managment of wear

Current concepts on the man-agement of tooth wear: part 2. Active restorative care 1: the management of localised tooth wearS. B. Mehta,1 S. Banerji,2 B. J. Millar3 and J.-M. Suarez-Feito4

VERIFIABLE CPD PAPER

•Symptomsofpainanddiscomfortmayexist

•Theremaybefunctionaldifficulties•Anunstableocclusionispresent1

•Therateoftoothsurfacelossmaybeofextremeconcerntoeitherthedentaloperatororpatient,whichfurthermoreifneglectedmayculminateinexposureofthedentalpulp.2

Itisprudent,however,toinitiallyimple-ment a preventative programme and aperiod of monitoring of 6-12 monthsbefore embarking upon what usuallyinvolvescomplex,technicallydemandingrestorativedentistry.Suchaperiodoftimewillnotonlyallowtheoperatortoensurethattheaetiologicalfactorhasbeenelimi-natedorgreatlyreduced,butalsoprovidetime for the patient to understand thenatureof the treatmentplanbeingpro-posedand importantly,aperiodof timefortheoperatortoestablisharapportwiththepatient.There may however, be special cir-

cumstances,suchas incasesofaggres-sive erosion-relatedwear,where activeinterventionwillneedtobeimplementedmorerapidly.Forthepurposesofdescription,active

restorative intervention will be sub-divided into that for localised wear(maxillary anterior, mandibular ante-rior, localisedposterior)andgeneralisedwearrespectively.

THE NEED FOR ACTIVE RESTORATIVE INTERVENTION

Whileformanycasesofpathologicaltoothwear,passivemanagementandmonitor-ingmaysuffice,foraproportionofcasesactiverestorativeinterventionwillbecomenecessary. The caseswhich require thisgenerallyfallintothecategoriesofwhere:•Theremaybeaestheticconcerns

This second of the four part series of articles on the current concepts of tooth wear management will focus on the provi-sion of active restorative care, where the implementation of a preventative, passive approach may prove insufficient to meet the patient’s expectations, or indeed prove to be sufficiently adequate to address the extent of the underlying pathol-ogy to the desired level of clinical satisfaction. The active restorative management of cases presenting with localised tooth wear (of either the anterior, posterior, maxillary or mandibular variety) will be considered in depth in this paper, including a description of the commonly applied techniques and treatment strategies, where possible illustrated by case examples.

LOCALISED MAXILLARY ANTERIOR TOOTH WEAR

Maxillary anterior teeth aremost com-monly involved in localised toothwear,especiallywhereerosionisamajorfactor.Thedecisiononhowtooptimallyrestore

these teethwilldependonthe interplaybetweenfivefactors:1. Thepatternofanterior,maxillary

toothsurfaceloss2. Inter-occlusalspaceavailability3. Spacerequirementsofthedental

restorationsbeingproposed4. Thequantityandqualityof

availabledentalhardtissueandenamelrespectively

5. Theaestheticdemandsofthepatient.

Thepatternofanteriormaxillarytoothwear has been classified byChu et al.3intothreecategoriesinordertofacilitaterestorativetreatmentplanning:1. Toothwearlimitedtothepalatal

surfacesonly2. Toothwearinvolvingthepalataland

incisaledges,withreducedclinicalcrownheight

3. Toothwearlimitedtolabialsurfacesonly.

Forcasesinvolvingvisiblesurfacessuchas the latter two categories, restorativetechniqueswill involve theuseof toothcolouredaestheticmaterials.Metallicres-torations,suchasmetalpalatalveneers,

1,2General Dental Practitioner and Senior Clinical Teach-er, Department of Primary Dental Care, King’s College London Dental Institute, Bessemer Road, London, SE5 9RW; 3*Professor, Consultant in Restorative Dentistry, Department of Primary Dental Care, King’s College London Dental Institute, Bessemer Road, London, SE5 9RW; 4Section of Periodontology, Faculty of Dentistry and Medicine, University of Oviedo, Oviedo, Spain *Correspondence to: Professor Brian J. Millar Email: [email protected]

Refereed Paper Accepted 14 November 2011 DOI: 10.1038/sj.bdj.2012.48 ©British Dental Journal 2012; 212: 73-82

• Identifies the need for active restorative intervention for any patient presenting with pathological tooth wear.

• Describes possible approaches to the successful restoration of a dentition presenting with localised pathological tooth wear.

• Discusses how contemporary treatment protocols have been significantly influenced by advances in understanding of adhesive dentistry and occlusion.

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1. Assessment, treatment planning and strategies for the prevention and the passive management of tooth wear

2. Active restorative care 1: the management of localised tooth wear

3. Active restorative care 2: the management of generalised tooth wear

4. An overview of the restorative techniques and dental materials commonly applied for the management of tooth wear

CURRENT CONCEPTS ON THE MANAGEMENT OF TOOTH WEAR

BRITISH DENTAL JOURNAL VOLUME 212 NO. 2 JAN 28 2012 73

© 2012 Macmillan Publishers Limited. All rights reserved.

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havelittleornoplaceforthesecases.Incontrast,forcaseswherethepathologyispalatalonly,metalpalatalveneersmayprovetobeanexcellentrestorativeoption.Themeritsofeachtechniqueandmaterialsusedtofacilitatetherestorationofworndentitionswillbediscussed indetail inpaper4ofthisseries.

