II. impression making for complete denture

3. II- Maxillary and mandibular
impression procedures
Dr. Amal Fathy Kaddah
Professor of Prosthodontic,
Faculty of Oral &Dental Medicine,
Cairo University

5.  Introduction and definitions
 Requirements and Objectives of Impression
Making
 Knowledge of Basic anatomical landmarks.
 Knowledge and understanding of basic reliable
techniques and materials
 Skill and Patient management
 Impression techniques in normal or
compromised situations (Modified impression procedures)
 Bibliography.
Outline

6. First steps in making a denture
 Diagnosis and treatment plan
 Primary impression
 Diagnostic cast
 Custom tray
 Final impression
 Master cast

7. Objectives of Impression Making
An ideal impression should provide:
 Maximum extension without muscle impingement.
 Intimate contact with the tissue area covered.
 Proper form of the borders including the posterior border of
the maxillary denture.
 Proper relief of hard and sensitive areas.
 To equalize forces on the denture foundation
area.

8. Objectives of Impression Making
1) Preservation of remaining structures
2) Retention
3) Esthetics
4) Stability and Bracing
5) Support Carl O. Boucher in 1944
PRESS

9. Preservation of the alveolar ridges
M.M. De Van’s dictum “It is more
important to preserve what already
exists than to replace what is missing”.
•Not to use heavy pressure
•Covering as much of the supporting
areas as possible - minimize the
possibility of soft tissue abuse and bone
resorption.

10. To be stable, a denture requires
• Good retention
• No interfering occlusion
• Proper tooth arrangement
• Proper form and contour of the polished surfaces
• Proper orientation of the occlusal plane
• Good control and coordination of the patient's
musculature.

11. Support
• The resistance to vertical forces of mastication
and to occlusal or other forces applied in a
direction toward the basal seat.
• Enhanced by selective placement of
pressures that are in harmony with the
resiliency of the tissues that make up the
basal seat.

12. Esthetics
• Thickness of the denture flanges
• Thicker denture flanges are preferred in
long-term edentulous patients - labial
fullness.
• Impression should perfectly reproduce the
width and height of the entire sulcus for the
proper fabrication of the flanges.

13. Final impressions
Final impressions are made
using special (custom or
individual) trays constructed
specifically for each patient on
the study casts.

14.  According to the BSSPD
guidelines, definitive impression
'should record the entire
functional denture-bearing area to
ensure maximum support,
retention and stability for the
denture during use'.
Definitive Impression

15. IMPRESSION TRAYS AND IMPRESSION
TECHNIQUES
IMPRESSION
An impression is a negative record or imprint of
the tissues of the oral cavity that forms the
basal seat of the denture.
Reproduce a positive form and shape of the same oral tissues (Cast)

16. Custom Tray
 Individually made for each mouth
 Rigid and stable
 Borders are slightly under-
extended from the desired
peripheral extension
 Frena should have adequate relief
 Tray and handle must not interfere
with functional movements of the
oral structures
Stable, Adapted, fitted and well extended

17. SPECIAL OR INDIVIDUAL TRAYS
1. Shellac base plates
TYPES
Advantages of Special Trays
1 . Fit more accurately the individual arch of the patient.
2 . Bulk of the impression material is reduced .
3 . More accurate border contour
4 . Less impression material is used .
5. More comfortable to the patient .
2. Self & light curing acrylic resin
3. Cast or swaged metal.

18. Shim or spacer
“ One thickness of modeling wax or shellac
base plate adapted on the study cast under the
special tray “
Advantages of Acrylic Resin Special Tray
Easily constructed.
More rigid than shellac trays.
Accept border tracing material.
Easily trimmed.

21. Custom Trays

22. Impression techniques may be classified
depending on:
Amount of pressure used
1. Pressure technique
2. Minimal pressure technique
3. Selective pressure technique
Based on the position of the mouth while making
impression
1. Open mouth
2. Close mouth
Based on the method of manipulation for border molding.
1. Hand manipulation
2. Functional movements
Depending on the material used
Depending on the purpose of the impression
Depending on the tray type

23. Open mouth technique
Made with tray held by dentist and mouth open
Muscle movements may be emphasized and
can be seen by the operator
The rationale behind this technique is that the
supporting tissues are recorded in a functional
relationship.
Requires occlusal rims to be made
Border molding done and final impressions made
Closed mouth technique
Impression techniques may be classified depending on the
position of the mouth while making impression:

