a brief history and current status of metal-and ceramic

Restorative Dentistry

A brief history and current status of metal-and ceramicsurface-conditioning concepts for resin bonding in dentistryMutlu Özcan, DDS*/Peter Pfeiffer, Prof Dr**/Ibrahitn Nergiz, Dr***

The bond strength of resin to metal or ceramic .\urfaces has been increased with the introduction of vari-ous surface-conditioning techniques. The principles of currently used conditioning methods and clinicaltrials with these methods are summarized. The advances in surface-conditioning methods have increasedbonding to a high level: however, interpretation of the literature review itidicates that chemical hondingby means of recently introduced techniques provides better results than does mechanical bonding.(Quintessence Int 1998:29:713-724)

Key words: ceramic surface conditioning, metal surface conditioning, resin bonding

Clinical relevance

Chemical bonding appears to give better results indifferent clinical applications, such as resin veneers,resin-bonded prostheses, and veneered clasps, thando other conditioning methods.

Although satisfactory bonding between porcelainand metal is achieved with current dental practices,

during the last decade many attempts have been madeto create and develop techniques for bonding compositematerials and dental metals. This has led to the develop-ment of various surface-condition ing techniques.

With the advent of adhesive dentistry, competition indeveloping techniques and adhesive materials with in-creased bonding strength has emerged between dentalscientists and manufacturers. Therefore, the intent ofthis article is to review the published literature on theadvantages and disadvantages of the most commonlyused surtace-conditioning concepts, concentrating ontheir brief history and their applications with differentdental materials, as well as to provide an overview ofclinical results obtained.

* Research Assistant, Deparlment of Prosthodonlics. School of Oral

and Demal Medicine. University of Cologne, Cologne, Germany.

'^Professor, Department of Prosthodontics. School of Oral and DenialMedicine, University of Cologtic, Cologne, Germany.

'»'Assistant Professor, Department oí Prosthoiionlics, School of Oraland Dental Medicine, university of Coiogne, Cologne, Germany,

Reprint requests: Prof Dr P. Pfeiffer, Department of Prosthodontics.School of Oral and Dentai Medicine, Utiiversily of Cologne, KerpenerStrasse 32. 50931 Coiogne, Germany, E-maii: peter.pfei [email protected]

Surface-conditioning methods

Mechanical bonding

In 1989, Hansson' reported that in clinical practice,either a direct or an indirect technique could be used forthe construction of resin-bonded prostheses. The directtechnique was first described in 1973, by both Ibsen-'and Portnoy,-' as a simple method in which an acrylicresin denture tooth or the patient's own tooth wasbonded, using a resin composite material, to the etchedenamel of the abutment tooth without metalreinforcement. In the same year, Rochette-' presented analternative method, an indirect technique, in which aperforated cast-metal splint was bonded to the enamelwith poly(methyl methacrylate) resin. On the basis ofthese investigations, mechanical bonding gainedimportance.

Macromechanical bonding

Macromechanical bonding is one of the oldest methodsused to retain metal restorations, allowing the cement tolock into the metal. This method involved a perforateddesign, which had the disadvantage of exposing theresin to saliva, causing piaque retention, and subjectingthe resin to wear and crack propagation.*" The simple,old technique of using mechanical beads had the maindisadvantage that considerable thickness was added tothe restoration. The network retainer system, first intro-dticed by Shen' in 1984, was composed of prefabricatedmesh casting patterns to provide undercuts in the re-tainer surface. This also had the disadvantage of requir-ing considerable metal thickness.

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From available information, it is clear that mechani-cal retention has the following disadvantages : unreliablebonding values, gap formation, and microleakage result-ing from differences in thermal coefficients of expan-sion, Furtbermore, mechanical retention requires athickness of materials that might result in overcontour-ing of the restoration, which is inconsistent with theconservative approach.*

Micromechanical bonding

Mi crome chani cal bonding systems involveii sandblast-ing, which improved the retention between the metal andresin by cleaning oxides or any greasy materials frommetal surfaces. Sandblasting created very fine roughnessand ihus increased the bonding surface area, enhancingmechanical and chemical bonding between some resinsand metals.* However, bond strengths obtained fromsandblasting were insufficient. Long-term durable bond-ing was obtained with resin composites (Panavia Ex,Ktiraray) that contained phosphate monomer,

¡Electrochemical etching

Electroetched retainers were developed in 1982 byLividitis and Thompson^ at the University of Maryland,Fine irregularities in the surface of base alloys wereformed to increase the bond strength, ehminating resinexposure. Furthermore, metal could be made thinner toavoid overcontouring and massive tooth reduction.Electrolytic etching is the most widely used procedure tocreate increased mechanical retention to metal surfaces,but only some nickel-chromium and cobait-chrotniumalloys have been successfully etched,''*'Electrochemicaletching has tbe di.sadvantages of difficulty in creatinga properly etched surface and not working well witb pre-cious alloys. It is also technique sensitive, requiresexpensive equipment, and is time consuming.

Electrochemical etching of the metal framework cer-tainly improves the longevity of tesin-bonded restora-tions; however, to circumvent its limitations, numerousalternatives have been proposed in recent years.

Electrolytic tin plating

Most debondings in resin-bunded prostheses resuit fromfailure at the resin-metal interface,"-'^ It was thereforenecessary to improve the retention between the resin lut-ing cement and the metal sutface of the prosthesis. Thetin-plating technique consists of coating the rnetal sur-face electrolytically, at 6 V, with a thin layer of tin oxide.The layer is placed on the freshly sandblasted metal sur-face, which acts as the cathode, with a felt-tipped anode

moistened with a solution of opaque resin and tin. Thesurface is then oxidized and air dried, A second coatingof tin is applied at 9 V, and the sttrface is oxidized,washed with water, and dried, A special opaque resin isthen applied before the resin veneer is built up.

Electrolytic tin plating is required particularly forprecious metal alloys because only base metal alloyscan be etched,'•• Other studies noted that tin oxides formcrystals on the surface of the alloy, making it easy forthe resin to penetrate and produce micromechanicaland chemical retention,'^"'

Chemical etching

The use of an acid-based gel is an alternative to etchingthe alloy retainer electrolytically. This alternative wasoriginated by Lividitis" in 1986, Although new chetni-cal-etching systems have been claimed to provide betterretention than either electrolytic etching or perforatedprostheses when used with some metals,'* these chemi-cal etchants produce a shallower etching pattem than isfound on electrolytically etched metal.'' This techniquehas the advantage of being very simple to use chaiiside;furthermore, the restoration can be re-etched in case offailure, without the need for sophisticated laboratoryprocedures.

