IMPRESSION TECHNIQUES IN COMPLETE DENTURE CONTENTS Introduction History Basic requirements of impression making Objectives of impression making Theories in impression making Recording the preliminary impressions Spacer designs & tissue stops Recording the final impressions Border molding Wash impression Conclusion References INTRODUCTION The journey towards successful complete denture fabrication begins with making accurate impressions. All subsequent steps that are necessary for complete denture fabrication will be greatly diminished if the denture base does not fit due to inadequate impression. DEFINITION IMPRESSION: An imprint or negative likeness of the teeth, of the edentulous areas where the teeth have been removed, or of both, made in a plastic material that becomes relatively hard or set while in contact with these tissues. WINKLER COMPLETE DENTURE IMPRESSION: A negative registration of the entire denture bearing, stabilizing, and border seal areas present in the edentulous mouth. HEARTWELL HISTORY Before the middle of the 18th century, no method was available for producing an impression of the alveolar ridge. Ridges were painted with a dye and a block of ivory or bone was pressed on the ridge. Areas of contacts were scraped away from the block until the best fit of the prosthesis was achieved. In 1711, Mathian Gottfried Purman recorded the use of wax. In 1728, Pierre Fauchard made dentures by measuring mouth with compasses and cut the bone to approximate shape for the space to be filled. In 1736, Phillip Pfaff of Germany made impressions in wax sections of half of the mouth at a time. 1782 -William Rae said that “he got the measurement of the jaws in a piece of wax pushed into the gum, afterwards making a cast of it with plaster of paris. 1840 - Charles De loude (london) made one of the earliest reference to impression trays . 1842- Montgomery discovered gutta percha. It was introduced as an impression material in 1848 by Colburn. 1844-Wescott, Dwinelle and Dunning used plaster of paris as an impression material. 1862 Franklin described the first correct impression. 1874 Modeling plastics was developed by S. S. White 1900 Green brothers introduced a method for manipulating the modeling plastics. First to use the term "posterior dam" in describing the posterior palatal seal. 1915 Rupert Hall perfected the first moderate-heat modeling plastic for making individual impression trays. 1925 Poller used agar for dental impressions. 1930s Ward and Kelly used ZOE for impressions. 1939 Trapozzano described one of the early techniques using Zinc oxide eugenol paste. 1936 Alginate-type materials patent awarded. 1940s Write and Denen were first to use alginate impression for corrective wash procedures 1942- Pendleton suggested a fluid wax technique using asiatic or india

1. IMPRESSION TECHNIQUES IN
COMPLETE DENTURE

2. CONTENTS
 Introduction
 History
 Basic requirements of impression making
 Objectives of impression making
 Theories in impression making
 Recording the preliminary impressions
 Spacer designs & tissue stops
 Recording the final impressions
 Border molding
 Wash impression
 Conclusion
 References

3. INTRODUCTION
 The journey towards successful complete denture fabrication begins with making
accurate impressions.
 All subsequent steps that are necessary for complete denture fabrication will be greatly
diminished if the denture base does not fit due to inadequate impression.

4. DEFINITION
IMPRESSION:
An imprint or negative likeness of the teeth, of the edentulous areas where the teeth
have been removed, or of both, made in a plastic material that becomes relatively hard
or set while in contact with these tissues.
WINKLER
COMPLETE DENTURE IMPRESSION:
A negative registration of the entire denture bearing, stabilizing, and border seal areas
present in the edentulous mouth.
HEARTWELL

5. HISTORY
 Before the middle of the 18th century, no method was available for producing an
impression of the alveolar ridge.
 Ridges were painted with a dye and a block of ivory or bone was pressed on the ridge.
 Areas of contacts were scraped away from the block until the best fit of the prosthesis
was achieved.
 In 1711, Mathian Gottfried Purman recorded the use of wax.
Starke, E.N., Jr. A Historical Review of Complete Denture Impression
Materials. JADA 91:1037-1041,1975

6.  In 1728, Pierre Fauchard made dentures by measuring mouth with compasses and
cut the bone to approximate shape for the space to be filled.
 In 1736, Phillip Pfaff of Germany made impressions in wax sections of half of the
mouth at a time.
 1782 -William Rae said that
“he got the measurement of the jaws in a piece of wax pushed into the gum,
afterwards making a cast of it with plaster of paris.
Starke, E.N., Jr. A Historical Review of Complete Denture Impression Materials.
JADA 91:1037-1041,1975

7.  1840 - Charles De loude (london) made one of the earliest reference to impression
trays .
 1842- Montgomery discovered gutta percha.
 It was introduced as an impression material in 1848 by Colburn.
 1844-Wescott, Dwinelle and Dunning used plaster of paris as an impression material.
 1862 Franklin described the first correct impression.

