Posterior Palatal Seal Parameters

Posterior Palatal Seal
Presented by: Swapnaneel P Guided by: Dr. Eswaran B

Contents
• Supporting and Limiting structures of maxilla
• Definition
• Functions
• Anatomic and Physiologic Considerations
• Parameters of PPS
• Techniques to record PPS
• Trouble shooting

Supporting Structures
• Mucous membrane
• Hard palate
• Residual ridge
• Maxillary tuberosity
• Rugae
Prosthodontic Treatment for Edentulous Patients, Jarb Bolender; pg. 212

Peripheral or Limiting Structures of Maxilla
1. Labial Vestibule
2. Labial frenum
3. Buccal Vestibules
4. Buccal frenum
5. Vibrating Lines
6. Hamular notch
Prosthodontic Treatment for Edentulous Patients, Jarb Bolender; pg. 214

Definition
Posterior Palatal Seal area:
“The soft tissue area limited posteriorly by the distal demarcation of
the movable and non-movable tissues of the soft palate and anteriorly by the
junction of the hard and soft palates on which pressure, within physiologic
limits, can be placed; this seal can be applied by a removable complete
denture to aid in its retention.” – GPT 9
Posterior Palatal Seal:
“That portion of the intaglio surface of a maxillary removable
complete denture, located at its posterior border, which places pressure,
within physiologic limits, on the posterior palatal seal area of the soft palate;
this seal ensures intimate contact of the denture base to the soft palate and
improves retention of the denture.” – GPT9

Functions of PPS
• Retention of Maxillary Denture
• Prevent food accumulation
• Increases patient comfort and reduces gag reflex
• Compensate for the volumetric shrinkage of methyl methacrylate resin
that occurs during polymerization.
Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 146

Anatomic and Physiologic
considerations

Soft palate
• Musculo-membranous curtain.
• Functions as flap valve closes off
nasopharynx during swallowing.
• Part of a dual valve system which
separates the oropharynx from the
oral space and the nasopharynx from
the nasal space.

Soft palate
• The function of the soft palate in these
dual valving actions requires freedom of
movement in three dimensions or
planes of space, i.e., superior-inferiorly,
mediolaterally and antero-posteriorly.
• An impression should be made patient is
seated in upright position, with head
flexed 30 degrees forward and placing
the tongue under tension against either
handle of impression tray or dentist’s
fingers, and should not protrude beyond
lips.

Muscles of soft palate
Palatoglossus
• Origin – Palatine aponeurosis
• Insertion - Side of tongue
• Action - Draws palate down,
raises tongue

Palatopharyngeus:
• Origin – Arises as 2 fasciculi –
Posterior fasciculi arises from
palatine aponeurosis and anterior
fascicule from posterior border of
hard palate.
• Insertion – Lamina of thyroid
cartilage, wall of pharynx and its
median raphe.
• Action – Helps in pulling up the
wall of pharynx and shortens it
during swallowing.

• Tensor Veli Palatini - When taut,
can influence the denture
contour in the hamular notch
area.
• Levator Palati - Closing of the
oropharynx from the
nasopharynx during swallowing
and determining the position of
the vibrating line.
• Palatopharyngeus – On
contraction, draw the tongue
and soft palate towards each
other.

Pterygomaxillary notch/Hamular notch
• Band of loose connective tissue lying between the
pterygoid hamulus of the sphenoid bone and the
distal portion of the maxillary tuberosity.
• Lateral boundaries for the PPS.
• The pterygomaxillary notch is covered by
pterygomandibular fold which extend from the
posterior aspect of the tuberosity posteroinferiorly
to insert into the retromolar pad.
• It influences the posterior border seal when the
mouth is wide open during the final impression
procedure.
• Hamular notch is covered by a thin mucous
membrane. Thus should not be covered by denture.

Hamular process
• 2-4mm postero-medial to the
distal limit of the maxillary residual
ridge.
• Affects the length and direction of
the pterygomaxillary seal.
• Covered by mucous membrane
and should not be covered by
denture.

Mid palatine raphe
• This overlies the medial palatal suture, contains
little or no submucosa and will tolerate little
compression.
• According to Heartwell and Rahn, this band of
tissues is not meant to be compressed, rather
should be relieved if prominent.
• When a prominent mid-palatine fissure is present
in hard palate, it often extends to the soft palate.
• When this fissure is present it should be carefully
reproduced in the master cast and posterior seal
should be extended into this fissure for proper
peripheral seal.

