complete denture impression

3. CONTENTS
1. INTRODUCTION.
2. HISTORY.
3. DEFINITIONS.
4. THE PHILOSOPHY AND GOALS OF IMPRESSION MAKING.
5. OBJECTIVES IN IMPRESSION MAKING.
6. RELATED ANATOMY.
7. PRELIMINARY IMPRESSIONS AND
8. BORDER MOLDING: MATERIALS AND TECHNIQUES.
9. THE MANDIBULAR IMPRESSION.
10. THE MAXILLARY IMPRESSION.
11. CONCLUSION
12. REFERENCES.

4. INTRODUCTION
• Impression making is an ART.
• This is a sophisticated procedure which cannot
be leaned easily and described easily.
• It requires certain amount of skill and proper
knowledge of the anatomy of oral cavity.

5. • “Ideal impression must be in the mind of the
dentist before it is in his hand. He must
literally make the impression rather than take
it” –
M.M. Devan
• Good impressions are basic for construction of
good denture. Every phase of denture
construction is important.

6. HISTORY
• Before 18th century no method of making impressions
found. Mostly used method then was
and a block of ivory or wood was pressed on
the ridge the areas in contact was scrapped away until a
best fit denture was found.
• In 1711, Matthias Gottfried Purman recorded use of wax.
• 1782- William rae-he got measurement of jaw by a piece of
wax pushed against the jaw and he poured the impression
using PLASTER OF PARIS.
• 1840- Charles de loude-first impression tray-used tin cups
or shapes for impression with wax.

7. • In 1844, Plaster of Paris was first used as an impression
material, the credit for which goes to three dentists—
WESTCOTT, DWINELLE AND DUNNING.
• In 1848, gutta percha was first introduced which was
placed in boiling water, kneaded and molded same way
as wax and immediately inserted firmly into mouth.
• 1874 – Greene brothers J W Geeene William Greene –
impression compound
• 1930s – Ward and Kelly – first ZOE impression
• 1938- Henry Page –mucostatic impression concept.
• 1940s – Write and Denen – first alginate impression
• 1950s – elastomeric impression materials .

8. DEFINITIONS
• IMPRESSION:
A negative likeness or copy in reverse of the
surface of an object . (GPT 8)
• COMPLETE DENTURE IMPRESSION
A complete denture impression is a negative
registration of the entire denture bearing, stabilizing
and border seal areas present in the edentulous
mouth.
• PRELIMINARY IMPRESSION:
A preliminary impression is an impression
made for the purpose of diagnosis or for the
construction of a tray

9. • Border molding:-
The shaping of impression material by manipulation
or action of muscles adjacent to it.
• FINAL IMPRESSION:
A final impression is an impression for making the
master cast .
• IMPRESSION MATERIAL:
Any substance or combination of substances used
for making an impression or negative
reproduction.(GPT 8)

10. THE BASIC REQUIREMENT OF IMPRESSION
MAKING:-
1. Knowledge of oral anatomy
2. Knowledge of basic reliable
technique
3. Knowledge and understanding
of materials
4. Skill
5. Patient management

11. OBJECTIVES IN IMPRESSION MAKING:-

12. 1. PRESERVATION OF THE ALVEOLAR RIDGES
• “ It is more important to preserve what
already exists than to replace what is missing”
M M Devan’s dictum
• In impression making  covering as much of
the supporting area possible

13. 2. Support
• Def:- “It is the resistance to vertical forces of
mastication and to occlusal or other forces
applied in the direction towards the basal
seat.”

14. • Alveolar ridge  never meant for bearing
masticatory forces  utilize as much area
as possible  without interfering in
function.
• Areas of support
– primary stress bearing
– secondary stress bearing
– slight

15. Primary stress bearing area:-
Areas of edentulous ridge that are at right
angles to occlusal forces and usually do not resorb
easily.
Maxillae:
– posterior ridges
– flat area of palate.
Mandible:
– buccal shelf area,
– posterior ridges and
– the pear shaped pad.

16. Secondary stress bearing area:-
Edentulous ridge right angle or are
parallel to occlusal force.
Eg; the anterior ridge resorb faster rate than
the posterior areas
Maxillae:
– anterior ridge and all ridge slopes.
Mandible:
– anterior ridge and all the ridge slopes.

