INTRODUCTION :The need to make accurate impressions is fundamental to the practice of

prosthodontics. This requires the clinician to make a careful assessment of which tissues include in the impression and also to consider how they should be recorded. There are 3 ‘M’ for successful denture :Mold (tray)Method (impression tech)Material (imp. material)Impression trays are used as rigid containers for carrying the impression material into the mouth for maintaining it in position during setting or hardening and supporting it during removal from the mouth and when pouring the cast.

The metal impression tray which is used to hold the substance, pushed against the gums when making an impression had been introduced in FRANCE about 1820 by Christopher Francois Delabarre.

DEFINITION : K.D. Rudd and R.M. Morrow – A receptacle or device used to carry the impression material to the mouth, confine the material in apposition to the surface to be recorded, and control the impression material while it sets to form the impression.

REQUIREMENTS FOR IMPRESSION TRAYS :They should confine the impression material to assure close adaptation to the teeth and soft tissues.They should permit the selection and control of impression material space between the tray and tissues to be recorded. They must be rigid to avoid distortion of the impression on removal. They should provide for mech. Locking of the impression material to the tray through rim-lock undercuts or perforations. They should be capable of being cleansed and sterilized is they are not disposable. They should be available in different sizes and shapes if they are stock trays. They must be inexpensive if they are disposable.

CLASSIFICATION :

Tray compound

N

ck tra

anslucent

se plate

RPD

plants

F

D

Uses

Custom t

y

Materia

Opaque

ays

Heat

n

Shellac base

plate rein

orced with

imp. compoun

Shellac

Impression

re

Self cure

L

ght cure

Acrylic re

cts

Close fit

Spaced

illofacial de

on, ploys

yrone, pol

carbonate

M

Tray compound

N

ck tra

anslucent

se plate

RPD

plants

F

D

Uses

Custom t

y

Materia

Opaque

ays

Heat

n

Shellac base

plate rein

orced with

imp. compoun

Shellac

Impression

re

Self cure

L

ght cure

Acrylic re

cts

Close fit

Spaced

illofacial de

on, ploys

yrone, pol

carbonate

M

PARTS OF TRAYS :Handle Body Tissue surface Non tissue surface Tissue surfaces Labial notch Labial flange Buccal notch Buccal flange Trough Post. margin (edge)Non tissue surfaces Molar stubs Buccal extension

SELECTION OF TRAYS – FOR PRIMARY IMPRESSION : STOCK TRAYS -

If stock tray is too large, it will distort the tissue around the borders of the imp. and will pull the soft tissues under the imp. away from the bone, distorting the dimensions of the sulcus in the process. If it is too small, the border tissue will collapse inward onto the residual ridge. This will also distort the accurate recording of the border extension of the denture and prevent the proper support of the lips by the denture flange. Neill – when the patient already possesses dentures they may provide a valuable guide to tray selection but if none is available it may be useful in choosening a tray to use calipers to measure the arch width.

Maxillary tray :The tips of the calipers are placed in the tuberosity regions and this distance is compared with the width of the tray flanges in the corresponding area. The tray is angled into the month and the post border raised to make contact with the anterior part of the soft palate. It can then easily be seen if the tray will cover the maxillary tuberosity and allow enough room for the impression material (2-3mm). The tray is then raised anteriorly and the lateral flanges watched for clearance of the alveolar ridges. As the tray is brought up at the front, the upper lip lifted so that the labial flange can be checked for fit in this region.The tray must be pulled forward during examination for buccal and labial clearance. Sufficient space must exist between the tray and the tissues for the impression material. In some cases, it maybe necessary to bend the metal tray slightly with pliers to provide adequate space or, with plastic tray to cut and trim the flange to accommodate frena and prevent pressure on bony structure such as the zygomatic process of the maxilla. The tray should be checked to make sure that it does’t rock from side to side through contact with