8.  1874 Modeling plastics was developed by S. S. White
 1900 Green brothers introduced a method for manipulating the modeling plastics.
 First to use the term "posterior dam" in describing the posterior palatal seal.
 1915 Rupert Hall perfected the first moderate-heat modeling plastic for making
individual impression trays.

9.  1925 Poller used agar for dental impressions.
 1930s Ward and Kelly used ZOE for impressions.
 1939 Trapozzano described one of the early techniques using Zinc oxide eugenol
paste.
 1936 Alginate-type materials patent awarded.

10.  1940s Write and Denen were first to use alginate impression for corrective wash
procedures
 1942- Pendleton suggested a fluid wax technique using asiatic or indian paraffin
for the final mandibular impression.
 Pierson in 1955 reported on a new elastic material of a polysulfide base. (thiokol)
 Shortly there after silicone base materials were introduced.

11. BASIC REQUIREMENTS FOR IMPRESSION MAKING:
 Knowledge of Basic anatomy.
 Knowledge of basic reliable technique.
 Knowledge and understanding of impression
materials .
 Skill.
 Patient management.

12. In an impression technique for complete dentures, the procedures must strive for
five primary objectives:
1) Preservation
2) Support
3) Stability
4) Esthetics
5) Retention
OBJECTIVES OF IMPRESSION MAKING :

13. PRESERVATION
 DeVan (1952) stated that, “the preservation of that which remains is of utmost
importance and not the meticulous replacement of that which has been lost”.
 Impressions should record the details of the basal seat and peripheral structures in an
appropriate form to prevent injury to the oral tissues.
 Pressure in the impression technique is reflected as pressure in the denture base and
results in soft tissue damage and bone resorption.

14. SUPPORT
It is the foundation area on which a dental prosthesis rests - GPT:9
 Denture support is the resistance to vertical forces of mastication and to occlusal or
other forces in a direction towards the basal seat.
 It is thus necessary, to enhance the available support by utilizing maximum coverage
of all usable ridge bearing areas.

15. -Acc to Bernard Levin
Areas of support:
 Primary
 Secondary
 Slight

16. PRIMARY:
 These are the areas of the edentulous ridge that are at right angles to
occlusal forces and usually do not resorb easily.
MAXILLARY:
Posterior ridges and flat areas of the palate.
MANDIBULAR:
Buccal shelf area , posterior ridges and pear-shaped pad.

17. SECONDARY:
 Areas of the edentulous ridge that are greater than at right angles to occlusal
forces or are parallel to them; also the areas of the edentulous ridge that are at
right angles to occlusal forces but tend to resorb under load.
MAXILLARY:
Anterior alveolar ridge and all ridge slopes.
MANDIBULAR:
Anterior alveolar ridge and all ridge slopes.

18. SLIGHT:
 Areas of very displacable tissues, that is ; all the vestibular areas that
provide very little support but are needed for the very important peripheral
seal.

19. Methods To Improve Support
 Surgical removal of pendulous tissue.
 Use of tissue conditioning materials.
 Surgical reduction of sharp or spiny mandibular ridge.
 Surgical enlargement of ridge.
 Implants.

20. RETENTION
 That quality inherent in the prosthesis which resists the force of gravity,
adhesiveness of foods and the forces associated with the opening of the jaws.
-GPT:9
 It is the resistance to removal in a direction opposite to that of insertion

21. FACTORS AFFECTING RETENTION
PHYSICAL
• Adhesion
• Cohesion
• Interfacial surface
tension
• Capillary attraction or
capillarity
• Atmospheric pressure
• Gravity
PHYSIOLOGICAL
• Saliva & it’s quality
• Intimate tissue
contact
• Border seal
ANATOMICAL
• Size of the denture
bearing area
• Quality of the denture
bearing area.
PSYCHOLOGICAL
SURGICAL
MUSCULAR
MECHANICAL
• Undercuts
• Parallel walls
• Retentive springs
• Magnetic forces
• Suction chambers
and suction discs
• Denture adhesives
RETENTION
21

22. STABILITY
The quality of a complete or removable partial denture to be firm, steady, or
constant, to resist displacement by functional horizontal or rotational stresses.
Factors affecting stability:
 Vertical height of the residual ridge
 Quality of soft tissue covering the ridge
 Occlusal plane
 Quality of the impression
 Teeth arrangement
 Contour of the polished surfaces

23. ESTHETICS
 The 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
 The vestibular fornix should be filled, but not overfilled, to restore facial contour.
 Impression should perfectly reproduce the width
and height of the entire sulcus for the
proper fabrication of the flanges.