Chemical bonding

SR Spectra Link. SR Spectra Link (Ivoclar) creates aphysicochemical bond between the resin and the metalwithout silane coating (Table 1), The adhesive resin is alight-cured bonding medium based on metliacrylic acid,which has a metal-active, a resin-active, and a water-repellent component. Because SR Spectra Link containsa fluorinated alkyl methacryiate, it greatly reduces thesusceptibility of the bonding system to hydrolysis,

Tbe metal-active part of Spectra Link reacts withmetal oxides and thus provides tbe necessary conditiottsfor an optimum bond. The Spectra Activator preparesthe polymerized surface of the Spectra Link for chemi-cal bonding with tbe specially developed light-curingSpectra Opaquer, Polymerization takes place in theSpectramat iu 5 minutes. This is followed by the appli-cation of the resin-activator component. SpectraActivator, The framework is coated with SpectraOpaquer and polymerized twice to make sure that allthe surfaces are irradiated. The surface treatment iscompleted by tbe use of tbe desired Spectrasit color.This method can also be used to provide a high-qualitybond between the metal and denture base material,

Silicoater Classical. Silicoater (Heraeus-Kulzer) wasdeveloped at Jena University by Tiller et al-" in 1984

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{Table 2), The method was initially developed for bond-ing veneer resins to metal. Mechanical retention, suchas beads or wires, was not required, aud tnicroleakagebetween the veneer and metal was eliminated. The pro-cedure originates from the need for an intermediatelayer containing silicon dioxide (SiO^), because thisprovides sufficient bonding of the resin via a silanebonding agent that does not ahsorb water.

The surfaces of precious alloys are sandblasted firstwith 25O-(tm aluminum oxide for 15 seconds at 0,4MPa, The sandblasted surfaces are coated with Silicleansolution (Heraeus-Kulzer), After washing, the metal isdried for 2 minutes at room temperature in air. This tech-nique consists of heating SiO^ with a flame (Siliflam,Heraeus-Kul/er) in a specially designed apparatus. Theflame should be adjusted to provide enough depositionof SiO^ molecules on the metal surface, Siliflam is ap-plied for 5 minutes (air-propane ratio of 20:1; air, ap-proximately l.iO L/h, propane, 6,5 L/h), After the speci-men is dried for 4 minutes in air, a silane layer (amixture of Silicoup A and B, Heraeus-Kulzer) is applied.

Silica coating leads to initial bond strengths 25%higher than those to etched metal-' and can be used tobond either composite or acrylic resin to any metalsurface.

The technique has the disadvantage of being expen-sive, and the internal resin interface caunot be alteredduring try-in,' The other shortcomings of the system arethe nneven distribution of the flame over the restorationaod chemically unstable silica layers. Assuming a usualdelay of 2 to 7 days between laboratory fabrication andclinical cementation, this layer requires protection dur-ing transportation. This problem can be overcome bycoating the inner surface of the retainers with a thicklayer of opaque base paste or a bonding agent (withoutits catalyst) from a resin composite luting cement,

Silicoater MD. The Siiicoater MD (metai-dotted)(Heraeus-Kulzer) is the new version of the 14-year-oldSilicoater Classical technique. The new techniquerequires a special oven tbat burns a chrome-endowingsilica layer onto the surface (Table 3), The differencebetween the techniques is that in the new method themetal surface is coated with SiO^ as a liquid and isfired at highly controlled and carefully regulatedtemperatures.

The surfaces of precious alloys are sandblasted firstwith 250-|jm aluminum oxide for 15 seconds at 0,4MPa. The sandblasted surfaces are coated with Silicleansolution. After it is washed, the metal should air dry for2 minutes at room temperature. Finally, the surface istreated with Sililink (Heraeus-Kulzer) and positioned inthe Silicoater MD oven, and the Sililink is activated for8 minutes. The framework is then allowed to cool for 5

minutes at room temperature. Following this, the surfaceis conditioned with Siliseal (Heraeus-Kulzer) bondingagent and dried at room temperature for 4 minutes.

This system has the advantage of avoiding flame-adjustment problems, ie, eiiminating the human factor.The principle of this technique is based ou a property ofchromium, whieh forms waterproof bonds with sili-cates. These bonds are obtained as a result of the com-plicated chemistry of chromium bonding at tempera-tures higher than 250"C, Similar waterproof bonds canalso be formed with certain alloy components, such ascopper, other metals, and their oxides,----''

Kevloc AC. Kevloc AC (Heraeus-Kulzer) is a rela-tively new system, introduced in 1995, that offers a com-bination of chemieiti and mechanical bonding. It haspresented promising results in resin veneer alloy bond-ing, inlays, onlays, and implant-supported restorationsas well as removable prostheses (Table 4},'^

The Kevloc method was designed to bond resin lay-ers to the surface of dental alloys. The temperatureneeded for the activation of the bonding layers is gener-ated by contact heat transfer and heat radiation in theactivation chamber of tbe Kevloc AC apparatus.

In this system, the surfaces of the alloys are sand-blasted with fresh llO-pm aluminum oxide at 0,2 MPa.The sandhlasted surface is cleaned with a clean bmsh,and the loose particles are removed. Kevloc-Primer(Heraeus-Kulzer) is applied with a clean brush in onedirection and dried at room temperature for 1 to 2 min-utes. Then, Kevloc Bond (Heraeus-Kulzer) is appliedwith a brush. After it is dry, the framework is placed inthe chamber of Kevloc AC, to be activated for 8 min-utes. Then the specimen is cooled at room temperaturefor 5 minutes. The specimen is then positioned in theactivating chamber. After the metal has cooled, whichtakes about 4 minutes, Dentacolor Opaquer (Heraeus-Kulzer) or Artglass Opaquer (Heraeus-Kulzer) is appliedin thin layers and polymerized for 90 seconds in theDentacolor XS (Heraeus-Kulzer),

Siloc. The surfaces are first sandhlasted with 250-pm aluminum oxide and dried with water-free and oil-free air at 0,3 MPa (Tahle 5), Siloc-Pre (Heraeus-Kulzer) is applied with a brush and dried at roomtemperature for 2 minutes. The specimen is placed inthe Siloc apparatus (Heraeus-Kulzer), and program 2 isselected. Later, the framework is cooled at room tem-perature for 4 minutes. The activated surface is coatedwith Siloc-Bond (Heraeus-Kulzer) and dried in the airfor 5 minutes. Following this, Dentacolor Opaquer isapplied and light polymerized in the Dentacolor XSunit for 90 seconds.

