Special impression techniques/ dentistry dental implants

INDIAN DENTAL ACADEMY
Leader in continuing dental education
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SPECIAL IMPRESSION TECHNIQUES
IMPRESSION PROCEDURE FOR THE SEVERELYIMPRESSION PROCEDURE FOR THE SEVERELY
ATROPHIED MANDIBLEATROPHIED MANDIBLE
WAX BASE DEVELOPMENT FOR COMPLETE DENTUREWAX BASE DEVELOPMENT FOR COMPLETE DENTURE
IMPRESSIONSIMPRESSIONS
IMPRESSIONS OF UNSUPPORTED MOVABLE TISSUESIMPRESSIONS OF UNSUPPORTED MOVABLE TISSUES

Severely resorbed mandibular ridge
• Lack of ideal amount of supporting structures decreases support and
encroachment of the surrounding mobile tissues onto the denture
border reduces both stability and retention. The main aim is to gain
maximum area of coverage.
• Flange technique by Lott & Levin(1966) involves making impressions
of the soft structures of the mouth adjacent to the buccal, lingual and
palatal surfaces and incorporating the resulting extension or flange
into the denture.
• Tryde(1965) used the dynamic impression method. – Dynamic
impression methods.JPD 1965;VOL-16
• Krammeck used modelling compound to record the extensions.

Hypermobile or hyperplastic ridges
• These ridges should be recorded without
distortion.
Zafrulla Khan technique( 1981).
Hobkirk technique – rubber base material
Filler technique- two tray technique.

WINDOW TECHNIQUE
• Jaggers, Shay and Zafrulla Khan : Impressions
of unsupported movable tissues; JADA october 1981,
103; 590-592

• In conditions where
patients have worn
maxillary complete
denture opposed only
by mandibular anterior
teeth.

COMBINATION SYNDROME
• KELLY (1972)
introduced the term
“Combination
Syndrome”

• The remaining soft tissues in the anterior maxillary
region are easily distorted by routine impression
procedures, resulting in an unstable denture base.
• Surgical reduction of the pliable tissues often results
in the loss of the anterior mucobuccal fold area.
this may cause retention problems

• To avoid these
problems, a technique
that minimises
distortion when
impressions of
edentulous arches with
unsupported, moveable
tissues are made is
used.

PROCEDURE
• A primary impression is made and
a cast is poured.
• An indelible pencil is used to
outline the unsupported movable
tissue.
• A single custom tray is made, and
an opening is cut in the tray as
indicated by the transfer of
indelible pencil line.

• Modelling plastic is adapted bilaterally on the
posterior aspect of the tray to act as handles.
• The tray is adjusted in the mouth, and a routine
border molding is formed.

• The tray is painted with
an adhesive and a
regular body impression
is made.
• The excess material is
trimmed to the outline
of the aperture

• The completed base impression is returned to the
mouth.
• This impression does not touch the unsupported
tissues.

• Then a highly mucostatic
impression material,
impression plaster is
brushed on the
unsupported movable
tissue.
• The initial layer precludes
entrapment of air and
enables visualisation of the
unsupported tissue.

• A separating media is
applied to the
impression plaster and
the master cast is made

AN IMPRESSION PROCEDURE FOR THE SEVERELY
ATROPHIED MANDIBLE : JPD 1995 ; 73(6); 574-577
DeFranco and Sallustio
JPD; june 1995; 73(6); 574-577

• The objective is to maximize the supportive aspect of
the available denture foundation by two approaches
- Functional
- Anatomic

• Peripheral borders are developed functionally with
the mouth closed
• The final phase of impression is made with the
mouth open to satisfy the anatomic approach

PROCEDURE
• A maxillary final impression is made and cast is
poured
• Construct a record base for the maxillary cast and
develop a flat wax occlusal rim.

• Make a preliminary impression of the mandible and
make a lower tray to be used initially as a record
base with a flat wax occlusion rim.
• Make a jaw registration at a selected vertical
dimension of occlusion.

• Develop the border
extensions with tissue
conditioning material.
• Develop the lingual borders
with the mouth open and
have the patient make
essential tongue
movements.
• Also instruct the patient to
border mold the material
physiologically by producing
“ooo” and “eee” sounds
while biting on the occlusal
rim.

• Repeat the step as often as necessary to develop
proper extension.
• Relieve the tray wherever it shows through the
conditioning material before each subsequent
addition.
• Remove overextensions with a hot knife blade.

• Leave each application of
conditioning material in the
mouth approx. 10 minutes
to allow it to stabilize.
• After the desired extensions
are formed with the
conditioning material, make
the final second impression
with a polysulfide rubber
impression material with
the mouth open and use
standard border molding
procedures.

• Pour the cast
immediately to avoid
distortion of the
material.

• This procedure will provide the patient with a
denture that has function with maximum support
and stability.
• The greatest disadvantage of this procedure is the
amount of the time necessary to develop the final
impression. The average appointment time needed is
45-60 mins.

• Appelbaum and Rivetti : WAX BASE
DEVELOPMENT FOR COMPLETE DENTURE
IMPRESSIONS; JPD; may 1985; 53(5); 663-666

Developing the base with mouth
temperature wax
• A preliminary functional impression tray with wax
occlusion rims is made with an opposing occlusion
rim or denture.
• The tray trimmed to relieve functioning muscle
impingements.
• A closed mouth impression with mouth temperature
wax is made to establish maximum coverage within
tissue tolerance.

• The IOWA wax is prepared in a container in a hot
water bath and is applied to the tray with a soft
brush. (firm contact produces glossy surface)
• After full ridge tissue contact is made, wax is applied
to the borders and is adapted to the functioning
musculature to develop the border and flanges of
impression tray.

• Essential actions :
- Protrusion and retrusion of the lips for the facial musculature
(“proo-wiss”)
- Moving the mandible laterally and protrusively to record
coronoid process of mandible
- Placing the tongue alternatively into the cheeks and by
wiping the lips by the tongue to develop lingual and
retromylohyoid flange of mandibular tray

• The impression is allowed to remain in the mouth
and allowed to remain for 8 to 12 minutes to permit
as close adaptation of the wax to all surfaces as
possible.
• During this period, the patient periodically performs
the approppriate muscle functions. And then ice-cold
water is poured into the mouth to chill the wax, and
the impression is carefully removed.

• Impression is boxed by plaster
and pumice and cast is poured.
• Separating media is applied on
the cast and after the separating
media has dried, an
autopolymerising soft resilient
liner is applied to the undercuts.
• Spacer is applied and a resin tray
is fabricated

• When the tray resin has set, the
bottom side of the cast is
reduced on a cast trimmer just
short of contact with the tray
material.
• The cast with tray is placed in hot
water to soften the wax shim and
the cast is fractured with a
hammer to permit recovery of
the tray without damage

• Wax spacer is removed, and
excess resin is removed from the
tray.
• The final impression material,
metallic oxide paste is mixed
according to manufacturer’s
directions and loaded into the
tray.
• Impression material is wiped
along all the flanges of the
impression tray in contact with
functioning musculature.

• The patient is instructed to perform the previously
described muscular movements while the impression
material is developing its body.
• The tray is removed from the mouth after the
material has set and the impression is inspected.

• This technique permits the harnessing and stabilizing
effects of an active musculature to operate on the
ultimate denture base.
• The musculature imparts properties of retention and
stability to the base that will tend to provide the
greatest longevity for the residual alveolar ridge.

Special impression techniques/ dentistry dental implants

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