24. IMPRESSION
MATERIALS
ELASTIC
HYDROCOLLOIDS
Reversible (agar agar)
Irreversible (alginate)
ELASTOMERS
Polysulfides
Condensation silicone
Addition silicone
Polyether
NON-ELASTIC
Impression plaster
Impression compound
Zinc oxide & eugenol
Wax
24
CLASSIFICATION OF IMPRESSION MATERIALS

25. Based On Mode Of Setting Reaction & Elasticity
RIGID ELASTIC
SET BY CHEMICAL
REACTION
• Impression plaster
• ZOE paste
• Alginate
• Non aqueous
elastomers
SET BY TEMPERATURE
CHANGE
• Impression compound • Agar hydrocolloid
25

26. Based On Type Of Impression & Area Of Use
a) Dentulous
Primary - Alginate
Secondary - Elastomers & Agar
b) Edentulous
Primary - Impression compound
Impression plaster
Alginate
Secondary - ZOE impression paste
Elastomers
26

27. Based On The Amount Of Pressure Applied
a) Muco-compressive - Impression compound
b) Muco-static - Impression plaster
Based On The Manipulation
a) Hand mixing
i) Kneading
Impression compound - wet kneading
Putty consistency elastomers
ii) Circular motion (with glass slab & spatula)
ZOE impression paste
Polysulfide
iii) Vigorous mixing
Alginate (figure of 8 motion)
b) Mechanical mixing
27

28. Based On The Tray Used For Impression
a) Stock tray
i) Based on types of tray
Rim locked perforated - Alginate & Elastomers
Water cooled - Agar
Plastic - Alginate
ii) Based on type of perforation
Perforated - Alginate
Elastomers putty wash
Non perforated - Impression compound
b) Special tray
Base plate wax - ZOE impression paste
Resin - Medium body
28

29. Based On Viscosity At Constant Shear Rate &
Temperature (23oc)
VERY HIGH
VISCOCITY
HIGH
VISCOCITY
MEDIUM
VISCOCITY
LOW
VISCOCITY
• Putty
elastomers
• Impression
compound
• Regular
elastomers
• Impression
plaster
• ZOE
impression
paste
• Hydrocolloid
a) Irreversible
b) Reversible
• Light body
elastomers
29

30. Classification Based On Wettability
a) Readily wettable - hydrophilic
Irreversible hydrocolloid
Reversible hydrocolloid
Poly ether
b) Resistant to wetting - hydrophobic
Poly sulphide
Poly vinyl siloxane
Condensation silicone
30

31. THEORIES IN IMPRESSION MAKING
The techniques used for impression making can be described into 4 categories:
 Amount of pressure used
 Based on position of the mouth while making the impression
 Based on method of manipulation
 Type of tray
31

32. AMOUNT OF PRESSURE USED
Four basic impression philosophies proposed over years for impression making based on
pressure application are:
 Mucostatic technique
 Mucocompressive technique
 Minimal-pressure technique
 Selective pressure technique
32

33. MUCOSTATIC TECHNIQUE
 1946 Page gave the concept of mucostatic based on Pascal’s law.
 According to this concept, the mucosa being more than 80% water, will
react like liquid in a closed vessel & thus cannot be compressed
 According to the principle of mucostatics, the impression material should
record every detail of the mucosa without distortion.

34. Demerits of the theory
 The lack of border molding reduces effective peripheral seal.
 The short flanges may reduce support for the face, prevent the wider distribution of
masticatory stresses, would mean less lateral stability.
 Furthermore the form of mucostatic denture minimizes the retentive role of the
musculature.

35. MUCOCOMPRESSIVE TECHNIQUE
 This theory was proposed on assumption that tissues recorded under functional
pressure provided better support and retention for the denture.
 Greene in 1896 gave this concept

36. Demerits of the theory
 Excess pressure could lead to increase alveolar bone resorption.
 Dentures which fit well during mastication tend to rebound when the tissue resume
their normal resting state.
 Pressure on sharp bony ridges results in pain.

37. MINIMAL-PRESSURE TECHNIQUE
 Is a compromise between mucostatic and mucocompressive techniques.
 In this technique, the minimal possible pressure, i.e., little more than the weight of
free-flowing material is applied during recording denture-bearing tissues.
 Limitation: There is lack of standardized protocol regarding the amount of pressure
to be applied during impression.
37

38. SELECTIVE PRESSURE TECHNIQUE
 Advocated by Boucher in 1950 it combines the principles of both pressure and
minimal pressure technique.
 The non stress bearing areas are recorded with the least amount of pressure and the
selective pressure is applied to certain areas of the maxilla and mandible that are
capable of withstanding the forces of occlusion.

