posterior palatal seal prostho 1 [edocfind.com][1]11

8/6/2019 Posterior Palatal Seal Prostho 1 [EDocFind.com][1]11

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POSTERIOR

PALATAL SEAL

SUBMITTED BY:

ANKUR GUPTA


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Definition

Function

Anatomic consideration

Physiologic consideration

Vibrating line Classification of soft palate

Techniques

Errors in recording PPS Summary


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DEFINITION

It is a soft tissue along the junctionof hard & soft palate on which pressure

with in the physiologic limit on thetissue can be applied by denture to aidthe retention of the denture. (GPT)


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The peripheral seal of maxillary dentureis a area of contact between the mucosa

& peripheral polished surface of thedenture base, the seal prevent passageof air between denture & tissue.

Retention stability of a denture isachieved from adhesion, cohesion &interfacial surface tension that resist

the dislodging forces that actperpendicular to the denture base.


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FUNCTION OF PPS

Stability

Prevention & retention

Compressibility Comfort


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STABILITY:The main function of PPSis to maintain contact with the anteriorportion of the soft palate ( the tissueunder go shallow displacement ) duringfunctional movement of the

somatognathic system ( that ismastication, deglutination & phonation)therefore the main purpose of PPS is

the retention of maxillary denture.


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PREVENTION :It also reduce gagreflex as there is no separationbetween denture base & soft palateduring normal functional movement.

COMPRESSIBILITY :It also reduce

food accumulation beneath theposterior aspect of denture owing toproper utilization of tissue

compressibility.


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COMFORT : reduce patient discomfortcontact occur between dorsum of thetongue & posterior end of denture base.

The correctly placed PPS creates apartial vaccum beneath the maxillarly

denture , this partial vaccum isactivated only one horizontal tippingforces act is very small & hence produce

no irreversible alternation of theunderlying mucosa.


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This pterygomaxillary notch is coveredby pterygomandibular fold which extendfrom the posterir aspect of thetuberocity posterio-inferiorly to insertinto the retromolar pad.

This fold of tissue influence theposterior border seal if the mouth iswide open position during the finalimpression process.

Hamular notch should never be coveredby denture as only covered by thin layerof mucous membrane.


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Fovea palatina are two glandular openingwithin the tissue posterior of hardpalate lying on the either side ofmidline.

Fovea palatina should be used only as a

guideline for the placement of posteriorpalatal seal.

Medial palatal raphe which overlies

medial palatal suture contain little orsubmucosa & will tolerate little or nocompression .


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VIBRATING LINE

The imaginary line acrossthe posterior part of thepalate marking the divisionbetween the movable &

immovable tissue of thesoft palate which can beidentified when the movabletissue are moving. (GPT)

Anterior vibrating line Posterior vibrating line


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ANTERIORVIBRATING LINE

It is an imaginaryline lying at the

junction betweenthe immovabletissues over thehard palate & the

slightly movabletissue of thesoft palate-GPT.


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METHOD OF LOCATINGA.V.L.

Instructing the patient to say AH withshort vigorous bursts due to projection

of the posterior nasal spine. Theanterior vibrating line is not a straightline between both hamular process.


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POSTERIORVIBRATING LINE

Itisanimaginarylineas junctionoftheaponeurosisoftensor vilipalatinimusclesinthemuscularportionofthe

softpalate.-S. Winkler.Itrepresentdemarcation between

thepartofsoftpalatethathaslimited

orshallowmovementduringfunction(quivers) &theremainderofthesoftpalatethatismarkedlydisplacedduringfunctionalmovement.


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Thustheplacementof PPSacrossmid-palatalsuturedemandcarefulattention.

PPS shouldalsoextendintomidpalatalfissuretoensureproperperipheralseal.

Cordlike bandoftissueextending betweentheposteriornasalspine &aponeurosisoftensorvilipalatinimusclesshouldreceiveslightamountofrelief.

Ifthetourspalatiniextendtothe bonylimit

ofthepalateleavinglittleornoroomtoplacethe PPSthenitsremovableisindicated.


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The presence of thick ropy saliva maycreate a problem for maxillary completedenture retention as it create

hydrostatic pressure in the areaanterior to PPS resulting in a downwarddislodging force everted major denture

base.


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METHOD OF LOCATING P.V.L.

Instructthepatienttosay AHina

shortvigorousburstinanormalunexaggeratedfashion. Theposteriorvibratinglinemarksthemostdistal

extensionofthedenturebase.


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CLASSIFICATION OF SOFTPALATE

Itisclassifiedin-

class Iclass II

class III


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CLASS I

It indicate soft palate that is ratherHorizontal as a extend posteriorly withminimum muscular activity.

