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The posterior palatal seal

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Posterior palatal seal

Defnition

Purpose

Functions

Anatomic considerations

Physiologic consideration

Anterior and posterior vibrating

lines

Soft palate

Techniques

Trouble shooting

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introduction

• The diagnostic evaluation and placement of posterior palatal seal often given minor attention in cd construction.

• The posterior border of the maxillary denture has definite anatomic and physiologic boundaries

• Once understood make PPS a quick and easy procedure.

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• Proper placement of PPS begins with intraoral examination such as –

1. Morphologic contours of hard and soft palate

2. Hamular notch regions3. Integrity and displaceability of the

mucosa and underlying glandular tissues .

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• Hardy and Kapur stated that adhesion cohesion and interfacial surface tension act only on perpendicular dislodging forces .

• Horizontal forces and lateral torquing resisted only by adequate border seal.

• Therefore primary purpose-retention of maxillary denture .

• If properly placed reduce gag reflex.

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Definitions: GPT 8

• Posterior palatal seal area/ Postpalatal seal area/ Postdam area: The soft tissue area at or beyond the

junction of the hard and soft palates on which pressure within physiologic limits, can be applied by a denture to aid in its retention.

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Signs of correctly placed PPS

1. Will not impinge non displaceable tissues of hard palate.

2. Will not limit muscular movements of the soft palate .

3. Create a partial vacuum beneath the maxillary denture .

4. Activated only when horizontal or tipping forces are directed .

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functions

• Complete dentureRetention of maxillary denture.Reduces gag reflex.Prevents food accumulation.Reduces patients discomfort.Compensates for volumetric

shrinkage.

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Functions

• Impression trayEstablishes positive contact posteriorly

and prevents impression wash material from sliding down the pharynx.

Guides the positioning of impression tray.Creates slight displacement of soft tissues

.Help verify retention and seal of potential

denture border.

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Anatomic and physiologic consideration

• Divided into 2 based on anatomic boundaries-

1. Extends medially from one tuberosity to the other .

2. Laterally extends through the hamular notch continuing for 3 to 4 mm anterolaterally approximating the mucogingival junction.

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• Hamular notch covered by the pterygomandibular fold .

• This fold can influence posterior border seal.

• Hamular process should never be covered by the denture-

location-: 2 -4 mm posteromedially to the distal limit of the maxillary residual ridge.

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• Fovea palatini, when present ,lie on either side of the midline .

• Location According to Lye-1.31mm anterior to

the anterior vibrating line .According to Chen-located either on

or behind the anterior vibrating line.

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• Placement of PPS in the region of posterior nasal spine demands extra attention.

• The PPS should be extended to prominent midpalatal fissure if it extends into soft palate.

• Narrow cordlike band of tissue- posterior nasal spine & aponeurosis of the tensor veli palatini muscle.

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• A/C Heartwell and Rahn-this band of tissue if prominent should given relief.

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• Torus palatinus if extends to the bony limit of the palate leaving little or no room to place PPS should be removed .

• Evaluation at initial diagnostic session.

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• Thick ,ropy saliva can create problem in maxillary complete denture retention.

• Treatment –a fine line or cupid’s bow can be scribed on the master cast anterior to the cluster of palatal mucous glands .

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Anterior and posterior vibrating lines

• Anterior vibrating lines –imaginary line located at the junction of the attached tissues overlying the hard palate and the movable tissues of the immediately adjacent soft palate .

• Note-should not be confused about location

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• Two ways of locating AVL1. Valsava maneuver 2. Visualizing while saying “ah” with

short vigorous bursts.• Always on soft palate .

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• Posterior vibrating lines –imaginary line at the junction of the aponeurosis of the tensor veli palatini muscle and the muscular portion of the soft palate .

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• Visualized by instructing the patient to say “ah” in short bursts in a normal, unexaggerted fashion.

• Marks most distal extension of denture base.

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Classification of soft palate

• Based on the degree of flexure that the soft palate makes with the hard palate and the width of the palatal seal area, the soft palate configuration may be classified as -

1. Class 12. Class 2 3. Class 3

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• Class 11. Almost horizontal with little

movement making <10degree with hard palate .

2. Most favourable as it allows best tissue coverage >5mm .

3. Development of wide posterior seal .

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• Class 21. makes a 45 degree angle with the

hard palate.2. Tissue coverage 3-5mm.

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• Class 31. makes a 70 degree angle with the

hard palate.2. Least favourable 3. Tissue coverage <3mm4. Usually associated with v shaped

palate .

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Muscles of the soft palate

• Tensor veli palatini • Levator veli palatini • Musculus uvulae• Palatoglossus • Palatopharyngeus

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Treatment of soft palate defects

• Palatal lift prosthesis Addresses velopharyngeal incompetence By physically displacing the disfunctional

soft palate. In the hope of closing the velophryngeal

port Enough to mitigate hypernasal speech

and/or prevents nasopharngeal regurgitation of liquids or solids

During pharngeal phase of swallowing

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Consists of an oral components that stabilizes and secures the prosthesis and

An oropharngeal extension that superiorly and and posteriorly displaces the impaired soft palate .