39. Demerits
 Cannot be used in flabby ridges
 Some believe that different pressures cannot be applied to different areas at the
same time

40. BASED ON POSITION OF THE MOUTH WHILE MAKING THE IMPRESSION
 Closed mouth technique
 Open mouth technique
40

41. CLOSED MOUTH TECHNIQUE
 Record the tissues in their functional position.
 The patient applies pressure by closing against occlusal rims or teeth that are attached
to the impression trays.
 In this closed jaw relation, the patient exerts pressure and executes muscle actions such
as swallowing, grinning, or pursing the lips while the impression material flows.
 Materials used in this technique are impression compound, waxes, soft liners.
41

42. ADVANTAGES
 Interferences of tray handles and
operator’s finger is eliminated.
 Time saving: border molding, final
impression, jaw relation can be
completed in one time.
DISADVANTAGES
 Rebound of tissues leads to denture
displacement.
 Tendency for over-extension or under-
extension.
 A constant pressure is exerted over
tissues, hence blood supply is
compromised leading to ridge
resorption.
42

43. OPEN MOUTH TECHNIQUE
 Made with a tray that is held by the dentist.
 Record the tissues in their undisplaced position.
 Preferred because the operator can see whether the border molding is done properly.
 The various muscle movements can be accomplished some what more easily.
43

44. BASED ON METHOD OF MANIPULATION
HAND MANIPULATION
 The contour of the denture borders may be obtained by the dentist with the use of
manipulation of lips and cheeks within functional limits.
 Patient’s tongue movements record the lingual borders.
44

45. FUNCTIONAL MOVEMENTS
 The denture borders are also formed by having the patient make functional or
physiological movement such as swallowing, grinning, or pursing the lips.
 Trench's neuromuscular concept values the functions of sucking and swallowing
while making the impression to bring the denture base into harmony with the
physiological behavior of the muscles.
45

46. TYPE OF TRAY
 Stock tray
Some prefer to use the stock tray and an impression material such as alginate,
impression plaster, or impression compound.
 Custom tray
On casts made from these primary impressions, special /
custom trays are fabricated
46

47. SELECTION OF MAXILLARY STOCK TRAY
 An edentulous stock tray that is approximately 5 mm larger than the outside surface
of the residual ridge should be selected.
 Place the tray - by centering the labial notch of the tray over the labial frenum.
 The posterior extent of the tray relative to the posterior palatal seal area should be
maintained.
 The handle should be dropped downward to permit
visual inspection.
 Posteriorly – cover the hamular notches and vibrating line.
47

48.  Areas of under extension need to be corrected with soft boxing wax before the
impression is made.
 A common site for under extension is around the tuberosities and into the buccal
vestibules.
 In addition, soft boxing wax can be used to line the entire border of the stock tray to
create a rim that helps adapt the borders of the tray to the limiting tissues.
 The objective is to obtain a preliminary impression
that is slightly overextended around the borders.
48

49. SELECTION OF MANDIBULAR STOCK TRAY
 Posteriorly the tray should cover the retromolar pad.
 Anteriorly should be centralized with labial frenum with adequate clearance.
 Common sites for under extensions are:–
 Retromolar pads
 Retromylohyoid fossae.
49

50. RECORDING THE PRIMARY IMPRESSIONS
50

51. PRIMARY IMPRESSION MAKING IN MAXILLARY ARCH
 Objective - To obtain a preliminary impression that is slightly
overextended along the borders.
51

52. 52

53. Maxillary preliminary impression with irreversible hydrocolloid
(Alginate)
53

54. 54

55. PRIMARY IMPRESSION MAKING IN MANDIBULAR ARCH
 Choice of material - impression compound / high viscosity alginate.
 Astringent mouthwash given to reduce the viscosity of the saliva.
55

56. 56

57. PRELIMINARY/PRIMARY CAST
 After making the preliminary impression, the preliminary casts are poured with
model plaster, irrespective of the impression material used.
 To remove compound impressions, the cast with tray is immersed in warm slurry
water at 65°C for 5 minutes. The impression is then easily separated once the
material softens.
57

58. CASTS FOR ACRYLIC RESIN IMPRESSION TRAYS
 To make an outline one must know how to interpret the anatomic
landmarks on the cast.
MAXILLARY CAST
58