Inter-occlusal space availabilityInthemajorityofpatients,toothwearisaccompaniedbydento-alveolarcompen-sation.4Thelatterphysiologicalcompensa-torymechanismallowsocclusalcontactstobemaintained, inorder toattempttopreserve theefficacyof themasticatorysystem.However,thepossiblelackofinter-occlusalspaceposesamajordilemmafortherestorativedentist.Figure 1depictsanexampleofawearcasewherebythelossoftoothtissuehasbeenfollowedbydento-alveolarcompensationandaresultantlackofinter-occlusalclearance.In somecases, particularlywhere the

rateoftoothwearmaybeveryrapid,orcompensatory mechanisms evolve at arelativelyslowerrate,orinthecaseofapatientwithananterioropenbite,deepoverbite or increased overjet adequatespacemaybeavailablebetweentheupperand lowerdentition incentricocclusion(CO) in order to accommodate restora-tionswithouttheneedtoreducehealthytoothtissueaggressivelyorfollowareor-ganisedapproach.Adhesiverestorationsmaysimplybebondedintotheavailablespaceinordertorestoreform,aestheticsandfunction,whileconventionalrestora-tionsmayrequireminimal reductionoftheaffectedsurfaces.However, for the majority of cases,

adequate inter-occlusalclearance issel-domavailable.Oneoptionwouldbe tofollow traditional prosthodontic proto-colsandtocreatespacetoaccommodaterestorations/restorativematerialsthroughtheprocessoftoothreductionandtocon-formtotheexistingocclusion.Itiswellknown, however, that the preparationofteethtoreceivefullcoverageindirectrestorationsmayculminateinirreversiblelossofpulpvitality.AstudybySaundersand Saunders in 19985 reported peri-radicularpathologyamong19%ofteethpreparedtoreceivefullcoverageindirectrestorations.Inthecaseofseverelywornteeth, tooth reductionmayeven in the

Figs 1a-b An example of a case where tooth wear has been accompanied by dentoalveolar compensation

Fig. 2 Clinical case 1. a) Pre-operative view. b-c) Study casts. d-e) Diagnostic wax up to conform to occlusal and aesthetic prescription. f-g) Silicone index (Optosil P plus, Heraeus) produced from post-operative model. h) Vacuum formed thermoplastic template which could also be used as a guide to restore the worn dentition and to display planned changes by using it to carry a provisional crown and bridge material. i-k) Case restored with direct resin composite

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worst scenario lead to iatrogenic pulptissueexposure.Theaggressive lossofdentalhardtis-

suethroughtoothpreparation,particularlyamongseverelywornteeth,mayalsoleadtoasignificantlyreducedaxialheight,andthusinsufficientretentionandresistanceformmayensue.IthasbeensuggestedbyEdelhoffandSorenssen6 thatastagger-ing62%to73%of toothstructuremayberemovedduringtheundertakingofapreparationofatoothtoreceiveeitherafullcoverageallceramiccrownorporce-lainfusedtometalcrown.Whilesurgicalcrownlengtheningmaybeanoptiontoconsider,thismayintroduceotherunde-siredeffectsuponthehealthofthedentaltissues,whichwillbediscussed inmoredetailinpaper3ofthisseries.Insomecases,therequiredinter-occlusal

clearancemaybepresentincentricrela-tion(CR).Thisisoftenbestconfirmedbythemeansofaccuratestudycastsmountedincentricrelationonasemi-adjustable(orfullyadjustable)articulator,withtheaidofdiagnosticwaxmock-ups.Occasionally,thespacecreatedbysuchareorganisedapproachmaybesufficienttopermittheuseofmorerigidmaterialssuchasmetallicalloyswhichrequirelessbulkthicknesstoensurelongevity,butnotenoughfortheuseofmoreelasticmaterialssuchasresincomposite.However, thisapproachmayculminate in several teeth (often unaf-fectedteeth)beinginneedofrestorationsin order tomaintain occlusal stability,whichwillfurtheraddtothecomplexityof care,maintenance requirements andproceduralcost.Clinicalcase 1,asshowninFigure 2,is

anexampleofacaseoflocalisedanteriormaxillarytoothwearina59-year-oldmalepatientwhopresentedwithanaestheticconcern. The pattern of wear affectedboththepalatalsurfacesandincisaledgesrespectively.Followingacomprehensiveclinicalassessment,studycastsweretakenandmountedonasemi-adjustablearticu-lator.Itwasdecidedtostabilisewearusingdirectcomposite resin.Therationale formaterial selection and their respectivetechniquesforsuccessfulapplicationwillbediscussedindetailinpaper4.Itisgen-erallyaccepted that for resincompositerestorationstodisplaylongevity,inareasofocclusalloading,theyshouldbeplacedataminimalthicknessof1.5to2.0 mm.7

Whilethislevelofinterocclusalclearancewasnotavailableintheintercuspalposi-tion,itwasascertainedfromthemountedcaststhatadequatespacewaspresentincentricrelation(withoutaneedtoincreasethepatient’sverticaldimension);henceitwasdecidedtorestore thewornden-tition ina reorganisedmanner.Adiag-nosticwaxupwasundertaken,accordingtowelldocumentedaestheticprinciples8.Theocclusalprescription includedcon-touring the wax build ups to provideeven,sharedanteriorguidance,acanineguidedocclusioninlateralexcursiveandprotrusivemandibularmovementswithposterior tooth separation on dynamicmandibularmovements.Avacuumformed thermoplastic tem-

plate (0.5 mmthickness,AcornPlastic)wasformedfromastoneduplicateofthediagnosticwaxup.Thelattercanbeusednotonlytocarryaprovisionalcrownandbridgematerialtotheuntreatedteethtocrudely display planned changes, butalsoassistintheplacementofdefinitiverestoration, tobedescribed indetail inpaper 4.Minimaltoothpreparationwasunder-