the hard palate and also that the upstand is sufficiently long that the tray handle does’t interfere with the lip movement. Mandibular tray In the lower arch tips of calipers are kept on the lingual aspects of the ridges of the left and right sides just below the retromolar pads. This measurement must be compared with the measurement between the lingual flanges of the tray.Insert the left heel of the selected tray into the mouth and with the patient right check retracted, rotate the right heel in, pass it backwards until the distal ends cover the retromolar pads, while at the same time the patient, protrudes the tongue slightly to facilitate placing the tray between it and the lingual surface of the ridge. Lift the tray anteriorly and slowly lower again observing in approximation to the ridge both lingually and buccally, when satisfied that the selected tray covers the ridge and allows sufficient space for the impression material the flanges are visually checked for over extension into the labial and buccal sulci.The lingual depth is confirmed by having the patient raise the tip of the tongue to the roof of the mouth. If the tray is not over extended lingually, only slight finger pressure in the premolar region will be needed to keep it in position. The flanges grossly interfere with the fremal or sulci. They must be trimmed or another tray selected before the imp. is made. Finally there should be sufficient flange depth in the region of the post. lingual pouches. Shortness in these areas can be corrected by adding a little warmed tracing stick (of a higher fathering point then that to be used for the imp) to the lingual flanges of the dried tray. Reinsert the tray into the mouth and ask the patient to protrude the tongue slightly. This will trim the added composition to the final depth of the pouches by raising the floor of the mouth and drawing forward the palatoglossus muscles. On removing the tray from the mouth displace the composition medially to provide space for the imp. material and then chill. A short tray can be extended distally in the same way, to cover retromolar pad. Stock trays for alginate impression :

The same type of stock metal or disposable plastic (nylon or polystyrene) tray described for imp. compound is suitable for alginate.

The alginate does’t adhere to the tray of their own accord. Fixation maybe effected by one of the following methods :Perforated trays will produce a mechanical union as the alginate flows through the holes. Adhesives consisting of polyamide in isopropyl alcohol which may be either painted or sprayed on the tray surface immediately before loading the alginate. Sticky wax may be melted onto the surface of a metal tray immediately before the alginate is placed on it. Wisps of cotton wool may be secured to the tray with sticky wax or varnish and will become incorporated into the alginate as it sets. CUSTOM TRAY Definition : GPT (1999) – A individualized imp. tray made from a cast recovered from a preliminary imp. it is used in making final imp. custom try fabrication and adaptation is one of the most important aspect of CD imp. procedure. The ideal features are :Stability Rigidity Proper extension to cover the basal seat areas of the edentulous arches (for stability)A consistency relieved approximation of the vestibular tissue, particularly those involved in the peripheral seal (for proper retention)Ease of modification (either by grinding or the addition of the appropriate material.

Design characteristics for custom trays : Tray material Tray extension Spacer thickness / relief area Tissue stops Tray handles 1) Tray material : materials available for custom tray construction are :Thermoplastic materials Thermoplastic vacuum adapted Thermoplastic shellac base plate Thermoplastic beads (polycaprotone)Self curing PMMA Visible light cured PMMAThermoplastic materials exhibit lower strength and lower elastic modulus compared with resin materials. Trays made from VLC resin have sufficient rigidity and have excellent dimensional stability ; they may also be immersed in commonly used disinfectant (NaOCl) without any significant changes in their physical and mechanical properties. Also quick and easy to fabricate. Disadvantages – Expensive

Hard – difficult to trim 2) Tray extension : This is to insure that the periphery of the tray does’t distort the tissues of the sulcus through overextension and to avoid the expend of valuable chairside time in trimming the tray to confirm to the correct extension. Maxillary : make an outline of the imp. tray on the cast with the pencil. 1st draw a line transversely across the post. border connecting the two hamular notches, in such a manner that the connecting line passes just post. to the fovea palatinus. i.e. 2 mm distal to fovea palatini – morrow

