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Current concepts on the man-agement of tooth wear: part 2.Active restorative care 1:the management of localisedtooth wearS. B. Mehta, 1 S. Banerji,2 B. J. Millar3 and J.-M. Suarez-Feito 4

VERIFIABLE CPD PAPER

Symptoms of pain and discomfortmay exist

There may be functional dif culties An unstable occlusion is present 1

The rate of tooth surface loss may beof extreme concern to either the dentaloperator or patient, which furthermoreif neglected may culminate in exposureof the dental pulp. 2

It is prudent, however, to initially imple -

ment a preventative programme and aperiod of monitoring of 6-12 monthsbefore embarking upon what usuallyinvolves complex, technically demandingrestorative dentistry. Such a period of timewill not only allow the operator to ensurethat the aetiological factor has been elimi -

nated or greatly reduced, but also providetime for the patient to understand thenature of the treatment plan being pro -

posed and importantly, a period of timefor the operator to establish a rapport withthe patient.

There may however, be special cir -

cumstances, such as in cases of aggres -sive erosion-related wear, where activeintervention will need to be implementedmore rapidly.

For the purposes of description, active

restorative intervention will be sub -divided into that for localised wear(maxillary anterior, mandibular ante -

rior, localised posterior) and generalisedwear respectively.

THE NEED FOR ACTIVERESTORATIVE INTERVENTION

While for many cases of pathological toothwear, passive management and monitor -

ing may suf ce, for a proportion of casesactive restorative intervention will becomenecessary. The cases which require thisgenerally fall into the categories of where: There may be aesthetic concerns

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 insufcient tomeet the patients expectations, or indeed prove to be sufciently 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 toothwear (of either the anterior, posterior, maxillary or mandibular variety) will be considered in depth in this paper, including adescription of the commonly applied techniques and treatment strategies, where possible illustrated by case examples.

LOCALISED MAXILLARYANTERIOR TOOTH WEAR

Maxillary anterior teeth are most com -

monly involved in localised tooth wear,especially where erosion is a major factor.

The decision on how to optimally restorethese teeth will depend on the interplaybetween ve factors:1. The pattern of anterior, maxillary

tooth surface loss2. Inter-occlusal space availability 3. Space requirements of the dental

restorations being proposed4. The quantity and quality of

available dental hard tissue andenamel respectively

5. The aesthetic demands of the patient.

The pattern of anterior maxillary toothwear has been classi ed by Chu et al. 3 into three categories in order to facilitaterestorative treatment planning:1. Tooth wear limited to the palatal

surfaces only 2. Tooth wear involving the palatal and

incisal edges, with reduced clinicalcrown height

3. Tooth wear limited to labialsurfaces only.

For cases involving visible surfaces suchas the latter two categories, restorativetechniques will involve the use of toothcoloured aesthetic materials. Metallic res -

torations, such as metal palatal veneers,

1,2General Dental Practitioner and Senior Clinical Teach-er, Department of Primary Dental Care, K ings CollegeLondon Dental Institute, Bessemer Road, London, SE59RW;3*Professor, Consultant in Restorative Dentistry,Department of Primary Dental Care, Kings CollegeLondon Dental Institute, Bessemer Road, London, SE59RW;4Section of Periodontology, Faculty of Dentistryand Medicine, University of Oviedo, Oviedo, Spain

*Correspondence to: Professor Brian J. MillarEmail: [email protected]

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

Identies the need f or active restorativeintervention for any patient presentingwith pathological tooth wear.

Describes possible approaches to thesuccessful restoration of a dentitionpresenting with localised pathologicaltooth wear.

Discusses how contemporary treatmentprotocols have been signicantlyinuenced by advances in understandingof adhesive dentistry and occlusion.

I N B R I E F

P R A C T I C E

1. Assessment, treatment planning andstrategies for the prevention and thepassive 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 techniquesand dental materials commonly applied forthe management of tooth wear

CURRENT CONCEPTS ONTHE MANAGEMENT OFTOOTH WEAR

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


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have little or no place for these cases. Incontrast, for cases where the pathology ispalatal only, metal palatal veneers mayprove to be an excellent restorative option.The merits of each technique and materialsused to facilitate the restoration of worndentitions will be discussed in detail inpaper 4 of this series.

