This document discusses various techniques for making impressions for complete dentures. It covers topics like border molding, anatomical considerations for different ridge types, and specialized techniques for resorbed or flabby ridges. For resorbed mandibular ridges, techniques discussed include the conventional, functional, elastomeric, admix, cocktail, and modified functional impression techniques. For flabby ridges, the mucodisplacive and mucostatic impression principles are covered, as well as the one part impression and controlled lateral pressure techniques. The document provides details on selecting the appropriate impression material and technique based on a patient's clinical situation.
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Complete denture impressions
1. CLINICAL ASPECTS OF IMPRESSIONS
COMPLETE DENTURE PROSTHODONTICS
AAMIR GODIL
SECOND YEAR P.G.
DEPARTMENT OF PROSTHODONTICS
M.A.R.D.C.
2. âAn ideal impression must be in the mind of a
dentist before it is in his hand. He must literally
make the impression rather than take itâ
-M.M. Devan
2
3. IMPRESSION MATERIALS
THEORIES OF IMPRESSION MAKING
HISTORICAL BACKGROUND
PRINCIPLES OF IMPRESSIONS
IMPRESSIONS IN
COMPROMISED SITUATIONS
ANATOMICAL
CONSIDERATIONS
3
BORDER MOLDING
CLASSIFICATION OF
IMPRESSIONS
CLINICAL
CONSIDERATIONS
5. OBJECTIVES OF IMPRESSION MAKING
5
RETENTION STABILITY SUPPORT
ESTHETICS
PRESERVATION
OF REMAINING
STRUCTURES
6. RETENTION
ANATOMICAL
FACTORS
⢠SIZE OF
DENTURE
BEARING AREA
⢠QUALITY OF
DENTURE
BEARING AREA
PHYSIOLOGIC
FACTORS
⢠SALIVA: QUALITY
AND QUANTITY
PHYSICAL
FACTORS
⢠ADHESION
⢠COHESION
⢠INTERFACIAL
SURFACE
TENSION
⢠CAPILLARITY
⢠ATMOSPHERIC
PRESSURE AND
PERIPHERAL
SEAL
MECHANICAL
FACTORS.
⢠UNDERCUTS
⢠RETENTIVE
SPRINGS
⢠MAGNETIC
FORCES
⢠DENTURE
ADHESIVES
⢠SUCTION
CHAMBERS AND
DISCS
MUSCULAR
FACTORS
⢠NEUTRAL ZONE
⢠CORRECT
OCCLUSAL
PLANE
6
7. STABILITYFACTORSAFFECTING
STABILITY
VERTICAL HEIGHT OF RESIDUAL ALVEOLAR RIDGE
QUALITY OF SOFT TISSUE COVERING THE RIDGE
QUALITY OF IMPRESSION
LEVEL AND CONTOUR OF OCCLUSAL RIMS
ARRANGEMENT OF ARTIFICIAL TEETH
CONTOUR OF POLISHED SURFACES
7
12. BEFORE MAKING THE IMPRESSION
⢠Examination and conditioning of the patient and the
mouth.
⢠Complete case history
⢠Clinical examination
⢠Identifying and correcting adverse conditions
⢠Factors that complicate impression making
⢠Old denture wearer.