Rocaiec. The Rocatec system (BSPE) introduced in1989, presented a new kind of acrylic resin-metal bond-

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TABLE 1 SR Spectra Link process

t

2

3

4

5

Application otretention beadsSandbiasting

Coating

Surface activation

Coating

Solvent evaporated after 30 seconds

Aluminum oxide, 50 to 250 |jm.steam cleaning, drying with oil-treecompressed airSpectra Link: Polymerization inSpectramat for 5 minutesSpectra Activator(resin-reactive component)Spectra Opaquer: Polymerizationin Spectramat and coating witfiSpectrasit Cclor

TABLE 2 Silicoater Classica! process

1, Sandbiasting

1. Hinsing3. Mounting4. Conditioning

5. Siianization

6. Coating

Aiuminum oxide, 250 [jm;pressure: > 0.4 MPa:time: approximately 15 secondsSilioiean: Air dryingPositioning in the Silicoater apparatusSilitlam' Approximately 5 minutes;tiame proportion ol air-propane 20:1(air application 130 L7h;propane 6.5 L/h for approximateiy4 minutes; cooling down in air)Silicoup A and B: Drying forapprcximateiy 4 minutesDentaooior Opaquer; 90-secondpoiymerizatioo in Dentaooior XSapparatus

TABLE 3 Silicoater IVID process

1. Sandblasting

2. Rinsing3. Conditioning

4. Siianization

5. Coating

Aluminum oxide, 250 |jm;pressure: 2 0.4 MPa;time: approximately 15 secondsSiliclean; Ait dryingBrushing a thin iayer ot Sililink;sample positioning in the middle ofthe apparatus; 2 minutes of cooiingdownCoating with Siliseal;drying for 2 minutesDentacolor Opaquer; Polymerizationin Dentaooior XS for 90 seconds

TABLE 5 Süoc process

1. Sandblasting

2. Conditioning3. Activation

4. Bonding

5. Poiymerization

Aiuminum oxide, 250 pm;drying with oil-free air at 0.3 MPaSiloc; Applied and dried for 2 minutesIn Siloc apparatus: cooling downfcr 4 minutesSiloc-Bond: Applied and dried for5 minutesDentacoior Opaquer: Poiymerizationin the iight unit Dentacoior XS for90 seconds

TABLE 4 Kevloc AC process

1. Sandblasting

2. Coating

3. Aotivation

4. Polymerization

Aluminum oxide, 110 [jm.pressure: 0.2 MPaKevloo-Primer; Appiied and driedfor 1 to 2 minutesKevloc Bond in Kevloc AC for8 minutes; cooling down tor 5 minutesDentacoior Opaquer or Artglassin thin layers, in Dentacolcr XSfor 90 seconds

TABLE 6 Rocatec process

1. Sandblasting

2. Conditioning

3. Siianization4. Coating

Rcoatec Pre in Rocatector;pressure; 0.25 MPaRocatec Plus in Rocatector;pressure; 0 25 MPa;distance: 1 cm trom the surface; _time; approximately 13 sec/cm' aESPE-Sil; Drying time, 5 minutes ^VisioGem or Slnfcny Opaquer

ing system (Table 6). The principle is a tribochemicalapplication of a silica layer by means of sandblasting.First, surface conditioning takes place in the RocatectorDelta (ESPE) with Rocatec Pre, llO-pm aluminumoxide (ESPE), at a pressure of 0.25 MPa. Then the sam-ples are blasted with 1 lO-pm aluminum oxide modifiedwith silicic acid, Rocatec Plus (ESPE), in theRocatector Delta at 0.25 MPa at a distance uf 1 cm fromthe metal surface for 13 sec/cm-.

The theoretic calculated speed of the Rocatec Plusparticles hitting the alloy surface is 200 m/s, producingspot heating up to !,000°C. This spot heating, together

with the hlasting pressure, results in the embedding ofsilica particles on the metal surface, rendering the metalsurface chemically more reactive to resin via silane.ESPE-Sil silane agent (ESPE) is applied before the sur-face is coated with the opaquer and dried at room tem-perature for 5 minutes.

The particular advantages of the process are thebpeed and accuracy of coating, the fact that the adhesivelayer can be checked visually, and the fact that thermalstressing of the framework is avoided. This is especiallyuseful in repairs hecause remaining acrylic resin doesnot have to be removed."

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Care should be taken to sandhlast the metal surfaceat an angle of 90 degrees and not to touch the treatedsurface during any steps of the preparation. The Rocatecsystem uses the mechanical energy of silica-coveredaluminutn grains as these are hlasted onto the metal sur-face. The silane coupling agent adheres to the surfacewhen the mechanical energy is transformed to thermalenergy, providing a chemical hond between the silicalayer and the resin cement. Gugg en berger-'' deñned theRocatec procedure as a novel acrylic resin-metal bond-ing system and concluded that shear/compression andtensile tests revealed bonding strength values obtainedwith the Rocatec system to be greater than thoseobtained with mechanical bead retention, even afterthennocycling and storage in water for 1 year.

Adhesive chemical bonding

Recently, chemical adhesive systems have become verypopular in bonding resin to metal. The greatest advan-tage of these systems is that they are very easy to applyand do not require laboratory processes. Sandblastingrenders the metal surface fresh and clean of any metaloxides or any greasy materials and makes the surfacechemically more reactive to resin by increasing themetal surface, Bxamples of these adhesive systems arePanavia Ex and Panavia 21 adhesive resin cements(Knraray). In both laboratory and clinical research,Panavia Ex is one of the most popular metal adhesivecements. Bonding to the sandblasted nonprecious alloysis highly satisfactory with good physical properties.*

Comparison of conditioning systems

Metal conditioning

Numerous studies over the years have assessed the sur-face conditioning of alloy surfaces. Crcugers et aV wereamong the pioneers of such studies. They compared thebond strength of silica coating in combination withMicroponI (Kulzer), sandblasting with Panavia Ex, elec-troplating with Panavia Ex, and etching in combinationwith Clearfil to nickel-chromium and cob alt-chromiumalloys. The mean tensile bond strengths of silica-coatedand sandblasted specimens were significantly higherthan those of both electrolytically tin-plated specimensand etched specimens. There was an overall effect ofluetal alloy on the bond strength but no significant dif-ferences between both alloy types for etched specimens.

In a subsequent study, Luthy et al" investigated fac-tors influencing metal-resin bond strength to filled com-posites. Apparently, bond strength was greater to silica-coated metal than to sandblasted and electroetched

specimens. In a similar study, statistically significantdifferences in bond strengths were observed betweenprecious and nonprecious alloys. It was observed thatsilica coating produced higher shear bond strengths thaneither electroetching or chemical etching.-" On the otherhand, the bond strength created by the Rocatee system,independent of the alloy used, proved the reliability ofchemical bonding over sandblasting alone and treatmentwith silane.-^

Caeg et aP^ and Ishijima et aP" demonstrated that thesilica treatment process always provided better resultsthan that of electroetching in palladium-, cobalt-chromium-, and nickel-chromium-based alloys.