Inter-occlusal space availabilityIn the majority of patients, tooth wear isaccompanied by dento-alveolar compen -

sation. 4 The latter physiological compensa -

tory mechanism allows occlusal contactsto be maintained, in order to attempt topreserve the ef cacy of the masticatorysystem. However, the possible lack of inter-

occlusal space poses a major dilemma forthe restorative dentist. Figure 1 depicts anexample of a wear case whereby the lossof tooth tissue has been followed by dento-alveolar compensation and a resultant lackof inter-occlusal clearance.

In some cases, particularly where therate of tooth wear may be very rapid, orcompensatory mechanisms evolve at arelatively slower rate, or in the case of apatient with an anterior open bite, deepoverbite or increased overjet adequatespace may be available between the upperand lower dentition in centric occlusion(CO) in order to accommodate restora -

tions without the need to reduce healthytooth tissue aggressively or follow a reor -ganised approach. Adhesive restorationsmay simply be bonded into the availablespace in order to restore form, aestheticsand function, while conventional restora -

tions may require minimal reduction ofthe affected surfaces.

However, for the majority of cases,adequate inter-occlusal clearance is sel -

dom available. One option would be tofollow traditional prosthodontic proto -

cols and to create space to accommodaterestorations/restorative materials throughthe process of tooth reduction and to con -

form to the existing occlusion. It is wellknown, however, that the preparationof teeth to receive full coverage indirectrestorations may culminate in irreversibleloss of pulp vitality. A study by Saunders

and Saunders in 19985

reported peri-radicular pathology among 19% of teethprepared to receive full coverage indirectrestorations. In the case of severely wornteeth, tooth reduction may even in the

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

Fig. 2 Clinical case 1. a) Pre-operative view. b-c) Study casts. d-e) Diagnostic waxup to conform to occlusal and aestheticprescription. f-g) Silicone index (Optosil Pplus, Heraeus) produced from post-operativemodel. h) Vacuum formed thermoplastictemplate which could also be used as aguide to restore the worn dentition and todisplay planned changes by using it to carrya provisional crown and bridge material. i-k)Case restored with direct resin composite

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worst scenario lead to iatrogenic pulptissue exposure.

The aggressive loss of dental hard tis -

sue through tooth preparation, particularlyamong severely worn teeth, may also leadto a signi cantly reduced axial height, andthus insuf cient retention and resistanceform may ensue. It has been suggested byEdelhoff and Sorenssen 6 that a stagger -ing 62% to 73% of tooth structure maybe removed during the undertaking of apreparation of a tooth to receive either afull coverage all ceramic crown or porce -

lain fused to metal crown. While surgicalcrown lengthening may be an option toconsider, this may introduce other unde -

sired effects upon the health of the dental

tissues, which will be discussed in moredetail in paper 3 of this series.

In some cases, the required inter-occlusalclearance may be present in centric rela -

tion (CR). This is often best con rmed bythe means of accurate study casts mountedin centric relation on a semi-adjustable (orfully adjustable) articulator, with the aid ofdiagnostic wax mock-ups. Occasionally,the space created by such a reorganisedapproach may be suf cient to permit theuse of more rigid materials such as metallicalloys which require less bulk thickness toensure longevity, but not enough for theuse of more elastic materials such as resincomposite. However, this approach mayculminate in several teeth (often unaf -fected teeth) being in need of restorationsin order to maintain occlusal stability,which will further add to the complexityof care, maintenance requirements andprocedural cost.

Clinical case 1, as shown in Figure 2, isan example of a case of localised anteriormaxillary tooth wear in a 59-year-old malepatient who presented with an aestheticconcern. The pattern of wear affectedboth the palatal surfaces and incisal edgesrespectively. Following a comprehensiveclinical assessment, study casts were takenand mounted on a semi-adjustable articu -lator. It was decided to stabilise wear usingdirect composite resin. The rationale formaterial selection and their respectivetechniques for successful application will

be discussed in detail in paper 4. It is gen -erally accepted that for resin compositerestorations to display longevity, in areasof occlusal loading, they should be placedat a minimal thickness of 1.5 to 2.0 mm. 7

While this level of interocclusal clearancewas not available in the intercuspal posi -

tion, it was ascertained from the mountedcasts that adequate space was present incentric relation (without a need to increasethe patients vertical dimension); henceit was decided to restore the worn den -

tition in a reorganised manner. A diag -

nostic wax up was undertaken, accordingto well documented aesthetic principles 8.The occlusal prescription included con -

touring the wax build ups to provideeven, shared anterior guidance, a canineguided occlusion in lateral excursive andprotrusive mandibular movements withposterior tooth separation on dynamicmandibular movements.

