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Implant-AssistedRemovablePartialDenturesAaronOmura,DMD,MDS,CDT(aaron.omura@gmail.com)

Advantages

• Esthetics:1) Attachmentsadjacenttodistal-mostteethmaypermit

eliminationofclaspsandimprovementinesthetics3,8,9• Function:1) Increasedsupportandstability3,8,9,102) EliminateKennedyClassI&IIsituationswithimplant

placementbeneathmostdistaltooth8,93) Favorablefunctionalloadtransferandincreasedcross-

archstabilization3,8,94) Occlusalstability3,5,9

• Comfort:1) Flangelengthmaybeshortenedduetoincreased

supportandstability82) Extensiontotuberosityandretromolarpadmaybe

removedwitheliminationofdistalextension83) Potentialforincreasedretention3,9,10

Disadvantages

1) Surgicalinterventionisnecessary2) Accuracyofimplantplacementiscrucial63) Increasedtreatmentcomplexity&cost34) Additionaltreatmenttimenecessary10

IARPDConsiderations

Diagnosis&TreatmentPlanningAfteraproperdiagnosticexamination,athoroughunderstandingofpropertoothpositioningtosatisfyfunctionalandestheticdemandsisnecessarytominimizefuturecomplicationsandobtainidealresults.Thisisaccomplishedviaadiagnosticmounting,diagnosticwax-upandeventualtoothtry-intoverifyesthetics.Onlywhenestheticandfunctionaldemandshavebeenmet,canimplantplanningtakeplace10.WiththehelpofCBCTimaging,potentialimplantsitescanbevisualized3-dimensionallyrelativetothedesiredtoothpositionsandcontours.Implantsitestoaidesthetics,function,andcomfortcanbeevaluatedwithanatomicandbiomechanicconcernsinmind10.Restorativespace(≈10mm)canbevisualizedrelativetoscannedprototype(3.5mmLocator+housing,2mmresin,1mmmetal,2mmteeth)2.Lastly,implantsmustbeplannedparalleltodeterminedpathofplacementifstudattachmentsaretobeused.AbutmentsIfattachmentsaretobeused,guideplanesmustbemadeparalleltoimplanttrajectoryforproperengagementofattachments3,4,8.Inclasplessdesigns,itmaybeprudenttoincludeadditionalrestsandundercutsasacontingencyplanintheeventofimplantfailure10.FrameworkDesign(AlltraditionalRPDconceptsstillapplytoIARPDS)8Aftermastercastshavebeenfabricatedandmounted,teethshouldbesetforestheticsandfunction.Matricescanthenbefabricatedtocapturetoothpositionsandaidinframeworkdesigntomaximizesupportwithoutinfringingonrestorativespace1,8,10.Astrutofmetal“overthetop”ofimplantattachmentsisrecommendedtominimizestressandpotentialfractureinthoseareas11.Maintenance

Naturalteeth,periodontium,peri-implanttissuesandedentulousridgesshouldbeexaminedforhealthandstability.Occlusionshouldbeevaluatedforstability/wearandmanagedappropriately.Implantabutmentsandattachmentsmustbecarefullyinspectedforwear/damagetoensureoptimalperformance10.

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Procedure:DigitalTransferofSurveyLineforiRPDImplantPlanning1.Makeprimaryalginateimpressionstogeneratediagnosticcasts.

2.Duplicatediagnosticcastsusingreversiblehydrocolloid(InstalloidDuplicatingMaterialAll-Purpose,CMPIndustries,Inc.)Duplicatecastsmustremainuntouchedthroughoutprocedure.

3.Fabricateresinrecordbases(Triad,DentsplyInternationalInc.)andwaxocclusalrimstoprescribeddimensions.12Recordbasesmustbetransferrabletountouchedduplicatesforlabscanninglater

4.MakeinterocclusalrecordsincentricrelationattheplannedOVDusingvinylpolysiloxaneregistrationmedium(Regisil,DENTSPLYInternationalInc.).Makeafacebowrecordandmountindexedcastsinanarticulator(WhipMix2340,WhipMixCorporation).