17. • Slight: -
Areas of very displaceable
tissues.
Ex; all the vestibular area that
provides very little support but are needed for
very important peripheral seal.

18. 3. RETENTION
• Def:- It is the resistance of denture to removal
in a direction opposite to that of its insertion.
Retention resists the adhesiveness of foods,
force of gravity, and the forces associated with
the opening of the jaws.

19. Factors affecting retention:-
1. Adhesion.
2. Cohesion .
3. Interfacial surface tension.
4. Mechanical locking
undercuts.
5. Peripheral seal and
atmospheric pressure.
6. Oral and facial musculature.

20. 1. Adhesion:-
– it is the physical attraction of unlike molecules.
– mucous membrane  saliva  denture.
– the quality of retention depends upon :-
• Close adaptation of denture.
• Size of denture bearing area.
• The type of saliva.
– Thin but containing some mucous  good adhesion.
– THIN WATERY
– THICK ROPY

21. 2. Cohesion:-
– it is the physical attraction
between like molecules.
– It is formed by the thin layer of
saliva present below the denture
base.
3. Interfacial surface tension:-
– It is the resistance to separation
between two parallel surfaces
that is imparted by a film of thin
liquid between them
– dependent on the ability of the
fluid to wet the surrounding
material
– high surface tension less wetting
and vice versa.

22. – Denture has high surface tension so decreased
wetting by saliva.
– But the pellicle formed on the denture decreases
the surface tension and increases the wetting.
– It is based on capillary action
– Close adaptation of denture base  thin saliva
film  by capillarity increases contact.

23. 4. Peripheral seal and Atmospheric
pressure:-
– It is the positive contact of the entire periphery of
the denture base to the resilient tissues that
outline the basal seat.
– Any dislodging forces are resisted by the
atmospheric pressure of 14.7 lb/in2

24. 5. Oral and facial musculature:-
– These are supplementary retentive forces.
– Teeth are arranged in neutral zone.
– The denture flanges are shaped accordingly(Fish)
– Brill, Trude .

25. • Mechanical factors:-
1. Undercuts.
2. Retentive springs.
3. Suction discs.
4. Magnetic forces.
5. Denture adhesives.

26. 4. STABILITY
• Def:- “It is the ability of denture to withstand
horizontal forces.”
• Factors affecting stability:-
1. Height of ridge.
2. Quality of soft tissue.
3. Occlusal plane.
4. Teeth arrangement.
5. Contour of polished surface.

27. 5. AETHETICS
 It is one of the prime factors in complete
dentures.
 Thickness of denture flange for esthetics.
 So impressions should be made accurately.

28. THEORIES OF IMPRESSION MAKING
1. Based on the amount of pressure used.
2. Open and closed mouth.
3. Hand manipulations or functional movements.
4. Type of tray.

29. • Based on the amount of pressure used:
1. Mucostatic impression technique
2. Mucocompressive impression technique.
3. Selective pressure impression technique.

30. 1. Mucostatic or passive impression-
• proposed by Henry Page and Richardson.
• It is made with oral mucous membrane and jaws in
normal relaxed position.
• Border moulding is not done.
• Impression is made with oversized trays with
impression plaster.
• Good denture stability
Disadvantages;-
• poor retention, retention only because of
interfacial surface tension and has lack of peripheral
seal.

31. 2. Mucocompressive impression technique:-
– Proposed by Greene
– Made with waxes, impression compound etc.
– Dentures made with this technique rebound back
at rest.
– But at function constant pressure is applied can
decrease circulation, leading to RRR.

32. 3. Selective pressure technique:-
– Proposed by Boucher.
– Impression extended as much denture bearing
area as possible, except the limiting structures.
– Forces only on stress bearing area.
– Made by using special tray .
– With use of relief wax.

33. • Based on technique:-
1. Open mouth technique.
2. Closed mouth technique.

34. 1. Open mouth technique:-
• Impressions are made with a tray
that is held by the dentist.
• The impression is made with
mouth made open wide.
2. Closed mouth technique:-
• Wax occlusal rims made on
preliminary cast.
• Jaw relation  border moulding
and final impression with mouth
closed, clenched with patient
performing function movement.
• Time saving but overextension
can be created.