A vacuum formed thermoplastic tem -plate (0.5 mm thickness, Acorn Plastic)was formed from a stone duplicate of thediagnostic wax up. The latter can be usednot only to carry a provisional crown andbridge material to the untreated teeth tocrudely display planned changes, butalso assist in the placement of de nitiverestoration, to be described in detail inpaper 4.

Minimal tooth preparation was under -

taken, largely con ned to the applicationof a labial bevel, and the removal of anyunsupported enamel with a brown sili -

cone rubber point (Shofu). Placement ofresin composite was accomplished withthe aid of a silicone matrix formed fromthe palatal anatomy established from thediagnostic wax up. Resin composite (FiltekSupreme XT, 3M ESPE was applied in lay -ered increments, no greater than 1.5 mmper increment). Shimstock foil of 8 mthickness (Roeko) was used to assess thepatency of the posterior occlusal con -

tacts following the placement of the resinrestorations. The patient was advised ofthe medium term longevity of these res -

torations, with risks of failure by meansof bulk fracture, wear, discoloration andde-bonding. The patient was also warnedabout possible phonetic changes associ -ated with the bulking out of the cingularareas and lengthening of the anterior max -

illary teeth. Alternative methods of resinapplication will be described in detail in

paper 4. The patient in this case was alsoprovided with a soft maxillary 3 mm ther -

moplastic splint for nocturnal use to affordsome protection for his newly placedresin restorations.

The Dahl concept

This concept is frequently referred to indental literature as a means of gainingspace in cases of localised tooth wear,where there is insuf cient space availablein either CO or CR.

In 1975, Dahl et al. 9 described the use ofa removable anterior bite platform, fabri -

cated from cobalt chromium, retained byclasps in the canine and premolar regionsto create inter-occlusal space in a patientwith tooth wear localised to the anteriormaxillary segment. The appliance wasdesigned to cover the cingulum areasof the affected teeth and increase theocclusal vertical dimension in the regionof 2-3 mm.

The placement of this appliance cul -minated in posterior teeth disclusion;occlusal contacts were only presentbetween the mandibular anterior teethand the bite platform. The appliance wasprescribed for continual wear for severalmonths until the posterior teeth re-estab -

lished inter-occlusal contact. Removal ofthe appliance resulted in an inter-occlusalspace between the anterior maxillary andmandibular dentitions respectively, whichwas subsequently utilised to restore theworn surfaces without the need for furthertooth reduction.

Dahl and Krungstad 10 proceeded torepeat the above on a series of patients,and reported that in most cases re-estab -lishment of occlusal contacts occurredwithin 4-6 months. It has been suggested,however, that it may take up to a period of18-24 months in some cases (Poyser et al. 11 ).

The actual Dahl concept refers to therelative axial tooth movement that isobserved to occur when a localised appli -

ance or localised restoration(s) are placedin supra-occlusion and the occlusion re-establishes full arch contacts over a periodof time. Other phrases used to describe thelatter concept include minor axial toothmovement, xed orthodontic intrusion,localised inter-occlusal space creationor relative axial tooth movement. 11 Thesame principle may be extended to thecontrolled movement of posterior teeth tocreate space.

The Dahl concept is thought to occurthrough a process of controlled intrusionand extrusion of dento-alveolar segments.It was reported by Dahl and Krungstad 10

that the inter-occlusal space created occurs



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through a process of combined intrusion(40%) and extrusion (60%). It has alsobeen suggested by Hemmings et al. 12 thatan element of mandibular repositioninginvolving the condyles may also be occur -

ring concomitantly. According to a review by Poyser et al. ,11

when considering studies which haveassessed the ef cacy of the Dahl concept,a success rate of between 94-100% hasbeen reported. Furthermore, the level ofspace creation was consistently found tobe irrespective of age and sex.