taken,largelyconfinedtotheapplicationofalabialbevel,andtheremovalofanyunsupported enamelwith a brown sili-conerubberpoint (Shofu).Placementofresin compositewasaccomplishedwiththeaidofasiliconematrixformedfromthepalatalanatomyestablishedfromthediagnosticwaxup.Resincomposite(FiltekSupremeXT,3MESPEwasappliedinlay-eredincrements,nogreaterthan1.5 mmper increment). Shimstock foil of 8 µmthickness (Roeko)wasusedtoassessthepatency of the posterior occlusal con-tactsfollowingtheplacementoftheresinrestorations.Thepatientwasadvisedofthemediumtermlongevityoftheseres-torations,withrisksoffailurebymeansofbulkfracture,wear,discolorationandde-bonding.Thepatientwasalsowarnedaboutpossiblephoneticchangesassoci-atedwiththebulkingoutofthecingularareasandlengtheningoftheanteriormax-illaryteeth.Alternativemethodsofresinapplicationwillbedescribed indetail inpaper4.Thepatientinthiscasewasalsoprovidedwithasoftmaxillary3 mmther-moplasticsplintfornocturnalusetoaffordsome protection for his newly placedresinrestorations.

The Dahl concept

Thisconcept is frequently referred to indental literature as ameansof gainingspace in cases of localised toothwear,wherethereisinsufficientspaceavailableineitherCOorCR.In1975,Dahlet al.9describedtheuseof

aremovableanteriorbiteplatform,fabri-catedfromcobaltchromium,retainedbyclaspsinthecanineandpremolarregionstocreateinter-occlusalspaceinapatientwithtoothwearlocalisedtotheanteriormaxillary segment. The appliance wasdesigned to cover the cingulum areasof the affected teeth and increase theocclusalverticaldimensionintheregionof2-3 mm.The placement of this appliance cul-

minated in posterior teeth disclusion;occlusal contacts were only presentbetween the mandibular anterior teethandthebiteplatform.Theappliancewasprescribedforcontinualwearforseveralmonthsuntiltheposteriorteethre-estab-lishedinter-occlusalcontact.Removaloftheapplianceresultedinaninter-occlusalspacebetweentheanteriormaxillaryandmandibulardentitionsrespectively,whichwassubsequentlyutilised to restore thewornsurfaceswithouttheneedforfurthertoothreduction.Dahl and Krungstad10 proceeded to

repeat theaboveonaseriesofpatients,andreportedthatinmostcasesre-estab-lishment of occlusal contacts occurredwithin4-6 months.Ithasbeensuggested,however,thatitmaytakeuptoaperiodof18-24 monthsinsomecases(Poyseret al.11).TheactualDahlconcept refers to the

relative axial tooth movement that isobservedtooccurwhenalocalisedappli-anceorlocalisedrestoration(s)areplacedinsupra-occlusionandtheocclusionre-establishesfullarchcontactsoveraperiodoftime.Otherphrasesusedtodescribethelatterconcept include ‘minoraxialtoothmovement’,‘fixedorthodonticintrusion’,‘localised inter-occlusal space creation’or ‘relativeaxial toothmovement’.11Thesameprinciplemaybe extended to thecontrolledmovementofposteriorteethtocreatespace.TheDahlconcept is thought tooccur

throughaprocessofcontrolledintrusionandextrusionofdento-alveolarsegments.ItwasreportedbyDahlandKrungstad10

thattheinter-occlusalspacecreatedoccurs



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throughaprocessofcombinedintrusion(40%) and extrusion (60%). It has alsobeensuggestedbyHemmingset al.12thatanelementofmandibular repositioninginvolvingthecondylesmayalsobeoccur-ringconcomitantly.AccordingtoareviewbyPoyseret al.,11

when considering studies which haveassessedtheefficacyoftheDahlconcept,a success rateofbetween94-100%hasbeenreported.Furthermore, the levelofspacecreationwasconsistentlyfoundtobeirrespectiveofageandsex.Hemmingset al.12have reported fail-

urestoalsooccur inpatientswithgrossclassIIImalocclusionsandincaseswithmandibular facialasymmetrythathadalackofstableocclusalcontacts ineitherCO or CR. The lack of eruptive poten-tial isalsoa factor thatshouldbecon-sidered.Patientswhomaypresentwithbonyankylosis,dentalimplants,conven-tionalfixedbridgework and thosewithanterioropenbites,willallhave limitederuptivepotential.The application of the Dahl concept

shouldalsobeundertakenwithgreatcau-tionamongpatientswhomayhaveactive/apasthistoryofperiodontaldisease,tempo-romandibularjointpaindysfunctionsyn-drome,whereendodonticallyteethmaybeinvolved,incasespost-orthodontictreat-ment (as stabilitymay become compro-mised)andamongpatientswhomaybetakingoralorIVbisphosphonatedrugs.Clinicalcase2,asshowninFigure 3,

isanexampleofanothercaseofanteriormaxillarywearpredominantlyaffectingthe palatal surfaces. Spacewas createdwiththeuseofa‘modified’removablecastcobalt-chromiumDahlappliance.Thelat-terappliancewasworncontinuallyforaperiodof twomonths (other thanwheneating),and the resultantspaceused torestore theworn surfacesby the appli-cationof adhesivegoldpalatal veneers(fabricatedfromTypeIIIcastgoldalloy),withouttheneedforanysignificanttoothpreparation,cementedwithanadhesivelutingagent(PanaviaEX,Kuraray,Japan).Theocclusalprescriptionincludedthepro-visionofacanineguidedocclusion,withshared,evenanteriorguidanceonprotru-sivemandibularmovement.Therestora-tionshavebeensuccessfullyinplacesince1997.Notetheestablishmentoftheposte-riorocclusalcontacts,post-restoratively.