Fovea palatini
• Two glandular openings within the tissues of
posterior portion of hard palate, usually lying on
either side of midline.
• They are the ductal openings into which the ducts of
other palatal mucosal glands drain.
• According to Lye, they are located, on average,
1.31mm anterior to anterior vibrating line.
• According to Chen, majority were located on or
behind the anterior vibrating line.
• Thus, they do not represent the junction of hard and
soft palate and should be used only as a guideline to
placement of posterior palatal seal.

Vibrating Line
“An imaginary line across the posterior part of the soft palate
marking the division between the movable and immovable tissues; this
line can be identified when the movable tissues are functioning.”
– GPT 9
• Anterior Vibrating line
• Posterior Vibrating line

Anterior Vibrating Line
• It is an imaginary line lying at the junction between the immovable
tissues of the hard palate and the slightly movable tissue of the soft
palate.
• Cupid bow’ shaped due to the projection of posterior nasal spine.
• Always on soft palate.

Locating:
1. Patient is asked to say “AH” with short vigorous bursts due to
projection of the posterior nasal spine.
2. “Valsalva” Maneuver

Posterior Vibrating Line
• An imaginary line at the junction of Tensor veli palatini muscles in the
muscular portion of the soft palate. – Sheldon Winkler
• It represents the demarcation between the part of the soft palate that has
limited or shallow movement during function and the remaining soft
palate that shows marked displacement during functional movements.
• Marks the most distal extension of the denture base.
• Locating: patient is instructed to say “AH” in short vigorous burst in a
normal unexaggerated fashion.

Classification of Soft Palate
• Classified as:
• Class I
• Class II
• Class III
• Based upon the angle the soft palate
makes with the hard palate.
• The more acute the angle of the soft
palate in relation to the hard palate, more
muscular activity will be necessary to
effect velopharyngeal closure (closing of
the nasopharynx).
• So the more the soft palate is markedly
displaced in function, the less that can be
covered by the denture base.
• Determined when the patient is in
upright position with the head held erect.

Class I
• Soft palate is rather horizontal
when extended posteriorly with
minimum muscular activity.
• Considerable separation (>5mm)
between anterior and posterior
vibrating lines. (Wide PPS)
• Most favorable configuration as
more tissue surface can be covered
and thus gives best Retention.
Posterior Palatal seal – A Literature Review, International Journal of Prosthodontics and Restorative Dentistry; Bindhoo et. al

Class III
• Soft palate is acute in comparison to
hard palate.
• <1 mm separation between anterior
and posterior vibrating lines.
• Small PPS area and thus less
retentive.
• Often found in conjugation with High
V shaped palatal vault.

Class II
• Soft palate contour lies
somewhat between Class I
and Class III allowing 1 to
5mm of seal area depending
on the muscular activity of
the soft palate.

Palatal Throat Form (House classification)
• Class I : Large and normal in form with a relatively
immovable band of resilient tissue 5-12 mm distal
to a line drawn across distal edge of the
tuberosities.
• Class II : Medium size and normal in form with
relatively immovable resilient band of tissue 3-5
mm distal to a line drawn across distal edge of the
tuberosities.
• Class III :- Usually accompanies a small maxilla. The
curtain of soft tissues turns down abruptly 3-5 mm
anterior to a line drawn across distal edge of the
tuberosities.

Pterygomaxillary seal
• Extends through pterygomaxillary notch continuing 3-4 mm
anterolaterally approximating the mucogingival junction.
• Occupies the entire width of hamular notch.

Size
• According to Hardy and Kapur (1958) , the dimension of PPS was 2 mm at
the mid-palatal region and hamular notch and 4mm at the greatest
curvature region of PPS.
• Silverman performed a study on 92 patients & found the following –
• The greatest mean anteroposterior width of PPS is 8.0 mm (with 5-12 mm
of range)
• The mean width was found to be different for right (8.2mm) and left side
(8. 1mm).
• The interhamular notch distance was found to be 35.8 mm (25-48mm
range)
• The interhamular notch distance was found to be different for males (37.1
mm) and females (35.6 mm)
Winland and Young, maxillary complete denture posterior palatal seal: variation in shape size and location, j prosthet
dent , march,1973