Hemmings et al. 12 have reported fail -

ures to also occur in patients with grossclass III malocclusions and in cases withmandibular facial asymmetry that had a

lack of stable occlusal contacts in eitherCO or CR. The lack of eruptive poten -

tial is also a factor that should be con -sidered. Patients who may present withbony ankylosis, dental implants, conven -

tional xed bridgework and those withanterior open bites, will all have limitederuptive potential.

The application of the Dahl conceptshould also be undertaken with great cau -

tion among patients who may have active/apast history of periodontal disease, tempo -

romandibular joint pain dysfunction syn -

drome, where endodontically teeth may beinvolved, in cases post-orthodontic treat -

ment (as stability may become compro -

mised) and among patients who may betaking oral or IV bisphosphonate drugs.

Clinical case 2, as shown in Figure 3,is an example of another case of anteriormaxillary wear predominantly affectingthe palatal surfaces. Space was createdwith the use of a modi ed removable castcobalt-chromium Dahl appliance. The lat -

ter appliance was worn continually for aperiod of two months (other than wheneating), and the resultant space used torestore the worn surfaces by the appli -

cation of adhesive gold palatal veneers(fabricated from Type III cast gold alloy),without the need for any signi cant toothpreparation, cemented with an adhesiveluting agent (Panavia EX, Kuraray, Japan).The occlusal prescription included the pro -

vision of a canine guided occlusion, with

shared, even anterior guidance on protru -sive mandibular movement. The restora -

tions have been successfully in place since1997. Note the establishment of the poste -

rior occlusal contacts, post-restoratively.

While there is little evidence in literatureto suggest that the process of controlledintrusion and extrusion is associatedwith possible adverse effects such aspulpal symptoms, periodontal problems,TMJ dysfunction symptoms and api -

cal root resorption,11

compliance withremovable appliances has been identi edas a concern. 10

To overcome the issues related to patientcompliance and aesthetic concerns of

the removable prosthesis, Ibbetson andSetchell 13 have described an alternativeapproach involving the provision of a xedmetal prosthesis which was cemented insupra-occlusion with the same occlusal pre -scription as with the removable appliance,

with a glass ionomer lute or dual af nitycement. With the subsequent establishmentof inter-occlusal clearance, the objectiveof the treatment plan was to replace thecasting with conventional indirect castings.

Fig. 3 Clinical case 2. a) Wear on the palatalsurfaces of the anterior maxillary dentition.b) Lack of intraocclusal space. c) Modiedremovable Dahl appliance, cast in cobalt-chromium alloy. d) Mirror view of appliancein situ. e) Lateral view of appliance in situ. f)Space created palatally over approximatelytwo months. g) Type III gold alloy palatal

veneers cemented with Panavia. Checkingfor canine guidance. h) Posterior teeth incontact, veried with the use of Shimstockarticulating foil. i) Mirror view of the palatal

veneers 13 years post-cementation

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Clinical case 3, as depicted in Figure 4,is an example of an anterior maxillaryerosive wear case, involving the use ofmetal (Nickel Chromium) palatal veneers(Dentetch), placed in supra-occlusionutilising the Dahl concept to gain space(hence the concept of a xed Dahl appli -

ance), in a 24-year-old male patient.Inadequate intra-occlusal clearance waspresent either in centric occlusion or cen -

tric relation; preparation of the affectedteeth to accommodate any form of palatal

restoration would have undoubtedly cul -

minated in pulp tissue exposure; hence aDahl approach was taken. Wear was causedby a previous gastric re ux condition.Consent was gained; the patient advisedof a risk of intolerance, greying of therestored teeth, initial speech and mastica -

tory dif culties. Veneers were fabricatedwith a thickness of 0.5-0.7 mm, cementedin supra-occlusion using Panavia 2.0F(Kuraray, Japan). The occlusal prescrip -

tion included an even/shared anterior

guidance and a canine guided occlusion inlateral excursive movements. Restorationswere contoured to include the presence ofprominent cingular areas to provide a atocclusal stop for the antagonistic teeth,to help reduce future wear of the loweranterior teeth and to permit the trans -