1.31mm distal to fover palatini – lye draw a line outlining the mucobuccal fold at the point where the buccal

reflection leaves the lateral wall of the alveolar ridge. Carry the line well above the frenum attachment. Mandibular : draw a line distal to the retromolar pad, confines this line buccal in an inf. and ant. direction following masseter groove to the beginning of external oblique ridge.Progressing anteriorly follow the oblique ridge to the buccal frenum attachment. Carry outline well above the frenum attachment and end at the buccal frenum Same extension is drawn on the opposite side, following the mucolabial reflection and allowing space for the labial frenum attachment. On the lingual border area drop a line inf. from the R.M. pad. Extend line ant. and into the mylohyoid ridge but 2-3 short of the mucous membrane reflection of floor of the mouth to a point opposite the cuspid eminence. Same is drawn on the opposite side. 3) Spacer thickness / relief area : it is determined by the material to be used in making the definitive imp. Relief areas : FENN: owing to the varying thickness of the mucose on which the dentures rests it is frequently necessary to relieve the denture over areas of thin mucosa in order to avoid pain and/ or rocking of the denture and the commonest position requiring such relief is -- Median sagittal raphae of the palate

Incisive papilla Buccal surface of prominent tuberosities Crest of lower ant ridge, mental foramen Prominent genial tubercle Areas of mucosal damage – lichen planus Torus mandibularis and palatinus Relief areas on dentures should always merge into the surrounding fitting surface and should never have a clearly defined outline as this can cause mucosal irritation. BOUCHER:Maxillary – Base plate wax (1 mm thick) is placed on the cast with in the outlined border to provide space in the tray for the final imp. material. The PPS area on the cast is not covered with wax spaces. Therefore, the completed custom tray will contact the mucous membrane across the post. palatal border and additional stress placed here during the final imp. , will help achieve a post border seal. A wax spacer is not used if a metallic oxide imp. paste has been selected for final imp. material. Tray should be 2-3 mm thick, with a stepped handle in the ant. region.Mandibular : 1 mm thick wax spacer is placed over the crest and slopes of the residual ridge, leaving the border uncovered. The buccal shelf on each side also maybe left uncovered so that the completed custom tray contacts the mucous membrane in the region of the buccal shelves. Extra wax can be placed over the lingual slopes of the cast below the level of the mylohyoid ridge to provide additional space for the action of mylohyoid muscle. Custom tray should be 2-3 mm thick with an ant. handle centered over the labial flange in the approximate position of the ant. teeth and shaped so as not to interfere with the position of the lip. Two additional handles, one on each side are placed in the 1st molar region. These are centered over the crest of residual ridge and are approx. 20 mm in ht. Flanges of the tray should be contoured like the flanges of the CD. III. DCNA :The Boucher tech. Halperin tech. Both tech. require that the completed custom tray be stable and extended properly during moderate function of the oral str. The tech. advocate by Boucher suggests that the custom trays be provided with 1mm thick wax relief over the entire basal seat area. Peripheral borders of the trays should be trimmed to within 2-3 mm of the anticipated peripheral extensions, including the PPS region. After completion of the border moulding procedure, the peripheral extensions are shortened by 1mm, and the wax relief is removed completely to provide space for the imp. material. Vent holes are advocated for both maxillary and mandibular custom trays and a master wash imp. is made. Halperin suggested that the custom trays be provided with 1mm thick wax relief over the peripheral extn. and buccal slope region of the tray, including the PPS region and that the custom trays be in intimate contact with the basal seat areas. The tray provides an internal finish line that forms a Butt joint of compound to the tray after the border moulding procedure are completed. Border molding is completed when the peripheral seal acceptably is provided with no border molding material extended to the internal aspects of the imp. trays beyond the internal finish line. Master cast is poured directly into the border molded custom tray without further perfecting using a wash imp. IV. J.A. HOBKRIK :

Spacer to be used when constructing special trays. For some commonly used imp. materials. ZOE – 0.5mm Alginate – 3.0 mm Plaster – 1.5 mm Elastomeric – 1.5 mm Relief materials :Base plate wax Non asbestos casting ring liner Metal foils – lead foil V. SHARRY :

A layer of base plate wax is adapted over the whole area outlined for the tray.

