Impressions in fixed partial denture

Impressions in Fixed Partial
Denture

Contents
2
1. Definitions
2. Introduction
3. Types of Impressions
4. Diagnostic Impression
5. Final Impression
6. Techniques
7. Review of Literature
8. Conclusion

Definitions
• Fixed Partial Denture : Any dental prosthesis that is luted,
screwed, or mechanically attached or otherwise securely
retained to natural teeth, tooth roots, and/or dental
implants/abutments that furnish the primary support for the
dental prosthesis and restoring teeth in a partially
edentulous arch; it cannot be removed by the patient
• Impression : A negative likeness or copy in reverse of the
surface of an object; an imprint of the teeth and adjacent
structures for use in dentistry
3
Glossary of Prosthodontic Terms, 9th Edition

Introduction
4
Shillingburg HT. Fundamentals of Fixed Prosthodontics. 4th Edition
• Transfer of an accurate replication of the patient’s hard and
soft tissue to the dental laboratory is important
• WHY?
• If the restoration is to fit precisely, the cast on which it is
made must be as nearly an exact duplicate of the prepared
tooth in the mouth as possible.
• This means an accurate, undistorted impression of the
prepared tooth must be made.

Ideal Requirements Of
Impression
• Exact duplication of the prepared
tooth, including the location and
configuration of the finish line.
• Teeth and tissue adjacent to the
prepared tooth
• Free of bubbles
5
> 50% of the
impressions - finish
line not discernible

Types of Impressions in FPD
Diagnostic
Impression
Final
Impression
6

Need
• Essential in treatment planning
• Examination of static and dynamic relationships of the teeth without
interference from neuromuscular reflexes,
• Unencumbered views of occlusion from all directions
• Reproducing the patient’s movements
• Occlusocervical dimension of edentulous spaces.
• Evaluation of the eventual outcome of proposed treatment.
8
Rosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics. Fifth edition

Steps
• Material Selection
9

• Alginate is the material of choice for diagnostic impressions.
10
Advantages Disadvantage
Dimensional
Stability
Storage
Stick To Teeth
Accuracy
Easy To Use
Relatively
Inexpensive
Material Of Choice
Cast should be
poured within
15-20 minutes
of making
impression –
Rudd&Morrow

Steps
• Tray Selection
11

12
Tray Selection
Non-
Perforated
Metal
• Clinically acceptable
accuracy
Perforated
Metal
• Less accurate casts than
plastic
Plastic
• More accurate casts

Tray Requisites
13
Tray extensions
• Impression extend
several millimeters
beyond cervical line of
teeth – more coverage not
required
• If extension required 
perimeter modified with
modeling compound
• If not done 
Unsupported area 
Distortion
Tray clearance
• Largest tray that will fit
comfortably in the
patient’s mouth.
• A greater bulk of material
produces a more accurate
impression
Bulky impression 
More favorable SA :
Vol  Less
susceptible to water
loss/gain  Lower
dimensional change.

Steps
14
• Tray Selection
• Impression Making

15
A small amount of alginate being wiped into the crevices of the occlusal surfaces
Seating of the tray
As the tray is
inserted - the patient
is instructed to
“close gently” on the
tray.
Impression Making
Finished Impression

Ideal requirements for Final Impression
17
1. Sufficient unprepared tooth
structure immediately adjacent to
the margins  clear finish lines.
2. Contour of the unprepared tooth
structure cervical to the
preparation margin  otherwise
fabricating the restoration with
proper contours impossible .
3. All teeth in the arch and the soft
tissues immediately surrounding
the tooth preparation  allows cast
for precise articulation
Particular attention
is given to lingual
surfaces of anterior
teeth  Anterior
guidance

Flaws To Avoid
1. Non-discernible Finish Lines
2. Voids And Bubbles
3. Impression Material Separated From Trays
4. Embedded Retraction Cords
5. Preparation Debris
18

• Saliva Flow
• Bleeding Control
Moisture
Control 
Voids
• Through mechanical,
chemical, or surgical means
• Preserve periodontal health
Gingival Tissue
Displacement –
Subgingival
Margins
Challenges
19
Except for
polyethers, all
elastomeric
impression
materials are
hydrophobic
Poor tissue
displacement
technique 
permanent soft
tissue damage.