59. MANDIBULAR CAST
59

60. CUSTOM TRAY
Construction of the custom tray
 Baseplate wax, approx. 1 mm thick, is placed on the
primary cast within the outlined border to provide
space in the tray for the final impression material.
 The posterior palatal seal area on the cast is not
covered with the wax spacer.
 A wax spacer will not be used if a metallic oxide
impression paste has been selected for making the final
impression.
 The custom tray should be 2 to 3 mm thick, with a
stepped handle in the anterior region of the tray.
60

61. Refining the custom tray:
 When the custom tray is removed from the preliminary cast, the wax spacer is left
inside the tray.
 The spacer allows the tray to be properly positioned in the mouth during border
molding procedures.
 For border molding to be carried out successfully, space must be created for the
border molding material.
 Therefore the flanges of the custom tray should be reduced until they are 2 mm
short of the reflections.
 The tray must contain both hamular notches and extend approximately 2 mm
posterior to the vibrating line.
61

62. THE CLASSIFICATION OF SPACER DESIGNS
1. FULL SPACERS: It is made to cover the whole residual ridge except PPS area in maxilla
and buccal shelf and retromylohyoid area in the mandible. Thus, providing space for
impression material.
2. PARTIAL SPACERS: Based on clinical needs. It is made to cover specific areas only.
Like the T shape and I Shaped Spacer.
3. SPACERS WITH TISSUE STOPPERS: Tissue stoppers/ windows are made bilaterally
at the canine and the molar region mostly 2mm in width. They help in proper vertical
seating of the impression tray and control the thickness of the impression material.
R Jain, A., & Dhanraj, M. (2016). A Clinical Review of Spacer Design for Conventional Complete Denture.
Biology and Medicine, 8(5).
62

63. MATERIALS USED FOR MAKING SPACERS
Tin foil: as recommended
by Roy mac Gregory in the
region of incisive papilla
and mid -palatine raphe.
Casting wax: as
recommended by Neil. In
thickness of 0.9mm to be
adapted all over except
PPS area.
Base-plate wax: used as a
spacer mostly when
acrylic resin is used for
custom tray fabrication.

64. THICKNESS OF THE WAX SPACER
i) 2 mm spacer with tissue stops and 0.5 mm spacer: used when impression plaster or
zinc oxide eugenol is being used for making impression in cases of non undercut ridges.
ii) 3 mm spacer with tissue stops: used with alginate for non undercut and undercut
ridges.
iii) 1.5 mm spacer with tissue stops: used with polysulphide elastomeric impression
material for undercut or non undercut ridges.
iv) 3mm spacer: used with silicones for undercut and non undercut ridges.
v) miscellaneous: in cases of different clinical situations and demands the spacer
thickness and design varies. Like for displaceable tissues.
64

65. TISSUE STOPS
 They provide even thickness of the impression materials in the custom tray.
 Tissue stops are made by removing wax at a 45 degree angle to the occlusal surface
which will have a tripod or quadrangular arrangement on the arch.
 This provides stability to the tray and will help center the tray during insertion.
65

66. DIFFERENT SPACER DESIGNS WITH
VARIOUS CONCEPTS
66

67. BOUCHER’S:
 Based on selective-pressure technique the placement of 1 mm base-plate wax on
the entire basal seat area except PPS area.
 According to him, PPS will act as guiding stop to position the tray properly
during impression procedures.
 1 mm thick base-plate wax covers mandibular ridge except buccal shelf area and
retromolar pad.
 He says a wax spacer must not be used in cases when metallic oxide impression
paste has been selected for making final impressions.
67

68. MORROW, RUDD, AND RHOADS:
 Based on minimal-pressure technique, recommend blocking out undercut areas with
wax and then adapting a full wax spacer 2 mm short of the resin special tray border
all over.
 Then they recommend placement of three tissue stops (4˟4mm) equidistant from
each other.
68

69. J. J. SHARRY’S:
 Based on minimal-pressure technique, recommends adaptation of a layer of base-
plate wax over the whole area outlined for tray (even in PPS area).
 He recommends the placement of four tissue stops (2 mm in width located in molar
and cuspid regions which should extend from palatal aspect of the ridge to the
mucobuccal fold) and one vent hole in the incisive papilla region before making the
final impression with the metallic oxide impression material.
69

70. BERNARD:
 Based on selective pressure technique, recommends a layer of pink base-plate wax
(about 2 mm thick) attached to the areas of the cast that usually have the areas of
softer tissues.
 He recommends the placement of wax spacer all around, except the posterior part of
the palate, which according to him are at high angles to the occlusal forces.
 Not employed as midpalatine raphe, not relieved, and exposed palatal area acts as a
stopper.
70