24. Advantage
 Saving of time
Disadvantage
 Tendency for overextensions
 Problem of limited space between the tuberosity and
pear shaped pad
 No control over the amount of pressure during the
final impressions
 Soft tissues – displaced- rebound
 Bone resorption
Closed mouth technique

25. Hand manipulation
Dentist uses hand manipulation for
movements of lips and cheeks
Functional movements
Patient makes functional movements
such as sucking, swallowing, licking
or grinning
Impression techniques may be classified depending
on the method of manipulation for border molding

26. Elastic
1. Reversible hydrocolloid
2. Irreversible hydrocolloid (Alginate )
3. Rubber impression materials
a. Polyether
b. Silicone
Non-elastic
1. Gypsum products (Plaster of Paris)
2. Metallic oxide pastes (Zinc Oxide/ Eugenol)
3. Impression compound
Impression techniques may be classified
depending on the Impression material used

27. Plaster of Paris
• 1800’s
• Low viscosity
• Non-elastic
• Low patient tolerance •
Impression Compound
1874
– Thermoplastic
– Corrections and additions
– High viscosity
– Non-elastic
– Colors indicate
consistencies and
thermodynamic behavior
Zinc Oxide & Eugenol
1930’s
• Dimensionally stable
• Low flow (relatively)
• Hydrophilic
• Untidy
• Inelastic

28. Preliminary impression materials :
 Impression compound
 Alginate
Final impression materials:
 Plaster of Paris,
 Zinc Oxide-eugenol Paste,
 Irreversible Hydrocolloid,
 Silicone, Polysulfide Rubber, Polyether,
 Tissue-conditioning material
Impression techniques may be classified
depending on the Prosthodontic use

29. 29
Diagnostic Impression
 The negative replica of the oral tissues used to
prepare a diagnostic cast.
 Used for study purposes like measuring the
undercuts, locating the path of insertion.
 Is made as a part of treatment plan and to
estimate the amount of pre-prosthetic surgery.
 Articulate the casts on tentative jaw relation
and evaluate the inter-arch space.

30.  Minimal pressure impression technique
(mucostatic impressions or open mouth
impression)
 Mucofunctional (Definite , Mucocompression
or Pressure Impression Technique: (Closed
mouth impression technique)
 Selective pressure impression technique
Classification of Final impressions
FINAL IMPRESSION TECHNIQUES OR
THEORIES

31. Final impressions
The 3 techniques for final
impressions differ according to
 Construction of The trays
 The impression material used
 The way of impression making.

32. How is pressure controlled?
 Spacer
 Perforations
 Material viscosity

34. Relationship of the wax relief and
the various impression techniques
 The thickness and position of
the wax relief in a custom tray
allows the dentist to control
how much and where pressure
is placed during the impression

35. Constructing the custom tray
 Outline for the wax spacer is drawn on the cast
 Posterior palatal seal area on the cast is not covered with
the wax spacer – maxilla
 Buccal shelf not covered - mandible
 Baseplate wax approximately 1 mm in thickness is placed
on the cast
 Self-curing acrylic resin tray material - uniformly adapted
over the cast
 Tray thickness - 2 to 3 mm
 Resin handle is attached in the anterior region of the tray

36. Spacer design
Roy Mac Gregor recommends placement of
a sheet of metal foil in the region of incisive
papilla and mid palatine raphae

37.  Neill recommends
adaptation of 0.9 mm
casing wax all over
except PPS area
Boucher recommends
placement of 1 mm
base plate wax on the
cast except PPS area

38.  Morrow, Rudd, Rhoads recommends to block out
undercut areas with wax, adapt full wax spacer 2 mm
short of resin special tray border all over & placement
of 3 tissue stops equidistant from each other
 Sharry recommended Base plate wax adapted over
whole area, four stops 2mm width cut from wax :
cuspid and molar region- extend from palatal aspect
of ridge: mucobuccal fold

39. Border molding
 Border molding is the process by which the
shape of the borders of the tray is made to
conform accurately to the contours of the
buccal and labial vestibules
 Manipulation of the border tissues, against a
moldable impression material
 Borders of the tray are molded to a form that
will be in harmony with the physiological
action of the limiting anatomical structures

40.  Border molding may be carried out in sections
either recording one part of the border at a
time or recording all parts of the borders
simultaneously.
Recording all of the borders simultaneously has
two general advantages:
 The number of insertions of tray is reduced.
 Developing all borders simultaneously avoids
propagation of errors caused by a mistake in
one section affecting the borders contours in
another.

