8. DEFINITIONS
IMPRESSION :
A negative likeness or copy in
reverse of the surface of an
object.
IMPRESSION MATERIAL :
Any substance or combination of
substances used for making an
impression or negative
reproduction.
8
9. CAST :
A life - size likeness of some desired form. It is formed within or is a
material poured into a matrix or impression or from a CAM printed
replica.
9
15. • Dual arch trays can be categorized by the amount and
location of the arch enclosed by tray.
• These categories include:
posterior sextant,
quadrant,
three quarters of an arch,
anterior sextant and
full arch.
15
16. • Accu-Bite trays are plastic disposable trays.
• Ultra-Bite trays are plastic reusable trays.
• Coe Check-Bite trays are supplied with disposable inserts of
paper.
• Triple trays are available with the designs for posterior as well
as the anterior (canine to canine) arches.
16
17. STOCK TRAY
A metal or plastic prefabricated
impression tray typically available
in various sizes and used
principally for preliminary
impressions.
17
20. • Rigid, with a consistent thickness of 2 to 3 mm.
• It should extend about 3 to 5 mm cervical to the gingival
margins and should be shaped to allow muscle attachments.
• It should be stable on the cast with stops that can maintain
an impression thickness of 2 or 3 mm.
20
23. 23
ADVANTAGES
• Impressions are free from defects that are often observed with the
traditional methods, such as poor margin reproduction, bubbles.
• There is no need for gingival retraction as the resin matrix
promotes gingival tissue displacement and expansion and
subsequent prevention of gingival collapse over the tooth.
• Fluids are removed from the gingival sulcus by pressure, and
therefore poor hydrophilicity of impression material is not a major
problem.
24. DISADVANTAGES
24
• Resin polymerization shrinkage may be continuing after the
impression making and possibly distort the impression.
• If the abutments are long and thin or they are not parallel,
there may be risk of breakage.
25. • This in vitro study was done to evaluate the linear dimensional
accuracy of impression made in stock trays and custom trays,
using polyvinyl siloxanes.
• Making custom tray is time consuming and costly; therefore putty
wash 2-step technique with controlled bulk in stock tray can be
used as an alternative to provide accurate impressions, as
obtained from custom trays.
COMPARISON OF CUSTOM TRAYS AND STOCK TRAYS USING
POLYVINYLSILOXANE TO EVALUATE LINEAR DIMENSIONAL ACCURACY:
AN IN VITRO STUDY
Patil, Padmakar & Chowdhary, Ramesh & Mishra, Sunil. (2008). Comparison of custom trays and stock trays using polyvinylsiloxane to
evaluate linear dimensional accuracy: An in vitro study. The Journal of Indian Prosthodontic Society. 8. 156-161. 10.4103/0972-4052.49021.
25
26. • Retention is provided by perforations, rim locks, and/or
adhesives.
• Adhesives should be applied sufficiently in advance to allow
thorough drying, although they may remain slightly tacky to
touch.
Spray-on adhesives have been shown to result in significantly less
retention of polyvinylsiloxane impression materials to both
autopolymerizing and photopolymerizing tray materials than paint-on
adhesives.
26
27. A STUDY ON TRAY ADHESIVES USED WITH ELASTOMERIC IMPRESSION
MATERIALS AND DIFFERENT TYPES OF TRAYS
Chandrasekharan Nair., et al. “A Study on Tray Adhesives Used with Elastomeric Impression Materials and Different Types of
Trays". Acta Scientific Dental Sciences 6.3 (2022): 81-87.
• Tray adhesives used with putty consistency AS and CS on different
types of trays: metallic trays and plastic trays.
• Comparison of tensile bond strength of two brands of tray
adhesives: Coltene and Zhermack.
27
28. A STUDY ON TRAY ADHESIVES USED WITH ELASTOMERIC IMPRESSION
MATERIALS AND DIFFERENT TYPES OF TRAYS
Chandrasekharan Nair., et al. “A Study on Tray Adhesives Used with Elastomeric Impression Materials and Different Types of
Trays". Acta Scientific Dental Sciences 6.3 (2022): 81-87.
• Plastic tray always exhibited a higher mean retention strength
than metallic tray.
• Between the two adhesives, Coltene recorded a higher mean
retention strength when compared to Zhermack.
28
33. • The agar has been used in dentistry for cast
duplication and impression making.
• Its use is now limited as it requires a complicated
setup
• Changes between sol and gel based on temperature
33
34. • Agar Hydrocolloid
Conditioner
• Hydrocolloid Material
• Water cooled rim lock trays
• Duplicating
Mould
• Rubber Hose
• Impression tray
34
40. • Alginate is a hydrophilic impression material and
can capture accurate impression in the presence of a
little blood or saliva.
• Alginate has got a poor dimensional stability and
must be poured immediately.
• Maximum 10-minute delay can be made otherwise
distortion will occur.
40
41. FOR MIXING:
• A clean flexible plastic bowl and
• A clean wide bladed, reasonably
stiff
metal spatula.
Note: It is better to use separate bowls for plaster and alginate as
plaster contamination can accelerate setting.
41
42. The mixing is started with a stirring motion to wet the powder with
water.
Once the powder has been moistened, rapid spatulation by swiping
or stropping against the side of the bowl is done.