12
13. SELECTION OF IMPRESSION TECHNIQUE
⢠Clinical findings
⢠Experience of the dentist
⢠Availability of materials
⢠Patient related factors
â Time
â Undercuts
â Old denture wearer
13
14. WHAT ARE THE OPTIONS?
⢠Preliminary impression materials:
â impression compound
â alginate
⢠Final impression materials:
â alginate
â silicon based elastomers
â zinc-oxide eugenol impression paste
â impression plaster
â tissue conditioners
â waxes
14
15. IMPRESSION COMPOUND
⢠Easily correctable
⢠Can be border molded
⢠Not influenced by saliva
⢠Can be used as impression tray
⢠Can be scraped easily to provide relief
⢠Viscous
⢠Cannot record fine details
⢠Compound sticks used for border molding
⢠Inelastic
15
16. ALGINATE
⢠Elastic
⢠Primary and final impression
⢠Records good details
⢠Not correctable but easily remade
⢠Not dimensionally stable
⢠Does not adhere to tray
16
17. ELASTOMERIC IMPRESSION MATERIALS
⢠Elastic
⢠Fine details
⢠Hydrophobic
⢠Adhesive required
⢠Available in different viscosities
⢠Dimensionally stable
⢠Cannot be adjusted after set
⢠Prolonged setting time
17
18. ZINC OXIDE EUGENOL IMPRESSION PASTE
⢠Rigid and inelastic
⢠Adheres to tray
⢠Flows readily and records fine details
⢠Burning sensation and tissue irritation
⢠Dimensionally stable
⢠Bulk of the impression is minimal
⢠Flaking or breaking during trimming
18
19. IMPRESSION PLASTER
⢠Minimal pressure technique
⢠Flows readily and records fine details
⢠Rigid
⢠Wash impression
⢠Absorbs saliva
⢠Dimensionally accurate with anti expansion solution
19
32. COMMON FAULTS
MANDIBULAR
⢠Insufficient depth in posterior
lingual sulcus
⢠Insufficient depth in lingual,
labial and buccal sulci
⢠Edge of the tray showing
through the impression
⢠An asymmetrical impression
MAXILLARY
⢠Deficiency in the midline of
palatal vault
⢠Excess material extending
beyond posterior palatal border
of the tray
⢠Insufficient depth in one or
more region of sulci
⢠Tray flange exposure
32
37. TISSUE STOPS
⢠Prevent seating of the tray too superiorly or posteriorly
⢠Stabilize the tray
⢠Uniform thickness of the material
⢠Molar or cuspid areas
37
38. BORDER MOLDING
⢠The shaping of the border areas of an impression material
by functional or manual manipulation of the size of the
vestibule.
⢠Materials:
â Modelling compound sticks
â Auto-polymerizing acrylic resin
â Metallic pastes
â Elastomeric materials
â Impression waxes
38
39. ⢠REQUIREMENTS:
â Have sufficient body
â Allow some pre-shaping of the borders
â Setting time 3-5minutes
â Retain adequate flow when seating in the mouth
â Allow finger placement of the material in to deficient parts after
seating of tray
â Not cause excessive displacement of tissues
â Readily trimmed and carved so that excess material can be carved and
borders shaped before the final impression is made
39
44. TESTS FOR RETENTION
MAXILLARY
⢠Upward and outward pressure in the
incisor region
⢠Upward and outward pressure in the
premolar region
⢠Pulling the upper lip downward
MANDIBULAR
⢠Protrude the tongue
⢠Move tongue in lateral direction
⢠Roll tongue back to touch palate
⢠Open the mouth.
⢠Exerting vertical pull on handle
⢠Forward pressure on distal aspect of
the handle
44
45. FINAL IMPRESSION
PREPARATION
⢠Removing the relief wax
⢠Removing spacer wax
⢠Escape holes
⢠Reducing the borders
⢠Applying adhesive
⢠Protecting the mouth
⢠Drying the mouth
⢠Instructing the patient
MAKING THE IMPRESSION
⢠Mixing
⢠Loading
⢠Seating
⢠Removing the impression
⢠Inspecting
⢠Correcting
⢠Remaking
45
54. PROBLEMS ENCOUNTERED IN MAKING AN
IMPRESSION OF RESORBED MANDIBULAR RIDGE
⢠Mucosa : thin and atrophic
⢠Inadequate denture bearing areas
⢠Attachment of muscles near the crest of the ridge
⢠Interference of tongue
54
55. FINAL IMPRESSION TECHNIQUES TO MANAGE
RESORBED MANDIBULAR RIDGES:
1. Conventional technique
2. Functional impression technique
3. Elastomeric technique
4. Admix technique
5. Cocktail technique
6. All green technique
7. Flange technique
8. Modified Functional Impression Technique
56. 1.CONVENTIONAL TECHNIQUE
(Boucher)
⢠Border moulding done with green
stick compound
⢠Final impression made using zinc
oxide eugenol impression paste.
