Posterior palatal s /certified fixed orthodontic courses by Indian dental academy

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Posterior palatal seal
Posterior palatal seal is the seal at the
posterior border of maxillary prosthesis.
(GPT 7).
Posterior palatal seal area: the soft tissues
area at or beyond the junction of the hard
and the soft palate on which pressure ,
within physiological limits , can be applied to
aid in retention.(GPT7)

Anterior and posterior vibrating lines:
PPSA lies between anterior and
posterior vibrating lines.
Anterior vibrating line: is an imaginary
line located at the junction of attached
tissues overlying the hard palate and
movable tissues of the immediately
adjacent soft palate.

One way to locate is to have patient
perform Valsalvamaneuver .
Second way is by asking the patient to
say “ah”in short vigorous bursts.


• Posterior vibrating line:
It is an imaginary line at junction of the
tensorveli palatine muscle and
muscular portion of the soft palate.
It is visualized by asking the patient say
“ah” in short bursts in a normal and
unexaggerated fashion.
It marks most distal extension of the
denture base.

The rationale for the placement of the PPS
in the impression tray is as follows:
1.To establish positive contact posteriorly.
2.To serve as a guide for positioning the
tray.
3.To create slight displacement of the soft
palate.
4.To determine adequate retention and
seal.

• Technique:
Method to mark PPSA:
“T” burnisher is used .
It is placed along the posterior angle of the
tuberosity until it drops into
pterygomandibular notch.
A line is placed through the notch and
extended 3-4mm anterolateral to the
tuberosity approximating the mucogingival
junction.

This completes outlining the
pterygomaxillary seal.
The posterior vibrating line is
recorded by asking the patient to
say “ah” in unexaggerated and
the line is marked by connecting
the pterygomaxillary seal.


Anterior vibrating line: the palatal
tissues anterior to the posterior border
are palpated with “T” burnisher to
determine their compressibility in
width and depth.
The termination of glandular tissues
usually coincide with the anterior
vibrating line.

• The visual
outline is of
cupids bow.


Border molding of the mandibular
tray:
Armamentarium:


Mandible: Border molding the labial
and buccal flanges:


Buccal flange: molded when cheek
is moved outward, upward and
inward.
Posteriorly the effect of masseter
muscle is recorded by asking the
patient to exert closing force while
the dentist exerts downward
pressure on the tray.

Lingual flanges:

In the anterior region the
compound is added and
placed in the patient’s mouth
and the patient is instructed to
protrude the tongue and push
the tongue against the front
part of the palate.

Protruding movement creates the
functional movement of the floor
of the mouth including the lingual
frenum and determines the length
of the lingual flange.


Pushing the tongue develop
thickness of the anterior part of
the flange.
The distal end of the lingual flange
is molded by asking the patient to
protrude the tongue and this
develops the slope for the lingual
flange in the molar region to allow
action for the mylohyoid muscle.

• Compound on the distal end of the
flange is heated, and the tray is
placed in the mouth .patient is asked
to protrude the tongue to activate
superior constrictor then he is asked
to close opposing the pressure.
• This results contraction of medial
pterygoid acting on retromyloid
curtain, can limit border extension in
the retromylohyoid fossa.

The length and form of the lingual
flange is formed by asking the
patient to wipe the tip of his
tongue across the vermillion
border of the lip.


Border molding with elastomeric
impression material.
Smith etal.,the effective
simultaneous border molding
material is polyether impression
material called impregum.


They are easy to use when there are
undercuts because they are elastic.
Disadvantages:
They are difficult to trim once it is set.
Final impression materials crack or craze
because the borders are not rigid.
They are hard to use, easy to abuse and
costly.
The tray should not be under extended
6mm or more.

Border molding with waxes:
Waxes were oldest material used.
Waxes were abonded as
pressure created by most of the waxes
causes tissue distortion.
Large undercuts distort the wax.
Chilled wax is brittle and subjected to
flaking and breaking.

Border molding with self-cure resins
and tissue conditioners.
Remiseal was the first one specifically
developed for border molding.
The monomer was irritating, so it was
further modified .
Flexacryl is the material which is nonexothermic, non irritant.

Resin called Peripheal seal was
recommended by smith.
Denturlyne and Reprodent are
premixed soft resins.