Whilethereislittleevidenceinliteraturetosuggest that theprocessofcontrolledintrusion and extrusion is associatedwith possible adverse effects such aspulpalsymptoms,periodontalproblems,TMJ dysfunction symptoms and api-cal root resorption,11 compliance withremovableapplianceshasbeenidentifiedasaconcern.10

Toovercometheissuesrelatedtopatientcompliance and aesthetic concerns of

the removable prosthesis, Ibbetson andSetchell13 have described an alternativeapproachinvolvingtheprovisionofafixedmetalprosthesiswhichwascementedinsupra-occlusionwiththesameocclusalpre-scriptionaswiththeremovableappliance,withaglassionomerluteordualaffinitycement.Withthesubsequentestablishmentof inter-occlusalclearance, theobjectiveof thetreatmentplanwastoreplacethecastingwithconventionalindirectcastings.

Fig. 3 Clinical case 2. a) Wear on the palatal surfaces of the anterior maxillary dentition. b) Lack of intraocclusal space. c) Modified removable Dahl appliance, cast in cobalt-chromium alloy. d) Mirror view of appliance in situ. e) Lateral view of appliance in situ. f) Space created palatally over approximately two months. g) Type III gold alloy palatal veneers cemented with Panavia. Checking for canine guidance. h) Posterior teeth in contact, verified with the use of Shimstock articulating foil. i) Mirror view of the palatal veneers 13 years post-cementation

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Clinicalcase3,asdepictedinFigure 4,is an example of an anteriormaxillaryerosivewear case, involving theuseofmetal (NickelChromium)palatalveneers(Dentetch), placed in supra-occlusionutilisingtheDahlconcept togainspace(hencetheconceptofafixedDahlappli-ance), in a 24-year-old male patient.Inadequate intra-occlusalclearancewaspresenteitherincentricocclusionorcen-tric relation;preparationof theaffectedteethtoaccommodateanyformofpalatal

restorationwouldhaveundoubtedlycul-minatedinpulptissueexposure;henceaDahlapproachwastaken.Wearwascausedby a previous gastric reflux condition.Consentwasgained; thepatientadvisedofariskof intolerance, ‘greying’of therestoredteeth,initialspeechandmastica-torydifficulties.Veneerswerefabricatedwithathicknessof0.5-0.7 mm,cementedin supra-occlusion using Panavia 2.0F(Kuraray, Japan).Theocclusalprescrip-tion included an even/shared anterior

guidanceandacanineguidedocclusioninlateralexcursivemovements.Restorationswerecontouredtoincludethepresenceofprominentcingularareastoprovideaflatocclusal stop for theantagonistic teeth,tohelpreduce futurewearof the loweranterior teeth and to permit the trans-missionofocclusal loadsalongthelongaxesoftheinvolvedteeth,withtheaimofreducingthelikelihoodofunwantedlabialtoothmovement.Posteriortoothocclusalcontactswerere-establishedafteraperiodofthreemonthspost-cementation.Duetomildincisaledgewear,anddullingoftheupperleftcentralincisortooth,directresincompositewasapplied(GradiaDirect,GC)torestorethelatterconcerns.Thiscasewasrestoredin2006.Theremovalofthemetallicbackingsmay,

however,occuratariskoffurthercom-promisinganalreadybrittle,worntooth.Furthermore,thepreparationofsuchteethtoreceiveconventionalrestorationsmayhaveanegativeimpactonthepulpalstatusandthequantityofremainingdentalhardtissue.Inmorerecenttimesmoreaestheti-callypleasingmaterialshavebeenavail-able,suchascompositeresinorceramic.Whiletheinitialrestorationsweredesignedwithmetalocclusalplatformsinthecingu-lumarea,theuseofsuchplatformsisnolongerdeemedabsolutelynecessary.Asmaterial technologyhascontinued

toevolve,ithasnowbecomeacceptabletoretainthecompositeresinrestorationsonanterior teeth,whichwere inprevi-oustimesappliedonaprovisionalbasis.Suchcompositerestorationsmaybecon-sideredtobe‘mediumtermrestorations’(particularlywhere thewear pattern islargelyfromerosivecauses).Itisimpor-tantthatthepatientunderstandsthatsuchrestorations are vulnerable to fracture,de-bonding,wearanddiscolorationandmay require eventual replacementwithindirectrestorations.Figure 5, clinical case4, provides an

exampleofawearpatienttreatedutilis-ingtheconceptsestablishedbytheDahlphenomenon.As therewas insufficientinterocclusalclearance toaccommodatea1.5to2.0 mmlayerthicknessofresincompositeineithertheinter-cuspalposi-tionorwhenthepatientwasmanipulatedcentric relation, theapproachwastakentoaddmaterial to theaffected surfacesin supra-occlusion. A silicone matrix

Fig. 4 Clinical case 3. Example of a ‘fixed metallic’ Dahl appliance. a) Clinical view of Case 3. b) Metal palatal veneers. Note the inclusion of location ‘lugs’ which can be readily removed post-cementation with the aid of a diamond bur. The resultant rough edge can be smoothed with the use of abrasive discs. c-d) Cemented Ni-Cr veneers in situ. Resin composite has been added to the incisal edge to restore lost tooth tissue and also to help mask the dulling effect at the incisal edge. e-g) Facial view, four years post-operatively. Note the ‘dulling’ of the anterior maxillary dentition and the visible appearance of metal at the mesial incisal corners of the canine teeth. Composite resin has been added to the incisal edge of UL1, to restore the worn incisal edge and mask the greying effect at this point. Posterior tooth contacts were re-established after a period of three months

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fabricatedfromawaxupformedfromadetailedaestheticandocclusalprescriptionwasusedtoaid theapplicationof resincomposite.Asshown,posteriorocclusalstopswerere-establishedafteraperiodofthreemonthspost-operatively.