Pre-requisites Before Impression Making
1. TISSUE HEALTH
20
•Greater
plaque
accumulation
•Inflammatory
sulcular
response
Defective
interim
restoration
•Returned to
optimum
state
•Impression
making
Soft
tissues
health

2. SALIVA CONTROL
21
Pre-requisites Before Impression Making
Rubber Dam
•Supra-gingival
Margins
•Difficult To
Use
Absorbent
Cotton Rolls
Saliva
Ejector
Prevent repeated
dislodgement by
“probing” tongue.

• ADDITIONAL
MEASURES
22
•Saliva Reduction With
Pain Control
Local
Anesthesia
•C/I - Older Patient
•Heart Disease Patient
•Glaucoma Patient
Antisialogenic
Medication
Clonidine 
Safer Than
Anticholinergics

Pre-requisites before impression making
3. Displacement of Gingival Tissues
23
Mechanical
• Displacement Cord
• Paste Systems
Chemical
• Aluminum
Chloride
• Ferric Sulfate
• Epinephrine
Surgical
• Curettage
• Excision With A
Scalpel
• Electrosurgery
• Laser

 Displacement Cord
24
Sulcus closes
< 30 sec
i. Mechanical means –
Chemically
Impregnated Cord
Aluminum Or
Iron Salts
Transient Ischemia
Shrink Gingival
Tissue
Metal Filament
Reinforcement
Maintain
Intrasulcular
Position

25
 Displacement Cord
Cutting a section of cord Cord-packing instrument to position intrasulcularly
Gingival recession and trauma if
excessive pressure

• Double cord technique –
• 1st thin cord - Bottom of the gingival crevice
• 2nd cord - On top to achieve lateral tissue displacement.
26
Removed Immediately
Before Impression
Making

 Displacement Paste
AlCl3 paste injected into gingival margins
Advantage
Good
hemostasis
with less
discomfort
Dis-
advantage
less
tissue
displacem
ent

 Displacement Foam
28
Polydimethylsiloxane
+ Tin Catalyst
Gas Release
4x Volumetric
Expansion
Condensed with a special
hollow cotton roll
Expanding Foam
Exposed margins
Covered Margins

29
 Occlusal matrix
Polyether index directly
over the prepared teeth.
Trim margin by 1 mm
Filled with medium-
bodied impression material
Seated over the tooth
preparations
Regular bodied impression
material over it in stock tray
Rosenstiel SF, land MF, fujimoto J. Contemporary fixed prosthodontics. Fifth edition
Scalloped margin close to
gingival crest

30
ii. Chemical Means –
1. Aluminum Chloride (Alcl3)
2. Ferric Sulfate (Fe2[so4]3)
3. Epinephrine
Alternative -
1. Eye Wash
Sympathomimetic
2. Nasal Decongestant
(Oxymetazoline)
“Cords containing
epinephrine performed no
better than aluminum
sulfate cords” – Jokstad’s
Randomized controlled
trial, 1999

Hemorrhage control
31
RosenstielRosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics. Fifth edition

• Curettage
• Excision With A Scalpel
• Electro-surgery
• Laser
32
iii. Surgical

Electro-surgery
33
• Potential gingival
recession
• C/I in pacemaker
patients
• Unsuitable on thin
attached gingiva
• Not to be used with
metal instruments
Inner epithelial
lining of gingival
sulcus removed
Improves
access
Controls
postsurgical
hemorrhage
Loop Electrode Irrigation with H2O2 before
displacement cord placed

Soft Tissue Laser
34
• Minimal or no discomfort
• No tissue recession
• More effective hemostasis
Diode laser at a low wavelength near
Infrared creates trough around preparation

• Heat generation –
Radiosurgery < Electrosurgery
35
Radiosurgery

Morrow RM, Rudd KD, Rhoads JE. Dental Laboratory Procdures Part II – Fixed Partial Dentures. Second edition
37
ImpressionMaterials
Inelastic
Impression
Compound
Single Crowns
Simple Inlays
Impression Plaster Not Used
ZOE Paste Wash Impression
Elastic Substances
Irreversible
Hydrocolloids
Dimensional
Instability
No Fine Detail
Reversible
Hydrocolloids
Polysulfide
Polyether
Silicone Based

Basis of Comparison of
Impression Materials
– Wettablity
– Viscosity
– Dimensional Stability
– Cost
Shillingburg HT. Fundamentals of Fixed Prosthodontics. Fourth Edition

Wettablity
S
 Lesser Wettablity
 Lesser Bubbles
Hydrophobic
Hydrophilic

Viscocity
• Thixotropism –
• Increase with
mixing time.
• So syringing
impression
material is
preferred over
spatulating

Dimensional Stability
Hydrocolloid
Condensation
Silicone
Polysulfide
Addition Silicone ≈ Polyether

42O’Brien WJ. Impression materials. In: O’Brien WJ (ed). Dental Materials and Their Selection, ed 4. Chicago:
Quintessence, 2008:96.