Classified as interim and defintive prosthesis .

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Recording the PPS

• This can be achieved by the following methods-

1. Scrapping of cast-functional &arbitrary

2. Impression technique-using fluid wax and using low fusing compund

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Functional scrapping of cast

• Done on the trial denture base • Pts sits in an upright position • PVL marked with T burnisher • The AVL marked by valsava

menoeuvre and transferred to the cast.

• Scrapping the master cast functionally .

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• After scrapping the master cast ,the post dam should be checked .

• Scrapped area should be readapted by shellac denture base or cold cure resin material added .

• Modified record base checked with mouth mirror as the pts say “ah”in an unexaggerated manner.

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• Presence of space indicates under postdamming

• Then the depth of the scrapping should be increased .

• The procedure repeated until no space exists .

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advantage

• The trial denture base has increased retention due to this technique ,thereby increasing the accuracy of the jaw relation procedure .

• The pts can experience and is aware of the retentive qualities expected from the final denture

• the dentist is also aware of the amount of retention denture will process .

• Adjustment for posterior extension is less

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Disadvantage

• Not a physiological technique hence, it is technique sensitive .

• Excessive scrapping of the cast can lead to over postdamming .

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Arbitrary scrapping of the master cast

• This is mostly done by the technician prior to processing the denture when the dentist fails to establish the seal clinically .

• It is an arbitrary notched line formed in the imaginary posterior vibrating line area extending to the hamular notches .

• It should be discouraged .

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Fluid wax technique

• Any wax that is designed to flow at mouth temperature

• Seal established after making final impression but before pouring master cast

• ZOE & impression plaster are suitable impression materials

• The AVL &PVL marked by conventional technique and transferred to the final in the mouth.

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• Final impression painted with fluid wax.• Pts head should be in frankfort’s horizontal

plane at 30 degree.• Pts tongue should be positioned against

the mandibular anterior teeth .• Pts is asked to periodically rotate the head

.• Glossy areas which represent tissue

contact should be checked after 4 -6minutes.

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• Wax is added to areas that appear dull &the procedure repeated .

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Advantage

• Physiological technique• Over compression of tissue avoided .• Increased retention of the record

base and convenience in jaw relation .

• There is no need of scrapping the master cast mechanical.

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Disadvantage

• Increased chairside time .• Handling of material difficult.• Care needed while pouring the

master cast.

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Low fusing compound

• Green stick compound can also be used to make an impression of the seal area using a similar procedure as described for fluid wax.

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Errors in establishing the PPS

1. Underextension2. Overextension 3. Underpostdamming 4. overpostdamming

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underextension

• Using fovea palatine as the limit for posterior denture extension results in loss of several mm of denture extension

• Gag reflex prompting the dentist to intestinally leave the posterior border short .

• Incorrect delineation of the AVL &PVL.• Asking the technician to establish the

seal on the cast arbitrarily.

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Overextension

• Can lead to ulceration and painful deglutition.

• Covering of the hamular process can also lead to sharp pain in the region .

• These ares should be indentified, trimmed and examined .

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underdamming

• Occur when the pts mouth wide open while making final impression .

• Seal areas becomes taut in this position and space is created in other position .

• Verified by inserting wet denture • If air bubbles escapes indicates

underdamming .• Corrected by adding a new seal to the

existing denture .

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Overdamming

• Occurs due to excessive scrapping of the master cast in the hamular notch region.

• Mild cases causes irritation and excessive displaces the denture .

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Summary

• The placement of the correct PPS area is not a difficult procedure once the anatomy and physiology of the areas are understood .

• Careful examination during the diagnostic phase of the treatment can alleviate many potential problems .

• Following established techniques for the placement of the border seal area will ensure a more retentive prosthesis for the pts whose satisfaction is the practitioner’s main concern.

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• Winkler; Essentials of complete denture prosthodontics

• Bernard Levin, impressions for complete dentures

• Chen MS: Reliability of the fovea palatini for determining the posterior border of the maxillary denture.J Prosthet Dent 1980;43:133-137

• Silverman SI: Dimensions and displacement patterns of the posterior palatal seal.J Prosthet Dent 1971;25:470-488

References

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• Winland RD, Young JM: Maxillary complete denture posterior palatal seal: Variations in size, shape, and location. J Prosthet Dent 1973;29:256-261

• Hardy IR, Kapur KK: Posterior border seal: Its rationale and importance.J Prosthet Dent 1958;8:386-397

• Boucher CO, Hickey JC, Zarb GA: Prosthodontic Treatment for Edentulous Patients

• Heartwell CM Jr, Rahn AO: Syllabus of Complete Dentures

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