A vigorous figure of eight motion can also be used
42
43. Disadvantages:
• Low tear strength
• Dimensional instability
Advantages:
• Affordable
• Short manipulation time
• Simple,single step
technique
• Few armamentaria
required
43
44. • The prepared teeth are bathed in warm water, and syringe
material is deposited in generous quantities only on the
occlusal surfaces of the teeth.
• The relatively viscous tray material is counted on to force the
lighter-body syringe material into the sulcus as the tray is
seated.
WET FIELD TECHNIQUE
44
45. • The hydraulic pressure of the viscous tray materials forces
the fluid syringe hydrocolloid down into the areas to be
recorded.
• This technique should be used only on preparations that do
not contain internal features, such as grooves, boxes or
isthmuses.
WET FIELD TECHNIQUE
45
46. • The syringe agar gives better details than alginate.
• Less air bubbles.
• Water cooled trays are not required and therefore more
convenient.
• It sets faster than the regular agar technique
ADVANTAGES:
46
47. LAMINATE TECHNIQUE
After injecting the syringe agar on to the
area to be recorded, an impression tray
containing a mix of chilled alginate that
will bond with the agar is positioned over
it.
The alginate gels by a chemical reaction,
whereas the agar gels through contact
with the cool alginate, rather than the
water circulating through the tray
SCHWARTZ (1951)
47
48. ADVANTAGES:-
• Less complicated (and less expensive) equipment
for liquefaction and storage.
• The impression is removed from the mouth in 3
minutes, which is faster than other elastic
materials.
48
49. DISADVANTAGES:-
• Fast gelation time of the syringe material, which
requires the impression to be handled very
quickly.
• There also have been problems with the syringe
material separating from the alginate in the tray
49
51. • These are the first elastomers to be introduced.
• Although messy to manipulate, it is useful when a long
working time is needed.
• Consistencies: Light body
Heavy body
• Mode of supply:
It is available in a two-paste system: base and
accelerator.
51
56. CONDENSATION SILICONE
• They are more affordable than other elastomeric
materials but have the disadvantage of being
prone to shrinkage, requiring immediate pouring.
• Consistencies: extra-low, Low, medium, and putty
• Mode of supply: In collapsible tubes(medium body)
In jars as base and catalyst (putty)
Syringes (ultralow and low)
56
57. • Proportioning is done by squeezing out a measured length of
base material and adding the specified number of drops of
liquid reactor.
• The permanent deformation of the condensation silicones is
superior to that of the polysulphides.
• However, the dimensional stability is inferior, and a
condensation silicone impression should be poured as soon as
possible after removal from the mouth
57
60. ADDITION SILICONE
• They are the most widely used impression materials in
fixed prosthodontics.
• Mode of supply: Available in all consistencies( extra-low,
low, medium, heavy, and putty)
• Composition: All the consistencies are supplied as base
and accelerator
60
61. In Custom Trays :
• The one step impression technique
• The impression material can be delivered from tubes/
cartridge systems
In Stock Trays :
1.Two Step Putty Wash Technique
2.One Step Putty Wash Technique
61
62. • Most often used
• The putty can customize the stock tray and offer
support and stability to the wash material.
• Addition silicones are not firm enough to be used in
stock trays without putty or heavy body as a tray
material.
TWO STEP PUTTY WASH TECHNIQUE :-
62
63. 63
•Excellent dimensional stability
•Elastic recovery
•Great accuracy
•Short setting time
•Good tear resistance
•Good compatibility with gypsum
•Can be cast multiple times without jeopardizing the details
ADVANTAGES:-
64. 64
•Hydrophobic - the impression area must be dry to
prevent inaccuracies in the impression
•The sulfur present in the latex gloves and rubber dam
may interfere with the polymerization of the base and
catalyst.
•Hydrogen gas may lead to pitting in the cast.
DISADVANTAGES:-
66. • It has become popular because it only requires a stock
tray and a single mix.
• Mode of supply: Available as light, medium, and heavy
body consistencies.
66
67. INDICATIONS-
• Fixed prosthodontics (crown and bridgework, particularly
for multiple preparations)
• Indirect inlay and onlay impressions
• It can be used for corrective impressions as it can be
added to previously set material.
67
68. 68
• Hydrophilic
• Accurate and high dimensional stability - makes it
possible to delay casting and allow multiple pouring.
• Good elastic recovery, shelf life
• Good compatibility with gypsum
ADVANTAGES:-
69. 69
• Most rigid of all the elastomers makes it hard to remove
(newer polyethers are slightly more flexible)
• May cause allergy due to sulfonate acid esters
• The impression should not be immersed in disinfectant
for more than 10 minutes since it's hydrophilic.
• Since it absorbs water, it should not be kept with
alginate impressions.
DISADVANTAGES:-
70. Bajoghli F, Sabouhi M, Nosouhian S, Davoudi A, Behnamnia Z. Comparing the Accuracy of Three Different Impression Materials in Making Duplicate
Dies. J Int Oral Health. 2015 Jul;7(7):12-6. PMID: 26229364; PMCID: PMC4513764.
This study aimed to evaluate the precision of three impression
materials: Additional Silicone (AS), Condensation Silicone (CS), and
Polyether (PE) in duplicating master dies.
PE (Impregum), CS (Speedex), and AS (Panasil) were the impression
materials used.