The tissue conditioning material
were suitable for treating abused
soft tissues as well as for
developing functional borders or
dynamic impressions.
Hydrocast

Final impressions:
Final impression materials:
Plaster of Paris: the setting time of the
plaster should be modified so that the
molding time will be increased.
It absorbs some of the mucous secretions.
Difficult to record undercuts.
It has enough body to support itself 1.5mm
beyond the tray.

Zinc oxide eugenol paste:

It accurately records surface
details.
It does not absorb the mucous
secretions and can cause defects
in palatal part of the mucosa.
Since the material is fluid the tray
should be accurately formed.

• Tissue conditioning materials:
They are resilient and can flow
under stresses up to 24hrs.
They are useful in making
functional impressions.


Silicone ,polysulfide rubber, polyether ;
They can record the shape of the soft
tissues accurately if they are
adequately supported by the tray.
The polysulfide material should be
closely confined to the soft tissues.
They are useful in making impressions
of thin high mandibular ridges with
soft tissue undercuts.

Poly ether:
They have sufficient body to make
up discrepancy up to 4-5mm.
Can be shaped by fingers.
They are accurate in reproducing
details.

Technique.
Preparing the tray to secure final
impression.
The spacer wax is removed from inside
the tray along with the border molding
material that has flown over it.
2-3mm of thickness should be reduced
from one buccal frenum to other.

Approximately 0.5mm is removed
from the inner outer and top
surface of the border.
Finally the holes are placed in the
tray with medium sized round bur
to provide escape holes for the
material.

• Richard P. Frank(1969):
He stated that reduced pressure
would most likely be achieved by
the use of zinc-oxide eugenol
paste in a tray with relief space
and escape holes.
(JPD 1969;22(4);400-12)

• Osamu Komiyama etal.,(2004)
• In there study they concluded that a
tray with 1mm dia or large or spacer
with 1.4mm wax produced pressures
in the mid palatal point significantly
lower than ridge crest.
• JPD 2004;91:570-6.


According to Heart well:2 holes
in the region of the rugae and
2 holes in the posterior area
are made to allow escape of
the air.

According to Sharry:

A small hole should be drilled
through the tray in the incisive
papilla region to prevent hydraulic
in the vault region.


• According to Boucher:
• Holes should be placed in the
palatal region because the
mucous membrane over the mid
palatal region and the
anterolateral and posterolateral
regions in the hard palate are not
excessively displaced.

• Holes can also be placed over the
RR where the soft tissues are
mobile and displaceable.
• The objective is to record denture
bearing area in undisplaced
position.

• In the mandible holes are placed
10mm apart in center of the alveolar
ridge and retromolar pads.


• According to Bernard levin: in
maxilla 8-10 holes are drilled over
the crest of the ridge.
• In mandible 8-10 holes are drilled
over the crest of the ridge.


Impressions:
Maxillary:
First the placement of the tray should
be practiced.
The tray is centered as it carried to the
upper ridge.
When the frenums are positioned within
the notch the index fingers are sifted
to the

First molar region and with
alternating pressure the tray is
carried upward until the posterior
seal of the tray fits properly in the
hamular notches across the
palate.
The tray is held in position with the
finger placed in the palate anterior
to PPS.

The final impression of choice is
mixed and loaded in the tray
uniformly.
When the material is set it is
removed and inspected.


• Establishing posterior palatal
seal:
Fluid wax technique:
Four types of waxes can be used
Iowa wax.
Korecta wax no4, orange.
H-L physiologic paste.
Adaptol.

The waxes are designed to flow at
mouth temperature.


• The advantages of this technique:
It is a physiologic technique
displacing tissues within their
physiologic limits.
PPS is incorporated into the trial base
for added retention.
Mechanical scrapping of the cast is
avoided.

• Establishing posterior seal during
final impression stage. (JPD
1997;78:324-25).


Mandidular: the tray is rotated into the
mouth until the anterior handle is on
the ridge.
At this time the patient is asked to raise
the tongue and the tray is moved
downwards towards it final position.

• The dentists fingers are placed
over the posterior handles and
with alternating pressure the tray
is seated until the buccal flanges
come in contact with the buccal
self.

The material is uniformly loaded
and the tray is seated and the
movements are performed .after
material sets the impression is
removed and inspected.


Closed mouth techniques:
Mac Millan in 1947 stated that
only these impressions are
capable of adequately
trimming the lingual borders of
the impressions as the tongue
movements are more forceful
when teeth are together.

