The seal area at the posterior border of a maxillary removable dental prosthesis.
POSTPALATAL SEAL / POST-DAM
FUNCTIONS (5)
- Retention (primary function)
- Acts as a barrier and prevents food accumulation beneath the denture.
- Maintains contact with the moving soft palate, thereby, reducing the gag reflex by reducing the patient’s awareness of the denture.
- Compensates for curing shrinkage.
- Reduces tongue irritation as posterior border merges better with palate.
COMPONENTS (2)
A. Posterior palatal seal
B. Pterygomaxillary seal – located immediately behind the maxillary tuberosity.
BOUNDARIES OF POSTPALATAL SEAL (3)
Anteriorly - Anterior vibrating line
Posteriorly - Posterior vibrating line
Laterally - Pterygomaxillary notch
Anterior Vibrating Line
- An imaginary line located at the junction of the attached tissues of the hard palate and the moveable tissues of the immediately adjacent soft palate.
- Bow shape – “Cupid’s Bow” due to the projection of the ______.
posterior nasal spine
- Located by: (2)
o ▪ Valsalva maneuver – both the nostrils are held firmly while the patient blows gently through the nose.
o Patient is asked to say “Ah” with short vigorous bursts.
Posterior Vibrating Line
- An imaginary line at the junction of the aponeurosis of the tensor veli palatini and the muscular portion of the soft palate.
- It represents the demarcation between that part of the soft palate that has shallow movement (quivers) during function and the remainder that is markedly displaced.
Posterior Vibrating Line
Posterior Vibrating Line
* Located by: (1)
o It can be visualized when the patient says “Ah” in a normal, unexaggerated fashion.
TECHNIQUES OF RECORDING THE POSTERIOR PALATAL SEAL
A. Arbitrary techniques
a. Conventional technique
b. Boucher’s technique
B. Physiologic techniques
a. Fluid wax technique
b. Stick compound technique
c. Extended palatal technique
CONVENTIONAL TECHNIQUE
Stage of recording: ________________
BOUCHERS TECHNIQUE
Stage of recording: _______________
At the start of jaw relations.
During jaw relation
FLUID WAX TECHNIQUE
Stage of recording: ___________
STICK COMPOUND TECHNIQUE
Stage of recording: ________________________
EXTENDED PALATAL TECHNIQUE (SILVERMAN)
___________________
After making final impression.
During border moulding of the special tray, before the final impression is made
Denture border is extended 8.2 mm beyond the anterior vibrating line.
- Occurs when the distal border of the denture extends onto the active portion of the soft palate.
OVEREXTENDED
OVEREXTENDED
* Symptoms:
o Patient complains that swallowing is difficult or painful.
o Areas of redness or ulcerations maybe seen.
o Patient may experience sharp pain specially during function.
OVEREXTENDED
* Correction: _____
the exact area of redness is marked with an indelible pencil and transferred to the denture. The denture is then shortened with a bur and repolished.
- Common cause of failure of the posterior palatal seal.
- Results in the loss of retention.
Underextension
Underextension
* Reason:
o Failure of the dentist to identify the posterior vibrating line.
o In the gagging patient, the dentist might have kept the impression tray underextended to reduce the gagging sensation.
- Failure to effectively place the tissues of the posterior palatal seal area results in poor seal and reduced retention.
UNDERPOSTDAMMING
UNDERPOSTDAMMING
* Diagnosed by:
o The trial denture base is wet and placed in the mouth. Using a finger in the palatal region, it is slowly pressed into position. With a mirror, the distal border is examined for scaping air bubbles. Escaping air bubbles indicate an underpostdammed area.
UNDERPOSTDAMMING
Correction:
o Further scrape the cast and readapt the trial base.
- Over scraping of the cast can result in
OVERPOSTDAMMING
can result in pressure symptoms on the tissues. An area of redness or tissue irritation may be seen.
o Moderate postdamming
causes downward displacement of the denture.
o Severe postdamming