In the last decade, a number of studies were focusedon comparison of Silicoater Classical, Silicoater MD,and Rocatec systems. Silicoater MD provided a notablylower degree of bond strength to nonprecious alloys,whereas Silicoater Classical and Rocatec systemsshowed superior bonding to all types of alloys, espe-cially to pure titanium.^'"" It has been possible to createa chemical bond resembling the metalloceramic bondbetween dental alloys and resin composites. Ruyter etal'-' attributed a 17% to 47% reduction in bond strengthin two palladium and three gold-based alloys coatedwith silica to water diffusion through the interfaciallayer; the moisture attacked the SiO layer between themetal and the composite. The process of sandblastingmakes the surface rough, which is essential for buildingup and locking in the silica oxides; this could explainthe differences in the bonding values among variousalloys. This study was one of the first explaining theimportance of the silica-coating mechanism.

The effect of water storage on bonds obtained withSilicoater Classical, Silicoater MD, Rocatec system,and Panavia Ex to different types of alloys was ad-dressed by Beldner et al, ^ who concluded that the bondstrength developed with both the Rocatec system andPanavia Ex to cobalt-chromium alloys remained thesame, without significant change. The values related toSilicoater MD dropped by a value of 30%, while thoseobtained with the Silicoater Classical system increasedslightly from the results obtained before water soaking.

When nickel-chromium-beryllium alloys weretreated with silica and then silanated (Silicoater MDand Rocatec), cohesive failure of the opaqtiers betweenthe composite veneering materials and the porcelainfusing alloys was ohserved in both experimentalgroups.^^ The analysis of pre sandblasting, which is rec-ommended as pretreatment to thermal silica coating oras part of a tribochemical silica-coating process, andthe influence of particle size on the loss of substancerevealed that volume loss, surface morphology, andcompositional changes are greater in noble alloys

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(gold-silver-copper) than in base alloys (nickel-chromium and cobalt-chromium); however, these dif-ferences did not seem to be critical for the fit of therestorations.-" Embedded alumina particles were alsofound in all alloys after sandblasting, and alumina con-tent was increased by 14 to 37 wt% as measured by en-ergy-dispersive K-ray spectroscopy. Also following tri-bochemical silica coating, a layer of small silicaparticles remained on the surface, increasing the silicacontent to between 12 and 20 wt%."

However, in another study,"* slightly higher loss ofsubstance was observed with palladium alloys, and par-ticle sizes smaller than 30 p m caused dust productionand obstruction of the nozzle during sandblasting.Therefore, it was recommended that the thin metal mar-gins be blasted only with silicated corundum with a par-ticle size of 30 |im before bonding. Unnecessary sand-blasting of the restorations should be avoided because itis likely to damage the margins of the restorations.

The bond strengths of two adhesives (Microfill pon-tic, Kulzer; Nimetic-grip. ESPE) and two metal pre-treatment methods (Silicoater MD and Rocatec) wereassessed by Stark and Holste"' for bonded fixed partialdentures. The test procedure was carried out in accor-dance with German Industrial Standards (DIN 532S3;DIN 8200), which ensure high reproducibility in sand-blasting and bonding pairs of metallic specimens.Although few differences were detected between theadhesives, the Rocatec method showed significantlylower strength values than Silicoater MD.

The same outcome was reported in a comparativestudy of the bonding of high-gold and nonprecious alloytreated with these systems and adapted with Microfillpontic to the enamel of extracted human teeth. The twomethods of veneering increased the composite strengthand the nonprecious alloy yielded the highest values forshear strength. The shear resistance of the Silicoater MDsystem was found to be higher than that of the Rocatecsystem.'* The results of these two studies contradictedthe findings of previous studies. Nevertheless, bothmethods can be used for bonded fixed partial denturesbecause the bond strengths they provide are adequate.

In summary, studies related to surface conditioningwith current methods revealed that silica coating of thealloy is an important advance in adhesive bonding ofresin composites to metal because it reduces the impor-tance of the alloy composition and its oxide formationto the bonding mechanism.

Ceramic conditioning

A new glass-infiltrated alumina ceramic (In-Ceram, VitaZahnfabrik) has shown greater ñexural strength than

other ceramic or glass materials. Because of its highstrength, this ceramic has been suggested as a core ma-terial for resin-bonded fixed partial den tu re s,"*"- ' Thisclinical application requires a stable resin bond to theceramic and is advantageous for other clinical applica-tions, such as inlays or artificial crowns. Etching silica-based ceramics with hydrofluoric acid or ammonium bi-fluoride creates a sufficient resin bond that is enhancedwith a silane coating of the etched ceramics. However,neither etching with these solutions, nor adding silane,resulted in an adequate resin bond to the alumina-basedIn-Ceram ceramic.'"—'"

Although In-Ceram ceramic can be etched with boil-ing sulfuric acid, all of the etched samples were foundto have debonded after 150 days of storage in isotonicartificial saliva solution because of a weakened bond tothe superficial alumina particles as a result of etch-¡i g .16,49 Therefore, the development of alternative meth-ods of bonding to In-Ceram was needed. In followingstudies, it was noted that the use of resin compositesthat contained phosphate monomer, in combination withsandblasting or silica coating, increased the bondstrength to In-Ceram.-"*" ''"-'"

After sandblasting or silica coating of In-Ceram, thetensile bond strength of the modified bis-GMA resinPanavia Ex {Kuraray) showed no significant changeswithin the first 30 days, but there was a pronounceddecrease after 150 days of storage and thermocyciing.Silica coating In-Ceram with the Roeatec system resultedin a better bond strength to the conventional resin. Micro-fill pontic. than did use of .silane only.'' In vitro shearstrength of the resin bond was found to be higher toglass-infiltrated aluminum oxide ceramic material treatedwith Sihcoater or Rocatec systems than to nonpreciousmetal alloys. With this method, the small marginal gapand film thickness of the luting cement was decreased. '

Most notably. Kern et ai," using alignment appara-tus, bonded resin composite filled in Plexiglas tubes todisk-shaped metal, core ceramic, glass-ceramic, andenamel .specimens. Specimen surfaces were conditionedcither by sandblasting and etching or the Silicoater MDprocedure. After storage, statistically significant differ-ences were recorded in bond strength between the testmaterials. The group treated with Silicoater MD gavethe best bonding results at the end of 150 days" waterstorage and thermal cycling.