There is considerable separationbetween anterior & posterior vibratingline does having white PPS area yieldingmore retentive denture base.


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.CLASS II

palatal contour lie between classI&classIII.


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CLASS III

it is seen in conjugation with highV shape palatal vault. There is few mmseparation of anterior & posteriorvibrating line thus there is small PPS

area & less retention.


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TECHNIQUES

There are several establishedtechniques for the placement of PPS.

The important once are:-1. Conventional approach

2. Fluid wax technique


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The rational for the placement of aseal in the impression tray as follows:-

1. To establish positive contactposteriorly to prevent the finalimpression material from sliding down

the pharynx.2. To serve as a guide for positioning the

impression tray, especially if a shim

has been used within the tray toestablish the borders.


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3. To create slight displacement of thesoft palate.

4. To determine if adequate retention &seal of the potential denture border ispresent.


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CONVENTIONAL APPROACH

Afterthespecialtrayisfabricatedtherearecertaininstructionsgiventothepatients:-

1. Torinsewithanastringentmouthwashthatisremovetostringysalivathatmightpreventcleartransfer

marking.Therearestepstobefollowed


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2. Locationofpterygomaxillarynotchisdonebymovingthe Tburnisher

posteriorangletothemaxillarytuberosityuntilitdropsintothepterygomaxillarynotch. Thisis

necessaryastherearetimeswhensmalldepressionintheresidualridgemayresemblepterygomaxillarynotch.

3. Identificationofposteriorvibratinglinethepatientaskedtosay AHinshortburstinanexaggeratedfashion.


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4. Identification of the anterior vibrationline. This is done by asking the patientto say AH with short vigorous bursts

(ValsalvaManeuver can also be used)


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PROCEDURE

Alineisplacedwithanindelible pencil(Thomsonsanitarycolourtransferapplicators)throughthepterygomaxillarynotch &extended 3-4 mmantero-laterallythetuberosityapproximatingthemucogingival junction

sameisdoneontheoppositeside. Thiscompletetheoutliningofpterygomaxillaryseal


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The tray is trimmed until the posteriorvibration line so that it decides the post

extent denture border. Returning to the mouth the palatal fissure are

palpated with the T barnisher or mouthmirror to determine their compressibility in

width & depth. The termination of glandular tissue usually

coincides with the anterior vibrating line.

The anterior vibrating line now markedstranseferred to master cast .this completethe transferring the outline of posteriorpalatal seal area.


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(A) A T burnisher is

used to palpate forthe hamular process.

(B) Palpating for the

pterygomaxillary

notch


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The visual outline is in the shape of cupid bowthe area between the anterior posterior

vibrating line is usually narrowest in the midpalatal region because of the projection ofthe posterior nasal spine.

Kingsley scraper used to score the cast the

deepset area are located on either side ofmidline, one third the distance anteriorlyfrom the posterior vibrating line. It is usuallyscraped to a depth of approximately 1-1.5 mm

. The tissue covering the medial palatal raffaeas little sub mucosa & cannot withstand samecompressive force as the tissue lateral to it


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Thisareaisscrapedtodepthofapproximately 0.5-1 mmwithinthe

outlineofcupidbow &castisscrappedtodepthofhalfamoungtopalataltissueinthatareacanbecompressed

beingtaperedposteriorly.

Failuretotaperthesealposterior

mainlytotissueirritation.


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3. Thepractionerwillbeabletodeterminetheretentive qualitiesofthe

finisheddenture,leavingnothingtochanceattheinsertionappointment.

4. The newdenturewearerwillbeabletorealizetheposteriorextentofthedenturewhichmayeasetheadjustment

periods.


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DISADVANTAGES

1. Itisnotaphysiologictechnique &thereforedependsuponaccuratetransferofthevibratinglines &carefulscrapingofthecast.

2. Thepotentialforovercompressionofthetissueisgreat.


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FLUID WAX TECHNIQUE

Alloftheprocedureremainthesameasconventionaltechniquethatistransferlocation &transfermarkingof

theanterior &posteriorvibratinglineThemarkingarerecordedinfinal

impressiononeofthefourtypeofwaxcanbeusedfortheirtechnique:-

1. Iowawaxwhitedevelopedby Dr. Earl S.Smith.


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2. Korectawaxno. 4,orangedevelopedbyDr. O.C. Applegate.

3. H.L. physiologicpaste,yellow-whitedevelopedby Dr. C.S. Harkins.

4. Adaptolgreendevelopedby Nathan G.

thesewaxaredesignedtoflowatmouthtemperature. Themeltedwaxispaintedintotheimpressionsurface &intheoutlineatsealarea,thewaxapplied

inslightly &excessoftheestimateddepth &allowedtocooltoblowmouthtemperaturetoincreaseitsconsistency&makeitmoreresistentofflow.