mission of occlusal loads along the longaxes of the involved teeth, with the aim ofreducing the likelihood of unwanted labialtooth movement. Posterior tooth occlusalcontacts were re-established after a periodof three months post-cementation. Due tomild incisal edge wear, and dulling of theupper left central incisor tooth, direct resincomposite was applied (Gradia Direct, GC)to restore the latter concerns. This case was

restored in 2006.The removal of the metallic backings may,

however, occur at a risk of further com -promising an already brittle, worn tooth.Furthermore, the preparation of such teethto receive conventional restorations mayhave a negative impact on the pulpal statusand the quantity of remaining dental hardtissue. In more recent times more aestheti -

cally pleasing materials have been avail -

able, such as composite resin or ceramic. While the initial restorations were designedwith metal occlusal platforms in the cingu -

lum area, the use of such platforms is nolonger deemed absolutely necessary.

As material technology has continuedto evolve, it has now become acceptableto retain the composite resin restorationson anterior teeth, which were in previ -

ous times applied on a provisional basis.Such composite restorations may be con -

sidered to be medium term restorations(particularly where the wear pattern islargely from erosive causes). It is impor -

tant that the patient understands that suchrestorations are vulnerable to fracture,de-bonding, wear and discoloration andmay require eventual replacement withindirect restorations.

Figure 5, clinical case 4, provides anexample of a wear patient treated utilis -ing the concepts established by the Dahlphenomenon. As there was insuf cientinterocclusal clearance to accommodatea 1.5 to 2.0 mm layer thickness of resin

composite in either the inter-cuspal posi -tion or when the patient was manipulatedcentric relation, the approach was takento add material to the affected surfacesin supra-occlusion. A silicone matrix

Fig. 4 Clinical case 3. Example of a xed metallic Dahl appliance. a) Clinical view of Case 3.b) Metal palatal veneers. Note the inclusion of location lugs which can be readily removedpost-cementation with the aid of a diamond bur. The resultant rough edge can be smoothedwith the use of abrasive discs. c-d) Cemented Ni-Cr veneers in situ. Resin composite has beenadded to the incisal edge to restore lost tooth tissue and also to help mask the dulling effectat the incisal edge. e-g) Facial view, four years post-operatively. Note the dulling of theanterior 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 restorethe worn incisal edge and mask the greying effect at this point. Posterior tooth contacts werere-established after a period of three months

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fabricated from a wax up formed from a

detailed aesthetic and occlusal prescriptionwas used to aid the application of resincomposite. As shown, posterior occlusalstops were re-established after a period ofthree months post-operatively.

In view of the short to medium term

longevity of resin composite restora -tions, coupled with the aesthetic limita -

tions imposed by such materials, theremay be a need to replace such restora -

tions with alternative restorations which

may overcome some of the aforementioned

limitations. Traditionally, full coverageporcelain fused to metal crowns wereapplied, however, with advances in dentalceramic technology and improvements inthe eld of adhesive dentistry respectively,

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 reux. c-f) Diagnostic wax up; note disclusion of posterior units. g) Immediate post-operative view following theplacement of resin composite (before nal polishing phase). h) The placement of resin composite has been aided with the use of a siliconekey 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 monthspost-operative view; note the re-establishment of occlusal stops; after a period of 12 weeks following resin placement

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it is now possible to apply less invasive,more durable, aesthetically superior allceramic restorations to dentitions wherethe process of tooth wear has been sta -

bilised by the former application of resincomposite, without the need for aggressivetooth reduction.

Figure 6, clinical case 5, is an example ofa localised wear case, where resin compos -

ite restorations have been placed in supra-occlusion to stabilise a wearing dentition.Having attained a stable occlusal schemeand ensured elimination of the aetiologi -

cal factor(s) causing the observed tooth

wear pattern, the direct resin restorationshave been replaced by labial feldspathicceramic veneers and palatally placed indi -

rect nanohybrid resin composite veneers,(placed in a sequential manner). The meritsof the latter materials will be discussed inmore detail in paper 4.