Among the tested impression materials, Impregum exhibited the best
accuracy for creating duplicate dies, while Speedex demonstrated the
lowest accuracy.
COMPARING THE ACCURACY OF THREE DIFFERENT IMPRESSION
MATERIALS IN MAKING DUPLICATE DIES
70
71. IMPRESSION MATERIAL MEAN WORKING TIME MEAN SETTING TIME
Agar 7-15 5
Alginate 2.5 3.5
Polysulfide 5-7 8-12
Addition silicone 2-4.5 3-7
Condensation silicone 3 6-8
Polyether 2.5 4.5
71
73. • This investigation was an in vitro evaluation of the accuracy of
reversible hydrocolloid, vinyl polysiloxane and polyether
impression materials using two Type IV die stones.
• Among the materials tested, the hydrocolloid and polyether
materials were the most accurate.
Comparing the accuracy of reversible hydrocolloid and
elastomeric impression materials
Federick DR, Caputo A. Comparing the accuracy of reversible hydrocolloid and elastomeric impression
materials. J Am Dent Assoc. 1997 Feb;128(2):183-8. doi: 10.14219/jada.archive.1997.0162. PMID: 9037971.
73
79. • In this technique, the light body (wash type) material is
laminated in a thin layer on the surface of the heavy
body material and immediately positioned upon the
preparation.
• The purpose of this lamination is to prevent the direct
contact of the heavy body with the preparation
surfaces, which may produce roughness of the cast
surface.
79
81. • Also known as SINGLE MIX/ SINGLE VISCOSITY/ MONOPHASE
TECHNIQUE
• The procedures for monophase impression are same as for
the dual-phase impression except that medium-viscosity
material is used as both as the tray material and the syringe
material.
81
82. 2)SINGLE MIX/ SINGLE VISCOSITY/
MONOPHASE TECHNIQUE
• The surface reproduction may not be as good as that of light body
material in this technique.
• Also the medium viscosity material will show a greater
amount of polymerization shrinkage than compared to that of
heavy body materials because of the lesser amount of filler
content
82
83. • This is a stock tray impression technique.
• There are two methods to make a putty wash
impression:
1. One step/ Single mix putty-wash impression
2. Two step/double mix putty wash impression
3)PUTTY WASH IMPRESSION-
83
85. • In this procedure putty impression made in suitable stock
tray and then the light body material is syringed over the
putty impression and also over the tooth preparation.
• Space for the light body material is created by placing the
polyethylene sheet as spacer before making putty
impression or by scraping the material using BP blade or
round bur.
B)TWO STEP/DOUBLE MIX PUTTY WASH IMPRESSION
85
86. Patient position:
• The patient is made to lie down
in supine position.
• The operator sits at 9'O clock position
• The assistant at 3'O clock position.
Choosing correct tray:
1. The tray is selected based on the relative need for
retention and personal preference.
2. The tray shape and size is selected based on the
patient's arch shape and size.
86
88. • This in vitro study compares the dimensional accuracy of a
monophase, one and two step putty/light-body impression
technique.
• It was found that the monophase technique yielded the lowest
cast accuracy than the other methods
• The 1-step technique yielded more accurate casts as compared to
the monophase technique but less accurate casts than those from
the two step technique.
• The two step technique produced the most accurate casts
Dimensional accuracy of resultant casts made by a monophase, one-step and two-step, and a novel two-step putty/light-body impression
technique: An in vitro studyCaputi, Sergio et al.Journal of Prosthetic Dentistry, Volume 99, Issue 4, 274 - 281
Dimensional accuracy of resultant casts made by a monophase, one-step
and two-step, impression technique: An in vitro study
88
89. • To evaluate the linear dimensional accuracy of the elastomeric
impressions using various impression techniques using different
combinations of viscosities of impression materials.
• Among the six techniques used, the heavy body light body two-
step technique using custom tray showed the least distortion
which was closely followed by the putty wash two-step technique
with 2 mm spacer using stock tray.
Effect of Different Impression Techniques on the
Dimensional Accuracy of Impressions using Various
Elastomeric Impression Materials: An in vitro Study
Singh K, Sahoo S, Prasad KD, Goel M, Singh A. Effect of different impression techniques on the dimensional accuracy of impressions using various
elastomeric impression materials: an in vitro study. J Contemp Dent Pract. 2012 Jan 1;13(1):98-106. doi: 10.5005/jp-journals-10024-1102. PMID: 22430701.
89
91. • Other names:- Closed mouth impression/ Triple arch/ Accu
Bite/ Closed bite method/ Dual arch method/Dual quad tray
method
• Wilson & Werrin in 1983
91
92. 1. The syringe material is injected into the area to be
recorded.
2. The high viscosity material is mixed and placed in excess
on both the arches.
3. The tray is placed in between the arches.
4. Patient is asked to occlude (bite) slowly
92
93. 5. After making the impression, the patient is instructed to
open his mouth slowly.
6. As the patient opens his mouth, the tray will adhere to one
arch.
7. Bilateral pressure (right and left) should be applied to
remove the tray as it helps to minimize distortion .
93
94. 8. Die stone is poured into the impression of the tooth
preparation.
9. The impressions are boxed and casts of both arches are
poured.
10. Articulation should be done on a hinge articulator with an
incisal
pin to maintain vertical dimension. 94
96. Advantages
• Less impression material is required
• Less time is taken as both the arches are recorded
simultaneously.
