PRIMARY AND
SECONDARY
IMPRESSION
MAKING FOR
COMPLETE
DENTURE &
RECORDING OF
POSTERIOR
PALATAL SEAL
2
TRAY SELECTION AND ADJUSTMENT
(Fenn)
• Examine the edentulous mouth and access the
length and the width of the arch.
• An edentulous stock metal tray is to be 5-6 mm larger
outside surface of the ridge .
• Undersized tray will effect the support and stability of
denture.
• The border of the stock tray are lined with a strip of
soft boxing wax to confine the impression material
(Alginate).
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MATERIALS FOR PRIMARY IMPRESSION IN
COMPLEATE DENTURE
1-IMPRESSION COMPOUND
2-ALGINATE
3-IMPRESSION PLASTER ( class I- Gypsum product)
SEQUENCE OF MAKING THE IMPRESSIONS
• Maxillary impression cause greater discomfort
- anxiety (retching reflex)
• Foreign body placed in the mouth produce an increase in rate of
salivation.
• So preferable Mandibular impression making first
.
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MAKING PRIMARY IMPRESSION WITH
IMRESSION COMPOUND(Fenn)
• Compound (Brown) has the highest working temperature(132-133 degree
F,or 55.5-56.1degree C), is stronger at room temperature ,and is suitable for
extending short borders on the custom tray .
1. The select composition is placed in water bath preferably thermostatically
controlled to maintain the recommended temperature after a few min.
2. The compound is removed from the bath ,folded repeatedly from the edges
to the center .
3. Kneading of the compound incorporate water which act as a plasticizer, this
procedure is repeated until the material has a uniform softness through out,
when compound is ready for use the metal tray is warmed, the compound
form into suitable size and placed in the tray.
4. And perform all border moulding movements
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Making Maxillary Impression (compound)
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The compound form into a ball and placed in the center of the palate of the
warm tray.
It is then moulded outward to the periphery until the whole tray is filled
leaving a smooth , uncreased surface indented to form a trough for the ridge.
Slightly rise in the middle for palatal vault, excessive pressure together with
an compound in the palatal region will cause it to flow backward cause
vomiting, once the compound has been adapted to the tray, the surface is
lightly flamed tempered in water bath insert in the mouth.
Keeping the tray handle in line with middle saggital plane of the face.
Firm upward pressure now seat the impression in place ready for peripheral
molding
The buccal sulci and labial sulci and frenum
are moulded by manipulating alternate cheeks and lips upward ,outward
,downward , inward and slightly backward and forward to obtain the functional
position.
After few minutes remove impression may be immersed in a 20 aqueous
solution of chlorhexidine gluconate to avoid infection
UPPER IMPRESSION
Making Mandibular Impression
• A trough may be indented in the compound with the finger
to simulate the ultimate ridge impression, the surface
quickly flame so surface detail will be recorded and
tempered by immersing in the warm water, to avoid
burning the patient.
• The tray is placed in the mouth after that, patient instruct
to rise and slightly protrude the tongue.
• As this movement begins the tray is pressed vertically
downwards to seat the impression to desired depth.
8
• Pressure in backward direction may also be required to contour the
forward thrust from the tongue when protruded.
• This movement of the tongue rises the floor of the mouth and tense
the lingual frenum. The buccal sulci that moulds the compound into
the lingual sulcus to rised positioned of these structure.
• The buccal sulci and frena are moulded by manipulating alternating
cheeks and lips downward ,outward,inward,and slightly backward
and forward to obtain approximate functional position .
• After the impression material set, remove it after few min, chill
thoroughly in cold water and inspect the upper impression.
LOWER IMPRESSION
Primary Impression in
Impression Compound
BORDER MOULDING
MANDIBULAR
MAXILLARY
FINAL IMPRESSION
• The wax spacer is removed from inside the tray along
with any border molding material that has flown over it.
• Finally holes are made in the impression tray with a
medium sized round bur.
• These holes furnish relief during the making of the final
impression and also provide escape ways for the final
impression material.
• The holes are drilled over the medial palatal raphe and in
the anterolateral and posterolateral regions of the hard
palate in the maxillary tray.
• In the mandibular tray holes are drilled in the centre of
the alveolar groove and over the retromolar pads.
• Materials available are Impression Plaster, Zinc oxide
eugenol impression paste, Poly ether, Silicone impression
materials, Irreversible hydrocolloid.
Final Impression in
Metallic Oxide Pastes
Recording Of Posterior palatal seal
• The posterior palatal seal extends medially from one
tuberosity to the other.
• Laterally the pterygomaxillary seal extends through the
hammular notch continuing for 3to 4 mm anterolaterally
approximating the mucogingival junction.
