Operative Dentistry

The rubber dam-retaining appliance: An adjunct to isolation duringplacement of multiple veneers

William H. Liebenberg*

The allure of multiple porcelain veneers resides in the consen'ative preparation and thepotential for e.xcellent esthetics. To uphold the pennant of adhesive teehtiology on which theprocedure is founded, the fastidious guidelines of direct adhesive techniques should becarried over to porcelain veneers. Delivery of porcelain veneers is compromised in theabsence of rubber dam isolation. Traditional rubber dam apphcation is cumbersome andimpractical, however, during placement of multiple veneers, with their priority of gingivaltnargin access. This article introduces a rubber dam-retaining appliance that improves accessand isoiation during the restoration of anterior teeth with multiple porcelain veneers.(Quintessence Int ¡995:26:493-500.)

Introduction

The use of facial porcelain veneers has been prodi-giously advocated as a reliable means of correctingunesthetic tooth discolorations as well as size andcontour deficiencies. Many prominent clinicians andeducators have revealed consistently predietable re-sults since the concept of etching porcelain wasintroduced in 1983. In many cases, the "before-and-after" photographic record belies the intensity andexactitude ofthe clinicians' effort. Although it may berelatively easy, with the assistance of an accomplishedceramist, to realize greatly improved esthetics, theterm marginal perfection (when applied to veneers onthe microscopic level) represents an incongrtiity initself. It is, without a doubt, the most demanding andtechnique-sensitive esthetic restorative option offeredto patients.

Innovations in materials and application techniquescontinue to elevate this restorative option toward thestatus of standard procedure. Yet veneers are still in theinfancy of their long-term elinieal record. It is the

' Private Practice, North Vancouver, British Columbia, Canada.

Reprint requests: Dr William H, Liebenberg, 20 i-2609 Westview Drive,North Vancüuver, Britisti Columbia, V7N4M2 Canada,

dentist's responsibility, therefore, to maintain themetieulousness of adhesive technology on which theprocedure is founded. At the very least, the vigilantand fastidious guidelines of the direct restorativeoptions should be carried over to porcelain veneers.

There is, however, a noticeabie trend among themany fine pubUcations and presentations on multipleveneers: The indirect restorations are dehvered withcompromised access in the absence of rubber damisolation. There is a good reason for this, becausetraditional rubber dam application is cumbersome andimpractical for application during placement of multi-ple veneers, with their priority of gingival marginaccess.

This article introduces the rubber dam-retaining(RDR) appliance as a praetical adjunct to the isolationof multiple porcelain veneers. It can be utilized duringboth the tooth preparation and bonding procedures.

Rubber dam-retaining appliance

Fabrication

Aiginate impressions are made of both arches. Muscletrimming ofthe buccal and labial borders is done withexaggerated movements as the index finger of onehand keeps the impression in place while the thumb

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and forefinger of the other hand grasp the circumoraltissues and pull outward, upward, forward, and back-ward to register the muscle attachments. The patient isinstructed to perform the usual tongtic movements toaccomplish the lingual registration.

These impressions are poured in dental stone andthe casts are hand articulated and evaluated forappliance design. With a pencil, the periphery' of thefiange is outlined on the cast. The buccal boundaries ofthe appliance are dictated by the soft tissue configura-tion, because the appliance must (as a decree ofretention) extend as far as possible without encroach-ing on the muscle attachments. The circumdentaloutline is arranged so that the isolated field extends aminimum of one tooth past the working field.

The appliance has two major components:

1. A circumdental flange, which follows the mucogin-gival line buccally and extends lingually andpalatally to seal the working field posteriorly. Thisflange, which encircles the designated workingfield, is made up of the walls, which approximatethe alveolar tissues without undue pressure on thealveolar mucosa, and the everted occlusal portion,shaped into a circumdental lip, which retains theslit rubber dam.

2. A posterior occlusal bite plane, which provides thenecessary appliance retention as the patient oc-cludes on the RDR appliance for the duration of theprocedure.