• Maximum intercuspation position can be recorded
more accurately as it is recorded during function.
Disadvantages
• Distortion is possible because the tray is not rigid
• Cannot be used for more than one casting per quadrant
96
97. 5)DUAL ARCH MONOPHASE TECHNIQUE
• Same as Dual arch multi
mix technique.
• But instead of using
heavy and light body
use Medium body
impression material.
97
98. • Initially, putty is manipulated and loaded into the tray.
• Over that thin cellophane, the sheet is adapted and an
impression is made.
• After complete polymerization, the tray is removed from
the mouth and the cellophane sheet is peeled off.
6)TWO STEP PUTTY WASH TECHNIQUE USING CELLOPHANE
SHEET AS SPACER:
98
99. • This putty impression act as a custom tray.
• Light body impression material is dispensed
around the prepared tooth and over the custom
putty tray.
• A loaded tray placed in the mouth and removed
after complete polymerization.
99
101. • Soften a sheet of base plate wax and adapt it around the teeth.
• 2 mm square sections were in the premolar regions to act as
occlusal stops.
• The closest fitting stock tray was selected to seat around the wax.
• Apply adhesive and load the tray with putty and insert it into the
mouth.
101
102. • On polymerization, the tray is removed from the mouth, and
the wax is peeled off.
• Now the putty will act as a custom tray.
• In the space previously occupied by wax, dispense low
viscosity impression material and insert the tray
102
103. Advantages
i. Reduced patients number of appointment required for custom tray
fabrication.
ii. The wax spacer prevents the putty from engaging undercuts
iii. Provides uniform thickness of wash material of approximately 2 mm.
iv. Modifications can be done easily in putty custom tray.
Disadvantages
i. Surface contamination of the putty may influence the adhesion with wash
impression 103
104. • This technique requires simultaneous manipulation of putty
and light body elastomeric impression material.
• Putty loaded stock tray is placed over syringed light body
around prepared tooth.
• No spacer is used in this method.
8)SIMULTANEOUS OR SQUASH IMPRESSION TECHNIQUE
104
105. Disadvantages:
1. Impossible to control the thickness of impression
material
2. Excess bulk of impression material is used
3. Light body impression material get displaced
4. Margin details are captured in putty which lacks the
ability to record the marginal details.
105
107. • A close-fitting stock tray is used for making a putty
impression.
• In the areas of tooth preparations, putty is relieved with the
help of a scalpel or bur to provide space for light body
impression material.
• An impression is washed with low-viscosity impression
material. 107
108. • M R Dimashkieh & Steven M
Morgano(1995)
• Temporary crown shells are
used for each tooth
preparation and a final over
impression is then made
using a stock tray.
10)IMPRESSION USING PREFORMED CROWN SHELLS:
108
109. 1. Select a preformed polycarbonate crown and adjust the
gingival margin to extend slightly to the finish line of the
preparation.
2. Coat the internal and external surfaces of the provisional
crown shell with the adhesive.
10)IMPRESSION USING PREFORMED CROWN SHELLS:
109
110. 3. Mix elastomeric impression material and fill the provisional
crown shell. Avoid air entrapment when the crown is filled.
4. Seat the crown shell onto the prepared tooth until it covers the
finish line and the material is allowed to set.
5. Finally make a pick-up impression using regular-body impression
material in a complete-arch stock tray.
110
111. • Edwin H Getz (1971)
• Procedure to combine
the functional
impression with the
checkbite impression so
as to benefit from the
best of each.
11)FUNCTIONAL CHECKBITE IMPRESSION
111
112. • Conventional Checkbite impression is made using a unilateral
tray with medium body rubber-base impression material.
• But a functional Checkbite impression is made after fabricating
a temporary fixed partial denture of acrylic resin.
• This technique eliminates many potential inaccuracies that may be
introduced when the impression and jaw relation records are made
separately
112
113. • The temporary restoration is removed from the mouth and
occlusal surface is reduced to add 1 to 2 mm of wax.
• Then centric relation record is first established accurately with
generous amount of wax.
• When finished, the opposing teeth used in developing the wax
chew-in record are dried and painted with a sheet of thin, wet
cellophane, and the patient is instructed to close the jaws in
centric position.
113
114. • The acrylic forms an accurate impression and then the
temporary restoration with the attached chew-in record
is removed from the mouth.
• The syringe and tray are filled with rubber-base
impression material and the impression is made in
centric position.
• Now the completed impression contains both the
abutment preparations as well as the edentulous ridges
on one side and functional index on the other side. 114
115. • The cast impression coping technique allows the use of stock
trays without serious consequences, even when a putty
wash impression is not preferred.
• Although the cast impression coping technique requires a
second impression appointment because of the laboratory
phase, the waiting period results in healthier periodontal
tissues and better impressions.
• Also, this technique negates the need for gingival
displacement.
12)CAST IMPRESSION COPING TECHNIQUE
115
117. • Primary impression is taken with alginate.
• Dies are prepared and coated with several layers of
die spacer so that the copings will have a space of at
least 0.7 mm for the light body impression material.
• Mark the buccal surface of each coping so they
can be oriented correctly during the impression
procedure.
117
118. • A polyether material is suggested, as it is accurate
enough for the wash and strong enough for the pickup
phase.
