2. ACKNOWLEDGEMENT
We are extremely thankful to all the staff members of
the Department of Prosthodontics throughout our
clinical posting.
The immense knowledge and experience of Dr.Tejasvi
Saigal and his continuous help,support and
encouragement has been extremely useful to us.
We would like to thank Dr. Krishan Dudeja for
their skillful and gentle support in the presentation of
content.Without their active participation and help
this project would have been impossible to complete.
3. The posterior palatal seal is defined as, “the soft
tissues along the junction of the hard and soft
palates on which pressure within the
physiological limits of the tissues can be applied
by a denture to aid in the retention of the
denture”.
4. FUNCTIONS OF THE POSTERIOR
PALATAL SEAL
The function of the posterior palatal seal in the completed
maxillary prosthesis is to :--
Maintain contact with the anterior portion of the soft
palate during functional movements of the
stomatognathic system (i.e mastication, deglutition and
phonation). Therefore,the primary purpose of the
posterior palatal seal is the retention of the maxillary
denture.
The posterior palatal seal that has been correctly
diagnosed and incorporated into the prosthesis reduces
the gag reflex.
5. Reduces food accumulation beneath the posterior
aspect of the denture.
Reduces patients’ discomfort when contact occurs
between the dorsum of the tongue and the
posterior end of the denture base,as the posterior
denture border will closely approximate the soft
palatal tissues.
Compensate for the volumetric shrinkage that
occurs during the polimerization of methyl
methacrylate resin.
6. ANATOMIC AND PHYSIOLOGIC
CONSIDERATIONS
The posterior palatal seal is divided into two
separate but confluent areas based upon
anatomic boundaries. The post palatal seal
extends medially from one tuberosity to the
other.
Laterally, the pterygomaxillary seal
extends through the ptrygomaxillary notch
(hamular notch),continuing for 3 to 4 mm
anterolaterally approximating the mucogingival
junction.
7. A. Pterygomaxillary seal extends through the
pterygomaxillary notch.
B. Postpalatal seal extends medially from one
tuberosity to the other.
C. Posterior palatal area lies between the
anterior and posterior vibrating lines.
8. ANTERIOR AND POSTERIOR
VIBRATING LINES
The posterior palatal seal area lies between the
anterior and posterior vibrating lines.
The anterior vibrating line is an
imaginary line located at the junction of the
attached tissues overlying the hard palate and
the movable tissues of the immediately adjacent
soft palate.
One way to locate the anterior vibrating line
is to have the patient perform the Valsalva
maneuver, which requires thet both nostrils be
held firmly while the patient blows gently
through the nose.
9. The anterior vibrating line can also be
approximated by visualizing the area while
instructing the patient to say “Ah” with short
vigorous bursts.
Due to the projection of the posterior
nasal spine,the anterior vibrating line is not a
straight line between both hamular processes.
The anterior vibrating line is always on soft
palatal tissues.
10. POSTERIOR VIBRATING LINE
The posterior vibrating line is an imaginary line at the
junction of the aponeurosis of the Tensor veli palatini
muscle and the muscular portion of the soft palate.
It represents the demarcation between
that part of the soft palate that has limited or shallow
movement during function and the remainder of the
soft palate that is markedly displaced during
functional movements.
11. The methods used to mark the posterior palatal
seal area are:-
i. Conventional approach
ii. Fluid wax technique
iii. Arbitrary scraping of the master
cast
12. CONVENTIONAL APPROACH
This procedure is done after the impression is
made and the master cast is poured.
A trial base is fabricated using shellac base plate or
a well-adapted self cure resin.
The patient is asked to sit in an upright position
and asked to rinse his mouth with some astringent
mouth wash.
The posterior palatal area is wiped with gauze.
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.
13. The hamular notch is marked using indelible pencil
The posterior vibrating line is marked between the movable
and immovable soft palate,using an indelible pencil by
asking the patient to say “Ah” in a non-vigorous manner
14. The line marked in the hamular notch is connected
with the posterior vibrating line using an
indelible pencil.This’ll form the posterior border
of the denture.
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.
15. The trial base is trimmed till the posterior border.
The anterior vibrating line is marked in the patient’s
mouth using an indeloble pencil.While recording the
anterior vibrating line,the patient should perform the
Valsalva maneuver.The markings are transferred to
the master cast.
The anterior vibrating line is marked at the junction
of hard & soft palate using an indelible pencil.
16. The area between the anterior and posterior vibrating line
is scraped 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 1mm in depth.
The posterior border of the posterior palatal seal should be
tapered so that it blends with the palatal tissues.The entire
border of the post palatal seal resembles the shape of a
Cupid’s bow.
The markings of the anterior and posterior vibrating lines
are transferred to the cast.The cast should be scraped to a
depth of 1 to 1.5mm in the area between the two vibrating
lines.
17. ADVANTAGES OF THE
CONVENTIONAL TECHNIQUE.
The trial base’ll be more retentive; this can
produce more accurate maxillomandibular
records.
Patient’ll be able to experience the retentive
qualities of the trial base.
