DR MUAIYED BUZAYANDr. Muaiyed. Mahmoud. Buzayan, BDS

MClinDent Malaysia

AF AAMP USA

DR MUAIYED BUZAYAN

Posterior Palatal Seal area

It is defined as a soft tissue along the junction of the hard

and soft palates on which pressure within the physiologic

limits of the tissues can be applied by a denture to aid in the

retention of the denture.

DR MUAIYED BUZAYAN

The seal area at the posterior border of a maxillary removable dental

prosthesis

It is a slight elevation at the posterior border of the maxillary denture

PPS area of the upper denture is the area that should be placed on non-

movable tissues of the soft palate just behind the hard palate.

The posterior palatal seal is formed through both hamular notches &

across the palate over the vibrating line.

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1. Compensates for polymerization shrinkage away from palate

2. Enhances the retention. The main function of PPS is to

maintain contact with the anterior portion of the soft palate (the

tissue undergo shallow displacement) during functional movement

of the somatognathic system (that is mastication, deglutination &

phonation) therefore the main purpose of PPS is the retention of

maxillary denture

3. It also reduces food accumulation beneath the posterior

aspect of denture owing to proper utilization of tissue

compressibility.

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4. It also reduces gag reflex as there is no separation between denture

base & soft palate during normal functional movement

5. Inconspicuous with the tongue: Reduce patient discomfort contact

occur between dorsum of the tongue & posterior end of denture base

DR MUAIYED BUZAYAN

Posterior palatal seal requirement:

1- Lies on easily displaced tissue

2- Should be in continuous contact with soft palate in the restand function

ANATOMIC & PHYSIOLOGIC CONCIDERATION

The PPS is divided in two anatomic separate boundaries-

1. Post palatal seal

2. Pterygomaxillary seal1.

A A B C B

A- Pterygomaxillary seal

B- Post palatal seal extends from

hamular notch to hamular notch

C- Post palatal seal lies between

anterior and posterior vibrating lines

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The post palatal seal is extending from one tuberosity to other.

Pterygomaxillary seal extend through pterygomaxillary notch

continuing for 3-4 mm anterolaterally approximation the

mucogingival junction.

It also occupies the entire width of pterygomaxillary notch. This

pterygomaxillary notch is covered by pterygomandibular fold

which extend from the posterior aspect of the tuberosity

posterio-inferiorly to insert into the retromolar pad.

This fold of tissue can influence the posterior border seal during

the mouth wide opening.

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The imaginary line across the posterior part of the palatemarking the division between the movable & immovabletissue of the soft palate which can be identified when themovable tissue are moving.

1. Anterior vibrating line

2. Posterior vibrating line1.

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It is an imaginary line lying at the junction between theimmovable tissues over the hard palate & the slightlymovable tissue of the soft palate

Instructing the patient to say “AH” with short vigorousbursts

The anterior vibrating line is not a straight line, due to theprojection of the posterior nasal spine..

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It is an imaginary line at the junction of the aponeurosis oftensor vili palatini muscles in the muscular portion of thesoft palate. It separates the movable and the immovableportions of the soft palate.

It represents demarcation between the part of soft palatethat has limited or shallow movement during function(quivers) & the remainder of the soft palate that ismarkedly displaced during functional movement.

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It is classified in-

CLASS I

It indicates soft palate that is rather horizontal or as anextension posteriorly with minimum muscular activity.The separation between anterior and posterior vibratingline does having wide PPS area yielding more retentivedenture base

CLASS II

The soft palate that has a medium curvature and allowfor a medium width of the posterior palatal seal area.Palatal contour lie between class I & class III

CLASS III

It is seen in conjugation with high V shape palatal vault. There is fewmillimeters of separation between the anterior and posterior vibrating linesthus the PPS area would be small and the retention is less.

DR MUAIYED BUZAYAN

1- The post dam extends from the hamular notch on one side to theother hamular notch of the other side. It should be wide enough toavoid cutting or irritating the soft tissues, but not so wide tocompress too large an area and thus prevent the denture from sealingproperly.