Shape
•BEAD
•DOUBLE BEAD
•BUTTERFLY
•BUTTERFLY WITH BEAD
Winland and Young, maxillary complete denture posterior palatal seal: variation in shape size and location, j prosthet
dent , march,1973

Classification of Techniques to record PPS
Techniques to record posterior palatal seal; Agrawal, et al.; 2021; Journal of Datta Meghe Institute of Medical Sciences
Hardy and Kapur (1958) –
• Functional : Final impression is border molded in PPS area
with soft stick modeling compound / wax by sucking
movements performed by the patient.
• Semi functional : Border molding is done by the dentist.
• Empirical : Developed on the cast by grooving the cast to the
• desired depth.
Hardy and Kapur, posterior palatal seal- its rationale and importance, j prosthet dent may 1958

Techniques to locate and record PPS
• Conventional technique
• Fluid wax technique
• Arbitrary scraping of the master cast
• Extended palate technique
• Adding PPS to an existing denture
• Determination of PPS by ultrasound

Conventional technique
• Final impression is made, boxed, and poured.
• A well-adapted resin/shellac tray is fabricated on the
stone cast.
• The posterior palatal area is then dried with gauge; a “T”
burnisher /a mouth mirror is used to palpate for the
hamular process and marked with an indelible pencil

• The instrument (“T” burnisher/mouth mirror) 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 3-4mm anterolateral to the tuberosity,
approximating the mucogingival junction.
• The same procedure is then performed on the opposite side.
This will complete the outlining of the pterygomaxillary seal.

• The resin /shellac tray is then inserted into the mouth and
the indelible pencil lines are transferred to the tray, which is
returned to the master cast to complete the transfer of
posterior border and tray is trimmed.
• The palatal tissues anterior to the posterior border are
palpated with the “T” burnisher /mouth mirror to determine
their compressibility in width and depth.

• The use of Valsalva maneuver / visualizing the area when the
patient says “ah” with short vigorous bursts may also be
used.
• This line is marked with the indelible pencil and transferred
to the master cast.
• A Kingsley scraper is used to scrape the cast.

• The deepest area of the seal are located on the either side of
the midline, one third the distance anteriorly from the post
vibrating line.
• It is scraped to the depth of the approximately 1-1.5mm.
• The tissue covering the median palatal raphe has little
submucosa and cannot withstand the same compressive
force on the tissues lateral to it. It is scraped to the depth of
approximately 0.5-1.0mm.

• Just posterior to the deepest portion of the seal, it is also
tapered to the posterior vibrating line. Failure to taper the
seal posteriorly may lead to tissue irritation.
• Shellac can be readapted to conform to the scored palatal
seal area and tried in the mouth to evaluate the retentive
qualities of the trial base.

Advantages
• Trial base is more retentive
• Psychologic security to the patient
• Practitioner can determine the retentive qualities in the finished
denture
• Patient realizes the posterior extent which may ease the adjustment
period

Disadvantages
• Not a physiologic technique.
• Potential for over compression of tissues.

Fluid wax technique
• Similar to the conventional technique except that in this
technique the indelible transfer markings are recorded
on the final wash impression.
• All the procedures for location and transfer marking of
the anterior and posterior vibrating lines are same as for
the conventional approach.
• Indelible transfer markings are recorded on the final
wash impression.

Fluid wax technique
• Zinc oxide and eugenol /plaster are preferred over the
elastic impression material, as they set rigid.
4 types of wax :
• Iowa Wax (White) – Dr. Earl S. Smith
• Korecta Wax no.4 (Orange) – Dr. O.C. Applegate
• H-L physiologic paste (Yellow-White) – Dr. C.S. Howkins
• Adaptol (Green) – Dr. Nathan G. Kyne

Fluid wax technique
• Designed to flow at mouth temperature.
• The melted wax is painted onto the impression surface
with the outline of the seal area and allowed to cool to
below mouth temperature to increase its consistency
and make it more resistant to flow.
• The impression is carried to the mouth and held in the
place under gentle pressure for 4-6 minutes to allow
time for the material to flow.

Fluid wax technique
• After 4-6 minutes, the impression tray is removed from
the mouth and the wax examined for uniform contact
through out the posterior palatal seal area.
• If tissue contact has not been established, the wax will
appear dull. If the tissue has been contacted, the wax
will have a glossy appearance.
• Where the wax appears dull, more wax should be
applied and the procedure repeated.