The new denture wearer’ll be able to realize the
posterior extent of the denture.
18. DISADVANTAGES
It is not a physiologic technique and therefore
depends upon accurate transfer of the vibrating
lines and careful scraping of the master cast.
The potential for overcompression of the tissues
is great.
19. FLUID WAX TECHNIQUE
This technique is done immediately after
marking the wash impression and before pouring
the master cast.
Zinc oxide eugenol and impression plaster are
suitable impression materials for this technique
as fluid wax adheres well to them.
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 wash
impression.
20. The markings are transferred to the secondary or
wash impression by reseating the impression in
the mouth.
The wash impression is painted with fluid wax.
Commonly used waxes are Iowa wax (white) by
Dr.Smith, Korecta wax no:4 (orange) by
Dr.O.C.Applegate, Adapted wax(green) by
Nathan.G.Kaye and H-L physiologic paste
(yellow-white) by CS Harkins.
The wax should be painted only within the
margins of the palatal seal marked on the
impression.Usually it is applied in excess and
cooled below mouth temperature so that it gains
resistance to flow.
21. These waxes soften at mouth temperature and
flow intraorally during impression making.
The patients’ head should be positioned such that
the Frankfort’s horizontal plane is 30o below the
horizontal plane.It is only at this position that
the soft palate is at its maximal downward and
forward functional position.Flexion of the head
also helps to prevent aspiration of the impression
material and saliva.
The patients’ tongue should be positioned such
that it is at the level the mandibular
anteriors.This action helps to pull the
palatoglossus anteriorly.
22. In completely edentulous patients’,the handle of the
maxillary custom tray should be designed such that it
acts like the lower anteriors to guide the tongue
during impression making.
After positioning the head and the tongue,the
impression tray is inserted into the mouth and the
patient is asked to make rotational movements of his
head without altering the plane to record the
functional movements of the palate.
The impression is removed after 4-6 minutes and
examined. In contrast to green stick compound, glossy
areas, show tissue contact. Dull areas show areas
which were not in contact with the tissues. The
impression should show uniform tissue contact. Areas
which appears dull,are added with more wax and the
procedure is repeated.
23. Every time the impression is reinserted, the
impression should be held for 3-5 minutes under
gentle pressure and 2-3 minutes under firm pressure
applied in the mid-palatine area.
The procedure is repeated till even tissue contact is
achieved. After achieving even tissue contact, the
impression is removed and reexamined.
The wane in the region of the anterior vibrating line
should have a knife-edge margin. Blunt edge margins
indicate improper flow and the impression should be
repeated.
Fluid wax extending beyond the posterior vibrating
line should be cut with a hot knife. The impression is
redefined again till feather-edge margins are
produced.
24. ADVANTAGES OF FLUID WAX
TECHNIQUE
Its is a physiological technique.
Chances of overcompression of tissues are less.
Increased retention of the trial base and
convenience in jaw relation.
25. DISADVANTAGES
Handling of the material is very difficult.
Increased chair-side time during patient
appointment.
26. 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. Scrapes 0.5 to 1mm 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.
27. ERRORS IN RECORDING THE
POSTERIOR PALATEL SEAL
The following errors can occur while recording the
posterior palatal seal.
Underextension:- Most common
cause. May be produced due to following reasons.
When the denture does not cover the
foveapalatina, the tissue coverage is reduced &
the posterior border of the denture is not in
contact with the denture border during functional
movements.
Improper delineation of the anterior and
posterior vibrating lines.
28. Excessive trimming of the posterior border of the
denture by the dental technician.
There are patients who inform the dentist on the
very first visit for complete denture therapy that
they are gaggers. The dentist intentionally leave
the posterior borders underextended in order to
reduce the patients’ anxiety in gagging…
OVEREXTENSION:- Overextension of the
denture base can lead to ulceration of the soft
palate and painful deglutition.Covering of the
hamular process can lead to sharp pain in that
region.In order to relieve these areas ,indelible
pencil markings are made on them (hamular
process, ulcers, etc) and transferred to the
denture.These regions are trimmed and polished.
29. UNDERPOSTDAMMING:- This can
occur due to improper head positioning & mouth
positioning, eg:- When the mouth is wide open
while recording the posterior palatal seal the
mucosa over the hamular notch becomes
taut.This’ll produce a space between the denture
base and the tissues.
Inserting a wet denture into a patient’s mouth
and inspecting the posterior border with the help
of a mouth mirror can identify underdamming..
If air bubbles are seen to escape under the
posterior border,it indicates underdamming.
In order to correct underdamming,the master
cast can be scraped in the posterior palatal area
or the fluid wax impression can be repeated with
proper patient position.
30. OVERPOSTDAMMING:- This
commonly occurs due to excess scraping of the
master cast.It occurs more commonly in the
hamular notch region.
Mild overdamming in the hamular notch region
can lead to tissue irritation of the mucosa and
excessive postdamming produces downward
displacement of the denture posteriorly.
Selective reduction of the denture border with a
carbide bur, followed by lightly pumicing the area
while maintaining its convexity will remedy the
problem.
