANDLE

# Differences between trays for complete denture and those for RPDs

TRAY MODIFICATIONS *Adding

**Bending

***Cutting (aluminum tray)

Preliminary (Primary) impression

Is an impression made for the purpose of diagnosis and construction of custom tray

Preliminary (Primary or diagnostic) cast

Positive replica of the upper or lower jaw tissues that is made in an impression and over which custom trays may be made

Preliminary Impression Materials *Alginate (irreversible hydrocolloid) and may be

used for• Primary impression for complete denture• Some cases of RPD• Some cases of FPD• Alginate impression should be poured

immediately• (WHY) ??????????** Modeling compound

Preliminary (Diagnostic) Cast

*A Positive Reproduction Of The Upper Or Lower Jaw Tissues That Is Made In An Impression And Over Which Impression Trays May Be Made

• ** Requirements and uses of diagnostic cast

Uses OF Diagnostic cast 1- Detection of ridge relationship and inter

ridge distance 2-To evaluate the size and contour of the

arch 3- To detect areas need to be relieved

4- To construct a custom tray

Custom)special &individual) Impression Trays And Construction Of Master Cast

Is an individual tray made over the diagnostic cast and it is used in making a final impression.

Materials for constructing a custom tray- Autopolymerizing acrylic resin (self- curing)- Heat cured acrylic resin- Vacuum adapted resin- Shellac base plate - VLC- Hydro plastic materials

Autopolymerizing Acrylic Resin

Easy To be used and require no special Equipment

Technique of construction ;

1) Finger dough adapted technique

2) Sprinkle on method

Shellac Baseplate

*Easily manipulate and quickly adapted

**Tend to warp, distort easily, brittle, lack rigidity.

(Dimensionally unstable)

VLC (visible light activated resin)

*Urethane dimethylacrylate

**Initiator

***Curing unit has light from quartz halogen lamp

VCL has no monomer, well adapted,,,

excess can be stored to be used later.

V.L.C

Materials Used For Final Impression

For example:- Zinc-euginol Impression Paste ( Close

Fitting Custom Tray,,, No Spacer

Elastomeric Impression Materials

Border Molding

Green Stick Compound Is Traced Along The Sections Of The Tray,,, Patient moves lips Checks And Tongue To Record The Proper Denture Extensions.

Pouring & Trimming And Indexing Of Master Cast

Boxing Is building up vertical walls around the

impression usually in wax, to produce the desired size, form of the base of the cast and to preserve the width, height and landmarks of the impression

Pour Master Casts b

Advantage of boxing 1) Preservation of the border of the impression 2) Controlling the thickness of the base 3) Conservation of time and materials 4) The produced cast free from air bubbles Methods; 1)Plaster And Pumice 2) Putty Methods. - Indices Permit Removal Of The Casts And Accurate

Replacement In The Articulator.

Am I natural or artificial molar?????

RECORD BLOCKSRecord blocks are fabricated to register

the relationships of the mandible to the maxilla at which the denture is made.

Record block consists of• Record base (temporary or permanent)• Record rim (occlusal rim)

base

Occlusal rim

#Record base*Temporary (same materials and techniques

used for special tray fabrication**Permanent may be made of heart cured

acrylic resin or metal

#Occlusal rim*Base plate wax**Modeling compound***Plaster & pumice

Requirements For Baseplate Well Adapted To The Basal Seat Area

AS The Finished Denture. Have The Same Borders As The

Finished Denture. Rigid & Dimensionally Stable Easily Manipulated Smooth & Rounded Edges Does Not Damage The Cast During

Removal or replacement

Uses of occlusion rim 1) To establish accurate maxillo-mandibular

relation record

2) To determining the length and width of the artificial teeth

3) In arranging the artificial teeth to form the trail denture.

Maxillary guide lines

Mandibular guide lines

MAXILLARY OCCLUSAL RIM

22MM

4MM

6MM

10MM

18mm

8-10MM

5MM

18MM

Any Question????????