Inviewof the short tomedium termlongevity of resin composite restora-tions,coupledwith theaesthetic limita-tions imposed by suchmaterials, theremaybeaneed to replace such restora-tionswithalternativerestorationswhich

mayovercomesomeoftheaforementionedlimitations. Traditionally, full coverageporcelain fused to metal crowns wereapplied,however,withadvancesindentalceramictechnologyandimprovementsinthefieldofadhesivedentistryrespectively,

Fig. 5 Clinical case 4. a-b) Pre-operative view. Mild pathological wear affecting the upper anterior dentition due to a combination of bruxism, xerostomia and gastric reflux. c-f) Diagnostic wax up; note disclusion of posterior units. g) Immediate post-operative view following the placement of resin composite (before final polishing phase). h) The placement of resin composite has been aided with the use of a silicone key formed from the palatal surfaces of the diagnostic wax up. i-j) Post-operative view, to show occlusal form established; even centric stops, canine guided occlusion. k-l) Note separation of posterior teeth immediately following the placement of resin composite. m-o) Three months post-operative view; note the re-establishment of occlusal stops; after a period of 12 weeks following resin placement

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it isnowpossibletoapplylessinvasive,more durable, aesthetically superior allceramicrestorations todentitionswheretheprocessof toothwearhasbeensta-bilisedbytheformerapplicationofresincomposite,withouttheneedforaggressivetoothreduction.Figure 6,clinicalcase5,isanexampleof

alocalisedwearcase,whereresincompos-iterestorationshavebeenplacedinsupra-occlusiontostabiliseawearingdentition.Havingattainedastableocclusalschemeandensuredeliminationoftheaetiologi-cal factor(s) causing theobserved tooth

wearpattern,thedirectresinrestorationshavebeenreplacedby labial feldspathicceramicveneersandpalatallyplacedindi-rectnanohybridresincompositeveneers,(placedinasequentialmanner).Themeritsofthelattermaterialswillbediscussedinmoredetailinpaper4.Hemmingset al.12havereportedasuc-

cessrateof89.4%for104directhybridresincompositerestorationsusedtotreatlocalisedanteriortoothwearwhichwereplacedatanincreasedverticaldimension.Restorationswerefollowedupforameanperiodof30months.Patientsatisfaction

wasreportedtobegood.Occlusalcontactswerere-establishedwithintheperiodoffourtofivemonths.Splayingofanteriorteethwasnotreportedtobeaproblematicfeature.Theauthorsaccountedforthelat-terobservationbythefactthatteethprefertomovethroughthecancelloustroughofboneinasimilarwaytoorthodontictoothmovement,ratherthansimplyinadirectresponse to theappliedocclusal force.14Theabsenceofperiodontaldiseaseamongthetreatedteethiscriticalinthepreven-tionofsplaying.Insomecasestheauthorsreportedthattoothmovementoccurredat

Figs 6a-m Clinical case 5. Maxillary anterior tooth wear pattern has been initially stabilised by the short to medium term application of direct resin composite restorations. The latter have been eventually replaced by more definitive palatal indirect composite and labial ceramic veneers

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arelativelyrapidrate(withinonetotwomonthsof theplacementof therestora-tions); itwas suggested that some ele-mentofmandibularrepositioningmayberesponsible.Theprimarycauseoffailurewasbulkfracture,which (discussedfur-ther inpaper4) isan inherentproblemassociatedwiththeuseofresincompos-ite;however,suchfailuresaregenerallynon-catastrophic and readily amenabletorepair.Thestudyalsoshowedhybridcompositestoperformbetterthanmicro-filledresins,perhapsrelatedtothereducedrigiditydisplayedbythelatter,whichmayculminateinincreasedflexionandsubse-quentde-bondinguponrepeatedloading.Despite advances in resin technol-

ogy, unfavourable differential wear ofdirect resin composite against antago-nistic teethandantagonistic restorativematerialsremainsaconcern(particularlyamongwearpatients),andforthisreasonHemmingset al.12suggestthatareason-able serviceperiodof such restorationstobeintherangeofthreetofiveyears.Similarmediumtermprognosticoutcomeshavebeenreportedbyseveralotherstud-ies,whichwillbeconsidered in furtherdetailinthesubsequentpaper.15,16

It has been suggested that where apatient is tobe treatedbythemeansofafixedDahlappliance/restoration, theymustbeadvisedoftherisksofinitialpost-operative discomfort, problems of foodcollectiononposteriorocclusalsurfacesandpossibledifficultiesassociatedwiththeeatingofcertain typesof foodsuchas lettuceandham.12Post-cementation,theocclusalschemeshouldbereviewedperiodicallyatone,two,six,nineand12monthsrespectivelypost-operatively.12