71. HALPERIN:
 Recommended the “custom tray” with peripheral relief.
 He suggested the custom trays be provided with 1 mm thick wax relief over the peripheral
extensions and buccal slope regions of tray including PPS region and that the custom tray
be in intimate contact with basal seat areas.
 This provides the internal finish line that forms a butt joint of the compound to the tray after
border molding is completed.
 No secondary wash impression is needed as tray surface and border-molded areas acts as
final impression surface.
 A master cast is directly poured into border molded trays without using wash impression.
71

72. ROY MAC GREGOR’S:
 Based on selective pressure technique, recommends placement of a sheet of metal
foil in the region of incisive papilla and midpalatine raphe.
 He also says that the other areas that may require relief are maxillary rugae, areas of
mucosal damage, and buccal surface of the prominent tuberosities.
 Finally, he concludes that the relief should not be used routinely in the dentures.
72

73. NEIL’S:
 Recommends the adaptation of 0.9 mm casting wax all over except PPS area.
73

74. HEARTWELL:
 Mentions two techniques for achieving selective pressure for maxillary impressions.
 In the first technique, he makes the primary impression with impression compound
in a nonperforated stock tray; the borders are refined.
 Later, space is provided in selected areas by scraping of the impression compound.
 In the second technique, he recommends the fabrication of a custom tray.
 Border molding is done with low fusing compound.
 He recommends the placement of five relief holes on the palatal region (three in the
rugae area and two in the glandular region) before making the secondary impression
with zinc oxide eugenol (ZOE) paste.
74

75. SHELDON:
 Describes two techniques:
 In the first technique, the primary impression is made with low-fusing modelling
compound (kerr white cake compound).
 The borders are refined with kerr green stick compound. Once the operator is
satisfied with the retention, selective relief is accomplished by scraping in the region
of incisive papilla, rugae, and mid palatal areas.
75

76.  In the second technique, he describes of making an alginate primary impression.
 A primary cast is poured. After analysis of cast contours, undercuts are blocked out.
 Later, he recommends the placement of spacer or pressure control.
 Border molding is done with green stick compound before making the secondary
impression with ZOE paste based on selective-pressure technique used on high
arched palate.
76

77. SHETTY:
 Described a technique in which a thin sheet of wax (0.4 mm major connector wax)
is required to be placed in all areas except the PPS area, as this area needs to be
compressed during the border-molding procedures.
 A 1.5 mm thick layer of modelling wax is applied on top of the already adapted wax
sheet.
 The modelling wax is removed in the region of the crest of the alveolar ridge and the
horizontal palate, as these are stress-bearing areas.
77

78. DALE E. SMITH’S DESIGN:
 1 mm thick base-plate wax covers the ridge and midpalatine raphe.
 Two tissue stops, each at the canine region and exposed hard palate, help in proper
vertical seating of the tray and control the thickness of impression material.
78

79. OTHER DESIGNS:
Miscellaneous design for maxillary arch:
 Based on minimal-pressure technique, a 1 mm base-plate wax is placed over the
basal area except right and left posterior hard palate.
 Four tissue stoppers, each at canine and molar regions and the exposed areas act as
stoppers.
79

80. Miscellaneous design for mandibular arch:
 Based on selective-pressure technique, a 1 mm thick base-plate wax is placed over
the entire alveolar ridge except at the retromolar pad area.
 Tissue stops are placed, each at canine region, bilaterally.
 Full coverage with tissue stops provides uniform thickness of impression material.
 The exposed retromolar pad acts as the stress-bearing area.
80

81. SPACER DESIGN FOR UNDESIRABLE CLINICAL SITUATION
 Partial spacers covers the specific tissues.
 I-spacer:
 In maxillary arch, based on selective-pressure technique, covers the incisive papilla
and midpalatine raphe when it is prominent.
81

82.  T-spacer:
 Covers the anterior residual alveolar ridge in maxilla when it is resorbed and flabby.
 It is based on selective-pressure technique.
 It also covers the prominent incisive papilla, rugae and midpalatine raphe, and the
exposed areas act as stoppers.
 Partial spacer designs in the mandible cover only the anterior residual alveolar ridge
when it is atrophic, resorbed, or flabby.
82

83. CONTRAINDICATION FOR SPACER:
 In cases of highly resorbed ridges, spacer is not used as a solid tray is easier to
manage.
 In such cases, carbide bur can be used to remove about 1 mm of the custom tray
material from the crest of ridge area.
R Jain, A., & Dhanraj, M. (2016). A Clinical Review of Spacer Design for
Conventional Complete Denture. Biology and Medicine, 8(5).
83