4. Tissue stops :Tissue stops allowed the tray to be located in the mouth while maintaining the

desired spacing for the imp. material. Boucher – PPS and buccal shelf area act as tissue stopSharry – four stops – 2 cuspid area 2 molar area

2 mm width The area extended from palatal aspect of the ridge to the mucobuccal fold. Derek Stananought - 3 stops 5 x 3 mm One in ant. Region of dental arch and One each in post region Rudd, Morrow- 4 mm – square Mandibular ant. – 2 ; post. –2 Maxillary ant. – 1 ; post - 2

5.Tray handles: Tray handles are particularly helpful when loading, placing and orientating custom trays in the mouth. They are also a potential source of inaccuracy in imp. making for CD cases. This problem chiefly arises when the handle distorts the form of the lip and hence functional suclus, or encourages the clinician to rest his fingers over the periphery of the tray, they leading to an over extended imp. In upper tray – single handle positioned in the midline, which should be stopped or angled to avoid interfering with the lips. For lower tray - three stub handles are suggested one in the midline, in the ant. Region, together with one each side in the premolar regions. The latter may be used to support the tray while the material is setting, thus avoiding the possibility of the dentists finger resting on the surface of the tray and distorting the recording of the peripheral form. In special situation of the flabby upper ant. ridge, where the clinician elect to use a selective pre. Imp, two handles should be positioned, one either side in the premolar or molar regions, thus avoiding the areas of the tray that is to accommodate the ‘open window’

IMPRESSION TRAYS FOR IMMEDIATE DENTURES When making tray for immediate dentures the considerations are different from making trays for conventional CD because of the presence of teeth on the cast. The immediate denture treatment sequence used by many dentists consist of removing the post teeth

after a healing period, making an imp. of relatively well healed post. ridges, completing the denture and then removing the ant. teeth and inserting the denture. Therefore two areas of imp. trays for immediate denture that require consideration are :

1. Imp. of the edentulous ridges

2. Imp. of the remaining natural teeth

There are 3 important methods for immediate denture and each require a different

type of tray.

1st Method :- A one piece full arch important tray covers the edentulous ridges and

natural teeth.

2nd Method :- Custom made imp. tray for post. edentulous portion of the imp. and then

make an overall imp. over the post. tray and natural teeth.

3rd Method :- Two piece tray 1st tray made over the ant. portion of the arch and the

anterior teeth joining the 1st tray.

I. FULL ARCH IMPRESSION TRAY :-

A) Finger adopted dough method

Appleby and Kerehoff (1955) have prescribed a method of making an overall

acrylic resin important tray for an immediate maxillary denture imp. Their method

requires placing the tray outline on the cast. Block out the natural teeth on the cast with

wax, adapt a layer of baseplate wax over the cast that extends to the border outline. Self

cure resin is used to make the overall imp. tray of 2 mm thick.

B) Vacuum – Adopted method

Outline is drawn

Block out undercuts and relief areas with a heat stable relief material (wet

asbestos)

Position a sheet of resin of the proper thickness in the heating frame of the

vacuum adopter.

Confer the cast

Start the heater and when the recommended sag occurs, lower the heating frame

and activate the vacuum after complete adaptation allow it to cool and trim the

borders. Resin that projects over the ant. Teeth act as a handle for this type of

tray.

II. CUSTOM POSTERIOR TRAYS :

Extend the imp. tray outline to contact lingual surfaces of the anterior teeth. This

extension aids in positioning the tray in the patients mouth and increases the

accuracy of the imp.

An alternate method is to use a wax ledge approximately 2 mm wide anterior to

the incisive edges of the teeth. It allows the tray to extend in front of the teeth and

aids the positioning the tray.

Block out spaces between the teeth with wax to keep resin from entering the

undercut areas and to prevent the teeth from braking when removing the tray

from the cast. After blocking out the spacer and undercuts, adopt one layer of

base plate wax for relief.

Apply separating medium on the cast and relief wax, mix acrylic tray material,

adopt the material to the cast, allow to set, excess is trimmed.