Thespacerequirementsoftherestorationswillbedeterminedbytheminimalthicknessatwhichacertaindentalmaterialcanbeappliedtotheaffectedsurface,inorderforittoprovideresilient,predictablefunction.Thetechniquesandmaterialsusedtorestoreworndentitionsarediscussedinmoredetailusingcaseexamplesasshownbelow.Insummaryspacerequirementswillrange

from0.5 mmforminimallyinvasivemetalpalatalveneers,upto2.0 mmforceramicbasedmaterials.Theprovisionofthisspacemaynecessitateaggressivetoothreductionofanalreadycompromisedtoothbywayofthequantityofdentalhardtissue,butmayalsocompromisethehealthofthedental

pulp.Whilespacemaybecreatedbyaxialtoothmovementasdescribedabove,theremaybesomecaseswherethereisalackoferuptivepotentialorothercontra-indica-tions,aslistedabove.Insuchcircumstances,acompromisedchoicemayhavetobemade.Thequantityandqualityofremaining

dentalhardtissuehasanobviousimpor-tance.Foradhesiverestorationstoenjoyanylevelofsuccessthereisaprerequisitefor the availability of a copious quan-tityandqualityof toothenamel.Whileimprovements in adhesive technologyhaveculminatedinbondingagentswhichmayoffersuperiorbondstrengthsofresintodentine than inpastyears, thebondstrengthisbynomeanscomparabletothatwhichcanbeachievedtoenamel.In cases where there is little remain-

ingcoronal tissue, thoughtmayneed tobegiventoclinicalcrownlengtheningortheuseorundertakingelectiverootcanaltherapyofaffectedteethfollowedbytheprovisionofpostretainedrestorations.Thedrawbacksofsurgicalcrownlengtheningwillbediscussedinmoredetailinpaper3.Theuseofmetalpostshasbeenwell

documentedtobeassociatedwiththerisksofrootfracture,whichmaybeexagger-atedincaseswhereduetoparafunctionalhabits,excessiveocclusalloadinghasbeenapplied.Themorerecentadventoffibre-resinpostshasbeensuggestedtoovercomethisconcern.However,astudybyMehtaandMillar17showedthattheuseofsuchresin-fibreposts inareasofhigh lateralloading,suchasonanteriorteeth,particu-larlyinpartiallydentatepatientsorthosedisplayinghabitsofbruxism,isassociatedwithahighriskof fractureof thepost,commonlyatthepost-coreinterface.Inextremecasesofanteriormaxillary

theonlyremainingoptionsmaybetocon-sidertheuseofanoverdentureoroverlaydenture,conventionaldentureor indeeddentalimplants.Theaestheticrequirementsofthepatient

arealsoimportanttoconsider.Theuseofmetalpalatalveneersmayresultinadulledappearanceoftherestoredtooth(evenwiththeadventofopaque/toothcolouredresinlutes)oreventhevisibledisplayofmetalonincisaledges.Itisoftenverydifficulttocon-sistentlygainsuperioraestheticoutcomesbytheuseofresincomposite,evenwiththeuseoflayeringtechniques;suchmaterialsmaydiscolour,wearandchipaway.

Theapplicationofconventionalporce-lainfusedtometalrestorationsmayresultinvisible ‘blackmargins’.Whenused inconjunctionwithsurgicalcrownlengthen-ing,un-aesthetic‘blacktriangularspaces’oftenresult,whichmaybeundesirable.Insummary,therearearraysoffactors

toconsiderwhenplanningtherestorationof aworn anteriormaxillarydentition.Comprehensive treatment planning andpatientconsentarevitalfactorstosuccess.

LOCALISED ANTERIOR MANDIBULAR TOOTH WEAR

AccordingtoMilosevic,18whereonlyloweranteriorteethareaffectedbytheprocessofpathologicaltoothwear,thenthepro-cessesofpreventionandmonitoringwillsuffice.If,however,bothupperandlowerteethareaffected, thenspaceshouldbegained through the process of theDahlconceptandthe lowerdentitionrestoredbeforetheupper.Localisedanteriorman-dibularwearisoftenseenamongpatientswhohavebeenprovidedwithmaxillarymetallo-ceramiccrowns,particularlywithporcelainoccludingsurfaceswhichhavebeenadjustedtoaccommodatetheocclu-sionandleftunpolished.Theprinciple for restoringa localised

worn lower dentition follows the samebasic tenets as the restoration ofwornmaxillaryanteriorteeth.Whereadequatespace may be present in CO, restora-tionscanbeplacedwithaconformativeapproach. In some cases spacemay bemadeavailableincentricrelation(CR)toaccommodaterestorativematerials,whichwouldavoidincreasingtheverticalcom-ponentofthepatient’socclusion.Alternatively, space can be created

through the use of theDahl concept.AfixedorremovableDahlprosthesismaybeappliedtothemaxillarydentitiontocre-ate space, or restoration fabricated resincomposite canbeapplieddirectly to theaffectedloweranteriorteeth,asillustratedbythecaseexamplesbelow.Thelattermayberetainedasdefinitiverestorations,asthetreatmentofchoiceforthemediumterm.Giventhediminutivenatureoftheseteeth,thepreparationofthelattertoreceivefullcoverageconventionalextra-coronalresto-rationsislikelytohavealongtermdeleteri-ouseffectontheprognosisoftheseteeth.10Averysuccessfulshorttermprognosis

hasbeendescribedfor theuseofdirect



PRACTICE

composite resinwhen placed in supra-occlusion, utilising the Dahl approachto restore thepresenceofaworn loweranteriordentition.11Inthelatterstudytheverticalocclusaldimensionsofthecasesincludedwere increased in therangeof0.5to5.0 mm.Clinicalcase 6,Figure 7,isanexample

ofacase treatedbythemeansofdirectresincompositeappliedusinga‘freehandtechnique’.Thesuccessoflattertechniqueis considerably dependant on operatorskill.Analternative,novelapproachforrestoringwornloweranteriorteethwillbediscussedfurtherinpaper4.