41. Custom tray fabrication and impression making

42. Border moulding
 Sectional
 Recording all borders simultaneously

44. The basic differences in techniques
for final impressions can be resolved
as those that record the soft tissues
in a functional position and those
that record the soft tissues in the
undisplaced or rest position.

45.  The soft tissues are not compressed nor
distorted
 The impression material must flow readily
 Trays constructed for this technique require a
spacer with stopers and one or two holes to
allow escape of the material
 Plaster of Paris was the only true mucostatic
impression material though the hydrocolloids
often give equally good clinical results.
1. Minimal pressure impression technique
(Mucostatic impressions or open mouth impression)

46.  Soft tissues that are displaced during
function will attempt to return to the
undisplaced position when the forces
are released.
 The dentures will be unseated from
their bases by this tissue action.
1. Minimal pressure impression technique
(Mucostatic impressions or open mouth impression)

47. The mucostatic technique
Results in a denture, which is
closely adapted to the mucosa of
the denture-bearing area but has
poor peripheral seal.
•Retention is mainly due to
interfacial surface tension.

49. Plaster of Paris impression

50. Advantages:
1. The operator can see and insure proper
border molding and muscle movements are
more easily accomplished.
2. There is less distortion to the mucosa. High
regard for tissue health and preservation:
better prognosis
3. It is the technique of choice for flabby and
thin wiry ridges.
Minimal pressure impression technique
(Mucostatic impressions or open mouth impression)

51. Disadvantages:
1. The mucosal topography is not
static over a 24-hour period.
2. The lack of border molding reduces
effective peripheral seal and
reducing retention as well as food
slip beneath the denture.
Minimal pressure impression technique
(Mucostatic impressions or open mouth impression)

52. 3. The short denture borders are readily
accessible to the tongue which
might provoke irritation.
4. The short flanges may reduce
support for the face which can affect
esthetics.
5. The shorter flange would mean less
lateral stability.

53. Technique
Primary impression is made with
impression compound
A baseplate wax space is adapted.
A special tray is adapted over the wax
spacer.
Spacer is removed and an impression is
made with a free flowing material.
Escape holes are made for relief.

54.  This theory was proposed by
Greene in 1896 gave this concept on
the assumption that tissues
recorded under functional
pressure provided better support
and retention for the denture.
2. Mucofunctional or Mucocompression impressions:
A- Closed mouth impression technique

55.  Records tissues in their
functional/supporting form
 All tissues are recorded under equal
pressure irrespective of their anatomy
 Mechanical rather than biological
2. Mucofunctional or Mucocompression impressions:
A- Closed mouth impression technique

56.  When tissues are held in a
displaced position, the pressure
limits the normal blood flow .
When normal tissues are deprived
of their blood supply, the result is
resorption.

57.  The impression material most
commonly used for this technique is
zinc oxide and eugenol paste.
 Trays require occlusion blocks set
at the required vertical dimension.
2. Mucofunctional or Mucocompression impressions:
A- Closed mouth impression technique

58. Primary impression is made with impression
compound
Special tray with bite rims with uniform
occlusal surfaces are then prepared.
Secondary Impression is made using zinc
Oxide and Eugenol impression material
The impression is inserted in mouth and held
under biting pressure for one or two minutes.
Borders are molded by asking the patient to
perform functional movements.
Technique

59. Border Mold
Accurate Registration of
Peripheries for
Retention

60. Advantages:
1. Better retention and support
2. The patient can exert his
own masticatory force on
the impression material
Stable during function

61. Disadvantages of the theory
1. Excess pressure could lead to increase
alveolar bone resorption.
2. Excess pressure on peripheral tissues and
the palate interferes with blood supply leads
to transient ischemia, and this may
accelerate ridge resorption.
3. Pressure applied during making the
impression is not identical to functional load

62. 4. Dentures constructed from such an
impression do not fit well at rest, as
the compressed tissues rebound when
the tissues resume their normal resting
state.
5. Pressure on sharp bony ridges results
in pain.
6. An overextended denture may result
due to improper border molding.