The appliance is easiiy fabricated in a laboratory byflasking a wax pattern and curing the acrylic resin.Alternatively (as in the following case report) theappliance can be fabricated with the salt and peppermethod and then processed in a warm, dry pressurepot. In this method, a bead of rope-type wax is pressedagainst the periphery of the penciled outline, and a2-mm sheet of baseplate wax is adapted around this tocreate a forming effect. This prevents the acrylic resinfrom slumping dtiring incremental application. Areleasing agent (Model Reiease Agent, Dentsply/York) is applied to the area that is to receive the acrylicresin. The flange is built up to the desired height. Thesuperior dimension of the flange should be 3 mm thickso that the occlusal portion of the flange can bemodeled to the required everted retaining lip shapewith an acrylic resin flame-shaped bur. As with allacrj'lic resin appliances, material can be added at anypoint. The appliance is pumiced and polished smooth.A slit rubber dam is stretched and applied lo the gutterof the retaining lip and checked for retention before theappliance is delivered to the patient.

DeliveryThe articulated casts are used for demonstration to givethe patient appropriate instructions regarding the needfor occlusal contact on the posterior bite plane of theRDR appliance. The appliance is checked for comfonand flt without the rubber dam while the patient is in anonanesthetised state. The appliance is relieved wherenecessary, paying particular attention to the areas ofmuscle attachment. Adjustments are not likely to berequired, providing the circumoral musculature issufficiently and vigorously manipulated during thealginate impression procedure.

The patient is directed to gently close on the biteplane of the appliance, and the lingual access isevaluated. It is easiest to instruct the technician tooverbuiid the height of the bite plane, because it is easyto reduce the acrylic resin material to provide the bestcompromise between adequate lingual access andpatient comfort.

Alternatively, the occiusal plane can be deliveredwith minimal height and multiple small round perfora-tions. A length of registration material that sets in 1mintite (Stat-Br polyvinylsiloxane. Kerr/Sybron) isadded to the occlusal portion of the perforated acrylicresin, the appliance is seated while the mouth is inmaximal opening, and the patient is guided and held inclosure until the registration paste has set at the chosenoptimal position. This propped mouth position mustallow adequate access to the lingual surfaces of theanterior teeth.

The medium-thickness rubber dam is slit withscissors and stretched to engage the gutter of theeverted flange. The extraoral rubber dam frame isapplied, ensuring that the dam is placed undersufficient tension to effect the required circumoralretraction. In patients with heav>' musculature, therubber dam can be glued to the gutter of the flange withcyanoacrylate adhesive. This is done extraorally, andthe entire RDR appliance is delivered as one unit. It isimportant to ensure that the rubber dam is sufficientlyretained, and this is best done by vigorous movementof the extraoral frame in an effort to unseat the retaineddam.

Advantage

The restoration of the anterior sextants of an esthetic-ally compromised 32-year-old woman under the isola-tion of the RDR appliance is depicted in Figs 1 to 18.This report is not organized under the traditional casereport format, because the intention is not to display

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Operative Dentistry

Fig 1 Preoperalively, the esthetics of tooth shade, size,and contour are compromised The tissue contours, whilevisually pleasing, need surgical enhancement to expose theanatomical crowns. Multiple porcelain veneers are chosenfor the anterior portion ot this esthetic rehabilitation

Fig 2 To fabrícale fhe rubber dam-retaining appliance,baseplate wax is adapted around the periphery of thepenciled outline to create a torming eftect on the workingcast.

Fig 3 The wax form prevents the acrylic resin fromslumping during incremental application. A releasing agentis applied to the area to receive acrylic resin. With salt andpepper application, the circumdental flange and posteriorocclusal bite plane are applied to the wax torm and thenprocessed in a pressure pot.

Fig 4 The wax is removed and curing is completed. Notethe superior dimension of the flange, A 3-mm thicknessallows for the creation of an everted rubber dam-retaininggutter on the tiange

Fig 5 The retaining profile ot the tiange is achieved withacrylic resin burs The appliance is trimmed, pumiced,polished, and prepared for delivery with conventionalacrylic resin-tinishing procedures.

Fig 6 The tmished maxillary RDR appliance will enhanceisolation during tooth preparation and cementation ofporcelain veneers. The appliance opening has been ex-tended to the first molar to demonstrate the ability lo provideadequate access through to the second premolar.

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Fig 7 The RDR appliance is positioned on study casts toconfirm the access afforded by the posterior bite block. Aslit rubber dam is stretched and applied to the gutter of theretaining lip and checked for retention before the applianceis delivered to the patient.

Fig 8 The RDR appliance is tried in tiiK im^uin without therubber dam sheet to evaiuate fit. The appliance is removed,the sill rubber dam is stretched over the retaining fiangesand attached to an extraotai rubber dam frame, and theappiiance is returned to the mouth.