84. Checking the custom trays intraorally
 Before border molding, the custom tray is placed in the mouth and checked for the
following and trimmed, if necessary:
 The borders of the trays should be 2 mm short of the sulcus and should provide
adequate clearance for the frenum.
 The posterior extension of the maxillary tray should cover the hamular notch and
extend up to the posterior vibrating line.
 The mandibular tray should cover the retromolar pads posteriorly.
 If a spacer is placed, it should be removed only after border molding.
84

85. RECORDING THE SECONDARY IMPRESSIONS
85

86. SECONDARY IMPRESSION MAKING
It includes:
 Border molding
 Tray preparation after border molding
 Making the wash impression
 Recording the posterior palatal seal
 Checking for errors in the posterior palatal seal
86

87. BORDER MOLDING (PERIPHERAL TRACING)
Border molding: Is the shaping of an impression material along the border
areas of an impression tray by functional or manual manipulation of the soft
tissue adjacent to the borders to duplicate the contour and size of the vestibule.
Two techniques for border molding:
1. Single step or simultaneous border molding
2. Incremental or sectional border molding
87

88. SINGLE STEP BORDER MOLDING:
 In this method, the entire periphery of the tray is refined in a single step.
 The border molding material is placed around the entire border in a single step
and molded similar to sectional technique all at once.
 Putty or heavy body elastomeric impression materials are ideal for this method.
88

89. INCREMENTAL BORDER MOLDING:
 In this method, sections of the periphery of the tray are refined individually,
according to the anatomic landmark in that area.
 The material of choice for this procedure is greenstick compound (low fusing
impression compound).
 Putty or heavy body elastomeric impression materials can also be used.
89

90. There are two methods of manipulating the peripheral tissues to mold them:
1. Active method: the patient performs various functions related to the concerned
areas to manipulate the borders.
2. Passive method: the dentist physically manipulates the tissues to mold them.
3. Either of these methods or a combination of both is used to mold the borders.
90

91. SEQUENCE OF BORDER MOULDING
MAXILLA MANDIBLE
91

92. MAXILLARY BORDER MOLDING
92

93. 93

94. MANDIBULAR BORDER MOLDING
94

95. 95

96. TRAY PREPARATION AFTER BORDER MOULDING
 The wax spacer is removed to provide space for the impression material.
 The material over the posterior palatal seal is not removed.
 Green stick compound removed using a scalpel.
 The thickness of the flanges & the border should be 2.5-3mm.
 Vent holes are drilled into the impression tray to allow escapement of the
impression material.
96

97. ESCAPE/VENT HOLES
 After removing wax spacer from inside of the tray, a series of holes are prepared, about
12.5 mm apart in the center of alveolar groove and in the retro molar fossa with no. 6
round bur.
 The relief holes provide escape way for the final wash impression material and relieve
pressure over crest of the residual ridge and in the retro molar pads when the final
impression is made.
97

98. MAKING FINAL IMPRESSION OF MANDIBLE
 Final impression of choice is mixed according to the manufacturer’s instruction
and evenly distributed within the tray and covering the borders also.
 The tray is rotated into the mouth in the horizontal plane with the anterior handle
until it is over residual ridge.
98

99.  At this time, the patient is asked to raise the tongue slightly, and the tray is
moved downward its final position.
 The operator’s index fingers of each hand are placed on top of the posterior
handles and with altering gentle pressure, the tray is seated until the buccal
flanges come into contact with the mucosa covering the buccal shelf.
99

100.  The tongue must be kept forward touching the upper lip, while the impression
material sets.
 When the material is set, the tray is removed and inspected.
 If it needs to be remade, it is carefully removed with care to preserve the border
molding.
100

101. MAKING FINAL IMPRESSION OF MAXILLA
 Material of choice – zinc oxide eugenol impression paste.
 Impression material is manipulated & loaded onto the tray. The patient made to sit in
an upright position. Operator stands towards the rear or the side of the patient.
 Tray is placed in the patients mouth using the labial notch as a guide.
101

102.  Tray is seated into position by applying alternating pressures on the right & left
molar regions using index fingers.
 Tray is maintained in this position by placing a finger in the palatal region of the
tray, immediately anterior to the posterior palatal seal.
 Passive movements are made.
 After material has set, the tray is removed in a single jerk.
 Impression inspected for deficiencies & voids and is repeated if necessary.
102

103. POSSIBLE ERRORS WHICH LEAD TO REMAKING THE IMPRESSION
 A thick lingual border on one side with a thin lingual border on the opposite side.
This indicates that the lower tray was out of position in the direction of the thin
border.
 A thin anterior lingual border with the tray showing on the inside surface of the
lingual flange. This suggests that the lower tray was too far forward in relation to the
residual ridge. This will be accompanied by a thick labial border.
103