63. 2. Mucofunctional or Mucocompression impressions:
B- Open mouth impression technique

65. Metallic oxide paste (Zinc oxide/Eugenol impression paste),
green stick impression compound. (close fitting tray)

66. III-Selective pressure imp.
 Advocated by Boucher in 1950 This technique
combines the principles of both pressure over
areas and minimal pressure on others
technique.
 The tray is constructed with relief over sensitive
areas and closely adapted over stress bearing
areas.
Applied aspect

67.  Boucher divided basal seat area into different
zones according to capacity to withstand
masticatory loads without undergoing
resorption.
Primary
stress
bearing area
Relief areas
Secondary
stress
bearing area

68.  The technique considers the
physiologic functions of the tissues of
the basal seat, and therefore appears
more sound and appealing.
 This theory is based on a thorough
understanding of the anatomy and
physiology of basal seat and
surrounding areas.

69. A. The plaster wash impression
It is the oldest technique of the selective
pressure impression technique:
1- Compound impression
2- Scraping the compound to make a
room for the impression material
3- Plaster wash impression

71. B. The light body wash selective
pressure impression technique:
Beumer et al (2011) advocate the selective
pressure technique as a combination of extension
for maximum coverage within tissue tolerance
with light pressure or intimate contact with the
movable, loosely attached tissues in the
vestibules. The impression is refined with
minimum pressure utilizing a wash of light body
impression material.

72.  They attempt to record the tissues at rest. The
only exception is the posterior palatal seal
area

73. After finishing the Border molding Place 2-3 mm
of compound on top of the tray in a butterfly
configuration to displace the tissues in the
posterior palatal seal area.
Developing the Posterior Palatal Seal- Area

74. What is the purpose of the vent
hole?
1. To permit proper seating of the
loaded master impression tray
while making the final impression.
2. To relieve the pressure over the
incisive papilla and the rugae.
3. To prevent entrapment of air
bubbles in the impression.
Caution: Do not drill
the palatal relief hole(s)
in the maxillary tray
until are borders have
been molded and the
peripheral seal
demonstrated.

75. Final Impressions:
 After establishing the health of the denture
bearing areas final impressions are made.
 Try in custom impression tray and adjust the
length of the flanges 2-3 mm short of the
vestibule depth.
 Establish the three dimensional contours of the
denture borders by border molding the
custom tray utilizing a thermoplastic
“compound” material.
 Final impression with a light body material to
achieve a final impression.

76. C. A sectional impression technique
A close fitting tray is constructed in cold-curing acrylic
resin and designed so that flabby area of the ridge is
a. Window Tray Impression Technique using zinc oxide imp.
material
This technique is used if the flabby tissue is in the anterior part of
the mouth.

77. Window Tray Impression Technique
1) Outline the mobile tissue on
your preliminary cast.
2) Construct the custom tray so
that there is a window (open
area) over the mobile tissue.
3) The handle should be placed in the
middle of the palate
4) Border mold and make the zinc
oxide impression in the usual
manner

78. 5) Cut out the zinc oxide
impression material in the
window with a sharp scalpel.

79. 7- Completed Impression
6) The mobile tissue area will
be recorded with a plaster of
Paris impression material
while the impression is
seated in the patient’s
mouth, with a small brush or
syringe.

80.  Mobile tissues are most often seen anteriorly and may
be particularly prominent in patients with combination
syndrome. It is inadvisable to remove these mobile
tissues because the underlying bony ridge is usually
knife edged. These tissues act as a cushion and rarely
impinge upon the interocclusal space.
b. Window Tray Impression Technique using
polysulfide impression
• This technique is used to
record highly mobile or
hypertrophic tissue with
minimum displacement .

81. 1. Outline the mobile tissue on your preliminary cast.
2. Construct the custom tray so that there is a window
(open area) over the mobile tissue.
3. The handle should be place in the middle of the palate
4. Border mold and make the polysulfide impression in the
usual manner
Window Tray Impression Technique

82.  Cut out the polysulfide impression material
in the window with a sharp scalpel.
 The mobile tissue area will be recorded with
a zinc oxide impression material (Krex).

83. Completed
Impression
Master cast
 Seat the impression back into the patient’s
mouth.
 Mix the Zinc Oxide (Krex) impression material
and apply it over the mobile tissue with a small
brush or syringe
 Master cast

84. Demerits
 Some feel that It is impossible to
record areas with varying pressure.
 Some areas still recorded under
functional load, the dentures still
faces the potential danger of
rebounding and loosing retention.