Fluid wax technique
• The secondary impression is reinserted and held for 3-5
minutes of firm pressure applied to the mid-palatal area
of the impression tray.

Precautions
• The patient should not protrude his tongue beyond the approximated
position of the incisal edge as this may shorten the posterior border
of the final impression.
• The patient should be cautioned against rinsing with cold water as
this may contract the tissues and reduce the flow properties of wax.
• The borders of the wax should terminate in feather edge towards the
vibrating line. If a butt joint is formed, proper flow may have not
taken place.

Advantages
• Physiologic technique
• Over compression of tissues is avoided
• Posterior palatal seal is incorporated into the trial denture base for
added retention
• Mechanical scraping of the cast is avoided

Disadvantages
• More time is necessary during the impression appointment
• Difficulty in handling materials

Extended Palatal technique (Silverman 1971)
• Denture border is extended 8mm approximately beyond the anterior
vibrating line.
• Not widely used currently.
Method -
• After border molding tray is extended by adding compound.
• Green stick compound is added to the seal area and record is made
with head flexed 30 degree downward.

Arbitrary Scraping of the Cast
• Anterior and the posterior vibrating lines are visualized by examining
the patient’ mouth and approximately marked on the master cast.
• Least accurate and leaves a chance at insertion appointment since it
relies on dentist’s recollection of palatal configuration and tissue
compressibility.
• Inaccurate and not physiological.

Boucher’s technique
• Stage of recording- during jaw relations
• Method the posterior vibrating line is
located and transferred on to the master
cast.
• The temporary denture base is reduced to
this line.
• This will create a raised narrow and sharp
bead along the posterior portion of the
denture which sinks into the tissues and
forms a seal.
• Advantage: According to Boucher a
narrow bead like seal is more effective.

Bernard Levin’s Technique
• For class III soft palate forms: He described a, “double bead”
technique for class III soft palate.
• In this technique, a depth of about 1mm and width of 1.5mm is
scraped in posterior vibrating line.
• A distance 3 to 4 mm from posterior border, anterior vibrating line is
beaded. This is known as rescue bead.

Bernard Levin’s Technique
• For class I and class II soft palate.
• Using no. 8 round bur of 2mm diameter, 2 holes of
2mm are drilled at the depth of the bur in the
area between the midline and hamular notch.
• One hole of 1mm depth is drilled to half the
diameter of the bur in the center.
• A cone shaped acrylic resin bur is used to rough
out the seal.
• The hamular notch region is not reduced more
than 0.25mm in width and 0.5mm in depth and
not extended onto the tuberosity and vestibule.
• The soft tissue part of the seal is scraped to 6mm
in width where , the median raphe region is
scraped to 4mm in width.

Swenson’s Technique
• A groove is cut along the posterior line to a depth of 1 to 1.5 mm that
will cause the posterior border stand straight out from the hard
palate, turning neither up nor down.
• Posterior line is tapered towards the anterior line by scraping the cast.

Calomeni, Feldman, Kuebker’s Technique
• In this technique a depth of 1 to 1.5 mm
scraped as posterior bead in which
extends through hamular notches and
distance of 5 to 6 mm from posterior
line, anterior line is beaded.
• Using a Kingsley scraper No.1 a depth 0
at anterior line to a depth of 1 to 1.5
mm along posterior border is scrapped.
• A distance of 2 to 3 mm should be
present in between the anterior and
posterior lines from the midline.

Pound’s Technique
• Pound recommends a single bead posterior
palatal seal with anterior extensions for
additional air seal.
• In the palate from the hamular notch to hamular
notch a ‘V’ shaped groove is carved measuring a
width of 1 to 1.5 mm and depth of 1 to 1.5 mm
and is placed 2 mm anterior to vibrating line.
• In order to provide adequate air seal a loop is
carved on either side of the midline.
• Palpate the area with a blunt of the instrument
to determine the width of anterior loop.

Hardy and Kapur Technique
• Using the ball portion of the T burnisher
depth of posterior palatal seal is examined.
• The posterior palatal seal is extended 4 mm
from distal border of denture .
• Then the hamular notch region is narrowed
to 2 mm in width through the hamular
notch.
• Posterior palatal seal is at its maximum
depth in center and minimizes to zero at its
anterior and posterior border by scraping
the cast.

