The document discusses principles and techniques for making impressions for complete dentures. It defines an impression and outlines objectives of impression making including retention, stability, support, preservation of tissues, and aesthetics. Techniques covered include pressure, minimal pressure, selective pressure, open vs closed mouth, and use of stock vs custom trays. Steps in impression making involve seating the patient, selecting a tray and material, and making primary and secondary impressions with border molding. Common materials used are alginate, elastomers, and compound.

1. PRINCIPLES AND TECHNIQUES
OF IMPRESSION MAKING IN
COMPLETE DENTURE
SHARI.S.R
JUNIOR RESIDENT
GDC , TVM

2. Contents
• Definition
• Principles of impression making
• Objectives
• Impression techniques
• Steps in impression making
• Preliminary impression
• Final impression
• Literature review
• conclusion

3. DEFINITION
• An impression is defined as a negative likeness
or copy in reverse of the surface of an object, an
imprint of teeth and adjacent structures ,for use
in dentistry (GPT-8)

4. Principles of impression making
• The tissues of the mouth must be healthy
• Proper space for the selected impression material should be
provided within the properly fitting impression tray
• A guiding mechanism should be provided for correct positioning of
the impression tray in the mouth
• The impression should extend to include the entire basal seat
within the limits of function of supporting and limiting structures
• border moulding should be performed in harmony with physiologic
limit
• Tissue surface of the impression must be similar to the intaglio
surface of the complete denture

5. OBJECTIVES
5 objectives of impression making by Carl.O.Boucher in
1944 :
RETENTION
STABILITY
SUPPORT
PRESERVATION OF RESIDUAL STRUCTURES
AESTHETICS

6. RETENTION
• That quality, inherent in the dental prosthesis,
acting to resist the forces of dislodgement
along the path of placement – GPT8
• Resist the forces of gravity, adhesiveness of food and
opening of the jaws

7. FACTORS AFFECTING RETENTION
Anatomical factors
a. Size of the denture bearing area
- increases with increase in surface area
b .Tissue displacability
-tissues displaced during impression making will
rebound during function and lead to loss of
retention

8. Physiological factors
- Thin watery saliva : best retention
- Thick ropy saliva : loss of retention
- Absence of saliva : irritation and soreness
of denture bearing tissues

9. Physical factors
Adhesion
-Between saliva &mucosa and saliva &denture base
-Depends on : close adapation of denture
size of denture bearing area
type of saliva

10. Cohesion
- Occurs within the film
of saliva

11. Interfacial surface tension
F = 4.7 X kr4 X V
h3
F= surface tension
K = viscosity of fluid
R = radius of contacting surface
V = velocity of force
H = space between the surface

12. Capillarity
• Due to surface tension causes elevation or
depression of the surface of a liquid that is in
contact with a solid.
• Close adaptation is important.

13. Atmospheric pressure
- Resist dislodging forces if denture has effective
peripheral seal
- Proper border molding is essential for this
retention

14. Gravity

15. Mechanical factors
1 Moderate under cuts enhance retention
2. Denture adhesives
3. Suction chambers and discs

16. Muscular factors
- Teeth must be positioned in the neutral zone
- The surface should be properly contoured
- Denture base must extend to cover maximum
surface area
- Occlusal plane must be at correct level

17. STABILITY
The quality of a denture to be firm ,
steady or constant , to resist the displacement
by functional horizontal or rotational stresses
;GPT 8

18. Factors affecting stability
• Vertical height of residual ridge
• Quality of soft tissue covering the ridge
• Adaptation of denture to the tissues
• Occlusal plane
• Teeth arrangement
• Contour of polished surfaces

19. SUPPORT
The resistance to vertical forces of mastication ,
occlusal forces and other forces applied in a direction
towards the basal seat tissues
• The denture base covering maximum surface area ,
distributes forces over a large area –snowshoe effect

20. PRESERVATION OF RESIDUAL RIDGES
“It Is The Perpetual Preservation Of What Already Exists
And Not The Meticulous Replacement Of What Is Lost,
Which Is Important .”
• Selective pressure impression making follows
this dictum

21. AESTHETICS
Role of esthetics in impression
making refers to the development of the labial and
buccal borders , so that they are not only retentive but
also support the lips and cheeks properly.

