Posterior Palatal Seal

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Posterior Palatal Seal
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The posterior palatal seal is placed in the
maxillary complete denture because the acrylic
will distort slightly and pull away from the
posterior palatal area of the maxillary cast.
The acrylic will shrink toward the areas of
greatest bulk, which are the areas over the
ridge where the teeth are placed. The posterior
palatal seal provides a vacuum seal between the
denture and the soft palate that holds the
maxillary complete denture securely in place.
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The amount of area in which the palatal seal
can be placed varies with the shape of the
posterior palate. In Houses classification of
the posterior palate, a class 1 palate will allow
5-10 mm of surface area to place the seal, a
class II posterior palate will allow 3-5 mm and a
Class III posterior palate will allow only 1-3 mm.
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Houses Classifications
House classified the soft palate according to how
it drapes.
Vibrating line
Vibrating line
Class I
5-10 mm
3-5mm
1-3 mm
Vibrating line
Class III
Class II
Class I easiest to tolerate, broadest range,
hardest to locate. Class II most common Class
III easiest to locate, hardest to tolerate.
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Posterior Palatal Seal
Posterior Nasal Spine
Velum
Glandular tissue
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Orally, the area of the vibrating line is
recorded by making marks with an indelible
transfer stick in the fovea palatina area and the
hamular notch areas on both sides of the palate
and then connecting them with a solid line.
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In the lab exercise, mark points on the
maxillary cast in the fovea palatina area and the
hamular notch areas.
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• Connect these points with a solid line which
  will appear as a gentle curve toward the
  anterior. This line will extend into the buccal
  vestibular areas of the hamular notch.

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• Place points in the glandular area 5-8 mm
  forward of this first line and about two mm
  anterior to this line in the mid palatal area.

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• Draw a second line anterior to the first
  line that connects these dots and forms a
  butterfly pattern. It looks like two mountains
  with a valley in between.

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• Make a depth cut on the posterior line with a
  cleoid/disoid or the point of a green-handled
  knife. It should be .5 mm deep in the middle of
  the posterior palate, 1 mm deep in the hamular
  notch area, and 1.5 mm deep in the glandular area
  between the hamular notch and the middle of the
  posterior palate.

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Use the back of the green-handled knife
to form the palatal seal. It should feather out
to zero at the anterior line. It should not
extend onto the maxillary tuberosities or onto a
torus.
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It should feather out to zero at the
anterior line. It should not extend onto the
tuberosities or onto a torus as these areas are
not depressable and would prevent the denture
from seating entirely.
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Dimensions of Post-Palatal Seal
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The End