UnitThirtyFourCOMPLETEDENTUREWhensomeonelosesallhisteeth(becomesedentulous),healsolosessomeoftheabilitytoperformcertainactivities-eating,speaking,facialexpression-andhisappearanceisimpaired.Hisappearanceisimpairednotonlybythelossoftheteeththemselvesbutalsobecauseofthelossofsupportforthefacialtissueslyingoverthem.Whentheteetharelost,someofthesupportingthemboneresorbs.Theartificialsubstitutes-completesdentures-mustnotonlyreplacethelostteethandlostsupportingboneandsofttissue,butalsorestoretheimpairedfunctionsandappearance.Clinicalstagel.HistoryandexaminationClinicalstage2.Primaryimpressions.Objectives:Toobtainanimpressionofthewholeofthedenture-supportingareaofeachjaw;torecordthefullextentofthesulcus;toobtainanimpressioninwhichcertainlandmarksontheedentulousjawsarerecorded.Byachievingtheseobjectivesamodelcanbeobtaineduponwhichacorrectlydesignedtraymaybeconstructedinordertomakethesecondaryimpression.Furthermore,onlyimpressioncompoundhasthecorrectpropertiesofconsistencyandabilitytobemanipulatewhicharenecessaryinaprimaryimpressionmaterial.LaboratoryprocedureslThepreparationforthevisitatwhichthesecondaryimpressionswillbemadeinvolvestheconstructionofcastsfromtheprimaryimpressionsandtheconstructionofspecialtraysonthesecasts.Clinicalstage2(continued)SecondaryimpressionsObjective:toobtainanimpressionfromwhicharetentivedenturebasecanbeconstructed.Thedenturebaseshouldsatisfythefollowingrequirements:l.Itmustbeextendeduntilitsborderliesondisplaceabletissuewhereasealcanbedeveloped.2.Thetissueadjacenttothebordershouldbedeformedenoughtoachieveasealbutnotsomuchthattheytendtodisplacethedentureorsufferinjury.Musclesrelatedtothebordermustnotbepreventedfromfreeactivity.3.Itshouldhavetheclosestpossiblecontactwiththesurfaceorthemucousmembranelyingbeneathit.4.Extensiontoprovideretentionensuresthemaximumcoverageofthejaw,andthisinturnensuresthattheminimumforceperunitareaistransmittedtothesupportingtissuesbythedentureduringfunction.TheadventofVinyl-polysiloxaneoffersanalternativematerialforupperandlowerimpressions.Itisofsuitableconsistencyandgivesanexcellentsurfacetothecastanddentures.Polyethermaterialsarealsoused.Laboratoryprocedures2Atthisstagethepermanentbasesaremadeandwaxocclusionrimsareaddedtotheminpreparationforthenextclinicalstepofrecordingthejawrelation.Clinicalstage3l)Checkingretentionofthebasespriortoestablishingjawrelationships2)Establishingjawrelationshipswithpermanentbases.Objectivesl.Toaccuratelyrecordcentricjawrelationship.2.Totakeafacebowrecordtoenablethebaseplateandocclusionrimstobepositionedinthearticulatorsothattheirrelationshiptotherotationalaxesofthearticulatoristhesameastherelationshiptheywillbeartotherotationalaxesofthemandiblewhentheyareinthemouth.ProcedureAssessthelipsupportMeasuretherestverticaldimensionEstablishtheocclusalverticaldimensionRecordthecentricjawrelationshipMethods,whichmaybeusedtoassistthepatientinclosingtoaretruded,position.3)ProtrusiverecordWhenapatientprotrudesthelowerjawthecondylesbothmoveforwardanddownward,guidedbytheformofthearticularfossae.Thedownwardmovementsofthecondylesresultinasimilardownwardofthelowermolarregion.Theprotrusiverecordmeasurestheamountofthedrop.Withitthearticulatorisadjustedsothatitwillproduceasimilaramountofdropwhenasimilaramountofprotrusionisused.Theteethonthedenturecanthenbearrangedsothatcontactbetweentheposteriorteethismaintainedinprotrusion(protrusivebalance).4)Thefacebowrecord5)Selectionofteeth.Tochooseartificialteethwhoseformandcolourwillharmonizewiththepatient'sfeaturees.Laboratoryprocedures3l)Addingthepost-damtotheupperdenturebase.2)Mountingthebaseplatesandocclusionrims.3)Selectingposteriorteeth.4)Settingtheteeth.Clinicalstage4ThetrialdenturesTocheckthatthearrangementoftheteethissuchthatspeechandmasticationwillberestoredandtoensurethatapleasingappearanceisobtained.Laboratoryprocedure4Atthisstagetheprotrusiverecordisusedtosetthecondylartrackanglesandthentheocclusionisadjustedtoprovidebalanceineccentricpositions.Followingthiswaxsurfacesarecontoured,thedenturesareinvestedinaflask,andthewaxisremovedandreplacedbyacrylicresin.l)Settingthecondylartrackangles2)Developingthelateralandprotrusiveocclusions.3)Contouringandfinishingthewaxsurfaces.4)Processingdentures.Clinicalstage5Insertingthecompleteddentures.Objective.l)Tochecktheretentionandtheaccuracyofthejawrelationsofthecompleteddentures,andtoadjustwherenecessary.2)Toinstructthepatientsinthecorrectuseoftheirdentures.3)Toadvisethepatientsonthepropercareoftheirdenturesandofthedenture-supportingtissues.4)Toadvisethemonthelimitationstobeexpectedofartificialdentures.Laboratoryprocedures5Alteracheckcentricjawrelationshiprecordhasbeentaken,thelowerdenturemustberemountedinthearticulator,andadjustmentofthecentricandeccentricocclusionsmade.l)Remounting2)Reformingcentriclateralandprotrusiveocclusions.Clinicalstage6Adjustmentofdenturesl)Useofdisclosingwax(ontheborder)andpressurereliefcream(onthefittingsurface).2)SubsequentvisitsVOCABULARYl.artificialsubstitute人工替代物2.denture-supportingarea義齒承托區3.sulcus(間隙)溝4.landmark標志5.edentulousjaw無牙