⢠Impression recorded using open
mouth technique.
57. ADVANTAGES:
1.Easy handling
2.No dimensional change
3.Reproduction of fine details.
DISADVANTAGES:
1.Short manipulation time
2.Hardens quickly before the functional movements can be recorded.
58. 2.FUNCTIONAL IMPRESSION TECHNIQUE
(Winkler)
⢠Closed mouth functional technique.
Jaw relations(horizontal and vertical) are recorded prior to the final
impression.
Tissue conditioners are added on mandibular tissue surface.
Patient is asked to close the mouth in pre recorded vertical dimension and
is asked to perform functional movements like puffing, whistling, blowing
and smiling.
Three applications of tissue conditioners done at an interval of 8-10
minutes and functional movements were recorded.
59. ADVANTAGES
1.Overall denture has better surface
contact
2.Improved retention
3.Interference due to tray handling is
eliminated
4.Less chances of over and under
extension as the movements are
performed by the patient
DISADVANTAGES
1.Restriction of tongue movement
therefore inaccurate recording of
lingual border.
2.Completely depended on patient.
61. ADVANTAGES:
1.Single step border moulding.
2.Minute details are recorded due to the use
of light body addition silicone.
DISADVANTAGES:
1.Single step border moulding is technique
sensitive
2.Comparatively expensive.
62. â˘
4.ADMIX TECHNIQUE
(Mc Cord and Tyson)
⢠This reduces the potential discomfort arising from atrophic mucosa.
⢠Impression compound and green stick compound are mixed in the
ratio of 3 : 7 parts by weight are placed in a bowl of water at 60
degrees Celsius.
RATIONALE
Viscous admix of impression compound and green stick compound removes the soft
tissue folds and smoothens them over the mandibular bone.
63. ADVANTAGES:
1.Functional position of muscle are recorded in
single step.
2.Less chair time and economical.
⢠DISADVANTAGE:
1.Overextension of impression
⢠Kneaded to a homogenous mass that provides a working time of about
90 seconds.
⢠Wax spacer is removed; this homogenous mass is loaded and patient is
made to do various tongue movements.
64. 5.COCKTAIL TECHNIQUE
⢠After making the primary impression, customized custom
tray is made with self cure acrylic resin.
⢠Rest are made on the custom tray with increased vertical
height, and impression compound softened and placed top
of mandibular rest.
⢠Patient is asked to close the mouth, so that mandibular
rests fit against the maxillary alveolar ridge.
65.
66. ⢠This would help in stabilisation of the tray during impression making
as it would prevent antero-posterior and medio-lateral displacement
of the tray.
⢠Impression and green stick compound are mixed in the ratio of 3:7
and loaded on the tissue surface.
⢠Patient is asked to perform functional movements and in this way
impression is recorded.
⢠ADVANTAGES:
1.Dislocating effect of muscles on the tray is avoided.
2.Rest made on the mandibular tray prevents displacement of the
tray.
67. 6. ALL GREEN TECHNIQUE
⢠Green stick compound is kneaded to a homogenous mass and is loaded
on the special tray and border movements are done.
⢠Final impression made using zinc oxide eugenol paste.
68. 7.FLANGE TECHNIQUE
(Lott And Levin)
⢠Labial and lingual borders are manipulated using Adaptol wax.
⢠Removal of excess wax from the inner surface of the tray.
⢠Carbide bur used to remove 1mm of resin from the crest of the ridge.
⢠Tray cleaned and painted with rubber base adhesive.
⢠Final impression made using polysulfide impression material.
69. 8. MODIFIED FUNCTIONAL IMPRESSION TECHNIQUE
(CHANDRASHEKHARAN et AL)
69
1. Preparation of acrylic custom tray on primary cast with a window
over Atwoodâs Class IV ridge.