Gobel et al'' studied the effect of surfaee conditioningon different dental ceramic materials—glass ceramics(Bioverit, Schott; Vita-Miirk2, Vita Zahnfabrik; Cerec,Vita Zahnfabrik), sintered ceramics (Vita Omega, VitaZahnfabrik), and aluminum oxide ceramics (In-Ceram)—in shear bond strength tests of the ceramic-cotnposite bond. Among the conditioning methods, silica


Ozean et al

coating with Silicoater Classical, Silicoater MD, audRocatec, as well as Siloc, Kevloc, and Spectra Link, pro-vided better results tban did sandblasting, grinding, oretching with phosphoric acid. Wben glass-infiltrated,cyhndrical alumina ceramic In-Ceram specimens werebonded to phosphoric acid-etched human enamel, theresults of the shear tests indicated that durable bond be-tween enamel and In-Ceram was more likely to be ob-laiued witb Rocatec than with Silicoater MD orPanavia.-"

Mode affaiiure

Altemative adhesive methods for bonding to In-Ceramexhibited different bond failure modes in scanning elec-tron microscopic studies, -" The reason for the adhesivefailure and low bonding in tbe presence of loose silicapanicles on the silica-coated alloy surface was studied. 'It was suggested that ultrasonic cleaning instead of sim-ple bench tapping, as recommended by the manufac-turer, should be performed to increase the bond strength.Scanning electron microscopy and chemical analysisdemonstrated adhesive failure patterns on tbe treatedsurface. With the Rocatec tribochemical silica-coatingsystem, failures occurred witbin the silica layer itself.When thermal silica coating witb Silicoater MD wasused, only cobesive failures within the resin layer werefound. On tbe otber band, sandblasting showed differentfailure modes, '

Effect of water storage and tbermocyclingon bond strength

Several authors conducted research concentrated on theeffect of water storage and thermocycling to simulatethe aggressive oral environment under laboratory condi-tions-' and found no significant differences betweenfresh silica-coated nonprecious alloys and those storedin water at 37''C for I week, except for sandblastedspecimens bonded witb Panavia Ex, where bonding val-ues were increased, A sbort-term storage study was per-formed by Laufer et al," and tbey concluded that ce-mentation significantly increased the bond strength forboth etched and silica-coated specimens after 30 min-utes to 3 days of water immersion. An increase in bondstrength of silica-coated, nickel-chromium alloy speci-mens after 30 days of water immersion was reported byGuggenberger, ^ No statistically significant decline wasfound in the adhesive strength of the Rocatec systemfrom baseline to long term; tbe initial bonding resultswere obtained after 20 hours of water storage at 36''Cplus 6 hours of thermocycling, repeated 180 times be-tween 15°C and 70°C, and long-term values were calcu-

lated after 1 year of water storage and 900 repetitions ofthermocycling between I5''C and 70°C,

Another study in the arena of water storage, byPeutzfeldt et al,-" found that immersing the samples inboiling water for 55 minutes and then storing them at22°C for 5 minutes, repeated four times before tensilebond testing, did not change the bond strength values ofsilica-coated Wirobond alloy (cobalt-chromium)(Bego), whereas it did cause a statistically significantdecline in the bond strength of gold-based and palla-dium-based alloys. Testing of nonsilicated specimensalso resulted in significantly lower bond strengths. Thisdecrease was related to the difference,'; in coefficient ofexpansions, which pre.sumably sped up the diffusion ofwater between tbe resin cetnent and the metal,

Pfeiffer" studied the bond strength of Panavia Exand Orthomite (J, Morita) to nickel-chromium andpal I ad iurn-silver alloys after 3 days aud 150 days ofwater storage at 37°C. He noted that tbe initially highbond strength values of nonprecious alloys bondedwith Panavia Ex remained unchanged. The palladium-silver alloys, in contrast, had initial bonding valueslower than those of the other alloys, and tbese valueswere further reduced by 33% after 150 days' waterstorage.

Kern et aF^ compared five different resin bondingsystems to cobalt-chromium alloys, Tbese were storedin artificial saliva for 150 days at 37°C and every sec-ond day were subjected to 1,000 thermocycles in a tem-perature range of 5°C to 55°C for a total of 75,000 cy-cles. Specimens were tested after 24 bours, 10 days. 30days, 90 days, and 150 days. The results indicated thatin contrast to the micromechanical bonding systems,mechanical-chemical ones (Rocatec system) showed nosignificant change in the tensile bond strength duringthis observation period. The ,system was recommendedas suitable for cobalt-chromium alloy used in resin-bonded restorations,

Tbe effect of short-, medium-, and long-term waterstorage and thermocycling on the bonding durabilityand failure bebavior of Rocatec and Silicoater systemsused witb gold-silver- and palladium-silver-based al-loys was studied, Silicoater produced better resultsafter 20 hours of water storage. Three hundred sixtythermal cycles between 15''C and 70°C for 12 weeksresulted in a significant drop of the bond strength andan adhesive mode of failure and without significantchange in adhesive failure after storage of the samples.On the otber hand, 1,080 thermal cycles for 22 weeksreduced the bond value between 38% and 69% in thegroup treated with Silicoater, which exhibited adhe-sive failure. They attributed this drop in bond values tothe effects of thermocycling. which facilitated water

Qtjintessence iniernationai719

attack of the SiO^-composite bonding. The Rocatecsystem recorded the lowest drop in bond values, rang-ing from 8% to 15%,"

Ishijima et aP" evaluated the effect of I week ofwater storage, 500 cycles, and 1,500 thermai cycles onthe hond strength produced with the Silicoater system,Panavia Ex, and Superbond used with different preciousand nonprecious alloys. They found that increasing thethermal stress led to the diminution of the bondstrengths of all systems.

Smith et al" compared bond strength and durabilityof the Silicoating, electroetching, and Panavia Ex sys-tems bonded to nickel-chromium alloy. After short-term (2,672 cycles) and long-term (10,584 cyeles) ex-posure, silica aud silane-treated specimensdemonstrated the greatest decrease in bond strength(39%), whether it was under aqueous or thermocycledconditions. The second highest value was obtainedfrom electroetched specimens, while Panavia Ex speci-mens had the least decrease in bond strength. TheSilicoating technique resulted in a significant reductionin hond strength with respect to time with or withoutthermocycling, which could indicate that there is a highinitial attachment of resin to metal but that this effectmay deteriorate over time in a water environment. Thebond quality achieved with Rocatec, Silicoater MD,and SR Spectra Link systems and different types ofprecious and nonprecious alloys was tested after thespecimens were subjected to 10,000 thermocycles. Theresults demonstrated that the Silicoater MD systemproduced the lowest bond values to the nonprecious al-loys, while the Rocatec system achieved superior bondstrength to all types of alloys, "

The bond strength of Panavia Ex. Cover up (Parkell),and silica-coated stainless steel and the effect of ther-mocycling on the bond values were evaluated in anotherstudy, Panavia Ex and Cover up produced bondstrengths superior to that produced by the Silicoater sys-tem. Interestingly, thermocycling was found to have nosigniflcant effect on the hond values, ^

In a similar study, the effect of storage conditions (24hours of water storage and 1,000 thermocycles) on thehond strength of eight different bonding systems, in-cluding Rocatec. Panavia Ex and Silicoater, to a nickel-chromium alloy was tested, Thermocycliug was foundto have no effect on the Rocatec system but resulted in adecreased bond strength for Panavia Ex and SilieoaterMD; the reduced values were close to the critical clini-cal values,**"

More recently, it was found that the retention ofresin to cobalt-chromium and titanium alloys treatedwith the Rocatec system was not affected by immersionof the samples in boiling water for 25 minutes, while

the bond was decreased in the case of gold alloys, '*Pfeiffer i reported that regardless of the resin type, theSilicoater MD system produced high initial bondstrengths, which deteriorated after thermoeycling andlong-term water storage. The Rocaiec system, in com-bination with Nimetie-grip, provided lower but clini-cally acceptable, stable bonding even after thermocy-cling and water storage.