• The cast copings are filled with light body impression
material using a impression syringe and placed
carefully on each prepared tooth.
• Then a stock tray is filled with heavy body impression
material and positioned onto the arch
118
119. The matrix impression system uses three impression materials:
1. A suitable elastomeric semi-rigid material required to form the
matrix
2. A high viscosity elastomeric impression material, which will
preferably bond to matrix-forming material
3. A stock tray with a medium viscosity elastomeric impression
material to pickup the matrix impression and the remaining arch
not covered by the matrix
13)MATRIX IMPRESSION SYSTEM
119
121. TECHNIQUE :-
Matrix is made in carrier with PVS material
before soft tissue is retracted
Slender bur or knife edge rubber wheel used
to enlarge interproximal embrasures
Matrix should extend 1/2 to 2/3 of tooth
beyond prepared teeth & close to gingival
crest
121
122. Impression syringe is used to fill matrix with
high viscosity impression material
Matrix impression is seated with light pressure
Stock tray filled with medium viscosity
impression material is placed over matrix
impression before matrix material sets
122
123. 14)VACUUM ADAPTED TEMPORARY SPLINT:
• Vacuum adapted splint was fabricated on the diagnostic
impression which acted as a matrix or trays former.
• Quick setting acrylic was loaded in tray former and an
impression of a prepared tooth was made after which tray
former was peeled off.
• The acrylic tray was reshaped from all the aspects and relieved
except one stop was left that acted as a vertical stop.
123
124. • Heavy body rubber base impression material was used to make a
preliminary impression.
• Escape vents are provided in impression material after
polymerization.
• Secondary impression of the preparation made by using a
combination of equal parts of regular and light body rubber base
impression material.
• A full arch impression is made in a stock tray using regular body
rubber base impression material. 124
125. Advantages:
• Vacuum-formed tray former acting as a carrier of impression
material provides closed adaptation.
• The primary impression deflects the gingival tissue away from
the cervical margins of the preparations, thus permitting the
viscous rubber base material of the final impression to flow
into contact with the cervical margins of the preparation.
125
126. • The copper-band or tube is used to obtain an impression of
multiple preparations when there are only vague margins on
one or two preparations that are not adequately replicated in
the impression.
• The patient's condition, the extent of the aberration
evaluated, and judgment determines whether the copper band
technique saves time or a remake of the original impression is
more appropriate.
15)COPPER BAND IMPRESSION TECHNIQUE
126
127. The copper band or copper tube impression in made with
the following combinations of techniques:
1. The original copper tube and modeling compound
method
2. A variety of copper tube and elastomer combinations
3. Resin copings and elastomer
4. Polycarbonate crowns and elastomers
5. Resin (provisional) crowns or FPDs with elastomer
127
129. Advantages:
1. Superior gingival retraction than indirect retraction
method.
2. Bubble and void free impression due to close adaptation
of wax lined tray
129
130. • This technique is indicated for teeth with root proximity as
it prevents strangulation of gingival tissues during
displacement.
• In this technique following multiple adjacent tooth
preparations, the matrix was made in the carrier with
polyvinyl siloxane bite registration material.
• Separate impressions of each tooth, mark them according
to tooth number, and relieve from the internal aspect.
16)EVERY OTHER TOOTH IMPRESSION TECHNIQUE
130
131. • Retraction of every alternate tooth was done
• Heavy body elastomer was loaded into the matrix,
and the impression was done.
• The same was repeated for the remaining teeth.
• Seat all the matrix on designated teeth, then
definitive pick-up impression with medium-
viscosity made.
131
133. • Before tooth preparation, impression with dual arch tray
done on preparation side.
• Preparation, tissue management, and retraction were done.
• Through a plastic tray, 2 holes were drilled on the facial
aspect.
• The secondary impression is produced with a low-viscosity
vinyl polysiloxane impression material with injection
continuing during withdrawal to prevent “sucking” of some
wash material from within the impression.
17)LAMINAR TECHNIQUE
133
134. Advantages
• Records prepared tooth, opposing arch, and maximum inter-
cuspation in single impression.
• Avoids waste of excessive impression material.
• Injection into an open system does not generate compressive
forces that can force impression material intra-mucosally and cause
a foreign body reaction until removed.
134
135. • This technique was put forward by Fusayama et al in 1974.
• Heavy and wash-type impression materials were dispensed at
the same time.
• A thin layer of wash type laminated over the surface of heavy
type.
• The loaded tray immediately impressed on the preparation.
• The purpose of this lamination is to prevent the direct contact of
the heavy type with the preparation, which roughens the stone
surface
18)LAMINATE SINGLE IMPRESSION TECHNIQUE
135
137. Arch is broken down into segments of multiple prepared
teeth.
Custom tray prepared for each segment with 1mm of wax
relief.
Overlay trays should extend 3 mm beyond the gingival
margin.
Alraheam et al,The segmental impression technique: A straightforward solution to a difficult problem, J of Prosthetic
Dentistry,
Vol 124, Issue 1,2020,Pages 10-13
137
138. Low viscosity material is loaded into the syringe as well as the
segmental tray, and then an impression made.
Procedure repeated with each segment.
Finally a pick up/ overlay impression is made using a stock
tray.