22. STRESS BEARING AREAS

23. PRIMARY STRESS BEARING AREAS SECONDARY STRESS BEARING AREAS
A. Hard palate on either sides of palatine
raphe
C. Alveolar ridge
B. Firm tuberosities D. Rugae
B
B
A A
C
C D

24. PRIMARY STRESS BEARING AREAS SECONDARY STRESS BEARING AREAS
A. Buccal shelves C. Alveolar ridge
B. Retromolar pads
A
A
B
B

25. Relief areas
Maxilla – midpalatine suture
incisive papilla
torus palatinus
Mandible – crest of the residual alveolar ridge
mylohyoid ridge
mental foramen
genial tubercles
torus mandibularis
secondary stress bearing areas

26. IMPRESSION TECHNIQUES
1.Amount of pressure used(based on theories)
Pressure technique – based on pressure theory.
Minimal pressure technique – mucostatic theory
Selective pressure technique – selective pressure
theory.

27. 2.Based on the position of the mouth while making
impression
1. Open mouth
2. Close mouth
3.Based on the method of manipulation for border
molding.
1. Hand manipulation
2. Functional movements
4.Depending upon purpose of impression making
1.Diagnostic impression
2.Primary impression
3.Secondary impression

28. Pressure/definitive pressure/muco
compressive technique
- Carole jones
- Compresses the denture bearing area during
impression making
- Recording the tissues under compression ,allows
them to withstand functional forces

29. • Disadvantages
- Overextended impressions
- Tissue rebound phenomenon
- Increased residual ridge resorption
- Good initial retention ,but eventual resorption
and loose dentures
- Pressure also gets transmitted to non stress
bearing areas.

30. • Usually this technique is used for preliminary
impression making as it gives a positive peripheral
seal and tissues are recorded in function.
• Amount of pressure applied is for short duration and
the areas can be relieved during the final impression.

31. Minimal pressure technique based on
mucostatic principle
- Proposed by Richardson (1896) and popularised by
Henry Page
- Oral mucosa is recorded in normal ,relaxed state.
- Impression taken with an oversized tray with spacer.
- Border molding not performed, so flanges are shorter.
-Mainly based on Pascal’s law

32. Advantages :
• High regard for tissue health and preservation.
• Well suited in those cases where the residual ridges
are sharp thin , flat and flabby ridges .

33. • Disadvantages
-Maximum coverage within physiologic limits is
not considered
-Results in closely adapted dentures with poor
peripheral seal ,so good stability but poor retention

34. SELECTIVE PRESSURE TECHNIQUE
- by Boucher
- Combines principles of both pressure and minimal
pressure techniques
- Pressure applied selectively on stress bearing
areas and non stress bearing areas are relieved.
- It is acheived through the design of the custom
tray.

35. OPEN MOUTH TECHNIQUE
-Made with tray held by dentist and mouth open
-Muscle movements may be emphasized and can
be seen by the operator

36. CLOSED MOUTH TECHNIQUE
- Oral mucosa is recorded in the functional form
-Based on the assumption that occlusal loading
during impression making is comparable to occlusal
loading during function
-Occlusal rims are attached to impression trays and
impression is recorded while patient applies pressure
and performs functional movements
- Indicated for atrophic ridges

37. • Disadvantages
-Difficult to control the amount of pressure
leading to pressure spots
-Can produce distorted impressions

38. • 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

39. STEPS IN IMPRESSION MAKING
• Seating the patient
• Selection of the tray
• Selection of the material
• Making impression-primary
secondary
Border molding
Lining with
impression
material

40. For maxillary impression
Patient position – head and neck are
in line with the trunk,head upright
Operator position – right rear or rear
position
Height of the chair – patient’s mouth
at the level of operators elbow

41. For mandibular impressions
Patient position – head and
neck are in line with the
trunk,head upright
Operator position – right
front position
Height of the chair – patients
mouth at the level of
operators shoulder

42. MATERIALS FOR IMPRESSION MAKING
• Preliminary impression
- Irreversible hydrocolloid
-Elastomers
-Impression cake compound
• Secondary impression
For Border molding
Low fusing impression compound
Putty elastomer
Polyether
for Lining
Zinc oxide eugenol
Elastomers

43. Selection of impression tray
• Tray is a device that is used to carry, confine and
control impression material while making an
impression.
• Can be – stock tray or custom tray
Perforated - for alginate and elastomers
Non -perforated trays - impression
compound

44. Selection of impression tray
• The beginning of good impression starts with the selection of
the correct stock tray.
• The tray should be 5mm larger than the residual alveolar
ridge
• Should cover the tuberosity and the retromolar pads
• If the tray is too large it will distort the border tissues by
pulling them away from the bone.
• If the tray is too small, the border tissues will collapse inward
the residual ridge thus reducing support for the denture.