When tensile bond strength was tested, the tribo-chemical silica-coating procedure with Rocatec wasfound to be suitable for cobait-chromium alloys inresin-bonded restorations after 18,750 thermocycles, ^Hansson and Moberg''' evaluated three different meth-ods of increasing the bond strength of resin to metal.The original Silicoater technique, Silicoater MD, andthe Rocatec systems were tested. The results provedthat with each system, the retention of resin to the goldspecimens decreased after thermocycling but retentionto the coba h-chromium alloy and titanium was not af-fected. The original Silicoater technique producedhigher hond strengths than its new version, SilicoaterMD,

Clinical studies

Resin veneers

Musil and Hàselbarth,''" after applying the Silicoatertechnique for resin veneers, carried out a follow-upstudy from 1984 to 1988 on 13,133 Den taco lor-coatedprosthetic applications. They ob.served only a 2,7% inci-dence of fracture failure,

WÖstman' ^ observed fracture failures of the facingsin 54 patients with 157 veneers (Silicoater/Dentacolor).Between the period of 6 and 18 months, in the silica-coated group, fractures were found in only 4 of 157 ve-neers ohserved, Bruhn et al"'' earned out a 3-year fol-low-up study comparing the Silicoater/Dentacolortechnique to other methods in 304 crowns. Surface con-ditioning with Silicoater gave clinically acceptable re-sults esthetically, although there were some small colordifferences that could be attributed to insufficient poly-merization. Over this period of time, a defect rate of 4%was observed,

Heidi'*' followed up on 4,893 crowns (Silicoater/Dentacolor), observing a fracture rate of 2,3% for gold-based alloys, van der Veen ** compared the Silicoatersystem clinically and experimentally with other systemsand, after thermocycling, obtained the highest bond val-ues with the Silicoater system. Clinically he evaluated40 flxed partial dentures. At the end of 2 years, 10%debonding was observed. The importance of a thin opa-quer layer was also emphasized, ^


Resin-bonded prostheses

Kerschhaum'''' evaluated 1,453 resin-honded prosthesesand found die probability of dehonding to he 75% lesswith the Silicoater system, 65% less with acid-etching,and 15% less with net technique than with sandhlastingover 4 years. The results suggested that resin-bondedprostheses can successfully survive if meticulous atten-tion is given to the procedures outlined. The survival ofposterior resin-honded prostheses was achieved follow-ing a common protocol.'"

A meta-analysis of posterior resin-bonded fixed par-tial dentures treated with electrolytic etching andClearfil F2 (Covex); sandblasting with 50-nm alu-minum oxide, and Panavia Ex: and silicate coating andMicrofill pontic was carried out after 2.5 years," Theresults of this clinical trial revealed that silicate coatingwas the most suitable of the tested adhesive systems.After complete polymerization, Panavia Ex was alsofound to be acceptable in combination with cobalt-chromium, nickel-chromium, Wiron 77 (Bego), orWiron 99 (Bego). A combination of silica coating andClearfil F2 was thought to he an interesting alternativefor clitiical use.

Verzijden et a l ' - evaluated 201 posterior resin-honded tlxed partial dentures and found no significantdilïerences among Clearfil with etching, Panavia Exwith sandblasting, and Microfill pontic C with silicatecoating or among the different preparation forms.

Three years of clinical experience in 47 patients with120 resin-honded restorations placed after Rocatecapplication demonstrated few failures.^' Of the 13failures, 11 fractured between the metal and the VisioGem(ESPE) opaque layer. The other two small fractures wereobserved at the acrylic resin and were difficult to see. Therest of the restorations U"eated with Rocatec exhibited nocolor changes and were resistant to abrasion.

Boening" evaluated 46 resin-honded prostheses for45 months. The metal surfaces were tribochemicallycoated with silica, and the abutments were etched wilh35% phosphoric acid for 60 seconds. Ten failures resuit-itig from bond failures and porcelain fractures were ob-served. Humidity control was also stressed as a very im-portant factor for long-term success in resin-bondedprostheses.

Veneered clasps

Despite its unesthetic appearance, resin coating report-edly made partial denture clasps look better. Schott'^reported that, as a result of silica coating, long-termbonding of the composite and the metal was possiblewithout the use of retention pearls and undercuts. U.se

of Dentacoior opaquer following SiO^ conditioningwith Silicoater and siianization imparted tooth color tothe partial denture clasps.

In some studies, the Rocatec/Visiogem system hasbeen used for veneering clasps, which has the advantageof having no thermal or mechanical effect on the dentureand opaquer, instead bonding the metal surface throughthe kinetic energy of Rocatec Plus.'"" However, the liter-ature reviews in these studies revealed no long-term clin-ical results, although t!ie esthetic advantages are obvious.

Discussion

Cuncnt research efforts in modern surface conditioninghave been reviewed in this article. A iiumher of tech-niques that mechanically facilitate alloy-resin hondingfor adhesive prosthodontics have heen discussed.

Although clinical studies proved the weakest link tobe hetween the resin and the metal, resin-bonded pros-theses have shown that Panavia Ex, which is an adhe-sive his-GMA resin composite, also exhibits very pre-dictahle results.'- Tin plating is a surface treatmentrecommended for improving the strength and durabilityof the bond between adhesive resins and the metal. Withelectrochemical etching, on the other hand, it is difficuhto create a properly etched surface, and the techniquedoes not work well with precious alloys. The method isalso technique sensitive, requires expensive equipment,and is time consuming.

A frequently mentioned criticism of etching non-precious alloys is the complexity and technique sensi-tivity of the treatment. In this regard, Sihcoater is alsocomplex and technique sensitive.

Rocatec treatment is simpler than tin plating. Roca-tec was developed to pemiit chemical honding hetweenresin veneers and the metal framework in fixed partialdentures, hut the simplicity of the technique makes it apotentially useful surface treatment in adhesive prosth-odontics. Rocatec, Silicoater. and tin plating surely im-prove bond strength compared to sandblasting.