86. Impression Materials either
Zinc Oxide and Eugenol
Border molding by green Stick compound
Light body Polysulfide Rubber Base Material
Border molding by green Stick compound Or
Medium body Rubber Base Material
Polyvinylsiloxane impression materials such as
Virtual
Border molding by a heavy body and a wash
impression is then made with the monophase
material

87. Steps of Impression making
 Examination and conditioning of the patient and the mouth.
 Seating of the patient
 Selection of impression material
 Selection of the impression tray
 Selection of impression technique
 Making the preliminary impression
 Constructing the primary cast
 Fabricating the custom tray
 Border molding
 Making the final impression

88. Examination and conditioning
of the patient and the mouth
 Inflammation of the mucosa
 Distortion of denture-foundation
tissues
 Excessive amounts of hyperplastic
tissue
 Insufficient space between the upper
and lower ridges

89. Seating of the patient
Position of the operator
for maxillary impression
Position of the operator
for mandibular impression

90. Maxillary Preliminary impression
 Border moulding
 Labial and buccal
vestibules
 Coronoid process
 Impression poured - stone

91. Mandibular Primary impression
 Posterior extent of tray – retromolar
pad
 Tray loaded with material and
catered over the ridge with tongue
slightly raised
 Alternating pressure on molar region
with index finger
 Functional movements done to get
the border limit

92. Constructing the custom tray
 Outline for the wax spacer is drawn on the cast
 Posterior palatal seal area on the cast is not covered
with the wax spacer – maxilla
 Buccal shelf not covered - mandible
 Baseplate wax approximately 1 mm in thickness is
placed on the cast
 Self-curing acrylic resin tray material - uniformly
adapted over the cast
 Tray thickness - 2 to 3 mm
 Resin handle is attached in the anterior region of the
tray

93. Note the finger rests and the
size and position of the handle.

94. The extension should be 2-3
mm short of the frenum and the
depth of the vestibules

96. Adequate clearance (relief)
between the undersurface of
the tray and the tissue to allow
for the flow and adaptation of
the impression material

97. Border molding the special tray
 The process by which the shape of the borders of the tray is
made to conform accurately to the contours of the buccal,
labial, and lingual vestibules, so that borders of the
impression are in harmony to the physiologic action of the
limiting anatomic structures
Border molding the special tray
a- Sectional border molding
 Labially…….
 Posteriorly……
 Lingually……
b- One step border molding

98.  A material that will allow simultaneous molding
of all borders has two general advantages:
1. The number of insertions of the tray for
maxillary and mandibular border molding is
reduced.
2. Developing all borders simultaneously avoids
propagation of errors caused by a mistake in
one section affecting the border contours in
another.
One- step border- molded tray:

100. Butterfly in shape

101.  The posterior palatal seal area an area that lies between the
anterior and posterior vibrating lines “Ah” line: saying “ah” will cause
the soft palate to lift. It is found to be very effective in locating the
posterior vibrating line.
 Blow-line (valsalva maneuver): an accurate method for locating the
anterior vibrating line which freely moves when the patient attempts
to blow through the nose when it is squeezed tightly. The blow-line a
close approximation to the junction of the hard and soft palate.
Cohesion, adhesion, and interfacial surface tension have limited value
unless an intact peripheral seal is present.

104.  Curvature of the soft palate
III
II
I
Class I  Gentle Curvature
Class Ii  Medium Curvature
Class Iii  Abrupt Curvature

105. Tray wax spacer remain in place
during border molding procedures

106. Remove Tray Spacer and
Load Impression Material

107.  The fully customised trays should exhibit
good retention, a matter of confidence
for both clinician and patient.
 Perforation of the upper tray may be
done at the chairside, to enhance
retention of, e.g. irreversible
hydrocolloid and/or to prevent the
occurrence of air bubbles being present
in the palatal vault.

108.  Stick modeling compound is added in
sections to the shortened borders of the
resin tray and molded to a form that will
be in harmony with the physiologic
action of the limiting anatomic
structures.
 The final impression material is mixed
according to manufacturer’s directions
and uniformly distributed within the tray.

111. Make Final Impression

113. The movement of the masseter muscle is recorded in the
compound border by creating its reactive contraction through
exertion of a downward pressure on the tray using the fingers.
The buccal shelf bone should be recorded during the
impression procedure.