43
Polysulfide contracts
slightly during
polymerization
minimized by custom
impression tray  reduce
the bulk of material
Continued
condensation
reaction
shrinkage even
after “ clinical set”
Syneresis and
Imbibition 
Maximise bulk 
Stock Tray

Avoid Failures
• Rigid Tray
• Tray Adhesives, Retentive Holes Or Locking Rims.
• Minimum Thickness Of Impression Material - Custom Trays
• Minimizing Undercut Areas In Tooth Preparation
• Appropriate material selection –
1. Long storage time – Polyether and Addition Silicone
2. If to be poured in epoxy or electroplated dies – Avoid reversible
hydrocolloid
44
Morrow RM, Rudd KD, Rhoads JE. Dental Laboratory Procdures Part II – Fixed Partial Dentures.
Second edition

Custom Tray Fabrication
• Materials –
1. Autopolymerizing acrylic resin
2. Thermo-plastic resin
3. Photopolymerized resins.
• Dimensions –
1. Resin thickness - 2 to 3 mm for adequate rigidity.
2. Clearance between the tray and the teeth - 2 to 3 mm (greater
clearance for polyether)
• Tray extensions –
1. Posterior border - extend farther than the demarcation between
hard and soft palates.
2. Border of the tray on the diagnostic cast approximately 5 mm
apically from the crest of the free gingiva
45

46
• Tray made at least 9 hours
before use.
• If needed urgently - placed in
boiling water for 5 minutes and
allowed to cool to room
temperature
1. Autopolymerizing Resin Tray

47
2. Thermo- Plastic Tray
Material softened in hot water and adapted to the spaced cast.
Final custom tray

48
3. Photo-polymerised Tray
Special Polymerization Unit
Final custom tray

Techniques
Single copper band
Impression
Compound
Monophase
technique
Only 1 viscosity
Single-step
technique
2 viscosities applied
at the same time
Double-step
technique
2 viscosities applied
in 2 steps

Single Copper Band Technique
• Confining tubular copper band for
support when material is in plastic
state and to prevent deformation
after chilling and for removal from
the prepared tooth or area being
impressed
• Use - Subgingival margins
• Care - Sharp edge of the band may
damage PDL fibers
51
(Precursor Of Silicone Two Stage)
Second edition

Monophase Technique
52
Machine Mixing
1.Void-free mixes
2.Bulk loading
larger quantities

Reversible Hydrocolloid
53
Heavy-bodied Tray Material
Less Viscous Syringe Material
Single- Step Technique
Produces A Mix Of
Slightly Higher
Viscosity In A
Slightly Shorter
Working Time.

• Special conditioning unit -
1. Liquefaction bath (100°C) -
State change – 12 mins
2. Storage bath (≅65°C) -
maintaining material in
liquefied state – atleast 10
mins
3. Tempering bath (≅40°C) -
reducing the temperature of
the heavy-bodied tray material
enough to avoid tissue
damage – 5-10 mins
54

55
Water-cooled impression
tray loaded with heavy-
bodied material
Wash hydrocolloid squeezed
onto tray material in the area
of the preparations
Filled tray placed in
tempering bath for 3
minutes
Sulcus flooded with
water (Wet field created)
Water-cooling tubes
connected & tray seated
Completed impression
“Rapid cooling by excessively
cold water  Stress
concentrations near the tray
 Distortion of the
impression” - Shillingburg

Modification – Laminate Technique
• Combine reversible and irreversible hydrocolloids
56
Advantage Disadvantage

Adhesive applied to tray Heavy-body tray material Light-body syringe material
Brown catalyst is thoroughly mixed with the white base Impression syringe loaded
Double Mix Technique
Single Step