2. Fabrication of a wax handle over the window.
3. Border molding of buccal and lingual flanges with A-silicone putty.
4. Trim the excess and overextended borders
5. Remove the wax handle
6. Inject light body A-silicone through the window
7. Final impression
Chandrashekharan et al. A Technique for Impressing the Severely Resorbed Mandibular Edentulous Ridge. Journal of Prosthodontics 00 (2011) 1â4 c 2011 by the American College of Prosthodontists
71. ⢠A so-called âfibrousâ or âflabbyâ
ridge is a superficial area of mobile
soft tissue affecting the maxillary or
mandibular alveolar ridges.
⢠It can develop when hyperplastic
soft tissue replaces the alveolar
bone and is a common finding,
particularly in the upper anterior
region of long term denture
wearers.
71
72. APPROACHES TO MANAGEMENT OF FLABBY TISSUE
72
Surgical removal of fibrous tissue prior to conventional
prosthodontics
Implant retained prosthesis
Conventional prosthodontics without surgical intervention.
73. There are two impression principles which are reported to
overcome this problem:
⢠Mucodisplacive impression technique:
with the aim of compressing the loose flabby tissue to allow functional
support from it by replicating the contour of the ridge during
compression by occlusal forces.
⢠Mucostatic impression technique:
which aims to achieve support from the other firm areas of the arch and
maximizes retention.
73
R. W. I. Crawford, A. D. Walmsley. BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005
74. One Part Impression Technique
(SĂŠlective Perforation Tray)
74
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
Lamb D J. Problems and solutions in complete denture prosthodontics. pp 57-60. London: Quintessence, 1993.
75. Controlled Lateral Pressure Technique
75
Tracing 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.
Grant A A, Heath J R, McCord J F. Complete prosthodontics: problems, diagnosis and management. pp 90-92. London: Wolfe, 1994.
76. Palatal Splinting Using A Two-part Tray System
⢠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.
Devlin H. A method for recording an impression for a patient with a fibrous maxillary alveolar ridge. Quint Int 1985; 6: 395-397.
77. Selective Composition Flaming
77
By performing the impression in this way, the original relatively undistorted shape of the fibrous tissues is
retained while the tissues more capable of functional denture support are recorded in a displaced state.
Lamb D J. Problems and solutions in complete denture prosthodontics. pp 57-60. London: Quintessence, 1993.
78. Two Part Impression Technique:
Muco-static And Muco-displacive Combination
78
Close fitting cold-cured or
light cured acrylic base is
constructed so that the
flabby ridge area is left
uncovered
Appropriate border
correction is then carried out
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
Osborne J. Two impression methods for mobile fibrous ridges. Br Dent J 1964; 117: 392-394
79. Modifications:
⢠Window Technique:
â An alternative, described by Hobkirk, McCord and
Grant, involves removal of acrylic from a complete
special tray creating a window over the displaceable area.
â The advantage of a window design means that the
appropriate border correction can be undertaken and
checked around the entire sulcus before the second stage
of the impression is completed.
79
80. 80
Cage Technique:
Used for multiple dispersed areas of fibrous tissue where
multiple small windows are made.
81. ⢠Modified Fluid Wax Technique (FOR RESORBED + FLABBY RIDGES):
81
Tan et al. Modified fluid wax impression for a severely resorbed edentulous mandibular ridge. J Prosthet Dent. 2009;101:279-282
83. 83
Baker et al
(J Prosthet Dent 2000;84:241-4.)
⢠Hydrocolloid primary impression using sectional plastic stock tray.
⢠Fabrication of sectional light cure custom tray segment by segment
connected by horizontal hinge.
⢠Elastomeric impression is made with first half of the tray followed by
the second part.
⢠Approximate both the sections while making the second sectional
impression and close the horizontal hinge. Allow the impression to set.
⢠Remove the impression in sections.
⢠Evaluate- reassemble- pour
85. Moghadam BK
(J PROSTHET DENT 1992;67:23-5.)
⢠Make an impression of the left side of the mouth with irreversible
hydrocolloid by using tray No. 1
⢠Pour this impression with dental stone as soon as possible.
⢠Separate the cast from the impression when the stone has set.
⢠Make a 45-degree bevel with a sharp knife at the medial border of
the cast anteroposteriorly to increase the contact area of this cast
with the next pour
⢠Make an impression of the right side of the arch with irreversible
hydrocolloid by using tray No. 2.