Alraheam et al,The segmental impression technique: A straightforward solution to a difficult problem, J of Prosthetic
Dentistry,
Vol 124, Issue 1,2020,Pages 10-13
138
139. USES :-
• When moisture control is difficult
• When making simultaneously impressions of
implants and prepared teeth/ multiple prepared
teeth
139
140. • Certain modifications of the basic impression technique are
sometimes needed, particularly for making impressions with
additional retentive features such as pinholes and post space.
20)SPECIAL CONSIDERATIONS
140
141. Pin-retained restorations:
• Elastomeric impression materials are strong enough to
reproduce a pinhole without tearing. However, to avoid
bubbles, they must be introduced carefully into the pinhole
with a lentulo or cement tube. With reversible hydrocolloid, a
special nylon bristle must be used for the impression
141
142. 1. Apply a separating medium (e.g., die lubricant) to the pinholes,
and isolate and displace the tissue in the conventional manner.
2. After mixing the light-bodied impression material, set aside a
small amount for placement into the pinholes.
142
143. Cement tube
3. Fill the tube and squeeze a small amount of material into each
pinhole. Make sure that no air is trapped in the base of the pinhole
(insert an explorer into the material, remove, and repeat the
application).
143
144. 144
Lentulo
4. Be sure that the slow-speed handpiece is rotating clockwise before
picking up a small quantity of impression material with the lentulo.
5. Deliver the material in a spiraling manner into the pinholes, rotating
the instrument slowly while moving the lentulo along the side of the
pinhole.
6. Increase the speed of the lentulo while backing it out (to prevent the
material from being pulled out)
145. Prefabricated plastic pin
7. When making a reversible hydrocolloid impression of a pin-
retained restoration, use plastic bristles to register the pinholes.
The bristles can be modified as necessary with a sharp scalpel to
eliminate any inaccuracy relating to fit.
Their lengths should be adjusted so that they do not contact the
impression tray. (A bristle should extend 2 mm above the opening
of the pinhole.)
8. Apply a separating medium to the pinhole before placing the
bristle and completing the impression
145
146. The elastomeric impression
should be reinforced with a
plastic pin or orthodontic wire.
21)IMPRESSION TECHNIQUES FOR POST AND CORE
146
147. Direct procedure
1. Lightly lubricate the canal and notch a loose fitting plastic
dowel.
2. Use the bead-brush technique to add resin to the dowel and
seat it in the prepared canal.
This should be done in two steps: Add resin only to the canal
orifice first. This is introduced into the canal and pushed into
place with the monomer moistened plastic dowel.
3. Do not allow the resin to harden fully within the canal. Loosen
and reseat it several times while it is still rubbery.
147
148. 4. Once the resin has polymerized, remove the pattern.
5. Form the apical part of the post by adding additional resin
and reseating and removing the post, taking care not to lock
it in the canal.
6. Identify any undercuts that can be trimmed away carefully
with a scalpel. The post pattern is complete when it can be
inserted and removed easily without binding in the canal.
148
150. Indirect procedure:
1. Cut pieces of orthodontic wire to length and shape them
like the letter J
2. Verify the fit of the wire in each canal. It should fit loosely
and extend to the full depth of the post space.
3. Coat the wire with tray adhesive. If subgingival margins
are present, tissue displacement may be helpful.
150
151. 4. Using a lentulo spiral, fill the canals with elastomeric
impression material. Before loading the impression syringe,
verify that the lentulo will spiral material in an apical direction
(clockwise).
5. Seat the wire reinforcement to the full depth of each post
space, use a syringe to fill in more impression material around
the prepared teeth, and insert the impression tray
6. Remove the impression, evaluate it, and pour the definitive
cast.
151
155. 155
• Impression material is supplied in pre-packaged cartridges with
a disposable mixing tip attached.
• The cartridge is inserted in a caulking gun-like device, and the
base and catalyst are extruded into the mixing tip, in which
mixing occurs as they progress to the end of the tube.
• The homogeneously incorporated material can be directly placed
on the prepared tooth and impression tray.
• One of this system’s advantages is the elimination of hand
mixing on pads; the elimination of this variable has been shown
to produce fewer voids in the impression
158. • The purpose of this study was to clinically evaluate the effect of
different mixing techniques on the accuracy of vinyl polysiloxane
(VPS) impressions by assessing metal framework fit of fixed partial
restorations
• Mechanical mixing(pentamix) yields more accurate impressions
leading to more accurate restorations, especially when combined
with two-stage impression technique.
Zelikman H, Rosner O, Naishlos S, Azem H, Meinster I, Glikman A, Melamed G, Ben-Izhack G, Nissan J, Matalon S. Effect of Mixing and
Impression Techniques Using Vinyl Polysiloxane (VPS) on the Accuracy of Fixed Partial Dentures. Applied Sciences. 2021; 11(17):7845.
Effect of Mixing and Impression Techniques Using VinylPolysiloxane (VPS) on the
Accuracy of Fixed Partial Dentures
158
159. • The purpose of this study was to clinically evaluate the effect of
different mixing techniques on the accuracy of vinyl polysiloxane
(VPS) impressions by assessing metal framework fit of fixed partial
restorations
• Mechanical mixing(pentamix) yields more accurate impressions
leading to more accurate restorations, especially when combined
with two-stage impression technique.