2- The post dam is usually narrow in its central part, wider as itextends laterally on each side, and narrow again as it approaches thehamular notch to fade out behind the tuberosity. It is sometimescalled butterfly (Cupid's bow) post dam

3- The post dam should be about 4-6mm wide in its widest part. Thedepth or thickness of the post dam should vary in differentindividuals, according to compressibility and softness of the tissue. Itsdepth should also vary (0.5 – 1mm) in different parts of the samemouth in exactly the same manner as its width. The average depth is1mm.

DR MUAIYED BUZAYAN

DR MUAIYED BUZAYAN

1- Impression making: To establish positive contactposteriorly to prevent the final impression materials fromsliding down the pharynx. And to serve as a guide forpositioning the impression tray, especially if a shim (waxspacer) has been used within the tray to establish theborders.

2- Jaw relation: To stabilize the trial denture base and todetermine if adequate retention & seal of the potentialdenture border is present.

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3- Finished denture: to gain all the benefit of theposterior palatal seal. Existing denture may have poorlength and depth of PPS. Properly examine existingdentures. If there are other problems in the dentures(vertical dimension, centric, esthetics etc.) then newdentures are to be made. If only PPS is short then correctionshould be undertaken.

Different materials and techniques can be used.

1) Heat cure material.

2) Self cure acrylic resin.

3) Light cure resin.

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There are several established for the placement of the posterior palatalseal:

1- Conventional method

2- Scraping of master cast (arbitrary post-damming)

3- Fluid wax technique

4- Post damming during try-in stage

1- Conventional method

PROCEDURE

1. The posterior vibrating line. A line is placed with an indeliblepencil, through the pterygomaxillary notch & extended 3-4 mm antero-laterally the tuberosity approximating the mucogingival junction(intraorally).

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2. The custom tray inserted into the mouth & seated firmly. Uponremoval from the mouth, the indelible lines will be transferred to the tray.The tray in return to master cast to complete the transfer of the completeposterior border.

3. The tray is trimmed to the posterior vibration line so that itdetermines the post extent denture border.

4. To get the anterior vibrating line, the soft palate is palpated with the‘T’ burnisher or mouth mirror to determine their compressibility in width &depth. The termination of glandular tissue usually coincides with theanterior vibrating line. The anterior vibrating line now marked andtransferred to master cast.

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5. The visual outline is in the shape of cupid bow the area between theanterior posterior vibrating lines is usually narrowest in the mid palatalregion because of the projection of the posterior nasal spine.

1.

6. Kingsley scraper used to score the cast. The deepest area is locatedon either side of midline. It is usually scraped to a depth of approximately1-1.5 mm. The tissue covering the medial palatal raphe is not scrapped (orminimally scraped).

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2- Scraping of master cast

This technique is the least accurate and leaves the most to chance of tissue

compressibility of the insertion of the denture.

The anterior and posterior vibrating lines are visualized by examining the

patient and then they are approximately marked on the cast. The technician will

scrap the 0.5 to 1mm depth of the stone in the posterior palatal seal area.

This technique is almost as non-physiologically correct as the technician's

attempt to place the posterior palatal seal arbitrarily.

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3- Fluid wax technique

It starts with locating and transfer of anterior and posterior vibrating line similar to

conventional approach. Then with the marks made, final impression is made using

ZOE/impression plaster (not with elastomeric impression material as they are resilient, non-

adherent to wax, and distort wax when reseated into oral cavity).

Impression waxes used to get seal. These waxes have specific characteristics like low-

melting point to permit their use intraorally without discomfort or trauma, high flow rate at

mouth temperature.

The melted wax is painted into the impression surface (within the outline of the proposed

seal area). The impression is carried to the mouth and held in place under gentle pressure

for 4-6 min and allow time for the material to flow. Take care for head position (30° to

Frankfort Horizontal plane). In this position the soft palate is impression in its most

functionally depressed position.

After 4 min remove the impression tray and trim any

excess (or) if no tissue contact is established then add and

redo the procedure

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4- Post damming during try-in stage

The trial denture base is inserted so the indelible pencil line marked on

vibrating line of the soft palate will be transferred from the soft palate to

the trial denture base. And the excess base plate is reduced to this line.

The trial denture base is placed on the cast and a knife or pencil is used

to mark a line following the posterior limits of the base plate.

DR MUAIYED BUZAYAN