45. Using impression compound
• Non perforated stock tray is selected
• Compound placed in hot water (60 oC) &
kneaded

48. • While using alginates, extension of the tray borders
with wax is preferred
• More accurate reproduction of surface details than
compound and putty elastomers

49. Making final impressions
1.Preliminary compound impression used as a
tray for wash impression
2.Custom tray constructed on primary cast and
final impression made in this tray.

50. Preliminary compound impression used as a tray
for wash impression
• The preliminary compound impression is separated
from the tray and a final wash impression is made in
this tray.
• ADVANTAGES :- No extra appointment is necessary
for final impression.
• DISADVANTAGES :- Bulk of compound tray cannot
select areas of pressure and minimal pressure.

51. Final impression made in custom tray
• Custom tray fabricated in the preliminary cast using
auto polymerizing acrylic resin.
• Tray tried in the patients mouth , should be 2-3 mm
short of the sulcus
• Maxillary tray should cover the tuberosities and the
vibrating line
• Mandibular tray should cover the retromolar pads

52. BORDER MOULDING
• Also known as peripheral tracing
• Determining the extension of prosthesis by using tissue function or
manual manipulation of tissues to shape the borders of an
impression material -GPT8
• Two methods
-Active method : patient performs various functions to
manipulate the borders
-Passive method: dentist physically manipulate the tissues
• Techniques
-Incremental or sectional border molding
-Single step or simultaneous border molding

53. INCREMENTAL TECHNIQUE
-using green stick compound
MAXILLARY BORDER MOULDING
• Labial flange
-Lips elevated and extended outwards, downwards and
inwards(passive)
-Patient is asked to pucker and suck(active)
• Buccal flange
Buccal frenum
-Cheek pulled outward ,downwards and
inwards and forward and backward
- Patient asked to pucker and smile

54. • Distobuccal area
-Cheek pulled outward downwards and inwards
-Patient asked to open the mouth wide and close(depth
and width of distobuccal flange) and move the mandible side to
side(for coronoid process)
• Posterior palatal seal area
Patient is asked to say ‘ah’ in short bursts

55. MANDIBULAR BORDER MOULDING
• Labial flange
-Lip slightly lifted outward , upward and inwards
• Buccal flange
-Cheek lifted outward, upward and inward
-Patient asked to pucker and smile
• Distobuccal area
-Cheek pulled buccally and moved upward and inward
-Masseteric notch recorded by asking to close while
dentist exerts a downward pressure on tray

56. • Anterior lingual flange
-Patient asked to protrude the tongue and push
the tongue against the anterior part of the palate
• Middle portion of the flange
- Protrude the tongue and lick the upper lip from
side to side
• Distolingual flange
- Protrude the tongue and touch the distal part of
the palate in right and left buccal vestibules

57. Single step border molding
Requirements of one step border molding material
• Setting time 3-5mins
• Allow preshaping
• Adequate flow
• Readily trimmed
• Not cause displacement of tissue

58. • Materials used
- Putty elastomer
-Heavy body elastomer

59. MAKING FINAL IMPRESSION
• Materials used
-Zinc oxide eugenol
-Elastomers
• 0.5 -1mm of tracing compound removed from the
periphery and impression material is mixed and
placed in the tray
• All the steps for border molding are again
followed to define the borders

60. Management of hyperplastic tissues
Hobkirk technique: (DOUBLE SPACER)
 Only a single custom tray is used with double spacer.
 Border molding is done in the usual manner.
 Spacer wax removed.
 Impression made with medium bodied elastomeric impression
material
 Impression material removed in the region of flabby tissue and relirf
holes made
 Tray was loaded with light bodied impression material

61. DOUBLE SPACER

62. Zafrulla Khan technique:
• A window is cut in the custom tray where the
unsupported area is present. The unsupported area
is recorded with impression plaster and the
remaining areas are recorded with final impression
material.

63. • A mucocompressive impression is first made of the
normal tissues using the custom tray and zinc oxide
and eugenol. Once set, it is removed, trimmed, and
re-seated in the mouth.
• A low viscosity mix of ‘plaster of Paris’ is then
painted onto the flabby tissues through the window.

64. ONE PART IMPRESSION TECHNIQUE
(A SELECTIVE PERFORATION TRAY)
• Custom tray fabricated with
spacer.
• Use perforations in the tray
overlying flabby tissues.