Fig 9 The tooth preparations are completed within theluxury of optimal access. The RDR appliance can beremoved at any point in the procedure and easiiy reinserted.

Fig 10 Flawless reproduction of the tooth preparations inthe working cast is reiiant on gentle retraction of gingivaitissues and e!<acting préimpression preparatory pro-cedures, such as piacement of perforated Mylar strips.Uncompromised access optimizes the quest for perfection.

Fig 11 The low-viscosity polylvinyl silcxane) impressionmateriai is applied unhurriedly within the hands-free accessof the RDR appliance. Once fhe wash maferiai has beenapplied, the RDR appliance is removed as the putty-loadedimpression tray is presented for insertion.

Fig 12 The same appliance is utilized during delivery of thelaminates. The predetermined seating sequence cailed forsome adjustments to the adjacent bonded veneers. The"keyhoie" seating of the last veneer in a sextant is difficult toaccompiish within the compromised access of operator-assisted isoiation.

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Fig 13 The mandatory use ot trial cements is accom-plished within the backdrop of the soft tissues, therebyerihanoing Ihe predictabJNty ot the finai esthetic result.

Fig 14 The naturalappea.'anceot tine maxillary arch beliesthe intensity of the finishing process. The access attordedby Ihe RDR appliance lends ilself weli 1o the exactitude ofthe marginal and inlerproximai finishing procedufes, whichare performed under magnilication.

Fig 15 A mandibular RDR appliance is fabricated toenhance isolation during tooth preparation and cementa-tion of mandibular porcelain veneers.

Fig 16 The mandibular RDR appliance is positioned onstudy casts. The circumdental flange is extended into thebuccal area in an effort io provide optimal retraction of thelower labial tissues

Fig 17 The unhindered access allows for the preciseexecution of the bonding sequence; a surgical-sizedevacuation tip is used fo remove fhe etching agenfmeticulously so that contaminates are not washed from theexposed mucosa across the conditioned tooth surfaces.

Fig 18 The mandibular RDR appliance provides unparal-leled access and isolation. Placement of laminates in themandibular anterior sextant is notoriously frustrating andmust rank as one of fhe most fechnclogically sophisticatedapplications of adhesive dentisfry.

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veneer procedures per se but rather to highlight someofthe advantages ofthe optimal access provided bythis isolatory adjunet.

Moisture control

The value of isolation as it relates to reducingmicroleakage at the resin-enamel interface has re-ceived ample attention. Clinical and laboratoryresearch has demonstrated that contamination oftheetched enamel surface with saliva prior to applicationof resin will prevent proper bonding beeanse themicropores become occluded.

The tenacity of tbis contamination has previouslybeen ascribed to the highly reaetive nature of theenamel as well as to its porosity,' With greaterappreciation of adhesive technology comes the under-standing that isolation is paramount—more so in thoseveneer applications with exposed dentin. whereresearch supports "wet bonding," The visual bench-mark of the frosted enamel surface is no longerdesirable, because desiccation has been associatedwith injurious sequela. Wet bonding places evengreater responsibility on the isolation setup, becausecontamination ofa wet surface is much more difficultto detect than contamination of a frosted facade.

The value of meticulous isolation, while universallyacknowledged as elementary to the successful appliea-tion of direct restorative efforts, has been noticeablyneglected in the indirect restorative repertoire in theanterior sextants.- Bonded ceramic restorations in theposterior sextants are restricted to supragingival appli-cations, where the integrity of the enamel-lutingresin-poreelain interface carries an appreciable degreeoí" predictability. In this supragingival application,isolation is rarely a problem and restorations arebonded under idea! eonditions. For the most part, thisisolation requirement has fallen dismally short whenapplied to the laminate restorative treatment option.

The apparent difficulty in satisfying the requirementof sufficient gingival access during the restorativeprocedure is often the one criterion that sways theclinician in favor ofthe less-than-adequate option ofcotton roll isoiation. The benefit and luxury of therubber dam are lost when the rubber dam is rejected onthe basis ofthe priority of gingival margin access. IL isarguable that most clinicians can maintain adequateisolation with cotton rolls and deliver satisfactorysingle veneers. Although tooth preparation for mul-tiple veneers is fairly speedy, the dehvery appointmentis notoriously time consuming when conscientiouslyexecuted. Most clinicians would be hard pressed todeliver and finish six anterior veneers in less than a

90-minute appointment. Moisture control occupiesthe greater portion ofthe clinical effort in adhesiveapplications, and, as such, the RDR appliance (pro-viding hands-free isolation in a rapid and practicalmanner) is a welcome adjunct during the procedure.