104. OTHER REASONS
 Voids or discrepancies that are too large to be corrected accurately.
 Incorrect consistency of the final impression material when the tray was positioned in
the mouth.
 Movement of the tray while final impression was setting.
 Incorrect border molding procedures.
 Use of either too much or too little material.
104

105. The different material used for final impression are:
 Impression plaster (rarely used)
 Zinc oxide eugenol paste – 2mm
 Reversible hydrocolloids – 6mm
 Elastomeric impression materials – 4mm, 2mm
 Mouth temperature waxes
105

106. CONCLUSION
 The main objective of impression making is to construct dentures, having maximum
retention and stability, without causing any damage to the supporting structures.
 A good impression often favorably impresses and relieves the anxieties of the
patient.
 Thus it is the responsibility of the dentist, to select the best possible procedure,
based on sound knowledge, for achieving, the best possible results for the patient.
106

107. REFERENCES
 Zarb. Bolender, Prosthodontic treatment for edentulous patients, 12th Edition.
 Boucher’s Prosthodontic treatment for edentulous patients, 9th Edition.
 Sheldon Winkler, Essentials of complete denture prosthodontics, 2nd Edition.
 Charles M. Heartwell, Textbook of complete dentures, 5th Edition.
 Kenneth J. Anusavice, Phillips’ science of dental materials, 11th Edition.
 Robert G. Craig, Restorative dental materials, 11th Edition.
 R jain, A., & Dhanraj, M. (2016). A clinical review of spacer design for conventional
complete denture. Biology and medicine, 8(5).
 Singla s. Complete denture impression techniques: evidence-based or philosophical.
Indian J dent res 2007;18:124-7.
107

108.  Posterior palatal seal area
 Impressions in compromised conditions
 Disinfection of the impressions
 Position of the patient and the operator while making impressions
 Review of literature

109. QUESTIONS??
109

110. Q: What are the basic objectives of impression
making?
a) Preservation of the alveolar ridge
b) Retention
c) Stability
d) Support
e) Esthetics
110

111. Q: Oral tissues are best recorded in functional state
by---------impression technique?
Selective pressure technique
111

112. Q: What is the purpose of shortening the borders of
the secondary impression tray (in complete denture
construction)?
To perfect the borders of the tray on the patient.
Softened compound is added to the tray to capture the
mucobuccal and mucolingual folds.
112

113. Q: Most common reason to repeat impression is?
a) Improper positioning of tray
b) Too less or excess material
c) Voids that are irreparable
d) Improper mixing
113

114. Q: What is the purpose of tissue stops?
The tissue stops in the custom trays prevents the
apical displacement of the tray while making the final
impression and helps to reseat the custom tray during
the final impression.
114

115. Q: While taking final impression tray should be
seated first?
a) Anteriorly
b) Posteriorly
c) Anteriorly and posteriorly simultaneously
115

117.  Boucher’s Prosthodontic treatment for edentulous patients, 9th Edition.
 Sheldon Winkler, Essentials of complete denture prosthodontics, 2nd Edition.
 Charles M. Heartwell, Textbook of complete dentures, 5th Edition.
 Mushtaq MA, Khan MWU., An overview of dental impression disinfection techniques-a
literature review., J Pak Dent Assoc 2018;27(4):207-12.
 Bhandari A et al., Int J Dent Health Sci 2015;2(5):1261-1267.
 Mariyam, A., Saurabh, C., Verma, A., Naeem, A., & Anuj, S. Posterior Palatal Seal
(PPS): A brief review., Journal of Scientific and Innovative Research 2014;3(6):602-605.

118.  D. krishna & mehra, divya & prasad d. anupama. Prosthodontic management of
compromised ridges and situations. Nitte university journal of health sciences
2014;(4):141-8.
 Prasad d. anupama & d. Krishna & hedge. chethan. Prosthodontic rehabilitation of a
patient with oral submucous fibrosis and microstomia: a case report. Journal of health
and allied sciences 2012;(02):68-71.
 Jain. vaibhav & Prakash. poonam & R. vijay & udayshankar. vishvnathe. Impressing
for excellence: special impression techniques for compromised ridges: case report.
International journal of contemporary medical research [IJCMR] 2019;(6):18-21.
 Rashid H, vohra FA, haidry TZ, karmani GD. Stabilizing mandibular complete
dentures using the neutral zone impression technique. J pak dent assoc 2013;22(2):154-
159.