Digital Design of CBCT Templates Carolyn Kincade, Fari Karimi-Boushehri, Martin Osswald, Suresh Nayar, John Wolfaardt

INTRODUCTION

Digitisationoftechnical/laboratorydentalproceduresisgainingmomentum.Theuseofdigitaltechnologyinadentallaboratory hasthepotentialtoincreasequalityandreproducibility,bettermeetclinicalfunctionalrequirements,andimproveaestheticoutcomesforpatients.Thisrequirestheappropriatesoftwareanddigitalequipment,alongwithspecializedtrainingtokeepupwithindustrystandards.Traditionalmethodscontinuetobeutilised;these‘analog’methodsinvolvethemanualmanipulationofdentalmaterials,whichcanbetimeconsuming.ManyareasofdentistryareturningtoComputerAidedDesignandComputerAidedManufacturing(CAD/CAM)solutionstoimproveworkflow.Thefieldofremovableprosthodonticshasbeenslowtoadoptthesetechnologiesduetothescopeandcomplexityoftheprostheses.Forexample,theconventionalprocessforfabricatingacompletediagnosticdentureasaradiographicscanningtemplateforsimulatedimplantplanninginvolvesaminimumoffourchairsideappointments,requiringtheclinicianandsupportstaffwithadditionallaboratoryworkateachappointment.Patientcareandworkflowcouldbenefitfromutilisingdigitalpathwaystoimprovetheprocessofcompletedenturefabrication.

OBJECTIVE

TheaimofthispilotprojectwastodeterminetheviabilityofdigitizeddenturetootharrangementsinthefabricationofConeBeamComputerTomography(CBCT)/radiographictemplatesusedfordiagnosticpurposesandimplantinstillationplanning,therebyreducingchairsidetimeandpatientvisits

METHODS

ThelaboratoryatiRSMproducedaccuratediagnosticprostheses/templateswithimbeddedradioopaquemarkerstobeusedintheacquisitionofCBCTscansandsubsequentCADimplantinstallationplanning.ThelaboratorydesignedCADdiagnosticprosthesesusinganopticalscanner(ShapeGrabber Inc,OttawaON)andCADsoftwareprograms(Magics:Materialise Technologielaan,LeuvenBelgium)(FreeformandControl:3DSystems,CircleRockHill,USA)ThediagnosticprostheseswerethenmanufacturedthroughaCAMprocessusingadditivemanufacturingor3Dprintinginamaterial withpropertiessimilartothoseofacrylic.

Theprocessbeganwiththecliniciansprovidingpreliminaryalginateimpressionsofthepatients’currentoralenvironmentfromwhichthelaboratoryfabricatedcastsandocclusalrimsfollowingstandardbiometrics.Thecliniciansutilizedtheocclusalrimstodeterminepatients’smilelines,planesofocclusion,condylarpositionsandtoprovide thelaboratorywithajawrelationrecording(JRR)(fig.1&2).

TheJRRswereusedformountingthemaxillaryandmandibularcasts.Uponcompletionoftraditionalmounting,thelaboratorydigitizedthemaxillaryandmandibularcastsandrimstoderivedigitalrelationshipsofthejawstoeachother(fig.3).Separatescansofthemandibularcastsandrims,maxillarycastsandrims,andbitewerealignedtoeachotherutilising virtualplanningsoftware(Control:3DSystems,CircleRockHill,USA).Thedigitizationprocesswascompletedwiththeuseofanopticallaserscanner(ShapeGrabber Inc.,OttawaON).Digitizeddentureteeth,selectedbytheclinician,werearrangeddigitallyusingCADsoftware(Magics :MaterialiseTechnologielaan)intotherequiredpositionsaspercliniciandirectionfromthejawregistrationsobtained(fig.4).