The influence of prolonged thermal cycling andwater storage seems to affect the hond strength of resinto alloy that has heen treated with trihochemical andthermal silica-coating procedures. Important variables,such as storage media, thermocychng, or medical fa-tigue, are likely to affect the hond strength of the com-binations tested and will ultimately influence the devel-opment of more reliable systems in the future. Althoughthe interim clinical results are encouraging, only long-term clinical studies will determine whether chemicaladhesion to metal surfaces resists not only masticatoryforces but also diffusion of water and temperature varia-tions in the oral cavity.


Ozean et al

According to their manufacturers, most of the newchemical bonding systems require sandblasting of themetals prior to honding to achieve a high bondstrength. Sandblasting the restorations has the potentialto remove significant amounts of material and could af-fect the cUnical adaptation of the prosthesis. Thus, thematerial loss resulting from these procedures is impor-tant to the clinical fit of restorations. Therefore, knowl-edge of the surface characteristics of different alloysafter these surface treatments is needed to improve theunderstanding of the bonding mechanism and the fail-ure modes involved.

Sandblasting with alumina not only resulted inmicromechanical roughening of the surface but also leftalumina particles embedded in the surface. The role ofthis alumina in honding for these systems is not known.Unfortunately, there are no data available to indicatewhether the adhesive failures reported appear within, at,or outside the silica layer, which necessitates furtherresearch. The encouraging results obtained from theapplication of silica coating indicate that it could betried in other types of porcelain.

In light of the previous disadvantages of mechanicalretention, it was necessary to develop an alternativegap-free system that consistently chemically bondsresin to any metal and allows the use of a large varietyof metal alloys. Panavia Ex and Panavia 21 have demon-strated good bond results in many studies, whereas thebond strengths oh tai ne d from sandblasting and bondingwith conventional bis-GMA adhesive are poor.

Recent advances in surface-conditioning methodshave increased bond strength values greatly; however,the interpretation of the literature review indicates thenecessity to focus more on an understanding of whyhond values achieved with the Silicoater and Rocatecsystems are different or similar, because the mecha-nisms of these methods are not the same.

Summary

Data examined in this review indicated that chemicalsurface conditioning by silica coating with the newly in-troduced methods gives better results than the mechan-ical retention used in current clinical practice. It is ap-parent that further research is necessary and that thebonding of resin-bonded prostheses should continue tobe investigated both in vivo and in vitro utilizing thelatest surface-conditioning methods.

References

1. Hansson O. The Silicoater technique for resin-bonded prostheies:Clinical and lahoratoiy procedures. Quintessence [nt 1989;20:85-99.

2. Ibsen RL. One-appointment technique using an adhesive compos-ite. Dent Surv 1973 ;49:30-32.

3. Ibsen RL. Fixed prastheties with a natural crown pontic using anadhesive eomposite. J South Calif Dent Assoc 1973;41;10i)-102.

4. Portnoy LL. Constructing it composite pontie in a single visit.Dent Surv l973;49:2Q-23.

5. Roebette AL, Attachment of a splint lo enamel of lower anteriorteetb. I Prosthet Dent 1973;3O;4I8^23.

6. Metal resin bonding. Adept Report l991;2:29-36.

7. Shen G. Resin bonded bridge bond strength using a cast meshtechnique [abstract 464]. J Dent Res 1984;2:221.

8. Lividitis GJ, Thompson VP Etched castings; An improved reten-tive mechanism for resin-bonded retainers. J Prosthet Dent 1982;47:52-58.

9. Thompson VP, Lividitis GJ, Del CE. Resin bond to eleetrolyti-cally etched nonprecious alloys for resin bonded prostheses.J Prosthet Dent 1981;(special issue);337.

10. Thompson VP, Pfeiffer P. Das elektrolytische Anätzen einerNi-Cr-Legiening. Disch Zahnärztl Z I986;4I ;82i)-83L

11. Marinello C, Lütby H. Scbarer P. Silicoater erhöht Verbund-festigkeit in der Adhäsivprothetik. Dent Labor 1990;38:1625-1629.

12. van der Veen JH. Resin-bonded bridges in vitro and in vivo [the-sis]. Groningen, Tbe Netherlands: University of Groningen, 1988.

13. Rammeisberg P, Pospieeh P, Cernet W. Clinical factors affectingadhesive fixed partial dentures: A 6-ycar study. J Prosthet DentI993;7O;3UO-3O7.

14. Zjdan O. Etched base metal alloys. Comparison of relief pattern,bond strength and fracture modes. Dent Mater \9S5;¡:209-213.

15. van der Veen JH, Krayenbtink JG, Bronsdijik AE, van de PoelACM. Resin bonding of tin-electroplated precious metal fixedpartial dentures; One year clinical results. Quintessence Int1986;171:299-301.

16. van der Veen JH, Jongebloed WL, Dijk F. SEM study of sixretention systems for resin to six differently treated metal sur-faces. Dent Mater 1988;4;272-277.

17. Lividitis GJ. A chemical etching system for creating micro-mechanical retention in resin-bonded retainers. J Prosthet Dent1986;5ö;181-188.

18. Sedbeny D, Burgress J, Schwar?. Evaluation of chemical etchingsystems for a base metal alloy [abstract 723]. J Dent Res1989;68;272.

19. Aquillino SA, Diaz AAM. Tensile bond strength of eleetroly-tically and chemically etcbed base metals [abstract 551]. J DentRes 19S9;68;250.

20. Tiller HJ, Musil R, Magnus E, Garschke A, Goble T, LoekowandtP Der Sandstrahlprozess und seine Einwirkung auf denOberilächenzustand von Dentallegieruagen II. Quintessenz1985;36:2151-2I58.

21. Re GJ, Kaiser DA, Malone WEP, Garcia GF Shear bond strengthand scanning electron microscope evaluation ot three different re-tentive methods for resin-bonded retainers. J Prosthet Dentl988;59;568-573.

22. Luthy H. Marinello CP, Schäfer P. Factors influencing metal resintensile bond strength to filled composite [abstract 884]. J DentRes I988;67:223.

23. Laufer EZ, Nicholis JIJ, Towsend D. SiO coating: A composite tometal bonding mechanism, J Prosthet Dent 198S;3;320-327.

24. niler HJ, Gobel R, Magnus B, MusU R, Bimberg R, Werkstoff-kundliche Grundlagen lum Silicoater-MD Verfahren. DentLabor l990:38;78-82.


özcan et al

25. Nergiz t, Pfeiffer R Niedenneier W. Effects of surface ireatment 4ñ.on resin veneer/altoy bond strength [abstract 2390]. J Dent Rest997;76:312.