58
The impression tray filled with
heavy-bodied material is seated
Mix heavy-body material Syringe material applied
into sulcus
The tip should be inserted
into the most distal
embrasure first

Automix Technique
60
Not available for polysulfide - too sticky
for proper mixing with cartridge tips.
(Addition silicone)
Long-barreled cartridge The light-bodied material
dispensed directly onto prepared
tooth with a special tip
Heavy-bodied material
dispensed into the
adhesive-coated tray
Steadier hand reqd.
to precisely track
the preparation
margin

Special Considerations For
Different Materials
• Condensation Silicone
• 1st step - Heavily filled putty
material with a poly-ethylene
spacer.
• 2nd step - Thin wash of light-
bodied material.
61
• Poysulfide
• Brown catalyst picked up first
before white base because
base sticks to spatula

• Vinyl Polyether Silicone
• Combines properties of
addition silicone and
polyether.
62
Special Considerations For
Different Materials
• Addition Silicone (PVS)
• Reaction with latex gloves
with di-thio-carbamates

65
Completed impression
The tray is loaded
The tray is selected &
evaluated
Impression material
delivered by syringe Patient closes into MI
• Use -
1. Single units
2. Mutually proteced
Angle Class I
occlusion.
• Impression include -
1. The prepared tooth
2. The adjacent teeth
3. The opposing teeth
at MIR
Closed-Mouth Technique
Dual-arch Or Triple-tray Technique
Average Occlusal Error - 5
mm ( 72 mm For Mounted
Casts From Full-arch
Impressions) - Shillingburg

Evaluation
1. If bubbles or voids in the
margin – Discard
impression.
2. Streaks of base or
catalyst material –
Discard impression
3. An intact, uninterrupted
cuff of impression
material present beyond
the margin
circumferentially.
67
Adequate amount of the unprepared tooth
structure cervical to the preparation
margin present
Cuff does not extend adequately

68
Flaws
Second edition

69
Second edition
...contd

70
Second edition

Disinfection
71

Digital Impressions
• Non-contact scanners
• Multiple scans – 3D rendition
• Light source – Laser/LED
• Current scanning accuracy - 10 to 20
μm.
• Two main types –
1. Triangulation principle scanners
2. Confocal principle scanners
73

74
1. Triangulation Principle Scanners
CEREC

Challenges
• Optical systems do not reflect light accurately from shiny
surfaces like the teeth
• Powdering is required - covered with a thin coating of
TiO2 that reflects light more uniformly.
• Applied to dry tissues.
75

• Uses a multitude (100,000)
concurrent beams of red light.
• Only light reflected at a known
distance will pass through the
filtering device and be used to
compute the geometry of the
substrate.
• Does not to require powdering of
teeth surfaces
76
2. Parallel Confocal Scanners
iTero

77
Virtual Model to
Immediate
Fabrication
• No die for correction
of contours
/occlusion
• Limits the no. Of
restoration materials
that can be used
Digital to
Definitive Cast
(STL)
• Similar accuracy as
of conventional
gypsum dies.
• Articulated on hinge
articulators  limits
precision
Virtual
Articulation
• Dynamic
mandibular
movement
• But anterior
guidance
preprogrammed
Digital Workflow

80
Dent Clin North Am 2017:779-796

82
J Adv Med Dent Scie Res 2018;6(4):55-58
Aim : To compare one-step technique and two-step technique for making impressions
using PVS for FPD.
Conclusion: The one step technique and two-step technique using
polyvinlylsiloxane are equally effective for impression making with voids as most
commonly seen defects in both the techniques.
Results : 35 patients considered.
1. Defects in one - step technique - 14
2. Defects in two – step technique - 15
3. Most common defect - voids (in
both the techniques)
4. Results statistically non-significant

83
Aim : To compare the defects present in impressions between three different
techniques - i) single stage double mix technique ii) two stage technique with a spacer
and iii) two stage technique without using a spacer.
Conclusion: The single stage double mix technique and two stage technique
without using a spacer had a more favorable outcome in comparison to the two stage
technique using a spacer.
Results : 32 crown preparations
included. Defects -
1. Single stage double mix technique -
21%
2. Two stage technique without using
a spacer - 35%
3. Two stage technique using a spacer -
44%
J Adv Med Dent Scie Res 2015;3(2):6-10