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REFERENCES

Karkar,I.G.,Huafeng,W.,&Karkar,P.G.(2010,April29).System,MethodAndApparatusForToothImplantPlanningAndToothImplantKits.RetrievedOctober14,2015,fromhttps://www.google.com/patents/US20100105011

Lin,W.S.,Harris,B.T.,Ozdemir,E.,&Morton,D.(2013).MaxillaryrehabilitationwithaCAD/CAMfabricated,long-terminterimandanatomiccontourdefinitive prosthesiswithadigitalworkflow:Aclinicalreport.JournalofProstheticDentistry,1-7.

Bidra,A.S.,Taylor,T.D.,&Agar,J.R.(2013).Computer-aidedtechnologyforfabricatingcompletedentures:Systematicreviewofhistoricalbackground,currentstatus,andfutureperspectives.TheJournalofProstheticDentistry,109(6),361-366.

Rudolph,H.,Luthardt,R.G.,&Walter,M.H.(2007).Computer-aidedanalysisoftheinfluenceofdigitizingandsurfacingontheaccuracyindentalCAD/CAMtechnology.ComputersinBiologyandMedicine,37(5),579-587.

Lin,W.S.,Harris,B.T.,Ozdemir,E.,&Morton,D.(2013).MaxillaryrehabilitationwithaCAD/CAMfabricated,long-terminterimandanatomiccontourdefinitive prosthesiswithadigitalworkflow:Aclinicalreport.JournalofProstheticDentistry,1-7.

RESULTS

12ofthefullycontouredprosthesesdidnotrequireanyfurtherchairsideadjustmentsandwereimmediatelyusedforCBCTscanning.Threecasesrequiredchairsidemodification,whichwascompletedatthesameappointmentwiththeprintedtootharrangementsasdescribed.TheCBCTscansforthemodifiedcaseswereobtainedatthesamevisitanddidnotrequireadditionalchairsideappointments.All15casesbenefitedfromthedigitalmethodandrequiredonlythreeappointmentsascomparedtotheconventionalmethodwhichrequiresfourpatientvisits.

DISCUSSION

ThethreecasesrequiredadditionaladjustmentsduetoocclusalfactorsasthedigitalmethoddescribeddoesnotaccountfordynamicfunctionalmovementsandtheCADprogramsdonothavetheadjustability/functionalityofadentalarticulator.

CONCLUSION

Thenewdigitalmethodreducedlaboratorytime,decreasedthenumberofpatientappointments,andhasthepotentialtoreduce operatingcosts.TheuseofadigitalJRRsystemsandarticulatorscouldalleviatetheocclusalerrorsencounteredinthisstudy.Futuredevelopmentofthistechniqueisrequiredtoexplorethepotentialforcompletedigitaldenturedesignandfabrication,furtherreducingtreatmenttimeandcostsforpatients.

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SculptingoftissuesurfaceswasperformedtoachievetraditionallyacceptedcontoursandextensionsusingCADsoftware(FreeForm :3DSystems,CircleRockHill,USA)(fig.5-7). Thecompletedmaxillaryandmandibulardiagnosticprosthesesweresenttoprint.Afullcontourtemplatewasprintedforeacharch,aswellastheisolatedtootharrangement(fig.8)Thisseparatearchformwastobeusediftoothpositionsrequiredadjustmentduringtryin.TheStandardTessellationLanguage(stl)filesdevelopedwerethensenttoaCAMadditivemanufacturing3Dprinter(Objet260Connex:Stratasys,MNUSA).

Theprinteddiagnosticprostheseswerecleanedpostprinting,inspectedandverifiedforpatientuse.Radioopaquemarkerswereadded(fig.9).Thecliniciansinsertedtheprinteddiagnosticprostheses(fig.10).Fit,contourandtoothpositioningwereverifiedormodifiedifrequired.TheCBCTscanswerecompletedandresultantDicomdataloadedintoplanningsoftwareforfurthersimulateddigitalimplantplanning(fig.11).Atotalof15caseswerecompletedusingthismethodfromJanuary2015topresent.