Theapplicationoflessinvasive,dentinebondedcrownsmayhaveapromisingroleinthemanagementofwornlowerante-riorteeth.Dentinebondedcrownsmaybedefinedas‘anallceramiccrownbondedtodentine(andanyavailableenamel)usingaresinbasedlutingmaterialwiththebondbeingmediatedbytheuseofanadhesivebondingsystemandamicro-mechanicallyretentiveceramicsurface’.19Effectively,thelattertaketheformofacompleteporce-lainveneer,wherebystrengthisderivedbybondingtotheunderlyingtissue.Burke20 has published a case report

describing the successfuluseofdentinebonded crowns fabricated from felds-pathicporcelain(treatedbyhydrofluoricacid)totreatacaseofseveretoothwearinabulimicpatient.Minimaltoothreduc-tionwasundertaken,involvinganocclusalclearanceof1.0 mm;preparationswerefinishedwithaknife-edgedmarginplacedatgingivallevel.Dentinebondedcrownsofferthemeritsofsuperioraesthetics (asthey do not have a metal substructureoropaqueporcelain sub-layer), further-more theability tobond to teethhas a

considerableadvantageinnotonlypro-vidingapatentmarginalsealbutwheretherehasbeencopiouslossofhardtoothtissue,particularlywheretheresidualtoothstructurehasanover-taperedpresentation.Thelatterformsofcrownhavealsobeenreportedtoprovideasatisfactoryleveloffracture resistance.21 However, the risksof fracture amongpatientswhodisplayparafunctionaltoothgrindinghabitsmustremainaconcern.20However,theirappli-cationiscostly,timeconsumingandsuchrestorationsareunsuitablewhereprepa-rationsextendsubgingivally. Ithasbeensuggestedthatthepresenceofa‘gingivalenamel ring’ is key tominimising theirrelativestrength(s).7

Dentinebondedcrownsmay,however,haveaninterestingapplicationintheman-agementofwearcases,whichmayhavepreviouslybeenstabilisedbytheapplica-tionofdirect resincomposite,yet thereis ademandby thepatient for a lowermaintenance,relativelyconservative,moreaestheticalternative.Finally,aswithanteriormaxillaryteeth,

conventionalcrownscanbeusedtorestoretheaboveteethinconjunctionwithproce-duressuchassurgicalcrownlengthening.

LOCALISED POSTERIOR WEARIthasbeensuggestedthatforcasesoflocal-isedwear,affectedteethshouldbemonitoredandaccepted,withtheaimofrestorativecarebeingtoprovideposteriordisclusionandcanineguidance.18Forcanineguidedocclusions,resincompositecanbeaddedsuperiorlytothecentricstopeitherdirectly(perhapswiththeaidofadiagnosticwax-in),soastoinsureposteriortoothseparationonlateralexcursiveandprotrusiveman-dibularmovements,topreventtheaffectedtoothfromfurtherwear.Alternativelyanindirectrestorationmaybeapplied.Clinicalcase7,Figure 8showsanexam-

pleofacanineriser,placed‘freehand’toprotecttheposteriordentitionfromfurtherwear,byensuringposteriortoothdisclu-sionuponlateralandprotrusivemandibu-larmovements.Metal adhesive onlays,whichwill be

discussed further in paper 3,mayofferconsiderablepotential (particularlywhenplaced inan initial supra-occlusalposi-tion)22 to treat cases of localisedposte-riortoothwear.Clinicalcase8,Figure 9,isanexampleofagoldadhesiveonlay,

Figs 7a-b Clinical case 6. Shows an example of lower anterior tooth wear treated using resin composite, applied ‘free hand’

Fig. 8 Clinical case 7. a) Marked wear on the tip of the canine. Note the wear on the occlusal surfaces of the posterior teeth. b) Occlusal contacts in right lateral excursion. c) Composite canine restoration placed to provide posterior disclusion to prevent further wear

Fig. 9 Clinical case 8: localised posterior tooth wear, treated by the application of an adhesive Type III cast gold onlay

a

a

c

b

b



PRACTICE

fabricatedfromType IIIcastgoldalloy,cementedinsupra-occlusionusingPanaviaEX(Kuraray,Japan),totreatacaseoflocal-isedposteriortoothwear.Thelongevityofanadhesiveonlaymaybeimprovedbytheadditionofresincompositetotheguid-ingtooth,toreducetheeffectofocclusalloadsontherestorationduringlateralandprotrusivemandibularmovements.Theplacementofrestorationsinsupra-

occlusionshouldbeavoidedamongperi-odontally involved or endodonticallytreatedteeth,aswellasamongcaseswhichdisplaysignsoflimitederuptivepotentialorTMJdysfunction.Theuseofresincompositeonlayshas

beenshownbyBartlettet al.23tobeassoci-atedwithahighleveloffailure,withafail-urerateof28%fordirectcompositeonlaysand21%forindirectlyfabricatedcompositeonlaysafteranobservationperiodofthreeyears(whenplacedatanincreasedverticaldimension).Whiletheauthorsconcludedthatresincomposite(regardlessofwhetherrestorationsarefabricateddirectlyorindi-rectly)isnotsuitablefortherestorationofwornposteriorteeth,theypointedoutthatthematerialsusedaspartoftheirinvestiga-tionwereofamicrofilledvariety;theuseofhybridmaterialsandtheprovisionofapostoperativeocclusalsplintmayhavehelpedtoimprovetheprognosticoutcome.Indeed,arecentstudyhasshownafavourableout-comefortheapplicationofdirectresincom-positerestorationswhenusedtotreattoothwearalsoaffectingtheposterioroccludingsurfaces,whereahybridbasedmaterialhasbeenused(overamediumtermobservationperiod).24Theapplicationofcompositeresinalsoprovidesaclinicaladvantageofallow-ingthepatienttoaccommodatetheocclusalchanges,aswellasenablingthecliniciantomakeanychangesifrequired.Oncethe

prescriptionisconfirmedthenthecompos-iteresinrestorationcanbereadilyreplacedwitharestorativematerialwithbetterlongtermdurability.