Access and procedural focits

It is difTicult for the practicing professional to keepabreast ofthe technological advances in materials andtheir specific applications. The backlog in publicationtime and the tardy transfer of technology invariablyresults in the use of "outdated" applicarion techniquesin good faith. Superior esthetics has been the trumpcard for porcelain veneers, and, while this is desirableand relatively easily attainable, clinicians must notloose sight of the fact that marginal fidelity is themeasure of long-term success of bonded restorations,Tlie prevention of ingress of microorganisms willcontinue to reign paramount. This article makes noattempt to cover the ever changing preparation andcementarion techniques that assure that fidelity.Rather, the artiele focuses on a means of improving thedelivery ofthe restorative option through improvingaccess and the ability ofthe practitioner to foeus on theprocedure at hand.

As a case in point, it would seem logical that bondstrength and microleakage have an inverse relation-ship, Kanca,' in a study of five dentinal bondingsystems, found no correlation between bond strengthand microleakage, Ofher research has revealed astrong association between the thickness ofthe bond-ing agent and microleakage.'' which indicates theimportance of air thinning the bonding agenl prior toapplication of resin,' Irrespective ofthe approachingimprovements in bonding technology, it is reasonableto anticipate that the successful delivery ofa bondedtreatment option will continue to depend on optimalaccess and adequate isolation.

Aecurate placement of a porcelain laminate veneeris reliant on precise and delicate seating ofthe fragilerestoration. Optimal seating is achieved with a slowrotational motion so that the excess resin flows freelyfrom the margins, without trapping air. This is adelicate procedure and relies on total proceduralfocus. The clinician cannot, at this stage, be competingwith the chairside assistant's retraction apparatus.Both hands are needed. There are many documentedapproaches to the pre-finishing resin cleanup. All ofthem rely on maintaining adequate moisture controland all require unobstructed access in this delicate partofthe placement technique.

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Shade matching

Porcelain veneers are overwhelmingly considered tohave more acceptable esthetics than porcelain-fused-to-metal crowns.'' Unlike their metal-based counter-parts, veneers can undergo some color modification atthe cementation stage. This control of shade is one ofthe features of veneers that has made them the idealchoice for superior esthetics. Nonetheless, shademodification is still dependent on the resin-mani-pulative acumen of the clinician at deliver}'.

Teeth change shade after rubber dam isolation,probably from loss of moisture from the interprismaticspace of enamel rods.' Although this lightening hasbeen shown to occur somewhat rapidly.^ the operatoroften does not notice it because ofa lack of reference tononisolated teeth.' In anticipation of this shade shift, ithas long been recommended that the shade be selectedbefore rubber dam application. In this way, with directrestorative techniques, exact shade matches arc acliicvcdby shade guides and spot applications of various layers,using combinations of shades where necessary. Indirectrestorations pose a unique problem, in that isolation ismandatory to trial seating and shade verification.Mtiltiple contiguous indirect restorations are lessshade sensitive than are single units bordered bynatural esthetics.

The author has found it useful to maintain thestuface moisture of the prepared teeth that are toreceive the laminates, as well as the adjacent isolatedteeth, for the duration of the procedure. The RDRappliance facilitates this, because the chairside assis-tant, who is not involved in maintaining isolation, isfree to periodically apply moisture to the said areas.

Weinberg,' Shelby.'" and Stein and Kuwata" allreported that the tooth is esthetically inseparable fromthe adjacent gingival tissue. The pink gingiva affectsthe hue ofa tooth. The full three-dimensional relation-ship of the anterior teeth to each other and to theiritivesting tissues must be exposed.

In such an enviromncnt. frame content, light, andcolor are complementary. '̂ This is a major advantageof seating veneers with the aid of the RDR applianceinstead of with classic rubber dam isolation with thetraditional No. 212 rubber dam retainer. The advan-tage of uncovering the gingival tissues with the generalfield isolation of this RDR appliance method isrevealed in Fig 13. The exposure of all the incisorstogether with the gingival background allows trialseating with try-in gels that mimic the shade of thecementing resin composite of the veneer during coiorevaluation.