65. CONTROLLED LATERAL PRESSURE TECHNIQUE
• Used for fibrous posterior mandibular ridge.
• Green stick is used to record denture bearing
area
• Remove greenstick related to fibrous crestal
tissues and perforated in this region.
• Light bodied silicone impression material is
syringed buccal and lingual aspects of greenstick.
• Fibrous ridge will assume a resting central
position having been subjected to even lateral
pressure

66. Green stick impression
Controlled lateral pressure
technique.

67. PALATAL SPLINTING USING TWO PART TRAY
SYSTEM
• OSBORNE, described this technique
• 2 trays
• Palatal tray fabricated with wax spacer over
flabby tissue and ridge crest around arch
• One usual maxillary custom tray.
• Impression of palate made using palatal tray and
ZNOE and allowed to set.
• Second tray inserted with silicone impression
material.
• Use of supporting ZNOE will prevent backward
displacement of mobile ridge.

68. Two tray is fabricated
Two part impression

69. SELECTIVE COMPOSITION FLAMING
• Watt and Mc Gregor first described .
• Custom tray fabricated
• Impression of the ridge obtained from primary
cast by using impression compound in custom
tray.
• Border molding done after reheating impression
all over except flabby tissue area.
• This step will compress the flabby tissue but will
not distort them.
• Impression paste is used over the impression
compound to make the final impression

72. Patients with hyperactive gag reflex
• The use of palateless upper denture for the patient
with gag reflex was successfully done in patients
suffering from this reflex and it was effective, retentive,
and restore good taste
AJPS, 2010, Vol. 8, No.2
Treatment of Edentulous Patients Having Exaggerated Gag Reflex
with Palateless Upper Denture

73. PROSTHODONTIC MANAGEMENT OF GAG
REFLEX
• Avoid thick or overextended trays.
• Avoid excess loading of tray
• Use a fast setting material
• SINGER'S MARBLE technique can be followed.
• Matte finish denture.

74. PRELIMINARY IMPRESSION TECHNIQUE FOR
MICROSTOMIA PATIENTS
• FLEXIBLE TRAY TECHNIQUE
• SECTIONAL TRAY TECHNIQUE

75. Preliminary impression techniques for
microstomia patients
The Journal of Indian Prosthodontic Society | Jul-Sep 2016 | Vol 16 | Issue 3
FLEXIBLE TRAY TECHNIQUE
TECHNIQUE I

76. TECHNIQUE II

77. SECTIONAL TRAY TECHNIQUE
TECHNIQUE III
ANTERIO- POSTERIORLY SECTIONED TRAYS

80. • MEDIOLATERALLY SECTIONED STOCK
TRAYS
• PLASTIC TRAYS WITH BUILDING BLOCKS
• USING CROSS PINS AND SLOTS
• USING MAGNETS.

81. IMPRESSION TECHNIQUE FOR HIGHLY
RESORBED MANDIBULAR RIDGES
• Admixed technique
• Functional impression technique
• All green technique
• Cocktail
• Elastomeric technique

82. ADMIXED TECHNIQUE
• Mc Cord and Tyson-Flat mandibular ridges.
• Impression compound:green stick in the ratio
of 3:7 respectively
• Kneaded into homogenous mass
• Wax spacer removed,homogenous mass
loaded and made various tongue movements

83. ADMIXED

84. ALL GREEN TECHNIQUE
• Green stick compound was
kneaded to a homogenous
mass
• Loaded on the special tray
• Border movements done
• Final impressions with
ZNOE

85. FUNCTIONAL IMPRESSION TECHNIQUE
• Closed mouth technique by WINKLER.
• Denture base with occlusal rim fabricated
in primary cast.
• Jaw relations were done .
• Tissue conditioning material applied on
tissue surface of mandibular denture
base.
• Close mouth in pre-recorded vertical
dimension.
• Do various functional movements.
• Final impression made with light body
addition silicone material.

86. COCKTAIL
• Customised tray fabricated with 1mm spacer and
cylindrical mandibular rest in posterior region.
• High fusing impression compound sofetened and
placed on rest and asked patient to close mouth
• Mc Cord and Tyson technique used
• Functional impression is used

88. ELASTOMERIC TECHNIQUE

89. CONCLUSION
• The main objective of impression making is to fabricate
dentures, having maximum retention and stability, without
causing any damage to the supporting structures.
• Dentist should be able to modify his technique based on
the conditions of basal tissues as presented by each patient.

90. REFERENCES
• Prosthodontic treatment for edentulous patients –Zarb 13th edition
• Essentials of complete denture prosthodontics-Sheldon Winkler
• Complete denture prosthodontics –Sharry
• Textbook of prosthodontics –V Rangarajan
• Treatment of Edentulous Patients Having Exaggerated Gag Reflex with
Palateless Upper Denture AJPS, 2010, Vol. 8, No.2
• A Systematic Review of Impression Technique for Conventional Complete
Denture J Indian Prosthodont Soc (Apr-June 2010) 10(2):105–111

91. THANKYOU