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Theimpressioniscarriedtomouth &heldundergentlepressure 4-6 minute

toallowthematerialflowpositionofhead &tongueduringthisisprocedure.

Thesoftpalateshouldbeimpressioninitmostfunctionallydepressedpositionsthatisbykeepingfrankfortplane 30

belowthe Hz &thetongueisfirmlypositionedagainstmandibularanteriorteeth.


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ADVANTAGE-THISPOSTION

1. Softpalateisimpressioninitsmostfunctionallydepressedposition.

2. Theflowofsaliva &impression

materialintothepharynxisprevented.After 4-6 minutesimpressiontrayisremovedfromthemouth &examined

foruniformcontact.Ifthetissuecontacthasnotestablishedthewaxwillappeardull.


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Ifthetissuecontacthasbeenestablisheditwillappearglossy.

Ifexcesswaxprotrudedoutofthetrayitshouldberemoved.

A Secondaryimpressionisreinserted &heldfor 3-5minutesundergentlepressure

followedby 2-3 minutesoffirmpressureappliedtomidpalatalareaoftheimpressiontray,uponremovaloftrayfromthemouthitiscarefulexaminedtoseewaxterminatein

featherededgeneartheanteriorvibratingline.


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Itabuttjointispresent &properflowhasnotbeentakenplace &impressiontrayisreinserted.

Ifthewaxisoverextendeditshouldbecarefultrimmedthescalpel.


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ADVANTAGES

1. Itisphysiologictechniquedisplacingtissueswithintheirphysiologicallyacceptablelimits.

2. Overcompressionoftissueisavoided.3. Posteriorpalatalsealisincorporated

intothetraildenturebaseforadded

retention.4. Mechanicalscrappingofthecastisavoided.


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DISADVANTAGES

1. Moretimeisnecessaryduringtheimpressionappointment.

2. Difficultyinhandlingthematerials &addedcareduringtheboxingprocedure.


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ERROR INRECORDINGOFPPS

1. Underextension

2. Underpostdamming

3. Overpostdamming4. Overextension


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2. Reducethepatientanxietytogagging.

3. Improperdelineationoftheanterior &posteriorvibratingline.

4. Prevention:Excessivetrimmingoftheposteriorborderofthecast.


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2. OVER EXTENSION

1. Thedenturebasecanleadtoulcerationofthesoftpalate &painfuldegulutition.

2. Themostfrequentcomplaintfromthe

patientwillbethatswallowingispainful &difficult.3. Thehamuliarecoveredbythedenturebase

,thepatientwillexperiencesharppain,

speciallyduringfunction.4. Prevention: Theseregionaretrimmed &poslished


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4. Thepterygoidhamulimustneverbecoveredbythedenturebase.

5. Theoverextensioncanberemovedwithabur &thencarefullyrepolished.


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3. UNDER POSTDAMMING

1. Thiscanoccurduetoimproperheadpositioning &mouthpositioning. E.g.themouthiswideopenwhilerecordingtheposteriorpalatalsealthemucosaoverthehamularnotchbecomesstretched. Thiswillproduceaspace

betweenthedenturebase &tissue.


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2. Inserting a wet denture into a patientsmouth & inspecting the posterior border

with the help of mouth mirror. If airbubble are seen to escape under theposterior border it indicates under

damming.3. Prevention: The master cast canscraped in the posterior palatal area orthe fluid wax impression can be

repeated with proper patient position.


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4. OVER POSTDAMMING

1. Thiscommonlyoccurduetoexcessscrapingofthemastercast. Itoccurmorecommonlyinthehamularnotchregion.

2. Pterygomaxillarysealarea,thenupon

insertionofthedenturetheposteriorborderwillbedisplacedinferiorly.


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3. Prevention: Reduction of the dentureborder with a carbide bur, followed bylightly pumishing the area while

maintaining its convexity.


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SUMMARY

So,itisconcludedthattheexistenceofposteriorpalatalsealplaysamajorroleinthedevelopmentofstability,retention &prevention,compressibility &comfortofthecompletedenture.


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REFERENCES

Sheldon Winkler,Essentialsofcompletedentureprosthodontcs.secondedition.

Zarb Bolender,Prosthodontic Treatmentforedentulouspatients,twelfthedition.

Boucher,sProsthodontictreatmentforedentulouspatient,ninthedition.

Deepak Nallaswamy,Textbookofprosthodontics,firstedition.


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