35. • Hand manipulated or functional
movements:-
– Hand manipulated:-
• Border moulding is done and impression is
made with the hands of the dentist.
– Functional movements:-
• The functional movements are done by the
patient like sucking, grinning, licking, swallowing
etc.
• Chase and Trude introduced dynamic
impression technique.

36. RELATED ANATOMY
• Maxillary landmarks.
• Mandibular landmarks.

37. MAXILLARY LANDMARKS.
LIMITING STRUCTURE:--
LACIAL FRENUM
LABIAL VESTIBULE
BUCCAL FRENUM.
BUCCAL VESTIBULE.
HAMULAR NOTCH
POSTERIOR PALATAL SEAL

38. SUPPORTING AREAS:-
POSTERIOR SLOPES OF HARD PALATE.
MAXILLARY TUBOROSITIES
RESIDUAL RIDGE
RUGAE
RELIEF AREAS:
INCISIVE PAPILLAE
MID PALATINE RAPHE
FOVEA PALATINI

39. MANDIBULAR LANDMARKS
Limiting structures.
LABIAL FRENUM
LABIAL VESTIBULE
BUCCAL FRENUM
BUCCAL VESTIBULE
LINGUAL FRENUM
ALVEOLOLINGUAL SULCUS
RETROMOLAR PAD.

40. SUPPORTING STRUCTURE:-
BUCCAL SHELF AREA
RESIDUAL ALVEOLAR
RIDGE
RELIEF AREA:
GENIAL TUBURCLES
MENTAL FORAMEN
TORUS MANDIBULARIS
CREST OF RIDGE

42. Steps in making an impression
1. Preliminary examination of the patient
2. Seating the patient
3. Selection of the tray
4. Selection of the material
5. Making primary impression
6. Border molding
7. Making secondary impression

43. 1. Preliminary examination of the patient:-
– A complete case history and thorough
clinical examination should be done.
– Factors that can complicate impression
making should be identified (flabby ridge,
atrophic ridge).
– Patient education.

44. Seating of the patient Position of the operator for
maxillary impression
Position of the operator for
mandibular impression Improper position

45. 3. Selection of the tray:-
– “A journey of a thousand miles
begins with a single step”- Lao-tzu
• The beginning of good impression
starts with the selection of the correct
stock tray.
• Too large – distort the tissues around
the borders of the impression and
pull the soft tissue away from the bone
• Too small – border will collapse inward
on to the ridge

46. 4. Selection of the material
– Alginate is the preferred material to make
preliminary impression.
– But impression compound can also be used.
– A heavy consistency alginate should be used to
record the ridge anatomy.
– For alginate  2-3mm gap between tray and
tissue.
– For compound  5-6 mm gap

47. 5. Making an impression:-
Preliminary impression-
– Stock tray should be beaded at borders with
boxing wax in order to prevent escape of material.
– The objective is to obtain a preliminary
impression that is slightly overextended around
the borders.

48. PRIMARY IMPRESSION IN ALGINATE.
1.Selection of stock tray. 2. Position borders at hamular
notches.
4. Tray should be adjusted by
bending .
3. Lift the tray anteriorly, 3-5
mm space for impression
material.

49. 5. Border of ray should be
short of tissue reflection.
6. Adequate clearance in frenal
areas.
7. Tray should be
smoothened.

50. 8. Deficient borders corrected by
adding utility wax.
9. Tray extension in buccal space
and tissue side of posterior border.
10. Tissue stop in central
portion of tray.

51. 11. Location of hamular notches. 12. Mark the vibrating line.
13. Some alginate to be
placed in vestibule.
14. Alginate to be placed in
deepest part of palate.

52. 15. Tray to be rotated into the
mouth and seated first at the
back of the mouth.
16. Upper lip elevated.
17. Tray is held in the mouth.
18. Labial and buccal borders to
be molded.

53. 19. Completed maxillary primary impression
with rounded and molded peripheries.

54. Mandibular alginate impression
1. Metal edentulous tray 2. Identification of
Retromolar pad.
3 . Tray should cover
retromolar pad and rest
against external oblique
ridge.

55. 4. Bending and cutting the tray for adjustment.
5. Adding utility
was to extend
lingual border.

