Posterior palatal seal By Dr Tanu Mahajan

1. FACULTY OF DENTAL SCIENCES
POSTERIOR PALATAL SEAL
Dr Tanu Mahajan
Professor & Head
Department of Prosthodontics

2. POSTERIOR PALATAL SEAL

3. Definition
The soft tissues along the junction of
hard and soft palates on which
pressures within the physiological
limit of the tissues can be applied by
a denture to aid in the retention of
the denture.
Glossary of prosthodontics

5. Anatomical location:
It is the line along the posterior part of the
palate that marks the transition between the
movable and the immovable tissues of soft
palate. The posterior palatal seal is divided
into two separate but confluent areas based
upon anatomic boundaries.
It extends medially from one tuberosity to the
other.
Laterally, the pterygomaxillary seal extends
from the hamular notch continuing for 3-4
mm anterolateral approximating the
mucogingival junction.

6. Physiological consideration of
posterior palatal seal area:
Pterygomaxillary notch
Pterygomandibular fold
The hamular process
The fovea palatini
The median palatal raphe
Midpalatal fissure

7. Function of the posterior
palatal seal
helps in the retention and stability
maintaining the adequate seal
prevents passage of air between
denture and the tissues.
reduction in the gag reflex.
Reduces patient discomfort

8. Diagnostic evaluation and
placement:
The proper placement of the posterior palatal
seal begins with the intraoral examination.
The morphological contours of the hard and
the soft palate hamular notch regions and the
integrity and displacability of the mucosa and
the underlying glandular tissue should be
evaluated and noted.
Observation and palpation are essential
elements in formulating the proper diagnosis
and treatment plan.

9. Anterior and posterior
vibrating line:
The posterior palatal seal area lies
between anterior and posterior
vibrating lines. The location of these
lines may vary according to the contour
of the soft palate.

11. THE ANTERIOR VIBRATING
LINE
It is located at the junction of the attached tissues overlying the
hard palate and the movable tissues of the immediately
adjacent soft palate. Due to the projection of the posterior nasal
spine the anterior vibrating line is not a straight line between
both the hamular processes. It is always on the soft palatal
tissues.
By making the patient performing the valsalva maneuver – in
which both the nostrils are held firmly while the patient blows
gently through the nose as it positions the soft palate inferiorly
at its junction with hard palate.
Asking the patient to say hah with short and vigorous bursts
and then visualizing the area.

12. The posterior vibrating line:
It is an imaginary line found at the junction of
the tensor veli palatini muscle and the
muscular portion of the soft palate. 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 movement. It marks the
most distal extension of the denture base.
It is located by asking the patient to say Ah in
short bursts in normal.

13. Soft palate classification
There are three classes
of the soft palate
configuration based on
the angle made by the
hard palate with the
soft palate.

14. PLACEMENT TECHNIQUE
A correctly placed posterior placed seal
will not impinge upon the non-
displaceable tissues of the hard palate
nor will it limit the movement of the
soft palate
Conventional Approach
Fluid Wax Technique
Arbitrary Scraping of Master Cast

15. Conventional Approach
well-adapted resin or shellac tray is fabricated on
the stone cast
The patient is seated in an upright position
The posterior palatal area is then dried with
gauze; a "T" burnisher or a mouth mirror is used
to palpate for the hamular processes
Once located, they should be marked with an
indelible pencil or noted visually to ensure that
they not covered by the denture

16. Conventional Approach
The instrument is then placed along the
posterior angle of the tuberosity, until it
drops into the pterygomaxillary notch
A line is placed with an indelible pencil
through the notch and extended 3 to 4
mm anterolateral to the tuberosity
This will complete the outlining of the
pterygomaxillary seal

17. Conventional Approach
The patient is asked to say "ah" in short bursts
in an unexaggerated fashion. While observing
the movement of the soft palate
By connecting the line through the
pterygomaxillary seal with the line just drawn
demarcating the "post palatal" seal (posterior
vibrating line), the posterior denture extension
is delineated
The resin or shellac tray is then inserted into
the mouth and seated firmly to place
Upon removal from the mouth, the indelible
lines should have been transferred to the tray

18. Conventional Approach
Returning again to the mouth, the palatal
tissues anterior to the posterior border are
palpated with the "T" burnisher
The termination of the glandular tissues
usually coincides with the anterior vibrating
line
The visual outline is in the 'shape Of Cupid's
bow
The area between the anterior and posterior
vibrating lines is usually narrowest in the
midpalatal region because of the projection of
the posterior nasal spine

19. Fluid Wax Technique
All of the procedures regarding the location and
transfer marking of the anterior and posterior
vibrating lines delineated under the conventional
approach are performed for the fluid wax technique
However, the indelible transfer markings are
recorded on the final wash impression
Zinc oxide and eugenol or plaster are preferred over
the elastic impression materials, as they set rigid.
Impressions made with elastic materials are slightly
resilient, and when reseated in the mouth under
pressure may distort the relationship between wax
added to the posterior border and the rest of the
denture bearing surface

20. ADVANTAGES
1. It is a physiologic technique displacing
tissues within their physiologically
acceptable limits.
2. Over compression of tissues is avoided.
3. Posterior palatal seal is incorporated into
the trial denture base for added retention.
4. Mechanical scraping of the cast is avoided.

21. DISADVANTAGES
1. More time is necessary during the
impression appointment.
2. Difficulty in handling the materials,
and added care during the boxing
procedure.

22. Arbitrary Scraping of Master
Cast
This technique is the least accurate and leaves
the most to chance at the insertion
appointment. It relies upon the dentist's
recollection of the palatal configuration and
tissue compressibility in order to
"guesstimate" the anterior and posterior
vibrating lines and the depth to which the cast
should be scraped- This technique is almost
as physiologically wrong as the technician's
attempts to place the posterior palatal seal at
the dentist's request.