Flexibility

The RDR appliance is easily removed and reinsertedto allow confirmation of the various parameters relatedto the restorative option, such as an evaluation of theexcursive movements for potential shearing stresses.This flexihiiity is a major advantage over traditionalrubber dam isolation during placement of multipleveneers. The appliance is ideal for those patients whoare only able to manage protracted treatment if tbey areallowed rest periods during the procedure. The ease ofremoval and reinsertion allows accurate and unhamperedrecording of the working field if the RDR apphanceis utilized at the impression phase. The hands-freeaspect of the isolation setup allows the clinician toconscientiously apply the first low-viscosity washphase of the impression with due regard for recoveringthe most exacting record of the prepared site. With thisdegree of control over the peripheral variables, thewash material can, for example, be thinned with an airsyringe to ensure that no air bubbles are entrapped.'^More wash material is then added to the preparations(see Fig l i) and the apphance is removed from themouth as the putty-loaded tray is presented forinsertion. The limitation caused by inhibition of set ofpoly(vinyl siloxanes) and supradammed impressions''*is no longer applicable, because the dam is removed forthe duration of the final impression. This allowsclinicians the choice of using poly(vinyl siloxanes),deemed superior in reproducing fine marginal detail. "

Comfort

With the RDR appliance, the patient is more comfort-able during the protracted bonding and finishingprocedures, because the bite plane functions as aposterior occluding support. In addition, with tradi-tional retainer-assisted rubber dam retention andgingival retraction, there is an inordinate degree ofgingival trauma that is noticeably lacking in thisappliance-assisted isolation method.

Summary

Traditional rubber dam application is cumbersome andimpractical when applied to multiple veoeers, withtheir priority of gingival mai^in access: consequently,multiple porcelain veneers are delivered with com-promised access in the absence of rubber dam isola-tion. A rubber dam-retaining appliance that optimizesaccess and improves isolation has been introduced.The appliance is fabricated from acrylic resin andconsists ofa circumdental flange that seals the worliitig

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area and retains the slit rubber dam, A posteriorocclusal bite plane provides the necessary applianceretention as the patient occludes on the appliance forthe duration ofthe procedure.

This case report highlights the need for optimalaccess and adequate isolation during the delivery ofone ofthe most technologically challenging applica-tions of adhesive dentistry.

Acknowledgments

The author would like to acknowledge liie laboratory skills of iEric Johnson of the Integra Denial Sludio.

References1, Silversione LM, Hicks MJ, Feathcrslone MJ, Oral fluid contamina-

tion ofetclied enamel surfaces; An SEM study, J Am Dent Assuct985;llO:329-332,

2, Lkbenberg WH, Supra-daramed impressions. J Esthet Dem 19y4;6:t21-128.

3, Katica J, Microleakagfi otflve dentin bonding sysleni5 DenI Muter

4. Buonocore MO Principles of" adhesive retention and adhesiverestorative materials. J Am Dent Assoc 1963^67:383-391,

5. Borem LM, Feigal lU, Reducing microleakage of sealams undersaliyarj' contamination; Digital-image analysis evaluation. Quintes-sence Inl i994;25;283-289.

scd-lo-meial crowns1994:125:311-3!4.

6, Christensen GJ, Ceramic vs. porcelainyour patients a choice. J Ani Dent As

7, Passon C, Lambert R, Tooth-shade shift after rubber-dam isolation.Gen Dent 1994;42:148-152,

8. Hatch RA, Spears SA, Osborne JW. Coior change of teeth underrubber dam isolation labstraetl, J Dem Res 1989;68;205,

9. Weinberg LA, Esthetics and the gingiva in full coverage. J ProslhetDent t960;10;737.

iO. Shelby DS, Anterior Restorations, Fued Bridgework and Aesthe-tics, Springfield. tL: Charles C, Thomas, 1976,

]). Siein RS, KuMWa M. A dentist and dental teciinologist analyzecurrent ceramometal procedures. Dent Ciin North Am 1977;31:729.

12 Diierzak J, Achieving Ihe optima! perio-esthetic results; The teamapproach, J Am Detit Assoc 1992;123:4i-48,

1.1. Christensen GJ. Tissue Management During Impressions Ivideo-tapel Provo UT: Practical Clinicai Courses, ]9S8,

14, NoonanJE, GoIdfogelMH. Lambert tlL, inhibited set ofthe surfaceof addition siiieones in contact with rubber dam, Oper Dent1985;i0:45-48,

15, Chee WHL, Donovan TE. Fine detail reproduction of very highviscosity poly(vinyl siloxanE) impression materiais. Int J Pros-thodont Í989;2:368-37O, D

500

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