56. 7. Patient told to do tongue
movements.
6. Patient told to raise the
tongue and tray is rotated in
the mouth.
8. Gently mold the labial and buccal areas.

57. Completed Mandibular Primary
Impression

58. ALTERNATIVE TECHNIQUE FOR PRIMARY
Alginate impression in compound tray.
1. Modeling compound. 2. Softened in water
bath and kneaded.
3. Compound placed in
the tray.
IMPRESSION

59. 5. Should cover mylohyoid ridge and
external oblique ridge.
4. Molded with fingers to ridge
form.
6. Gently warmed over a flame. 7. Before insertion, tempering
in warm water bath.

60. 9. Patient instructed for tongue
movements and to purse lips.
8. Tray should be gently
seated.
11. Any short areas can be
remolded.
10. Impression should cover
all denture bearing area.

61. 12. All borders reduced by 2-3 mm.
13. Inside surface reduced by 1-2 mm.
14. Thin mix of alginate loaded.

62. 15. Completed preliminary impression made
with alginate using a compound tray.

63. “Applying a thin wash of alginate over the compound
impression assists in delineating the residual ridge.
Impression compound may not provide good surface
detail, and where the residual ridge is resorbed, this
technique is useful for distinguishing the crest of the
ridge from the sulcus.”
Complete Dentures- A Manual for the General Dental
Practitioner
Hugh Devlin

64. Preparation for Secondary or Final
Impression (Lab Procedures)
Denture outline marked on the
primary impression.

65. MAXILLARY AND MANDIBULAR SPECIAL TRAYS.

66. BORDER MOULDING:
Armamentarium required:-
• Border molding compound
• BP handle with blade
• Slow speed handpiece
• Acrylic bur
• #7 wax spatula
• Indelible marking sticks
• Custom impression trays
• Alcohol torch
• Water bath

67. • Most commonly used border molding
materials are:-
1. Modelling compound sticks.
2. Autopolymerising acrylic resin
3. Metallic paste
4. Elastomeric materials
5. Impression waxes.

68. RECOMMENDED SEQUENCE OF MAXILLARY BORDER
MOLDING

69. 1.Borders should be beveled. 2. Vibrating line marked.
3. Tray inserted in mouth. 4. Overextensions
trimmed.

70. 5. Tray should be short of 2
mm from base of sulcus 6. Borders should be adjusted.
8. Softened compound added from
hamular notch to buccal space.
7. Extra clearance in frenal
areas

71. 12. The tray rotated in mouth and
cheek gently massaged.
9. Compound molded with
fingers.
10. Softened again with a gas
torch or spirit lamp.
11. Tempered in warm water
bath.

72. 13. Appropriate molding will have mat
surface.
14. Compound added in buccal frenum
area.
15. To record the frenum patient told to
purse the lips.

73. 16. Molded buccal and labial 17. Recording the frenum.
borders.
19. Excess compound on tissue
side trimmed.
18. Compound placed on
posterior border.

74. 21. Junction of tray and
compound smoothened.
20. Tray seated in mouth with firm
pressure.
22. Border molded maxillary
custom tray.

75. RECOMMENDED SEQUENCE OF MANDIBULAR BORDER
MOLDING

76. Secondary Impression
B) Mandibular
4. External oblique ridge marked.
1. Tray outline marked 2-3 mm short
of denture outline.
2. Custom tray fabricated.
3. Posterior border of tray should
cover anterior half of the pad.

77. 5. Pencil mark
transferred to fitting
surface.
7. Anterior border of the tray
adjusted.
6. Tray border should be
resting against the ridge.
8. Lingual border adjusted.

78. Dry the tray. Slowly heat
the
compound and apply to area
“A” on
one side of the tray.

79. Seat the tray evenly. Define the tray extension by
molding
the lateral border “A” by massaging the cheek and
having the
patient pucker and smile.
The cheek is lifted outward, upward, inward,
backward, and
forward to activate movement of the frenum.

80. Add compound to area “B” (masseter groove region and the
posterior border associated with the retromolar pad).
Ask the patient
To close while holding the tray in position, resisting
the closure with
Your forefingers on the finger rests.

81. The effect of the masseter muscle on the border of the
impression is recorded by asking the patient to exert a
closing force while the dentist exerts a downward
pressure
on the tray.