Swetha.G, Jayalakshmi Somasundaram,Leslie Rani.EFFECT OF MIXING METHODS ON PROPERTIES OF IMPRESSION MATERIALS--Palarch’s
Journal Of Archaeology Of Egypt/Egyptology 17(7), 3391-3402. ISSN 1567-214x
EFFECT OF MIXING METHODS ON PROPERTIES OF IMPRESSION MATERIALS
159
161. 161
• The impression must be inspected for accuracy when it is removed.
• If bubbles or voids appear in the margin, the impression must be
discarded.
• An intact, uninterrupted cuff of impression material should be present
beyond every margin.
• Streaks of base or catalyst material indicate improper mixing and may
render an impression useless.
162. Finish line errors; tissue over finish line, b Finish line errors; tears in finish line, c Errors in preparation
area; voids, d Errors in silicone impression technique; lack of wash materials in finish line
Al-Odinee NM, Al-Hamzi M, Al-Shami IZ, Madfa A, Al-Kholani AI, Al-Olofi YM. Evaluation of the quality of fixed prosthesis impressions in
private laboratories in a sample from Yemen. BMC Oral Health. 2020 Nov 4;20(1):304. doi: 10.1186/s12903-020-01294-1. 162
164. 164
• An impression that contains visible streaks of base or catalyst material
should be rejected.
• Is there an area where the custom tray shows through? This must be
identified and its potential effect on the quality of the impression
assessed.
• Are there any voids, folds, or creases?
EVALUATION
165. 165
• Is there an even, uninterrupted extension of impression
material beyond the margins of the prepared teeth?
• Has the impression material separated from the tray? This is a
common cause of distorted impressions and results from
improper application and/or inadequate drying of the adhesive.
169. Franco, Eduardo Batista, Leonardo Fernandes da Cunha and Ana Raquel Benetti. “EFFECT OF STORAGE PERIOD ON THE
ACCURACY OF ELASTOMERIC IMPRESSIONS.” Journal of Applied Oral Science 15 (2007): 195 - 198.
EFFECT OF STORAGE PERIOD ON THE ACCURACY OF
ELASTOMERIC IMPRESSIONS
• To investigate the effect of the storage period on the accuracy
of polyethers and vinyl polysiloxanes (Impregum and
perfectim).
• The impressions were poured after 2 hours, 24 hours, and 7
days. Impressions were stored at approximately 55% relative
humidity and room temperature.
169
170. Franco, Eduardo Batista, Leonardo Fernandes da Cunha and Ana Raquel Benetti. “EFFECT OF STORAGE PERIOD ON THE
ACCURACY OF ELASTOMERIC IMPRESSIONS.” Journal of Applied Oral Science 15 (2007): 195 - 198.
EFFECT OF STORAGE PERIOD ON THE ACCURACY OF
ELASTOMERIC IMPRESSIONS
• Smaller discrepancies were observed when pouring
was performed up to 24 hours for the polyether
• Up to 7 days for the vinyl polysiloxane.
• Significant dimensional discrepancies were observed
when polyether was stored for 7 days
170
171. • Six commercially available impression materials (one polyether
and five silicones) were tested after being stored for 30 min to
2 weeks under both static and dynamic testing.
• The materials were tested 1 h after setting under creep for
three hours and recovery was recorded for 50 h.
• As storage time affects the materials properties, pouring time
should be limited in the first 48 h after impression.
Dimitris Papadogiannis, Roderic Lakes, George Palaghias, Yiannis Papadogiannis,Effect of storage time on the
viscoelastic properties of elastomeric impression materials, Journal of Prosthodontic Research, Volume 56, Issue
1,2012,Pages 11-18
EFFECT OF STORAGE TIME ON THE VISCOELASTIC PROPERTIES OF
ELASTOMERIC IMPRESSION MATERIALS
171
174. • Computerized impressions are cutting edge feature
that enable dentists to use lasers and other optical
scanning technologies to make realistic, machine-
generated recreation of soft tissues and hard tissue
in the jaw
• Computerized impressions represent the first phase
in the digital workflow transferring the intra-oral
state to a digital model.
Digital impressions in dentistry,Dalal et al,Journal of Research in Medical
and Dental Science 2022, Volume 10, Issue 7, Page No: 076-081
174
175. There are mainly eight systems available from six different
organizations, with three basic systems now in use to create digital
impressions:
1. Lava chair side oral scanner by 3m
2. CEREC AC by Sirona systems
3. The CADENT iTERO systems
175
176. • First, make sure that the system’s software is up to date and that
hold with the camera is ready for scanning.
• The prepared tooth must be dehydrated and separated, and the
tissue retracted with a gingival cord.
• Retraction is necessary for taking digital impressions because the
scanner may not be able to scan the profile margin if they are not
visible.
176
177. • A scanner, synonymous to an intraoral camera, is available to
scan the images.
• The prepared tooth and its nearby teeth are scanned from
various angles, and its neighbours are created in software.
• The patient is then instructed to seal their mouth in maximum
interception while an image of the occlusion is taken.
• The image data is then transferred to the suitable laboratory or
milling machine in the office together with the patient’s
information for the prosthesis.
177
179. • Less chair time.
• Patient and dental team will have more comfortable and stress-
free experience
• Improve the impression quality for better fitting restorations.
• Reduce possibility of impression-taking errors.