84
Conclusion:
1. One-stage putty-wash technique can be recommended
2. These in-vivo findings support the results of previous in vitro investigations.
Quintessence Int 2010;41:845–853
Objective: To investigate the three-dimensional correctness of impressions for
final restorations applying three different impression techniques - one-stage putty-
wash, two-stage putty-wash, and monophase
Method : 48 patients included for all impressions using metal stock trays with
either PVS or polyether materials. The double-cord technique was applied at all
abutment teeth. The precision of the impressions was three-dimensionally analyzed
using the resulting gypsum models.
Results: Discrepancies between the one-stage putty-wash impressions and the
monophase impressions are significantly lower compared with two-stage putty-
wash impressions..

85
J Prosth. Dent 2008;99:274-281
Aim : To compare the dimensional accuracy of a monophase, 1- and 2-step putty/
light-body, and a novel 2-step injection impression technique
Material & Method : A stainless steel model with 2 abutment preparations
was fabricated, and impressions were made 15 times with each technique.
2-step injection impression
technique -
• Heavy body material injection
-Preliminary impression
• Hole made through this
impression at each abutment
edge
• Extra-light-body material
injection – Second impression

86
Result :
1. The highest to lowest deviation
from original dimension :
Monophase > 1-step putty/light
body > 2-step putty/light body > 2-
step injection
2. Significant differences in
deviation of dimension among
all of the groups from original
Conclusion: The 2-step injection techniques were the most
dimensionally accurate impression methods in terms of resultant casts

87
Aim : To evaluate dimensional accuracy
using various elastomeric impression
materials with 5 different techniques
Materials and Methods :
• 55 impressions were made with
different techniques
• 1 impressions for each of the technique
Results:
Heavy bodied-light bodied two step
technique with a custom tray yielded
most accuracy
Conclusion:
The study revealed that the heavy
body light body two-step technique
with custom tray provided the best
results
J Contemp Dent Pract 2012;13(1):98-106

88
J. Prosth. Dent.2002:87(5);510-15
Material and methods : 35 addition silicone impressions were made
(1) complete-arch, custom acrylic trays loaded with heavy-bodied material
(2) double-arch, disposable plastic trays loaded with heavy-bodied material
(3) double-arch, disposable plastic trays loaded with putty material
(4) double-arch, reusable brass metal trays loaded with heavy-bodied material.
Purpose : Compare the dimensions of dies fabricated with 3 types of double arch
impressions to dies fabricated with the conventional complete-arch, custom tray
method.
Results :
1. The plastic double-arch tray loaded with heavy-bodied addition silicone and a
low-viscosity wash produced the least accurate combination inter- and intra-
abutment dimensions - 1.17% mean dimensional change recorded (Statistically
significant)
2. No significant differences were found between the complete arch method and
protocols in which putty was loaded in a plastic or metal tray.
Conclusion :
1. Within the limitations of this pilot study, the more rigid tray/impression
material combinations more accurately replicated stone dies.
2. Impressions made with plastic double-arch trays should not be loaded
with heavy-bodied material.

90
Aim : The purpose of this study was to
evaluate and compare different
impression techniques in relation to
accuracy of the occlusal plane.
• Group I Putty impression with
reline on prepared area
• Group II Putty impression with
complete reline
• Group III Putty impression with
spacer on prepared area and
relining
• Group IV Single impression
technique using custom tray:
Materials and Methods :
• 20 impressions were made with
different techniques
• 5 impressions for each of the technique
were made using PVS.
Results: Casts poured with custom tray
yielded the most accurate models from
the impression (statistically significant)
Conclusion:
1. Impression technique using
custom tray yielded most accurate
model from the impressions.
2. Among relining putty with spacer
on the prepared area produced
more variation in occlusal plane
Indian J Oral Sci 2015;6:22-5

Aim - To determine the effect of wash space on the accuracy of impressions
made with different techniques -
Result –
1. The controlled wash space is
essential for accuracy of
putty-wash impressions.
2. The controlled wash space
was provided by uniform
spacer thickness of 1 and 2
mm.
Conclusion - The clinical implication of this study will be to use
temporary crowns to create controlled wash space.
• Group I: One-step putty-wash
technique
• Group II: Two-step technique with 1
mm thick metal copings to create a
uniform 1 mm wash space.
• Group III: Two-step technique with 2
mm thick metal copings to create a
uniform 1 mm wash space
• Group IV: Two-step technique with a
0.3 mm polyethylene spacer
Int J Clin Pediatr Dent 2012;5(1):33-38