82. Area “A” and area “B” have been completed and trimmed.
Avoid
displacing the tissues associated with the retromolar pad.

83. Apply compound to area “C”.
Temper, insert and gently
massage the lower lip. Simulate
muscular activity by
slightly lifting the lower lip outward,
upward, and
inward

84. The anterior lingual flange is
molded by asking the patient
to protrude the tongue and
then to push the tongue
against the front part of the
palate.

85. This area is molded by asking the patient to lip the upper lip from
One corner to other or is asked to touch the cheeks on both sides
With the tongue. He also asked to swallow

86. 15. Border molded
mandibular tray

87. With the edge of your knife blade scrape away a thin layer
of compound from the
border molded periphery. This will create space for your
impression material and
avoid excessive tissue displacement.

88. Impression tray loaded
with Zinc oxide eugenol.
•Clearance provided for frenum.
•Tray held gently in place. •Lips and cheek movements to
be done as material sets.

89. • SECOND TECHNIQUE:- ONE- STEP
BORDER- MOLDED TRAY:
• 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.

90. • The requirements of such a material are that
it should:
1. Have sufficient body
2. Allow some preshaping
3. setting time of 3 to 5 min
4. Retain adequate flow
5. Allow finger placement of the material into
deficient parts after the tray is seated
6. Not cause excessive displacement of the tissues
7. Be readily trimmed & shaped

91. • The following procedure utilizes polyether
impression materials for border molding.
1. Place adhesive for polyether impressions on the
borders of tray.
2. Express a 3- inch strip of polyether material from
large tube onto a mixing pad. Next express 2.5
inches of catalyst to provide sufficient working time
to complete border molding.
3. Thoroughly mix material for 30 to 45 seconds using
a metal spatula.

92. 4. Position the polyether material on the borders, making
certain that a minimum width of 6 mm exists on inner
portion.
5. Quickly preshape material to proper contours with
fingers moistened in cold water
6. Place the impression tray in the mouth .
7. Inspect all borders to be sure that impression material is
present in the vestibule
8. Border molding is done

93. 9. Remove tray when impression material is set.
10. Examine border molding to determine that it is
adequate.

94. • THIRD TECHNIQUE:- CUSTOM TRAY DESIGN
BASED ON PREVIOUSLY WORN DENTURE:
1. The denture is treated like a standard impression,
and a stone cast is poured.
2. An acrylic resin tray is made on the cast over a wax
spacer that is outlined just short of the borders of
the impression.
3. The tray is tried in the mouth and checked for
overextensions.
4. The spacer is removed, relief holes prepared, an
adhesive is applied and an impression is made with
the preferred material.

95. LANDMARK MOVEMENTS MUSCLE ACTING
1. Labial frenum Elevation of lip upward No muscles
2. Labial vestibule Elevating the upper lip
outward downward inwards
Orbicularis oris
3. Buccal frenum Elevating the cheek outward
inward downward and
backward forwards
Orbicularis oris
Buccinattor
Levator anguli oros.
4. Distobucaal region Elevating the cheek outward
downward and also opening
the mandible wide, and
moving the mandible side to
side
Coronoid process of
manibule.
5. Posterior palatal seal area By asking the patient to say
ah in unexxagerated manner
with his head bent
downward
Junction of hard and soft
palate.
MAXILLAE :-

96. LANDMARKS MOVEMENTS MUSCLES ACTING
1. Labial frenum Recorded by elevation of lower lip incisivus
2. Labial flange Recorded by elevating the upper lip and
extended it outward, downward inwards
Orbicularis oris, incisive labii
inferioris
3. Buccal frenum Recorded by elevating the cheek outward
and downward inwards backwards and
forwards
Triangularis(depressi anguli oris)
Buccinator
orbicularis
4. Distobuccal region Recorded by extending the cheek
outward inwards upwards
Masseter
5. Lingual flange Recorded by moving the tongue from side
to side
Ant region: genioglosus
Middle region: mylohyoid.
Posterior region: superior cons,
palatoglossus
6. Lingual frenum. Protrude his tongue outward to touch his
lip
7. Massetric notch Asking the patient to close against force
or bite
Masseter on the buccinator
MANDIBLE:-

97. • Before the final impressions are made the spacer
wax is scrapped off.
• The patient is asked to rinse with cold water or
mouthwash to remove away the saliva.
• The acrylic margin inside tray left after removing
the spacer is trimmed of .
• Relief holes are made in tray.
• The patients mouth can be cleaned with
anaesthetic especially at the posterior palate
region to temporarily paralyse the salivary gland.
• Sufficient amount of material is loaded and the
impression is made.