114. Zinc Oxide Final Impression

115. Smooth well defined peripheries
Maximum extension
Even pressure distribution (there should be no
areas where the underlying tray or compound
shows through)
There should be intimate tissue contact
Rubber base Final Impression

116. Rubber base impression material with border
molding using Elastomeric impression material
Medium body type elastomeric
impression material along the
periphery of the tray.
Heavy body type elastomeric impression
material along the periphery of the tray.
The elastomeric impression material which
flowed inside the tray should be removed
The final maxillary impression is completed with
light bodied type elastomeric impression material

117. Alternate Technique- Virtual PVS
Polyvinylsiloxane impression material
 Paint the tray with a thin layer of
adhesive
 Border molding of the tray is
accomplished with the heavy body
material.
 A wash impression is then made with
the monophase material.
 Gently massage the pts lips and cheeks.
 After 1 min. Have the pt. Gently pucker,
smile and move their jaw side-to-side,
forward and back.

118. Check the final impression for
clinical acceptability
- Flange extensions -soft tissue detail
- Posterior palatal seal hamular notch
The material
should have
hydrophilic
properties and
adequate viscocity
to reduce the
probability of
gagging

119. Definitive impression with well-defined area for
the placement of carding wax prior to boxing
the impression, thereby preserving the
functional width and depth of the sulci

120. Box Impression
Stronger cast with peripheries for Processing

121. Boxing of impression
Dental stone
Boxing wax
Special tray
Impression material

122. Boxing of impression

123. Inspect the impression for voids
or bubbles
Box impression and pour master
cast
Final Impressions: Boxing & Pouring

125. MASTER CASTS
ADVANTAGES OF BOXING
1. The border of the impression are preserved
2. The thickness of the base of the cast
can be controlled
3. Permit vibrating the stone material
into the impression
4. Time is conserved
5. Material are conserved

126. ‫ماتشاء‬ ‫تفعل‬ ‫األيام‬ ‫دع‬
‫القضاء‬ ‫حكم‬ ‫إذا‬ ‫نفسا‬ ‫وطب‬
‫الليالى‬ ‫لحادثة‬ ‫والتجزع‬
‫بقاء‬ ‫الدنيا‬ ‫لحوادث‬ ‫فما‬

127.  Beumer John III, DDS, MS, Robert Duell, DDS and Eleni Roumanas: Final Impressions; Division of
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India, pp 88-105
 Zarb G, Hobkirk JA, Eckert SE, Jacob RF, editors. Prosthodontic treatment for edentulous patients. 13th
ed. St. Louis: Elsevier Mosby; 2013 pp 161-179
 Zimmer I.D. and Sherman, H. An analysis of the development of complete denture impression
techniques. J Prosthet dent 46: 242-249, 1981.
References

128. ‫الصخر‬ ‫في‬ ‫تحفر‬ ‫المطر‬ ‫قطرة‬
‫بالتكرار‬ ‫ولكن‬ ‫بالعنف‬ ‫ليس‬
A rain drop digs in the rock
Not by violence but by repetition

131. Stub handles will not distort the lower
lip; any distortion is likely to alter
sulcular form of the definitive impression

132.  If the trays interfere with the
function of the peri-denture soft
tissues, instability of the completed
denture will occur if overextension
is not relieved. The extent of the
overextension may be determined
by pressure-relief paste.

133.  Do Not perforating the customised
trays for complete dentures prior to
establishing a peripheral seal.
 Similarly, in order that the form of
upper and lower labial sulci are not
overextended, there is merit in
having stub handles that will not
distort the lips

134. •Addition of tracing compound to a lower tray
considered to be underextended distally and posteriorly
•Underextension may be corrected by adding tracing
compound or a similar material
•the compound should be added to displace the retro-
molar pad sufficient to give a posterior seal.

135. Tracing compound added to effect a peripheral
seal. Note that some compound has been added
on the areas relating to the ridge of the canine
areas to act as anterior spacers. Add the
tracing compound to increase the functional
width and depth of one buccal periphery

136. The tracing compound should extend
uninterrupted from one border of the
tray to the other. This allows
 The creation of a post dam,
 Facilitates location of the tray
posteriorly and,
 Finally, serves as a spacer for the
impression material.

137.  Add a small amount of soft tracing
compound or suitable material to the
special trays in the region of the upper
and lower canines and gently place into
the mouth. These, as for the posterior
placement, will serve as a spacer and
prevent the incorporation of support
problems by avoiding undue and uneven
displacement of the impression material

138. the additional acrylic on
the right side
strengthens the tray
and "lifts" the finger
away from the tray
borders preventing it
from becoming part of
the denture impression.
Prevent breakage by adding a spine of
acrylic along the crest of the ridge,
extending the spine right to the handle.