⢠Position the cast made from the first impression in this impression
and stabilize the cast in the impression.
⢠Pour the impression containing the cast in dental stone.
⢠Separate the cast from the impression after the stone has set and
trim the borders.
85
McCord JF, Tyson KW, Blair IS. A sectional complete denture for a patient with microstomia. J Prosthet Dent 1989;61:645â7.
86. Luebke RJ
J Prosthet Dent 1984;52:135â7.
⢠A plastic tray was chosen by measuring the ridge with calipers and then cut in two sections with a disc
with the handle in the larger section.
⢠Three building blocks (toy) (LEGO Systems, Inc., EnďŹeld, Conn) were selected to reapproximate
sectional trays as one unit which were ďŹxed to the tray by the help of autopolymerising resin.
⢠Depending on whether the patient is dentulous or edentulous, polyether or zinc oxide eugenol paste was
used to make impressions.
⢠With the larger section tray, impression of two thirds of the arch was made after which the impression
was removed from the mouth, allowed to set and trimmed ďŹush the edge of the tray using surgical blade.
⢠This was further repeated with second sectional tray and both were joined and poured
86
87. Cura et al
J Prosthet Dent 2003;89:540â3.
⢠Putty-type impression material can be manually dispensed intraorally to
serve as custom trays to make diagnostic maxillary and mandibular
impressions.
⢠Once the impression putty is placed onto the denture bearing areas, the
impression material was border moulded to the appropriate contour.
⢠The impression putty custom tray was removed after the material
polymerized. Impression material was loaded onto the silicone custom
trays and inserted intra orally.
87
88. 88
Mandibular sectional stock tray to be joined with
acrylic hook and steel bur at the handle region.
A is the metal pin
B is the bend to hook around handle C
C is bent handle sections
D is the metal tubing within acrylic into which A will be ďŹtted
E is the ďŹns to approximate tray sections
Maxillary sectional tray locked at the
handle region with steel pins into
tubings and acrylic hook into bent
handles.
Hegde C. et al
Journal of Prosthodontic Research 56 (2012) 142â146
89. 89
Foldable mandibular sectional tray with steel
burs and acrylic blocks which are folded while
inserting into the oral cavity and opened on
the arch to seat on the pins.
Anterior and posterior tray sections joined by steel burs
91. General Management and Useful Tips
⢠Call well rested patient
⢠Avoid patient visits - immediately after meals
- early morning appointment
⢠Calm environment
⢠Continuous reassurance to the patient
⢠One technique common to all
Shipmon and Massad described it as âCARING ATTITUDE FACTORâ
93. Singerâs Desensitisation Technique
⢠Also called âmarble techniqueâ
⢠Involves 7 visits
1st visit: 5 marbles placed in mouth, patient instructed to keep them for 1 week
2nd visit: ability to tolerate marbles evaluated
3rd visit: before making impressions, topical anaesthetic applied , primary impression made, base plates
made with a rough finish
4th visit: lower base plate inserted , 3 marbles placed and a âtraining beadâ
5th visit: upper base plate inserted , asked to discontinue marbles
6th visit: patient able to endure the presence of both base plates , occlusal rims constructed
Jaw relation taken , try in completed.
7th visit: completed lower denture inserted first + upper base plate + a training bead.
Next upper denture inserted
Singer JL. The marble technique : method for treating the hopeless gagger for complete dentures. J. Prosthet. Dent. 1973;8
94. Impression Technique
⢠If stock trays are used, a posterior dam can be constructed in the
tray using wax or silicone putty. This will help to prevent material
exuding from back of the tray.
⢠In patients with a history of gagging, consider using a less fluid
impression material with faster setting characteristics.
⢠Avoid overloading trays and initially seat the tray posteriorly.
⢠Use of sectional impression trays
96. ⢠The neutrocentric concept requires that posterior mandibular
denture teeth be arranged to occupy as central a location as
possible, relative to the denture foundation, without disturbing
adequate tongue function
⢠This tooth arrangement is said to facilitate mandibular denture
stability during occlusal loading
⢠The term neutral zone concept was coined by Beresin and
Schiesser in 1976. It is that region where forces imposed by the
tongue directed outward are neutralized by inwardly directed
forces originating from the cheeks and lips during normal
neuromuscular function.
