NEW PRODUCTS AND TECHNIQUES

Esthetics in the Composite Resin VeneerTechnique

Christof Oik, ZTM*

n this time of structural changes indental technology, techniciansmust become familiar with alterna-

tives to ceramic materials. As these materialsfind application, for economic reasons aswell as the special properties that make themcompetitive with ceramics, the demandsmade of them are correspondingly great.The case report presented in this articledemonstrates that composite resin materi-alscombined with an innovative adhesivetechnologycan meet the expectationsplaced on them.

In addition to resin veneer techniques,other procedures have been developed forcomposite resin materials. The widely knowndisadvantages of the resin veneer technique,ie, flawed marginal seals, tendency to dis-color, insufficient resistance to abrasion,affinity for plaque, poor esthetics, and diffi-cult shade matching, are overcome by thenew techniques.

The newer composite resin materialsmostly are composed of inorganic matter.

'Dental Technician, Hermeskeii, Germany,

Reprint requests: Mr Christoph O\k. Reictiei Zahntechnik,Borwiesenstrasse 43, D-5'1411 Hermeskeii, Germany.

contain ceramic microfillers, and are signifi-cantly harder than ordinary composites. Fur-thermore, their bending strength and elastic-ity are higher, they are more homogeneousand more resistant to abrasion, and theircolor is more stable.

New adhesive systems also provide a bet-ter marginal seal and the possibility of ve-neering highly stressed regions such as oc-clusal surfaces. In this application, Rocatec(Espe, Plymouth Meeting, PA) is particularlyuseful. Combined with Solibond adhesivesilane (Shofu, Lab Div, Portland, OR), thisbonding system is most effective (Table 1),

In addition to the advantages mentionedpreviously, another positive factor of the newcomposite materials is that they can be usedfor most applications: telescopic and conicalcrowns, implants, precision attachments,crowns and bridges, inlays and onlays, long-term provisional restorations, jacket crowns,occlusal surface veneers, and shell veneers,as well as for customizing conventional resinteeth.

If restoration of a tooth is to be satisfactoryboth functionally and esthetically, many inter-dependent work phases, described briefly inthe following case report, are necessary,(Preparation of the cast is not included, as ithas been described thoroughly elsewhere,)

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Table 1 Processing with Espe Rocatec According to Manufacturer'sInstructions

Type of silane

Espe-Sil Espe-Sil Solibond

Composite Conventional Solidex Solidex23 h in 37C water 74.4 kgf/cm= 103.3 kgf/cm' 115.0 kgf/cm'2000 thermocycles 21.7 kgf/cm^ 52.2 kgf/cm^ 74.5 kgf/cm'

Case Report

This reconstruction involves placement ofsingle crowns in the maxilla (right first pre-molar to second molar) of a young patient.Because a high-quality bonding system isbeing used, the occlusal surfaces can be ve-neered to the lingual surfaces to provide ahighly esthetic result (Figs 1 and 2).

Framework Cast Preparation

The framework cast should be anatomicallycorrect, ie, the metal lingual margin shouldform a smooth, harmonious course without in-terruption. To obtain even layer thickness, andthus to provide the proper shade, the frame-work must be made thin at certain criticaland difficultsites, eg, in the incisai and cer-vical regions. In contrast, the framework mustbe somewhat thicker than usual in the centralregion and at the cusp slopes. Retentionbeads 100 to 200 pm thick are then placed(Figs 3 and 4). The framework is sprued in thelaboratory's usual manner, invested, and castwith the patient's choice of metal.

Framework Finishing

When the cast has been deflasked andsandblasted, and the framework has beenseparated and fitted to the cast, finishing

can begin. The first step involves finishing ofthe entire surface with a carbide bur at lowspeed. In this step, the optional retentionbeads at the previously indicated difficultregions are reduced to half size. This doesnot lead to loss of retention, as the upperhalves of the beads do not provide reten-tion for the resin. The margin is smoothed inthe customary manner with a rubber wheeland polished with a mixed-hair brush andpolishing paste. In this case, a bison-hairbrush and Paris red for the gold alloy wereused (Figs 5 and 6).

Bondir]g System

As noted earlier, I prefer Espe's Rocatec sys-tem for bonding for the several advantages itoffers:

1. Silicate surface layering proceeds with-out heating (as in, for example, the Sili-coater process), at room temperature, sononmetallic materials, eg, ceramic, com-posite resins, artificial teeth, can becoated.

2. The Rocatec layer can easily be checkedvisually because the surface colorchanges are readily apparent.

3. No crazing occurs between the surfaceto be veneered and veneering material.

4. In most instances, mechanical retentionis not necessary.

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Figs 1 and 2 Initial condition; starting point for the re-construction.

Figs 3 and 4 Anatomic framework with retention beads.

Figs 5 and 6 Finished and polished frameworks.

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Fig 7 Blasting with Rocatec (shown here at low pres-sure for photographic purposes).

Fig 8 Application of Sollbond.