Hemmings et al. 12 have reported a suc -cess rate of 89.4% for 104 direct hybrid

resin composite restorations used to treatlocalised anterior tooth wear which wereplaced at an increased vertical dimension.Restorations were followed up for a meanperiod of 30 months. Patient satisfaction

was reported to be good. Occlusal contactswere re-established within the period offour to ve months. Splaying of anteriorteeth was not reported to be a problematicfeature. The authors accounted for the lat -ter observation by the fact that teeth preferto move through the cancellous trough ofbone in a similar way to orthodontic toothmovement, rather than simply in a direct

response to the applied occlusal force.14

The absence of periodontal disease amongthe treated teeth is critical in the preven -

tion of splaying. In some cases the authorsreported that tooth movement occurred at

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

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a relatively rapid rate (within one to twomonths of the placement of the restora -

tions); it was suggested that some ele -

ment of mandibular repositioning may beresponsible. The primary cause of failurewas bulk fracture, which (discussed fur -ther in paper 4) is an inherent problemassociated with the use of resin compos -

ite; however, such failures are generallynon-catastrophic and readily amenableto repair. The study also showed hybridcomposites to perform better than micro -

lled resins, perhaps related to the reducedrigidity displayed by the latter, which mayculminate in increased exion and subse -

quent de-bonding upon repeated loading.Despite advances in resin technol -

ogy, unfavourable differential wear ofdirect resin composite against antago -

nistic teeth and antagonistic restorativematerials remains a concern (particularlyamong wear patients), and for this reasonHemmings et al. 12 suggest that a reason -able service period of such restorationsto be in the range of three to ve years.Similar medium term prognostic outcomeshave been reported by several other stud -

ies, which will be considered in furtherdetail in the subsequent paper. 15,16

It has been suggested that where apatient is to be treated by the means ofa xed Dahl appliance/restoration, theymust be advised of the risks of initial post-operative discomfort, problems of foodcollection on posterior occlusal surfacesand possible dif culties associated withthe eating of certain types of food suchas lettuce and ham. 12 Post-cementation,the occlusal scheme should be reviewedperiodically at one, two, six, nine and 12months respectively post-operatively. 12

The space requirements of the restorationswill be determined by the minimal thicknessat which a certain dental material can beapplied to the affected surface, in order forit to provide resilient, predictable function.The techniques and materials used to restoreworn dentitions are discussed in more detailusing case examples as shown below.

In summary space requirements will rangefrom 0.5 mm for minimally invasive metalpalatal veneers, up to 2.0 mm for ceramic

based materials. The provision of this spacemay necessitate aggressive tooth reductionof an already compromised tooth by way ofthe quantity of dental hard tissue, but mayalso compromise the health of the dental

pulp. While space may be created by axialtooth movement as described above, theremay be some cases where there is a lack oferuptive potential or other contra-indica -

tions, as listed above. In such circumstances,a compromised choice may have to be made.

The quantity and quality of remainingdental hard tissue has an obvious impor -

tance. For adhesive restorations to enjoyany level of success there is a prerequisitefor the availability of a copious quan -

tity and quality of tooth enamel. Whileimprovements in adhesive technologyhave culminated in bonding agents whichmay offer superior bond strengths of resinto dentine than in past years, the bondstrength is by no means comparable to that

which can be achieved to enamel.In cases where there is little remain -

ing coronal tissue, thought may need tobe given to clinical crown lengthening orthe use or undertaking elective root canaltherapy of affected teeth followed by theprovision of post retained restorations. Thedrawbacks of surgical crown lengtheningwill be discussed in more detail in paper 3.

The use of metal posts has been welldocumented to be associated with the risksof root fracture, which may be exagger -

ated in cases where due to parafunctionalhabits, excessive occlusal loading has beenapplied. The more recent advent of bre-resin posts has been suggested to overcomethis concern. However, a study by Mehtaand Millar 17 showed that the use of suchresin- bre posts in areas of high lateralloading, such as on anterior teeth, particu -larly in partially dentate patients or thosedisplaying habits of bruxism, is associatedwith a high risk of fracture of the post,commonly at the post-core interface.

In extreme cases of anterior maxillarythe only remaining options may be to con -

sider the use of an overdenture or overlaydenture, conventional denture or indeeddental implants.

The aesthetic requirements of the patientare also important to consider. The use ofmetal palatal veneers may result in a dulledappearance of the restored tooth (even withthe advent of opaque/tooth coloured resinlutes) or even the visible display of metal on

incisal edges. It is often very dif cult to con -sistently gain superior aesthetic outcomesby the use of resin composite, even with theuse of layering techniques; such materialsmay discolour, wear and chip away.