98. Completed maxillary
final impression.
Primary impression

99. Completed mandibular
final impression
Primary impression

100. POSTERIOR PALATAL SEAL AREA
• Def:- “The soft tissue at or
along the junction of hard and
soft palate where the pressure
within the physiological limit
can be applied inorder to aid in
retention of denture”
a) Pterygomaxillary seal area
b) Posterior seal area

101. Methods of recording
• Arbitrary scrapping.
• Fluid wax technique or functional
technique
• Convention technique

102. • Arbitrary scrapping.

103. • Fluid wax technique

104. • Conventional technique

106. IMPRESSION PROCEDURES FOR FLABBY
RIDGES:
ONE PART
IMPRESSION
TECHNIQUE
(SÉLECTIVE
PERFORATION
TRAY).
CONTROLLED
LATERAL
PRESSURE
TECHNIQUE.
PALATAL
SPLINTING
USING A TWO-PART
TRAY
SYSTEM.
TWO PART
IMPRESSION
TECHNIQUE:
MUCOSTATIC
SELECTIVE
COMPOSITION
FLAMING.
AND
MUCODISPLAC
IVE
COMBINATION
A review of prosthodontic management
of fibrous
Ridges R. W. I. Crawford1 and A. D.
Walmsley2 BRITISH DENTAL JOURNAL
VOLUME 199 NO. 11 DEC 10 2005

107. • ONE PART IMPRESSION TECHNIQUE
(SÉLECTIVE PERFORATION TRAY):-
– Used in cases of decreased mucosal
disposal.
• Procedure:-
– Preliminary impressions are taken in stock
trays using low-viscosity alginate after
appropriate border correction.
– A spaced special tray is fabricated from the
primary cast for use with a low viscosity
impression material, such as impression
plaster, low-viscosity silicone or alginate.
– Pressure on the unsupported, displaceable
soft tissue can be minimised further by the
use of perforations in the tray overlying
these areas
A review of prosthodontic management of fibrous
Ridges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH
DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

108. • CONTROLLED LATERAL PRESSURE
TECHNIQUE
– Used in fibrous posterior mandibular ridge region.
• Procedure:-
– Compound (green stick) is used to record the denture
bearing area using a correctly extended special tray.
– A heated instrument is then used to remove the
greenstick related to the fibrous crestal tissues and the
tray is perforated in this region.
– Light bodied silicone impression material is then
syringed onto the buccal and lingual aspects of the
greenstick and the impression gently inserted.
– The excess material is extruded through the perforations
and theoretically the fibrous ridge will assume a resting
central position having been subjected to even lateral
pressures.
A review of prosthodontic management of fibrous
Ridges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME
199 NO. 11 DEC 10 2005

109. • PALATAL SPLINTING USING A TWO-PART
TRAY SYSTEM:-
– By Osborne in 1960.
– Used in anterior maxillary region.
• The aim of this technique is to maintain the
contour of the easily displaceable tissue while
the rest of the denture bearing area is recorded
A review of prosthodontic management of fibrous
Ridges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME
199 NO. 11 DEC 10 2005

110. • Procedure:-

112. SELECTIVE COMPOSITION FLAMING;-
– Procedure:
• A preliminary impression in a
fluid material such as alginate is
cast producing a model of a
relatively undistorted ridge.
• A 3-4 mm spaced rigid special tray
is constructed and used to take a
composition impression of the
primary cast.
• The impression periphery is
carefully softened and
functionally trimmed.
• The fibrous part of the ridge can
be outlined on the impression
surface.
• The composition overlying the
firm denture bearing areas is
softened with a flame before the
tray is seated under heavy
pressure, attempting to replicate
functional force.