Adding PPS to existing denture
• Mark the vibrating line in the mouth with an indelible
marker.
• Form the desired thickness and extension of the PPS on the
denture in the patient’s mouth with softened green
modeling compound.
• Transfer the locations of the vibrating line to the denture.
• Make a cast of the intaglio surface of the denture; the cast
must include all of PPS addition and extend 5 to 6 mm
posteriorly
• Use a scalpel to cut channels which will allow excess auto
polymerizing acrylic resin to escape.
• Remove the green stick compound and replace with auto
polymerizing resin in a pressure pot.

Correction of posterior palatal seal by using a
visible light cured resin (Arthur Nimmo)
• Identify and mark the vibrating line in the mouth with an indelible marking
stick.
• Roughen the denture surface in the posterior palatal seal area with a
carbide bur.
• Adapt the VLC resin.
• Place the denture in the mouth and allow it to remain in place for
approximately 3 minutes. During this time the material will flow.
• Position a hand-held visible light source near the border of the denture and
apply light directly to the region for several minutes.
• Remove any excess resin with a carbide bur and smooth the junction
between the seal and the polished surface of the denture.

Advantages of using VLC resin
• No exothermic reaction to irritate the oral tissues.
• Minimal volumetric shrinkage during curing.
• More closely approximates a physiologic technique.
• Can be performed with relatively little chair time.

Determination of PPS by Ultrasound
• Rajeev M. Narvekar, and Marc B. Appelbaum investigated the
anatomic position of posterior palatal seal by ultrasound.
• Ultrasound refers to sound with frequencies higher than the audible
range (20 to 20,000 Hz).
• Basic elements of an ultrasound scanning system include –
1. Transducer
2. Couplant

Trouble shooting
• Under extension
• Under postdamming
• Over postdamming
• Over extension

Under extention
• Most common cause for failure of the seal in the posterior palatal area
Causes:
• Practitioner’s use of the fovea palatine as the landmark for terminating the
denture base. By doing, so he may be depriving the patient of as much as 4
to 12 mm of tissue coverage.
• Failure of the dentist to carefully examine the hard and soft palates,
making note of the palatal configuration.
• Over trimming of posterior border by laboratory technician
• Due to fear of gagging

Under Postdamming
• May be the result of recording the tissue when the mouth was wide open
during the final impression.
• When the mouth is in the wide open position, the pterygomandibular fold
becomes taut.
• When the patient assumes any position other than a wide open position, a
space will be present between the denture base and the tissue since the
fold is no longer activated.
• Diagnosis : place the wet denture base into the mouth and slowly press in
the mid-palatal region until it is firmly seated while observing the distal
denture border.
• If air bubbles are seen escaping from beneath the distal border, then at
that point the denture base is under postdammed.

Correction
• Further scrap the cast and readapting the trial base if the
conventional approach is used
• Add more wax and remind the patient to refrain from opening the
mouth so wide if the fluid wax technique employed.

Over Postdamming
• Over scrapping of master cast and the posterior palatal seal displaces
too much tissue.
• Significant over post damming especially in the pterygomaxillary seal
area - posterior border will be displaced inferiorly.
• Moderately over post dammed - tissue irritation across the posterior
palatal region.
Correction:
• Selective reduction of the denture border with carbide bur, followed
by lightly pumicing the area while maintaining its convexity.

Over extension
• The most frequent complaint from the patient will be that swallowing
is painful and difficult. Small ulcerated areas in the region of the soft
palate will be evident.
• If the hamuli are covered by the denture base, the patient will
experience sharp pain, especially during function.
Correction:
• By marking the lesion with an indelible pencil and transferring it to
the denture base, the precise position of the overextension can be
removed with a bur and then carefully repolished.

Referances
• Essentials of Complete Denture Prosthodontics, Sheldon Winker
• Prosthodontic Treatment for Edentulous Patients, Jarb Bolender
• Techniques to record posterior palatal seal; Agrawal, et al.;
2021; Journal of Datta Meghe Institute of Medical Sciences
University
• Posterior Palatal seal – A Literature Review, International Journal of
Prosthodontics and Restorative Dentistry; Bindhoo et. al
• Hardy and Kapur, posterior palatal seal- its rationale and
importance, j prosthet dent may 1958
• Winland and Young, maxillary complete denture posterior
palatal seal: variation in shape size and location, j prosthet dent,
march,1973

Posterior Palatal Seal Parameters

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