• There's no need to buy any materials, and there's no need to store
them.
• Air bubbles are not a concern with this procedure.
• The elimination of the "unclean" cabinet, as well as patient's
distress.
ADVANTAGES
179
180. • The identification of deeply positioned gingival margins is a
difficulty and IOS scanning is especially problematic in cases of
haemorrhage, as it might hide the prosthetic edges and cause
the scan to be imprecise.
• IOS is unable to prevent dislodging of soft tissue edges or
registering fluid- tissue interactions.
• The machinery is complicated, though it has recently been
considerably simplified
DISADVANTAGES
180
181. Digital impression techniques are a clinically acceptable
alternative to conventional impression methods in
fabrication
of crowns and short FDPs.
Digital impression techniques are faster and can shorten
the
operation time.
Based on this study, the conventional impression technique
is
Digital Versus Conventional Impressions in Fixed Prosthodontics: A
Review
Ahlholm P, Sipilä K, Vallittu P, Jakonen M, Kotiranta U. Digital Versus Conventional Impressions in Fixed
Prosthodontics:
A Review. J Prosthodont. 2018 Jan;27(1):35-41. doi: 10.1111/jopr.12527. Epub 2016 Aug 2.
181
182. This study compares the marginal and internal fit of fixed dental
restorations fabricated with digital techniques to those fabricated using
conventional impression techniques and to determine the effect of
different variables on the accuracy of fit.
The digital impression technique provided better marginal and internal fit
of fixed restorations than conventional techniques did.
Digital versus conventional impressions for fixed prosthodontics: A
systematic review
Chochlidakis, Konstantinos & Papaspyridakos, Panos & Geminiani, Alessandro & Chen, Chun-Jung & Feng, I Jung & Ercoli, Carlo. (2016). Digital versus
conventional impressions for fixed prosthodontics: A systematic review. The Journal of Prosthetic Dentistry. 116. 10.1016/j.prosdent.2015.12.017.
182
183. A novel digital technique for the design and fabrication of an
individual tooth tray, which can be prepared before crown
preparation, and used for efficiently and accurately taking
subgingival impression of complete crown preparations, without
the requirement of time consuming chairside adjustment and
gingival displacement with retraction cords.
A DIGITALLY DESIGNED AND 3D PRINTED INDIVIDUAL TOOTH TRAY FOR
TAKING SUBGINGIVAL IMPRESSION OF COMPLETE CROWN PREPARATION
Xu, Xiaoxiang & Xie, Qiufei & Zhang, Lei & Zhao, Yijiao & Cao, Ye. (2021). A digitally designed and 3D printed individual tooth
tray for taking subgingival impression of complete crown preparation. Journal of Dental Sciences. 16. 10.1016/j.jds.2021.06.002. 183
184. Figure 1 The computer-aided design of individual tooth tray. (A) The fractured bilateral upper central incisors have received
root canal therapy for making full crown restorations. (B) The digital model of the anterior dental arch region. Note the
subgingival
defect of the palatal cervical part of the right upper central incisor. (C) The placement of the marge line on the abutment tooth.
184
185. The impression taking procedure with individual tooth tray. (A) Try in the individual tooth tray after crown preparation.
(B) Insertion the individual tooth tray with final impression material. (C) and (D) The final impression of abutment teeth with
intact
185
187. • The accuracy as well as dimensional stability of an
impression may be depending on the type of the
material used, type of the tray selected, and the
technique followed.
• With availability of various techniques and
advancements the clinician has the freedom of choice
based on evidence and clinical experience provided that
those are based on sound fundamental prosthodontic
principles.
187
189. 1. Schillingburg: Fundamentals of fixed prosthodontics, 4th edition.
2. Stephen F. Rosenstiel - Contemporary fixed prosthodontics, 4th edition.
3. Impression techniques for fixed partial dentures- deviprasad nooji?Nooji D, Sajjan MC.
Impression techniques for fixed partial denture. 2014, LAP LAMBeRTacademic publications???
4.Tylman. S.D. and Tylman S.G.: Theory and practice of crown and bridge prosthodontics 4th
edition. ????
5.K.S, Sumanth & Shetty, Gautam & Sonnahalli, Nithin. (2019). Impression Techniques in Fixed
Prosthodontics - A Review. International Journal of Scientific Research.
6. Priyanka Singh Raghav, Sabzar Abdullah, Shaista Afroz; Impression Techniques for Tooth-
Supported Fixed Partial Denture; Int. J. Drug Res. Dental Sci.
2022; 4(2): 38-48, doi:10.36437/ijdrd.2022.4.2.
189
190. 7. Osio, Mary A.. “The effect of storage time on dimensional accuracy of elastomeric
impression materials.” (2008).
8. Barry Marshak and David Assit. A controlled putty – Wash impression technique. J.
Prosthet. Dent 1990 Dec 64 (6).
9. Fusayama T, Iwaku M, Daito K, Kurosaki N, Takatsu T. Accuracy of laminated single
impression technique with silicone material. J Prosthet Dent 1974 vol. 32: 270-276.
10. Livaditis GJ. A matrix impression system for fixed prosthodontics.J Prosthet Dent 1998
vol. 79: 208-216.
11.George VJ, Vasilakis MD. A cast impression coping technique.Gen Dent 2003: 48-50
190