III. TWO PIECE TRAYS :

If permdenture in a two stage procedure.

Outline in formed for the post section of the tra

.

Adopt relief wax and block out wax as required.

oat the cast and wax with tinfoil substitute

Mi

the acrylic resin, adept it during the dough

tage on the cast and trim excess resin from the border of the cast.

After setting separate the tray and relief wax fr

m the cast.

Replace the tray on the cast

Adopt two layers of

base plate wax over the teeth

on the cast.

Apply tinfoil substitute to the cast.

Coat out p

rt of the previously formed tray with

ilicone lubricant or cover it with a layer of tinfoil.

Mix the resin, form it into sheet, adopt over the

locked out teeth and the previously constructed tray.

After setting, remove the tray from the cast and t

im them. Make certain that the important trays overlap sufficiently for a positive,

accurate fit them wherever necessary.

FIXED PARTIAL DENTURE :

Custom resin tray :

tom resin trays have seen utilized in e

astomeric important t

ch because these materials are more accurate in uniform thin layer of 2-3 mm. Many

authors advise against the use of stock trays because uneven bulk of important material is

condusive to distortion. It has also been reported that the difference in material thickness

between custom and stock tray is less then 1.0 mm and that variation from uniform

thickness exist in both custom and stock tray.

Gordan et al reported that the inter preparation distance

n casts made from polysulphides, polyvinyl siloxine and Polyether important was 50-

100( greater when stock trap were used instead of custom acrylic or thermoplastic trays

smaller discrepancies have been reported for the length of dies poured in polyvinyl

sicoxane important in custom trays than those made from important in stock trays.

However Bomberg et al found no significant di

ference in the marginal fit of single tooth restorations on cases made from polyvinyl

siloxine important stock and custom trays.

Tray preparation :

Mark the borders of th

tray on the diagn

stic coat, approx, 5mm apically to the crest of froe gingive (Rosen). 2-3 mm

beyond the neck of the teeth (skillin).

Adopt 2 sheets of base plate wax to the cast.

Tr

m the excess till the pencil line

Cover wax wi

h thin tinfoil or (Polyethylene) she

t to protect resin from wax during the exothermic heat.

Cut 3 x 3 mm hard tissue stops which are located

n non flual cusp of the post on both sides and one on incisor. Is all the teeth are

invalued, a larger soft tissue stop can be placed on the crest of the alveolar ridge

or in the center of the hard palate.

Mix the self cure resin and at dough stage adopt it over the

axed spacer till the outline. Excess material in used to make the

Remove the tray after set and trine.

Dual quad trays :

(Doubl

Arch tray, Triple Tray, Accue – bi

)

This tray is used

to make the important of single casting in pa

ient with suitable interdigitation. And also there should be sufficient space distal

to the terminal tooth in the arch to allow tray approximation.

Advantage :

Physical deformation of the mandible during op

ning is min

mized.

Shifting of teeth occurring during maximum intercuspation

s recorded.

Less material is needed so the patient is more comfortable

Less gagging may occur.

Disadvantage :

Tray is not rigid

depends on important ma

erial for rigi

ity.

Distribution of the important material is not uniform

Modified custom tray :

Obtain an irreversible hydroco

d impression of the prepa

1) ed teeth, then pour a model for custom tray fabrication.

Apply a layer of wax on soft and hard tissues to create the

2) space for the impression material. (As an alternative, a plastic sheet can be applied on

the die).

Pierce the wax or plastic sheets so the resin comes into co

3) tact with the tissues. Create the stops to stabilize tray positioning and guarantee that a

uniform thickness of the material is obtained.

Fabricate tray by applying a uniform layer of autopolymeri

4) ing resin. (A thickness of 3 to 4 mm provides sufficient rigidity). Place the resin so it

surrounds every single abutment to provide hydrostatic pressure and support for the

material during impression making. Extend the tray handle into the posterior lateral

areas to obtain an axial traction during impression withdrawal. Allow resin

polymerization for at least 24 hours.