139. Your finger is too close
to the tray border (not
even touching it), then
the impression material
will follow around your
finger, making a
circular and obviously
incorrect impression.
Note imprint where fingers were
placed to seat the tray.

140. Note small white pointer showing
area of distortion on right
distobuccal border.

141. Enlarged view of right distobuccal
border.

142. Rubber base is
5mm thick
preventing
the borders
from
reaching the
fold.

145. The choice of material,
within reason, is of
secondary importance

146. Modified impression procedures because of
perceived support problems
1. Displaceable (flabby) anterior maxillary
ridge
2. Fibrous (unemployed) posterior
mandibular ridge
3. Flat (atrophic) mandibular ridge covered
with atrophic mucosa.

147. Support Problems May Be
Overcome By
 Appropriate relief of the master
cast,
 Modified impression techniques.

148. 1.Displaceable (Flabby)
Anterior Maxillary Ridge

149. Displaceable area removed from special tray. In this case, a medium-
bonded PVS impression was used.
b) Completed impression. Here a light bodied PVS impression material
was syringed onto the displaceable tissue

150. 2. Fibrous (Unemployed)
Posterior Mandibular Ridge

151. Fibrous posterior mandibular ridge.
This ridge as such is not useful for support
This condition may be recognized by the presence of a
thin, mobile thread-like ridge which is essentially
fibrous in nature

152. a-c Staged sequence of techniques:
a) Preliminary stage an impression of the denture-
bearing area recorded using tracing compound.

153. b) Crestal area cleared of tracing compound
- tray perforated on crestal area;

154.  Inject some light-bodied PVS onto the
buccal and lingual shelves of the greenstick
and gently insert the impression.
 Excess material will be extruded through
the perforations, and the fibrous ridge will
assume a resting central position, having
been subjected to even buccal and lingual
pressures.
 The impression is now treated as for a
conventionally made impression.

155. c) Definitive impression using light-
bodied polyvinyl siloxane

156. 3. Flat (atrophic) mandibular ridge
covered with atrophic mucosa
(Atwood's ridge )
View of atrophic mandibular ridge
suitable for admix impression material

157. Selective pressure impression techniques
Complicated by folds of
atrophic and/or non-
keratinised tissue lying
on the ridge
A viscous admix of impression compound and tracing
compound removes any soft tissue folds and smoothes
them over the mandibular bone; this reduces the
potential for discomfort arising from the 'atrophic
sandwich', ie the creased mucosa lying between the
denture base and the mandibular bone.

158.  An Admix of 3 parts by weight of
(red) impression compound to 7
parts by weight of greenstick;
the admix is created by placing
the constituents into hot water
and kneading with vaselined,
gloved fingers.

159. Two variations are commonly
used for functional
impressions.
(i) Local areas of modification
(ii) Problems associated with
denture space/neutral zone
Functional Mandibular
Impression

160. A- Local areas of modification
Functional impression using a
chairside resilient lining material
Dentures may exhibit looseness, not arising primarily
from retention problems but because of localized
areas of poor functional adaptation

161. Chair side Reline
•Reline material: Pink/white
•Apply Vaseline (very slight
coating)
•Mix according to instructions

162.  Seat reline
impression
 Check on extensions
and patient border
mold
 Have patient close
teeth in CR gently!!
7-10 min

163.  Remove denture
from mouth
 Trim the tissue
conditioning
material

164.  Evaluate
peripheral roll
 Can add on, or
grind
 Functional
impression
technique: Tissue
surface adaptation

165.  We must trim tissue
conditioner
 Unacceptable
 Acceptable

166. 1. Reduce periphery 1-2 mm
2. Relieve undercuts
3. Mix tissue conditioner according to
instructions
4. Spread uniform layer over surface of
denture
5. Insert and have patient close in centric
relation
6. With teeth in light contact, carry out
border molding procedures
7. Allow denture to remain in mouth until
material looses its tackiness (7-10 min)
Procedures of the Functional impression Procedure

167. Indications for Functional
impression technique
 Geriatric patient
 Medically compromised patient
 Lack of retention: New denture
 Reasonably good occlusion

168. Tissue Recovery Program
1. Removal of the prosthesis at night
2. Initiation of oral hygiene measures:
rinses, brushing, bubble gum
3. Location and removal of acrylic base
pressure areas.
4. Correction of base extensions
5. Correction of occlusal disharmony
6. Use of a resilient tissue conditioner.