The application of conventional porce -

lain fused to metal restorations may resultin visible black margins. When used inconjunction with surgical crown lengthen -

ing, un-aesthetic black triangular spacesoften result, which may be undesirable.

In summary, there are arrays of factorsto consider when planning the restorationof a worn anterior maxillary dentition.Comprehensive treatment planning andpatient consent are vital factors to success.

LOCALISED ANTERIORMANDIBULAR TOOTH WEAR

According to Milosevic, 18 where only loweranterior teeth are affected by the processof pathological tooth wear, then the pro -

cesses of prevention and monitoring willsuf ce. If, however, both upper and lowerteeth are affected, then space should begained through the process of the Dahlconcept and the lower dentition restoredbefore the upper. Localised anterior man -dibular wear is often seen among patientswho have been provided with maxillarymetallo-ceramic crowns, particularly withporcelain occluding surfaces which havebeen adjusted to accommodate the occlu -

sion and left unpolished.The principle for restoring a localised

worn lower dentition follows the samebasic tenets as the restoration of wornmaxillary anterior teeth. Where adequatespace may be present in CO, restora -tions can be placed with a conformativeapproach. In some cases space may bemade available in centric relation (CR) toaccommodate restorative materials, whichwould avoid increasing the vertical com -

ponent of the patients occlusion. Alternatively, space can be created

through the use of the Dahl concept. Axed or removable Dahl prosthesis may be

applied to the maxillary dentition to cre -

ate space, or restoration fabricated resincomposite can be applied directly to theaffected lower anterior teeth, as illustratedby the case examples below. The latter maybe retained as de nitive restorations, as thetreatment of choice for the medium term.Given the diminutive nature of these teeth,the preparation of the latter to receive full

coverage conventional extra-coronal resto -rations is likely to have a long term deleteri -

ous effect on the prognosis of these teeth. 10 A very successful short term prognosis

has been described for the use of direct



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composite resin when placed in supra-occlusion, utilising the Dahl approachto restore the presence of a worn loweranterior dentition. 11 In the latter study the

vertical occlusal dimensions of the casesincluded were increased in the range of0.5 to 5.0 mm.

Clinical case 6, Figure 7, is an exampleof a case treated by the means of directresin composite applied using a free hand

technique. The success of latter techniqueis considerably dependant on operatorskill. An alternative, novel approach forrestoring worn lower anterior teeth will bediscussed further in paper 4.

The application of less invasive, dentinebonded crowns may have a promising rolein the management of worn lower ante -

rior teeth. Dentine bonded crowns may bede ned as an all ceramic crown bonded todentine (and any available enamel) using aresin based luting material with the bondbeing mediated by the use of an adhesivebonding system and a micro-mechanicallyretentive ceramic surface. 19 Effectively, thelatter take the form of a complete porce -

lain veneer, whereby strength is derived bybonding to the underlying tissue.

Burke 20 has published a case reportdescribing the successful use of dentinebonded crowns fabricated from felds -

pathic porcelain (treated by hydro uoricacid) to treat a case of severe tooth wearin a bulimic patient. Minimal tooth reduc -

tion was undertaken, involving an occlusalclearance of 1.0 mm; preparations were

nished with a knife-edged margin placed

at gingival level. Dentine bonded crownsoffer the merits of superior aesthetics (asthey do not have a metal substructureor opaque porcelain sub-layer), further -

more the ability to bond to teeth has a

considerable advantage in not only pro -

viding a patent marginal seal but wherethere has been copious loss of hard toothtissue, particularly where the residual toothstructure has an over-tapered presentation.The latter forms of crown have also beenreported to provide a satisfactory level offracture resistance. 21 However, the risksof fracture among patients who displayparafunctional tooth grinding habits mustremain a concern. 20 However, their appli -

cation is costly, time consuming and suchrestorations are unsuitable where prepa -

rations extend subgingivally. It has beensuggested that the presence of a gingivalenamel ring is key to minimising theirrelative strength(s). 7

Dentine bonded crowns may, however,have an interesting application in the man -

agement of wear cases, which may havepreviously been stabilised by the applica -

tion of direct resin composite, yet thereis a demand by the patient for a lowermaintenance, relatively conservative, moreaesthetic alternative.