During the appointment for abutment refining and impression

5) making, reline the tray with autopolymerizing resin. Mix the resin with minimum

concentrations of monomer (the component that undergoes the maximum shrinkage).

Pour the mixture into the tray and wait until it becomes opaque. Place the tray on the

teeth and apply a light pressure until it settles completely. When the resin becomes

rubbery, remove the tray to reduce contact time between resin and teeth and let the

exothermic resin reaction take place outside the oral cavity. If the abutments are not

parallel, the tray should be removed during resin elastic hardening phase. Eliminate

undercut, if present, during the finishing phase by removing a greater and more

uniform layer of resin, because it would prevent modified custom tray reinsertion. As

previously described, impression material uniform thickness between to 4 mm

should be considered ideal.

Cure the resin in hot water at a temperature of 1000C for 5

6) minutes.

Use a fine-tipped permanent marker to mark abutment contour

7) obtained after relining so that they can be easily identified. After relining, use a

multiblade spherical bur to drill 2-mm deep grooves inside the abutments. Use a

multiblade inverted cone bur (CM 30F /023, Sveden Martina, Italy) to join the

grooves without getting any deeper into the abutments. For teeth with supragingival

finish lines, trim away 2 mm of resin around the margins. For teeth with subgingival

finish lines where the material requires an additional push, remove only 0.5 mm of

resin from around the edges. For further refining, trim off the resin around the

abutments with the spherical bur, in soft tissues areas. (In this way, a space is created

for gingival tissue displacement caused by the penetration of impression material into

the gingival crevice. In pontic regions, remove 2mm of resin by using deep groves

and maintain a uniform impression material thickness.

Apply the adhesive onto the tray, wait until it dries, and

8) roceed with impression making. Any kind of elastomeric material can be used for

this procedure. This procedure describes the use of polyvinyl siloxane in 2 grades of

viscosity, heavy body and regular body. Apply higher viscosity material to the tray,

leaving no voids around the prepared teeth to prevent air bubbles from being

incorporated in the mix. Apply the lower viscosity material around the abutments by

means of a syringe.

REMOVABLE PARTIAL DENTURE

Stock trays :

Perforated or ri

ock trays that are large enough to provide a 6

m broader thic

ness of important material.

Individual important trays :

Outline the extent of the tray on the cast. The

tray must include all teeth a

d tissues that will be involved in RPD.

Adequate space must be provided for fremal attachment.

Mark the area of the

ost palatal seal on the maxillary cast and cut 1 x 1 mm

groove following the line that designates the post extent of the tray.

Adept a layer of base plate wax over the tissue surfaces and teeth of the cast

to serve as a spacer for important material. Excess wax is trimmed upto the

outline wax covering the PPS area should be removed so that intimate contact of the

tray and tissue in this region may serve as an aid in correctly orienting the tray

necessary is rubber base materials are used.

Expose portions of the incisal edges of the central incisor to serve as a out stops.

Paint the exposed surfaces of the coat that may be contacted by the resin with a tinfoil

substitute.

Mix the soft cure

acrylic resin and adopt it on the cast at dough stage.

With extra material handles a

e attached to the tray over the region of CI.

After it sets, remove it from the cast. Wax is removed

and borders are perfected.

Perforations are placed with in the tray at 4

5 mm intervals. Within the exception of alveolar groove areas, if an algicut

material is to be used.

Lower tray is also made by following the source procedu

e. Buccal shelf region are left uncovered by the wax pacer to serve as post. Stops

in orientating the tray.

IMPLANT SUPPORTED DENTURE

1. Preliminar

or diagnostic important (study cast)

Preliminary important are necessary to make study cast. After coping are connected,

select a stock tray and check fit intra

ally. Due to the ht. Of the important coping,

a stock trays for a dentulous arch should be used fo

extra space occlusally.

2. Custom tray fabrication

The square important coping are used when marking the custom trey.