169. Completed functional impression of
denture form - recorded in PVS putty
B- Problems associated with
denture space/neutral zone

170. Indications of denture
space/neutral zone
It is designed for patients with
 Poor track records of (lower)
denture stability,
 A large tongue or other anatomical
anomaly.

171. • The stops must contact the upper teeth at the
selected OVD.
 The upper denture is set
up conventionally to the
prescribed occlusal
vertical dimension
(OVD).
 Opposing the upper set-
up is a resin base with
three vertical stops
joined by a wire bent in
a sinusoidal manner

172. These exercises provide an indication of
where inward-directed forces from the
buccinator muscles are equalled or
'neutralised' by outwardly-directed lingual
forces ie the zone of minimal conflict
Polyvinylsiloxane putty is
added to the conventional
fitting surface and also to
the buccal and lingual
aspects of the lower base
which has been coated
with the requisite
adhesive, and placed in
the patient's mouth. the
upper try-in is inserted
and the patient asked to
close to the OVD, swallow
and carry out closed mouth
exercises.
Completed functional impression of
denture form - recorded in PVS putty

173. These enable an exact wax form to be poured to give a
functional form to the polished surfaces and occlusal
form of the lower denture.
Setting of the lower teeth to match with the functional
template
Plaster or laboratory-
putty keys made of
the functional
impression to give A
functional form to the
polished surfaces and
occlusal form of the
lower denture.

174. Reline and rebase techniques (including
secondary template impressions)
Addition of Material to the tissue side
of a denture to improve its
adaptation to the supporting mucosa
This impression technique is
performed in an old denture
Reline

175. Replacement of the entire
denture base material to
improve its adaptation to
the supporting mucosa
Rebase

176. Reline- Indications
 Loss of retention
 Instability
 Food under denture
 Abused mucosa
 Reasonably good occlusion
 Irritation and inflammation on one side
 Teeth stained on one side.

177. Reline Contraindications:
 Worn out dentures.
 Vertical dimension loss greater than 7-10
mm.
 Significant mucosal inflammation.
 Poor denture esthetics.
 Denture related speech problems.
 Severe tooth wear.
 Severe vertical overlap with tooth wear
(posterior tooth concept).
 Severe occlusal wear.

178. C D Reline
Check extensions Indicate amount of peripheral
reduction required
Border Reduction Peripheral reduction + Tissue surface

179. Border Molding Completed
Palatal surface vented after B. M.
Border molding completed
C D Reline

180. In the case of the maxillary impression, there
is also merit in perforating the palate in the
midline of the rugae to prevent any
possibility of imperfections in the impression
wash comes through vents

181. • With teeth in contact in centric relation, carry
out border molding procedures
• Allow denture to remain in mouth until material
sets (7-10 min)
• Check on extensions and patient border mold

182. Complete Denture method-ZnO
With Rubber Base Reline
Final Impression
with PVS

183. ZnO wash. Posterior
palatal seal area
using impression
wax
Trim
excess wax
beyond
anterior
line
Reline final
impression

184. BOXING

185. Relined cast:
Do not separate
Roughened border to blend new acrylic
with old. Won’t show finishing line
After processing: Note junction lineFlasking

186. Reline
Trimmed and polished

187. Delivery of Reline
Examine:
•Peripheral extensions

188. Delivery of Reline
 Pressure Indicator
Paste (PIP)
 Ask the patient to
bite on cotton rolls
for 5 min.

189. 1. Patient is instructed to leave his denture out of his mouth at least 48 hrs to allow for
recovery of tissues and reduce irritation caused by ill-fitted denture
2. Denture preparation : Any undercuts are removed from the denture base.
3. Peripheral extensions are checked and adjusted.
4. Borders are reduced and squared to provide a definite edge for addition of new base
material.
5. A hole is made in the palatal surface to allow escape of excess impression material.
Slight reduction in the fitting surface may be done to create some space for the
impression material.
6. Border tracing & new impressions are made under centric occlusion to maintain
occlusal relationship.
7. The denture with impression material is boxed and poured into stone
8. The denture is flasked, and the old resin material is thoroughly cleaned and roughened.
9. New acrylic resin material is packed, and the denture is cured in pressure curing unit
containing water at 45°c for 20 min. to prevent porosity of new resin materialand
warpage of the old resin material (release of internal stresses).
10. Finishing and polishing is done in the usual manner.
Procedures of Relining of Complete Denture