The objective of this technique is to
record the functional form of the
denture bearing area.
Rationale: the thought the natural
movements by patients will
confirm the impression material to
anatomic limitations when the
mouth is closed under pressure

Initially waxes were used . But now
softliners are advocated.
Technique:
Impression trays with occlusal rims
are used instead of handles.
Impression material is loaded in the
tray and placed in the patient’s
mouth.

• Both upper and lower impressions
are made simultaneously.
• The patient is asked to apply
pressure by closing against the
occlusal rims.
• He is asked to perform functional
movements like swallowing,
wetting the lips, grinning, sucking,
etc.

Disadvantages :
Does not allow for the adequate
muscle trimming of the periphery.
The dentures are over extended.
Because of continuous pressure
there is resorption of the bone.

Modified Functional Impression
Technique for
complete dentures


Specialised techniques.
Impression technique in flat
mandibular ridges:
The technique uses the tissue
conditioning materials.
A preliminary impression is
obtained to a generally
overextended registration.

Using the cast the resin tray is
fabricated with occlusal rim and
tried in patients mouth
The buccal and labial extensions of
the tray are adjusted short of the
reflections of the cheeks and the
lips.
The retromolar pad is covered but
show no influence on the tray.

• The operator can use close
mouth or open mouth technique.
• The closed mouth technique
requires the use of well fitting
maxillary tray, well occluding rims
and acceptable vertical
dimensions.

Technique;
3 applications of tissue conditioning
material are used.ie coe product.
2applications of viscous material
i,e.,coe soft.
Each application allowed to remain in
mouth 8-10 min. then it is checked .
Pressure areas are corrected.

Final wash is made with relatively light
bodied material.
The impression obtained has very
thickened comforting buccal borders
and a relatively thick lingual and
subcreascent area.
Overall denture is more bulkier with
more surface contact area with
minimal bony contact in the alveolar
ridge area with improved retention.

Impression techniques for flabby
ridges:
Mucocompression without
displacement:
This is a two stage technique
design to compress the flabby
tissue so that the compression
throughout the whole denture
bearing area is uniform as
possible.

Preliminary impression is made with
plaster.
Pour impression and make cold cure
acrylic tray.
The tray is checked in the mouth.


A compound impression of the tray
is made.
The flabby area is marked with the
pencil and the tray is inserted in
the mouth and removed to outline
the impression surface.

• With a pin point flame soften the
area surrounding the flabby ridge.
• The impression is tempered and
inserted in the mouth.
• Load should be applied in vertical
direction to compress the flabby
ridge without displacing it.

The procedure is repeated for two
times.
The impression is dried and
completed with zinc oxide
eugenol impression paste.
If the impression is correctly made
the compound should show
through the ZOE in the flabby
ridge area.

• Mucostatic, open window
technique:
On the priliminary cast an custom
tray is made with an opening
surrounding the flabby ridge.
The tray is border molded and the
impression paste wash is made.
Reinsert the tray and apply thin mix
of plaster over the flabby ridge
which lies through the window

When the plaster has set remove
the whole.


Impression technique in minimal mouth
opening
A sectional impression tray was
designed with right and left sections
that could be detached and then
joined together in the correct original
position. Maxillary and mandibular
impression trays were then fabricated.

Putty silicon impression paste
(Speedex, Coltene Whaledent
Inc, Mahway, NJ) was placed
intraorally with finger pressure,
and maxillary and mandibular
impressions were made. The
impressions were cast in dental
stone

Summary.


Conclusion.


References:
Text book of complete denturesHeartwell 5 Edn.
Essentials of complete dentures –
Winkler
Prosthodontic management of
edentulous patients- Zarb- Bolender.
Clinical dental prosthesis – A. Roy
Mcgregor.

Impressions for complete dentures:
Bernard Levin.


• physical considerations in impression
making. JPD 1953:3(4);449-62)
• complete denture impressions
.JPD1965:15;603-14.
• Posterior border seal – its rationale and
importance.JPD1958:8;386-97
• complete denture impressions
.JPD1965:15;603-14

• Impression border molding with a
cold cure resin.JPD1973:30;914-17
• principles involved in complete
dentures.JPD1973:29;594-9
• border molding of complete denture
impressions using a polyether impression
material.JPD1979:41;347-517

• the sublingual crescent extensions
and its relation to the stability and
retention of mandibular complete

• Functional metallic handles for
final impressions of complete


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Posterior palatal s /certified fixed orthodontic courses by Indian dental academy

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