Medium or long guide pins is used for custom tray fabrication

After all coping have been secured into position with their respec

ive screws adopt base plate

wax around the using

Sheet of base plate wax can be cut into 1

5 cm strips and two sheets are warmed together. Adopt and pres

the wax around the coping, maintaining an even thickness.

Mix the self cure resin tray material and in dough stage,

dopt it over the residual ridge, blocked out copings and pins

Tray material is pressed over the guide pins exposing about 5mm of pins.

After the

esin has set, holes created by the guide pins are enlarged to 5mm diameter.

Tray should be trimmed to finish rough or sh

rp edges.

Square important copings and guide pins are removed from the study cast.

After

tray disinfection the tray is fitted I/o.

Synthetic casting tape as a facial impressio

tray material :

Various methods and materials have be

n used to make facial impressions easier, safer, and less time consu

ing. The following impression technique describes the u

of a reusable thermoplastic synthetic casting tape (Zimmer, W

rsaw, Ind.) tray that can be disinfected and reused. Synthetic casting tape is

a fiber glass fabric that is impregnated with polyurethane resin components.

The material is supplied in 3, 4, or 5-inch width rolls that can be cut and

adapted to any form. When exposed to moisture, the material gradually sets

(5 minutes) and produces a slight exothermic reaction. a pliable material,

such as gauze or orthopedic felt, is used as a spacer to allow the tray to be

directly fabricated over the patient’s face ; when removed, the material

provides a uniform thickness for impression material. The tray is light

weight, which reduces the possibility of soft tissue displacement during the

impression. Modification to the size and shape of the tray can be

accomplished by trimming the borders of synthetic tape or the adaptation of

compound or acrylic resin to provide support for complicated shapes or

defects. The tray can also be disinfected for reuse, thus making the use of

the synthetic casting tape economical.

Technique :

Position, drape, and review the procedure with the patient.

Position the spacer (gauze or orthopedic felt) over the face, identify the

borders, and trim away the excess material. Locate and cut out an airway in

the

spacer. Pos

1) tion the desired airway through the spacer.

Cut the casting

2) tape into 4- to 6-inch long strips. Immerse the strips in warm water (650F to

750F) to initiate the chemical reaction, then remove and squeeze out the excess

water.

Place the strips over the spacer, alternating

3) one strip over the other. Two to three layers of tape are required for adequate

strength.

Once set 3 to 5 minutes, remove the tray from the face and remove the spacer and

airway.

4)

Complete the tray by trimming away the edge of the casting strips with scissors.

DEPARTMENT OF PROSTHODONTICS

INCLUDING

CROWN

5) BRIDGE AND IMPLANTOLOGY

SEMINAR

ON

IMPRESSION TRAYS

6) PRESENTED BY

DR. SHALABH KUMAR

Tray compound

N

ck tra

anslucent

se plate

RPD

plants

F

D

Uses

Custom t

y

Materia

Opaque

ays

Heat

n

Shellac base

plate rein

orced with

imp. compoun

Shellac

Impression

re

Self cure

L

ght cure

Acrylic re

cts

Close fit

Spaced

illofacial de

on, ploys

yrone, pol

carbonate

M

IMPRESSION TRAYS

Introd

i

n

quirements for impression tr

ys

Class

fication

Parts of the tray

Com

e dentu

e

pression trays pression trays

ays

Custom trays

Definition

Ideal fea

ures

Design characteristics

Tray materi

l

Tray extension

Spacer thickn

ss

Tissue stops

Tray handles

Imme

iate denture im

. trays

Full arch

imp. tray

Custom post tray

Two p

o ece trays

Fi

o ed partial de

ture imp. t

ays

Custom res

n

Dual quad tray

Modi

ied custom tr

y

Removable par

ial denture imp.

trays

Implan

supported de

tures

Tray for the facial im

ression

Conclusion

eferences

Metal

Edentulous

entulous

Non perforated

Perfor

o ted

Rim lock

o

Non perfora

o ed

Perforated

Sect

onal

Water coolant

Dual quad

Non

metal

Disposable

Reusab

e

Perforated

Sectional

Pe

forated

Sec

ional

St