Finally, as with anterior maxillary teeth,conventional crowns can be used to restorethe above teeth in conjunction with proce -

dures such as surgical crown lengthening.

LOCALISED POSTERIOR WEARIt has been suggested that for cases of local -

ised wear, affected teeth should be monitoredand accepted, with the aim of restorativecare being to provide posterior disclusionand canine guidance. 18 For canine guidedocclusions, resin composite can be addedsuperiorly to the centric stop either directly(perhaps with the aid of a diagnostic wax-in), so as to insure posterior tooth separationon lateral excursive and protrusive man -

dibular movements, to prevent the affectedtooth from further wear. Alternatively anindirect restoration may be applied.

Clinical case 7, Figure 8 shows an exam -

ple of a canine riser, placed free hand toprotect the posterior dentition from furtherwear, by ensuring posterior tooth disclu -sion upon lateral and protrusive mandibu -

lar movements.Metal adhesive onlays, which will be

discussed further in paper 3, may offer

considerable potential (particularly whenplaced in an initial supra-occlusal posi -

tion) 22 to treat cases of localised poste -

rior tooth wear. Clinical case 8, Figure 9,is an example of a gold adhesive onlay,

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

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

Fig. 9 Clinical case 8: localised posteriortooth wear, treated by the application of an

adhesive Type III cast gold onlay

a

a

c

b

b



10/10

PRACTICE

fabricated from Type III cast gold alloy,cemented in supra-occlusion using PanaviaEX (Kuraray, Japan), to treat a case of local -

ised posterior tooth wear. The longevity ofan adhesive onlay may be improved by theaddition of resin composite to the guid -ing tooth, to reduce the effect of occlusalloads on the restoration during lateral andprotrusive mandibular movements.

The placement of restorations in supra-occlusion should be avoided among peri -

odontally involved or endodonticallytreated teeth, as well as among cases whichdisplay signs of limited eruptive potentialor TMJ dysfunction.

The use of resin composite onlays hasbeen shown by Bartlett et al. 23 to be associ -

ated with a high level of failure, with a fail -ure rate of 28% for direct composite onlaysand 21% for indirectly fabricated compositeonlays after an observation period of three

years (when placed at an increased verticaldimension). While the authors concludedthat resin composite (regardless of whetherrestorations are fabricated directly or indi -

rectly) is not suitable for the restoration ofworn posterior teeth, they pointed out thatthe materials used as part of their investiga -

tion were of a micro lled variety; the use ofhybrid materials and the provision of a postoperative occlusal splint may have helpedto improve the prognostic outcome. Indeed,a recent study has shown a favourable out -

come for the application of direct resin com -posite restorations when used to treat toothwear also affecting the posterior occludingsurfaces, where a hybrid based material hasbeen used (over a medium term observationperiod). 24 The application of composite resinalso provides a clinical advantage of allow -

ing the patient to accommodate the occlusalchanges, as well as enabling the clinicianto make any changes if required. Once the

prescription is con rmed then the compos -

ite resin restoration can be readily replacedwith a restorative material with better longterm durability.

SUMMARY While the majority of cases presentingwith tooth wear in general practice can be

very successfully managed by the prescrip -tion of appropriate preventative means,undoubtedly there will be a small propor -

tion of such cases which will require activerestorative intervention.

Where possible , reversible, addi tivetechniques should be applied to restoreworn dentitions (at least in the short tomedium term). Conventionally retained

indirect restorations may be applied whereadhesive resin bonded restorations may beinappropriate or display recurrent failures;however, it is paramount that the patienthas a clear understanding of the implica -

tions of providing them with conventionalindirect restorations (in particular the lev -

els of tooth reduction[s] required) and thepotential risks to the pulp health.

Discussed in this paper are cases of local -

ised wear. Paper 3 will include a detaileddescription (illustrated by case examples)of the management of generalised wearcases and an overview of the materialsand restorative techniques which can beapplied to treat cases of tooth wear.

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82 BRITISH DENTAL JOURNALVOLUME 212 NO 2 JAN 28 2012

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