Aim - To demonstrate the clinical feasibility of autoclaving certain silicone
impression materials in order to avoid potential cross-contamination during
handling, transport, and subsequent processing.
Result –
• Displayed a maximum difference of only
50 μm in the dimensions of the preparation
area before and after steam sterilization.
• The fitting accuracy of both metal-ceramic
crowns determined subjectively by the
dentist was identical.
• Both crowns appeared to have the same
quality of fit intraorally
Conclusion - Impressions made with AFFINIS® silicone impression materials in a
rigid reinforced polycarbonate impression tray or in a metal
dual-arch tray can be autoclaved
Cochrane Database of Systematic Reviews 2018, Issue 4
J Contemp Dent Pract . 2010 July;

96
J. Prosthodont 2016;1(7)
Purpose: To conduct a systematic review to evaluate the evidence of possible
benefits and accuracy of digital impression techniques vs. conventional impression
techniques.

97
Conclusions:
1. Digital impression techniques are a clinically acceptable alternative to
conventional impression
2. Digital impression techniques are faster and can shorten the operation time.
3. However, the conventional impression technique is still recommended for
full-arch impressions.
Results:
1. Digital impression accuracy is at the same level as conventional impression
methods in fabrication of crowns and short fixed dental prostheses (FDPs).
1. In full-arch impressions, conventional impression methods resulted in better
accuracy compared to digital impressions

Conclusion
• There are vast numbers of impression techniques
available in the field of fixed partial prosthodontics.
• Each and every technique has its own advantages and
disadvantages, but still no impression technique is
superior with all the qualities inherent in it and will be
universally claimed superior.
• It is the role of operator to select the appropriate
technique for a particular clinical condition by evaluating
the various factors involved
98

References
1. Rosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed
Prosthodontics. Fifth edition
2. Shillingburg HT. Fundamentals of Fixed Prosthodontics.
Fourth Edition
3. Morrow RM, Rudd KD, Rhoads JE. Dental Laboratory
Procdures Part II – Fixed Partial Dentures. Second edition
4. O’Brien WJ. Impression materials. In: O’Brien WJ (ed).
Dental Materials and Their Selection, ed 4. Chicago:
Quintessence, 2008:96.
5. Kumar VK, Shubha, LN Akshatha, HG Suhas,
Thopachiche S. Comparison of One-step technique and
Two-step technique for Making Impressions using
Polyvinylsiloxane for FPD. J Adv Med Dent Scie Res
2018;6(4):55-58
99

6. Caputi S, Varvara G. 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 study. J Prosth. Dent 2008;99:274-281
7. Cox JR, Brandt RL, Hughes HJ. A clinical pilot study of the
dimensional accuracy of double arch and complete-arch
impressions. J. Prosth. Dent.2002:87(5);510-15.
8. Punj et al. Dental impression materials and techniques. Dent
Clin North Am 2017:779-796.
9. Ahlholm P. Digital versus conventional impressions in fixed
prosthodontics: a review. J. Prosthodont 2016;1(7)
100

10. Luthardt et al. Comparison of the three-dimensional correctness
of impression techniques randomized controlled trial.
Quintessence Int 2010;41:845–853
11. Thippanna RK, Meshramkar R, Sajjan S. A comparative study to
evaluate different impression technique in relation to accuracy of
the occlusal plane in fixed partial denture. Indian J Oral Sci
2015;6:22-5.
12. Shrestha P, Poudel S, Shrestha K. A clinical comparison of
polyvinyl siloxane impressions for fixed partial dentures using
three different techniques. J Adv Med Dent Scie Res 2015;3(2):6-
10
13. 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;13(1):98-106.
101

14.Chugh A, Arora A, Singh VP. Accuracy of Different Putty-
Wash Impression Techniques with Various Spacer
Thickness. Int J Clin Pediatr Dent 2012;5(1):33-38.
15.Kollefrath R, Savary M, Schwela J. An Evaluation of the Fit
of Metal-Ceramic Restorations Made with an Autoclaved
Silicone-Based Impression Material. J Contemp Dent Pract
[Internet]. 2010 July; 11(4):063-070.
102

Impressions in fixed partial denture

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