113. TWO PART IMPRESSION TECHNIQUE:
MUCOSTATIC
AND MUCODISPLACIVE COMBINATION
• Osborne in 1964
• Pressure exerted by the tray does not cause
distortion of the mobile tissues.
• Procedure:-
– The preliminary impressions are taken and cast. The
displaceable tissue can be marked on the impression and
transferred to the primary cast.
– A close fitting cold-cured or light-cured acrylic base is
constructed so that the flabby ridge area is left
uncovered.

114. • Appropriate border correction is then carried out before an
impression of the firm, supported mucosa is recorded in zinc
oxide-eugenol or medium-bodied silicone.
• An impression of the displaceable mucosa is then recorded by
applying or syringing a thin mix of impression plaster or
light-bodied silicone.

115. IMPRESSION TECHNIQUE FOR
SEVERELY RESORBED RIDGES.
• Method:-
• The mandibular primary impression  alginate in a stock tray
• The primary cast is pour and a tray devoid of spacer or relief wax is
fabricated
• the custom tray is adjusted to be 2 mm short of the functional depth of
the labial and lingual sulci.
• The crest of the ridge is marked using an indelible pencil and is
transferred to the tray via placement of the tray on the ridge.
• A window is cut in the tray using a straight bur outlining the marked
area, corresponding to the crest of the ridge.
• The tray is then seated onto the cast, and softened modelling wax is
placed into the window, shaped to form a handle.
A Technique for Impressing the Severely Resorbed
Mandibular Edentulous Ridge
Nair K. Chandrasekharan, et al, Journal of Prosthodontics 21 (2012) 215–218

116. • The tray is seated in mouth labial
and lingual borders are border
molded with putty
• Areas of overextension indicated by
exposure of the tray borders are
corrected ,
• A second application of putty is
made over the first, and the borders
are molded again .
• The borders of the impression are
trimmed by 0.5 mm
• The wax handle is removed and the
putty material over the window is
cut out
• Light-body elastomeric impression
material is loaded into the tray,
which is then seated on the ridge.

117. • Additional light-body material is then expressed into
the window.
• Lingual and facial borders are molded, ensuring the
tray remains steady until the impression material
sets.

118. Suggested Impression Techniques
CLINICAL FINDING PRIMARY
IMPRESSIONS
SECONDARY
IMPRESSIONS
TECHNIQUE
Good ridge form Impression
compound
Plaster of Paris, zinc
oxide/eugenol,
alginate or elastomer
Conventional
Sound denture supporting
tissues
No undercuts
As above but undercuts
present
Impression
compound
Alginate or
elastomers; depends
on degree of
undercuts
Impression technique conventional
but plan path of insertion and
removal of tray to match that of the
proposed denture.
Good ridge form but the
upper ridge is displaceable
Alginate Use a two stage
impression technique
Controlled minimally
displacive impression techniques
Ridge may look satisfactory
but consists of fibrous tissue or
is
non-corticated (e.g. knife-edge)
ridge-pain elicited when
palpated
Alginate or
medium- bodied
elastomer
Zinc-oxide/eugenol or
light-bodied
elastomer
Controlled pressure impression
technique
Very atrophic ridges or where
optimum peripheral extension
is indeterminate
Impression
compound
Functional impression
method
Modify denture appropriately and add
impression material which is molded
by functional movements
Complete Prosthodontics-Problems, Diagnosis and Management, Grant, Heath and Mc Cord

120. References.
• Hugh Delvin, Complete Dentures- A clinical manual for the general
dental practitioner
• Zarb- Bolender, Prosthodontic treatment for Edentulous Patients-
Complete dentures and Implant supported prostheses, 12th edition.
• Impressions for complete dentures- Bernard Levin.
• Boucher’s prosthodontic treatment for edentulous patients- 10th ed.
• Boucher’s prosthodontic treatment for edentulous patients- 12th ed.
• Complete Prosthodontics-Problems, Diagnosis and Management,
Grant, Heath and Mc Cord.
• A Technique for Impressing the Severely Resorbed Mandibular
Edentulous Ridge Nair K. Chandrasekharan, et al, Journal of
Prosthodontics 21 (2012) 215–218
• A review of prosthodontic management of fibrous Ridges R. W. I.
Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL
VOLUME 199 NO. 11 DEC 10 2005