SUMMARYWhile themajority of cases presentingwithtoothwearingeneralpracticecanbeverysuccessfullymanagedbytheprescrip-tionofappropriatepreventativemeans,undoubtedlytherewillbeasmallpropor-tionofsuchcaseswhichwillrequireactiverestorativeintervention.Where possible, reversible, additive

techniques shouldbeapplied to restoreworndentitions (at least in theshort tomedium term). Conventionally retainedindirectrestorationsmaybeappliedwhereadhesiveresinbondedrestorationsmaybeinappropriateordisplayrecurrentfailures;however,itisparamountthatthepatienthasaclearunderstandingoftheimplica-tionsofprovidingthemwithconventionalindirectrestorations(inparticularthelev-elsoftoothreduction[s]required)andthepotentialriskstothepulphealth.Discussedinthispaperarecasesoflocal-

isedwear.Paper3willincludeadetaileddescription(illustratedbycaseexamples)of themanagementofgeneralisedwearcasesandanoverviewof thematerialsandrestorativetechniqueswhichcanbeappliedtotreatcasesoftoothwear.

1. Allen P. Use of tooth coloured restorations in the management of tooth wear. Dent Update 2003; 30: 550–556.

2. Sundaram G, Moazzez R, Bartlett D. Trial protective effect of fissure sealants in vivo on the palatal surfaces of anterior teeth, in patients suffering from erosion. J Dent 2011; 39: 26–29.

3. Chu F, Botelho M, Newsome P, Chow T, Smales R. Restorative management of the worn dentition 2: localised anterior tooth wear. Dent Update 2002; 29: 214–222.

4. Berry D, Poole D. Attrition: possible mechanisms of compensation. J Oral Rehabil 1976; 30: 201–206.

5. Saunders W, Saunders E. Prevalence of

peri-radicular periodontitis associated with crowned teeth in an adult Scottish subpopulation. Br Dent J 1998; 185: 137–140.

6. Edlehoff D, Sorenssen J. Tooth structure removal associated with various preparation designs for anterior teeth. J Prosthet Dent 2002; 87: 503–509.

7. Poyser N, Porter R, Briggs P, Kelleher M. Demolition experts: management of the parafunctional patient: 2. Restorative management strategies. Dent Update 2007; 34: 262–268.

8. Levin E. Dental aesthetics and the golden propor-tion. J Prosthet Dent 1978; 40: 244–252.

9. Dahl B, Krungstad O, Karlsen K, An alternative treat-ment of cases with advanced localised attrition. J Oral Rehabil 1975; 2: 209–214.

10. Dahl B, Krungstad O. Long term observations of an increased occlusal face height obtained by a combined orthodontic/prosthetic approach. J Oral Rehabil 1985; 12: 173–170.

11. Poyser N, Porter R, Briggs P, Chana H, Kelleher M. The Dahl concept: past, present and future. Br Dent J 2005; 198: 669–676.

12. Hemmings K, Darbar U, Vaughn S. Tooth wear treated with direct composite at an increased verti-cal dimension: results at 30 months. J Prosthet Dent 2000; 83: 287–293.

13. Ibbetson R, Setchell D. Treatment of the worn dentition; 2. Dent Update 1989; 16: 300–307.

14. Ricketts R. Bioprogressive therapy as an answer to orthodontic needs. Part II. Am J Orthod 1976; 70: 359–397.

15. Welbury R. A clinical study of microfilled composite resin for labial veneers. Int J Paediatr Dent 1991; 1: 9–15.

16. Redman C, Hemmings K, Good J. The survival and clinical performance of resin based composite restorations to treat localised anterior tooth wear. Br Dent J 2003; 194: 566–572.

17. Mehta S B, Millar B J. A comparison of the survival of fibre posts cemented with two different resin systems. Br Dent J 2008; 13: 1–7.

18. Milosevic A. Tooth wear: management. Dent Update 1998; 25: 50–55.

19. Resinkior H. The dentine bonded porcelain crown. In Clinical procedures manual. Cedar Rapids: Dental Prosthetic Services Inc., 1987.

20. Burke F. Treatment of loss of tooth substance using dentine bonded crowns: report of a case. Dent Update 1998; 25: 235–240.

21. Burke F, Qualtrough A, Hale R. The dentine bonded ceramic crown: an ideal restoration. Br Dent J 1995; 179: 115–121.

22. Chana H, Kelleher M, Briggs P, Hooper R. Clinical evaluation of resin bonded gold alloy veneers. J Prosthet Dent 2000; 83: 294–300.

23. Bartlett D, Sundaram G. An up to 3-year rand-omized clinical study comparing indirect and direct resin composite used to restore worn posterior teeth. Int J Prosthodont 2006; 19: 613–617.

24. Schmidlin P, Filli T, Imfeld C, Tepper S, Attin T. Three-year evaluation of posterior vertical bite reconstruction using direct resin composite – a case series. Oper Dent 2009; 34: 102–108.



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