• It is defined as the soft tissue area at or beyond the
junction of the hard and soft palate on which pressure
within physiologic limits can be applied to aid in retention.
GPT 8
Functions
• Aids in retention
• Aids in compensating for the dimensional changes in
curing
• Firm contact with the tissue of the soft palate reduces the
tendency to gag.
• Reduces food accumulation beneath the posterior aspect
of the denture.
Macroscopic anatomy
Anterior
vibrating line
Posterior Palatal
Seal area
Posterior
vibrating line
Pterygomaxillary
seal
Vibrating line
• Anterior Vibrating Line
Imaginary line located
at the junction of the
attached tissues
overlying the hard
palate and movable
tissues of immediately
adjacent soft palate.
Posterior vibrating line:
• It represents the demarcation between the part of the soft
palate that has limited or shallow movement during
function and remainder of the soft palate that is markedly
displaced during the functional movements.
Methods to record the Posterior palatal
seal
• Conventional approach
• Fluid wax technique
• Arbitrary scraping of the cast.
Conventional approach
• This procedure is done after the final impression
is done and the master cast is poured.
• A trial base is fabricated using shellac base plate
or a well-adapted self-cure resin.
• The "T” burnisher is used to locate the hamular
notch by palpating posteriorly to the maxillary
tuberosity on both sides. The full extent of the
hamular notch is marked with an indelible pencil
• The posterior and the anterior vibrating line is marked
in the patient’s mouth by asking the patient to say “ah”.
• The trial base is inserted into the patient's mouth so
that the indelible markings are transferred to the trial
base.
• The trial base is seated on the master cast to transfer
the markings marked in the patient's mouth to the cast.
• The area between the anterior and posterior vibrating
line is scrapped in the master cast to a depth of 1 to
1.5 mm on either side of the mid-palatine raphe.
• In the region of the mid-palatine raphe, it should be
only 0.5 to 1 mm in depth.
Advantages of the conventional technique :
• The trial base has increased retention due to this
technique.
• The patient can experience the retentive qualities of the
denture at an earlier stage.
• The patient has an idea of the posterior extent of the
denture base.
• Final adjustments during insertion are minimized.
Disadvantages of the conventional
technique
• It is not a physiological technique, hence, it is
technique- sensitive.
• Excessive scrapping of the cast can frequently lead
to tissue compression.
Fluid Wax Technique
• This technique is done immediately after making the
final impression and before pouring the mater cast.
• The anterior and posterior vibrating lines are marked as
described in the conventional technique.
• These lines are marked in the patients mouth
immediately after making the final impression.
• The markings are transferred to the secondary impression
by reseating the impression in the mouth.
• The final impression is painted with fluid wax. Commonly
used is korecta wax no.4
• The wax should be painted only within the margins of the
palatal seal marked on the impression.
• The patient’s head should be positioned such that the
Frankfort’s horizontal plane is 30 degrees below the
horizontal plane.
• It is only at this position that the soft palate is at the
maximal downward and forward functional position.
• The impression tray is inserted in the mouth and the
patient is asked to make rotational movements of his
head.
• The glossy areas show tissue contact whereas the dull
areas show areas which were not in contact.
• The wax in the region of the anterior vibrating line should
have a knife edge margin.
Advantages of fluid wax technique
• It is a physiological technique.
• Chances of over compression of tissues are less.
• Increased retention of the trial base and
convenience in jaw relation.
• There is no need for scrapping the master cast
arbitrarily.
Disadvantages of fluid wax technique
• Handling of the material is very difficult.
• Increased chair-side time during patient
appointment.
Arbitrary Scrapping of the Master Cast
• In this technique, the anterior and posterior vibrating lines
are visualized by examining the patient's mouth and
approximately marked on the master cast.
• The lab technician scrapes 0.5 to 1 mm of stone in the
posterior palatal seal area of the master cast and
fabricates the denture.
• This technique is inaccurate and not physiological and
should be avoided.
• Ansari in 1997 described a procedure for adding posterior
palatal seal at the final impression stage with green stick
modeling compound. 2
• After the final impression is made using zinc oxide
eugenol paste, anterior and posterior vibrating lines are
marked in the mouth which are then transferred onto the
impression.
• Criss cross grooves are
made within the pencil
outline.
• Soften green stick
compound is placed within
the outline of the PPS area.
• Chill the compound and then re-soften the compound with
a pinpoint flame.
• Carry the impression in the patients mouth and hold it in
place under gentle pressure.
• The effect of the PPS is checked with an upward pressure
on the anterior region of the impression tray.
• An easy break of the seal indicates further compression of
tissue is required.