Although the last point has been experi-mentally confirmed, I use the well-recog-nized nnethod with adhesive beads at esthet-ically less critical points (ie, where sufficientspace is available). This provides additionalundercut regions. The previously used hour-glass shape is ignored. Rocatec-Pre issprayed on the framework to clean It and toincrease the size of the available surface.Then a silicate surface is obtained with Ro-catec-Plus; this process is controlled visuallythrough a color change to a gray tone (Fig7). Spraying proceeds at 2.5 bar pressure,from 1 cm at a right angle to the surface.This coats the surface properly. Excess spraymaterial should not be air-blasted or washedaway, as the layer may be disturbed.

Solibond (Shofu) silane solution is appliedto provide a durable bond between metaland the opaque layer of the veneering mate-rial. It must be exposed to air for 60 seconds.Solibond was made to be used in the fabri-cation of a Solidex composite resin veneer(Shofu) and therefore yields higher bondstrengths than other silane solutions (Fig 8and Table 1).

Next the framework is prepared for ve-neering with the Solidex composite system.

Opaque Layer

Solidex opaque materials are ready to use;they need not be nnixed, as required in othersystems. They contain a special light-curingfiller that provides complete hardening in un-dercut regions. The viscosity can be alteredby thorough mixing with a composite spat-ula. Application of heat (with a hair dryer) issuggested to obtain a low-viscosity opaque.Covering the mixing plate increases theworking time.

As a rule, opaque is applied In three lay-ers. The first layer is thin, for better bonding.Light from the Kulzer XS curing unit (HeraeusKulzer, Wehrheim, Germany) can then pene-trate with certainty to the metallic surface(Figs 9 and 10). To provide thorough curing,each layer is exposed to the light for 180seconds. At its deepest points proximallyand cervically, the occlusal surface can becharacterized with a brown- and yellow-shaded opaque {Fig 11).

Cervical Region Layer

The cervical material (AC 1) is shaped into athin layer on a modeling plate. A semilunarshape is cut out, applied to the margin, andpolymerized (Fig 12).

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Figs 9 and 10 First and second opaque layers following polymerization in the XS unit.

Fig 11 Opaque layer is further characterized. Fig 12 After application of cervical material.

Dentin Layer

The reconstruction is ready now for cuspbuild-up. Pressing the ceramic-filled material[A 2) on the mixing pad avoids air bubble for-mation. A portion of the material is placed onthe framework. First the lingual cusp, the dis-tal slope, and Carabelli's tubercle are shaped(Fig 13). After polymerization in the XS unit,the buccal cusps are shaped and light curedfor 90 seconds. Layer thickness must bechecked in this process, as thicker layers re-quire more polymerization time (Fig 14).

Enamel Layer

The upper third of the cone is completedwith enamel material (S 58 and S 59) andgiven the appropriate shape.

Characterization

Stains (A-brown, yellow, brown) also made ofhybrid composite are used to highlight fis-sures and special characteristics (Fig 15).

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Fig 13 Lingual view of the cusp modeled in dentinmaterial.

Fig 14 Buccal view.

Fig 15 The enamel layer can be characterized morestrongly.

Translucent Layer

The crown can be completed with thetranslucent material (T). I prefer the HVT ma-terial for the cusp tips, as it works tostrengthen the perception of depth. Thecrown is then polymerized for an additional180 seconds (Figs 1 and 17),

Finishing

Dura green burs and diamonds are used forfinishing, A silicon rubber wheel is used forpolishing, with a goat's-hair brush and polish-ing paste (Fig 18),

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Figs 16 and 17 Completely polymerized single crov

Fig 18 Crown after finish-ing.

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Figs 19 to 22 Finished restorationcomposite or ce-ramic?

Summary

Solidex is extremely hard as a result of its ce-ramic microfilier, which makes up 53% of itscomposition. Solidex is also easily manipu-lated; it can be adapted well without model-ing liquid and it does not adhere to instru-ments. Moreover, it polishes very well,without loss of surface material.

This composite material is much harder,yet it has better flexural strength and is moreelastic than conventional veneering materi-als. It can be used successfully for inlays andonlays because of its homogeneity and goodabrasion resistance.

The enamel acid-etch technique makesdurable, esthetically appropriate solutionspossible. The outcome of the case report

presented in this article is quite satisfactory(Figs 19 to 22). Figures 23a to 23e show a re-movable partial denture veneered withSolidex; this new restoration replaced a ce-ramic veneer fixed prosthesis that was un-suitable for reasons of oral hygiene. The re-sult is also quite presentable and was entirelysatisfactory to the patient.

The handling ease of Solidex, in combina-tion with the Rocatec process, allows rapidfabrication of restorations. Apprentices canlearn the system without difficulty.

AcknowledgmentsSpecial thanks to ZTM Kurt Reichel for prosthetic support, andto my wife for her understanding.

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Figs 23a to 23e Removable partial denture veneered with Solidex; from cast to insertion.

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