96
98. Historically, different terminology has been loosely associated with this concept, including
⢠dead zone
⢠stable zone
⢠zone of minimal conflict
⢠zone of equilibrium
⢠zone of least interference
⢠biometric denture space
⢠denture space
⢠potential denture space
Arranging artificial teeth within the neutral zone achieves 2 important objectives:
(1) Prosthetic teeth do not interfere with normal muscle function
(2) Normal oral and perioral muscle activity imparts force against the complete dentures
that serves to stabilize and retain the prostheses rather than cause denture
displacement
98
99. ⢠A soft material that can be molded by the action of the
tongue, cheek, and lips is used to establish the neutral
zone.
⢠Modelling compound softened at 65 0F is adapted to
the top of the lower tray and shaped similar to a wax
occlusion rim. The tray and modeling compound are
placed in the mouth, and the patient is instructed to
swallow.
⢠The actions of the muscles and tongue during
swallowing mold the soft compound into the neutral
zone and shape the polished surfaces of the denture.
⢠The modeling compound is allowed to harden in the
mouth sufficiently to prevent distortion and is placed
in cold water to harden for trimming.
⢠The modeling compound is trimmed so that the
occlusal plane is established approximately 1 to 2 mm
below the lateral border of the tongue when it is at rest.
99
Easy and can be done with limited clinical expertise
Only limited functional movements can be recorded since material sets quickly
Easy to use.
Can be used on existing dentures
âAll movements done by patient, cannot be employed in patients who have lost neuromuscular control
Tissue conditioners:
Introduced in the year 1967 by KYDD And Mandley
They are soft denture materials applied on the fitting surface of the denture and they act as temporary cushion which minimize transfer of excessive masticatory forces to the underlying tissue.
Remain plastic from 24-36 hours
Should be changed once in 3 days
:pink viscuous COE-SOFT
Apart from this light body polysulfide can also be used.
Single step border molding can be used in uncooperative patients or patients with atrophic mucosa who cannot withstand warmth of modelling compound or burning sensation due to final impression materials like ZOE
However, the borders may be thicker due to the consistency of the putty
Smith et al described a technique using a polyether impression
material for border moulding the complete denture
impression trays. The major advantages of this technique
were that the border moulding could be accomplished in one step
and that the patientâs functional movement was used in
forming the borders
Tan et al. [19] concluded that polyether
impression material requires less time to complete the border
moulding process; the border recorded was longer and of less
operator variability when compared with modelling plastic.
Follows dynamic impression technique for the construction of tray.
Primary impression:alginate
Tray is made and perforated and is extended within the limits of muscular activity
Then stops are made on the try using green stick modelling compound
Madibular rest is constructed on the tray surface
First described by Osborne in 1964 for use in the mandible, this is a popular technique described by many authors as it ensures that pressure exerted by the tray does not cause distortion of the mobile tissues.
Modified by Devlin
RELAXATION
Relaxation abolishes gag reflex
Patient should be made comfortable with the surroundings.
Provide assurance in a calm atmosphere.
Avoiding obvious display of instruments, using soothing pictures an music in reception areas and surgeries.
DISTRACTION
Temporarily diverts patients attention
Techniques employed:
Deep rhythemic breathing (Hoad reddick)
Breathe rhythemically through nose and rhythemically tap right foot on floor(Kovats)
Engage patient in a conversation of special interest to the patient (Landa)
Ask the patient to hold one leg in air, as muscles get fatigued more concious efforts will be required to hold the leg in that position(Krol)
SUGGESTION
Distraction technique refined by adding an element of suggestion
Patient must be informed that retching will not occur during distraction activity
Use of visual imagary & hypnosis
SYSTEMIC DESENSITIZATION
In this technique patient is gradually exposed to some aversive stimuli.
And then Duration, intensity & frequency of stimulus is slowly increased
Ex: Singer technique