5.Surveydiagnosticcastsandduplicateddiagnosticcaststothedesiredtilt.Completediagnosticwaxuptodesiredcontoursanddimensions.Setteethoccupyingedentulousspacesonresinrecordbasesfabricatedinstep3.

6.Evaluateestheticsandphonetics.Verifyocclusionanddiscusspatientacceptanceoftooth

arrangementatthewax-tryinappointment.

7.Drillarecesslargeenoughtooccupysurveyorientationrod(SOR)intotonguespaceorpalate

ofuntouchedduplicatecast.Arrangeduplicatecasttodeterminedtiltandlockthesurveytable.

8.Usingthesurveyor,lower(SOR)intorecessandlute(SOR)intoplacewithresin(GCPattern

Resin).Allowresintofullypolymerizebeforedisconnecting(SOR)fromsurveyorarm.

9.Usingalaboratoryscanner(NobelProceraScanner),scanduplicatecastwith(SOR)inplace.

Checktomakesure(SOR)iscapturedaccuratelyinscan.NowaddresinrecordbasewithwaxedprostheticteethandscanagaintocreatealayeredSTLfile.

10.TakeaCBCTonpatienttogenerateaDICOMfileofthedesiredarch/archesforimplant

planning.Then,importDICOMandSTLfilesintoimplantplanningsoftware(NobelClinician)andallowsoftwaretooverlaythetwodatasets.

11.Planimplantsparallelto(SOR)instrategicimplantpositionstofacilitateimprovedRPDfunction/esthetics.Allthewhilebeingconsciousofanatomicstructures,restorativespace,andsoundRPDprinciples.Overlaydiagnosticwaxup.

12. Incaseswherebonedoesnotallowparalleltrajectory,leaveimplanttoserveaslocal

reference.Insertandalignimplant,addappropriateanglecorrectingabutment,andparallelscrewaxistoreference

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13.Onceplanisverifiedtobesoundprostheticallyandsurgically,orderCAD-CAMtooth-bornesurgicalguide

14.Placeimplants,allowforproperhealingandcontinueIARPDfabricationasnormal.

ReferenceList

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4. GulizioMP,AgarJR,KellyJR,TaylorTD.Effectofimplantangulationuponretentionofoverdentureattachments.JProsthodont.2005;14(1):3-11.

5. SaundersTR,GillisRE,DesjardinsRP.Themaxillarycompletedentureopposingthemandibularbilateraldistalextensionpartialdenture:treatmentconsiderations.JProsthetDent.1979;41(2):124-128.

6. GiffinK.Solvingthedistalextensionremovablepartialdenturebasemovementdilemma:aclinicalreport.JProsthetDent.1996;76(4):347-349.

7. Al-GhafliSA,MichalakisKX,HirayamaH,KangK.Theinvitroeffectofdifferentimplantangulationsandcyclicdislodgementontheretentivepropertiesofanoverdentureattachmentsystem.JProsthetDent.2009;102(3):140-147.

8. SchneidTR,MattiePA.Implant-assistedremovablepartialdentures.In:PhoenixRD,CagnaDR,DeFreestCF,eds.Stewart’sClinicalRemovablePartialProsthodontics.4thed.HanoverPark,IL:Quintessence;2014:259-277.

9. MitraniR,BrudvikJS,PhillipsKM.Posteriorimplantsfordistalextensionremovableprostheses:aretrospectivestudy.IntJPeriodonticsRestorativeDent.2003;23(4):353-359.

10. OmuraAJ,LattheV,MarinMM,CagnaDR.Implant-assistedremovablepartialdentures:practicalconsiderations.GenDent.2016Nov-Dec;64(6):38-45.PMID: 27814254.

11. GondaTetal.Fractureincidenceinmandibularoverdenturesretainedbyoneortwoimplants.JProsthetDent2010;103(3):178-181.

12. AlsiyabiAS,FeltonDA,andCooperLF.Theroleofabutment-attachmentselectioninresolvinginadequateinterarchdistance:aclinicalreport.JProsthodont2005;14(3):184-190.