26. Guggenbcrger R. Das Rocatec-System-Haftung durch tribo- 47,chemische Beschichtting. Dtsch Zahnürztl Z 1989:44:874-87ñ.

27. Creugers NHJ, Welle PR, Vrijhoef MMA. Four bonding systetns 48.for resin-retained cast metal prostheses. Denl Mater I988;4:85-88.

28. Peutzfeldt A, Asmussen E. Silicoating. Evaluation of a new 49,method of bonding composite resin to metal. Scand J Denl Res1988;96:171-176.

29. Caeg C, Leinfelder KF, Lacetleld WR, Bell W. Effectiveness of amethod in bonding resins to metáis. J Pro^thet Dent i99Q; 50.64:37-41.

30. Ishijinia T, Captito AA, Mito R. Adhesiotl of resin to castingalloys. J Prostbet Dent 1992:67:445^149. 51.

31. Wirz J, Schmidii F, Mignaval A. Neue Kunststoff-Metall-Verbundsysteme und ihre legierungsabbängige Haftqualitäl. 52.Quintessenz 1996,47:1231-1240.

32. Hansson O. Strengtb of bond witb Conipspan opaque to threesilicoated alloys and titanium. Scand J Dent Res 1990:98: 53.248-256.

33. May KB, Fox J, Razzoog ME, Lang BR. Silane to enhance tbe 5i.bond between polymethyl methacrylate and titanium. J ProsthetDent 1995:73:428-431.

34. Ruyler IE, Warrli ML, Hero H. Adhäsionmechanism des Kunst-stoff-Metall-Verbundes hergestellt mit dem Silicoaler-Verfahren. 55.¡n: Hofmann M (ed). Siiicoater-Symposiiim: KlinischeErfahrungen und experimentelle Ergebnisse. Heidelberg: Hüthig 56.1990:133-141.

35. Beldner W, Marx R. Silikatisieren als Oberflächenkondition- 57.ierung von Metallen für den hydrolysebeständigen Verbund mitKunststoffen. Quinteîsenz 1992:43:103-115.

36. Wietboff B, Ratzke T. Stender E Vergleichende Untersuchung 58.zur Verbundfestigkeit bochgoidhaltiger und edelmetalifreierLegierungen bei unterschiedlichen Konditionierung für dieAdhäsivbrückentechnik. Zahnärztl Welt 1994:4:235-237. 59

37. Kem M. Thompsoti VP Sandblasting and silica-coating of dentalalloys: Volume loss, morphology and cbanges in tbe surfacecomposition. Dent Mater 1993:9:1.')5-16I. 60.

38. Pfeiffer P. Haftung von Kunststoff an Legierungen abhängig vonder Korngrösse bet tribocbemischer Bescbichtung. Dtîch ¿iZahnärztl Z 1993:48:692-695.

39. Stark H. Holste T. Untersuchungen zur Verbundfestigkeit silika- 62.tisiertcr Mctalloberfliäcben. Dtsch Zahnarzll Z I992;47:624-626.

40. Kern M, Thompson VP Bonding to glasí infiltrated alumina 63.ceramic: Adhesive methods and their durabiiity. J Prostbet Dent1995:73:240-249. 64.

41. Claus H. Vita In-Ceram, ein neues Verfabren zur Herstellungoxid-keramiscber Gerüste für Kronen und Brücken. QuintessenzZabntech l990;16:35-46.

42. Pfeiffer P, Schwickerath H, Sommer MC. Festigheit dentalkera-mischer Massen. Zahnär^tl Weit i99t: 100:938-942. 65.

43. Geis-Gerstorfer J, Kantantra P Zum Einfluss der Prüfmethodeauf die Biegcfestigheit von IPS-Empress und In-Ceram. DtschZabnärztl Z I992;47:618-62I.

44. Giordano R, Pelletier L, Campbell S, Pober S. Flexural strength ö^.of infused ceramic, glass ceramic, and feldspathic porcelain. JProstbet Dent 1995:73:4i i-418.

45. Kern M, Knode H, Strub JR. The aII-porcelain, resin-bondedbridge. Quintessence tnt t99l;22:257-2ö2.

Kern M. Neikes MJ, Strub JR. Haftfestigkeit deí Klebever-bundes auf In-Ceram nach unterschiediicher Oberflächen-konditioniertnig. Dtsch Zahnärzil Z 1991:46:758-761.Pape FW, Pfeiffer P, Marx R. Haftfestigheit von geätzlem In-Ceram an Schmelz. Zahnarzt! Weil 1991 ;IÜ0:450-453.Kravixien-Vongphantuset R, Pietrobon N. Nalhanson D. Bondstrength of resin cement to Iii-Ceram core material |ab.stract533]. J Dent Res 1992:71.

Fiscber J, Schmid M, Kappen HF, Strub JR. Gefügeausbildungder dentaikeramischen Kernmasse In-Ceram und thermischeDehnung ihrer Einzelkomponenten. Disch Zabnärztl Z 1991;46:461-463.

Neikes MJ, Kem M, Strub JR. Tensile bond strength of two siii-coating (silicate/silanization) systems on the Al,O,-ceramic In-Ceram [abstract 144). J Dent Res 1992:71:533.Pröbster L Untersuchung zur Scherfestigkeit des In-Ceram-Kunstîtoff-Verbundes. Dtsch Zahnärztl Z 1992:47:292-294.Kem M, Thompson VP. Eine einfache Versuchsanordnung ¿ur uni-versellen Prüfung des Klebeverbundes im axialen Zugtest. DtschZatinärztl Z i993;48:769-772.

Göbel R, Welker D, Musil R. Keramikkondition ierung fur Einglie-derung und Reparatur. Dtsch Zahnärztl Z 1994;49:629-631.Kem M, Thompson VP. Sandbiasting and silica coating of a glassinñltrated alumina ceramic: Volume loss, morphology, and cbangesin tbe surface composition. J Prosthet Dent 1994:71:453^61.Pfeiffer P. Spezifische adhärente Klebung abgestrahlterLegierungsoberflächen. Dtsdi Zahnärztl A 1989;44:936-937.Meiners H, Herrmann R, Spitzbarth S. Zur Verbundfestigkeit desRocatec .-Systems. Dent Labor 1990:38:185-188.Smith RM. Barret MG, Gardner WA, Marshall T, McLean MJ,McMichael DW, et al. Effect of environmental stress and surfacetreatment on resin to metal bonding. Am J Dent 1993;4:111-115.Wiri J, Müller W, Schmidii F. Neue Verfahren fur den Kunststoff-Melai Verbund. Eine vergleichende in-vitro Studie. SchweizMonatsschr Zahnmed 1992:102:13-19.Bahannan S, Lacefieid WR. An evaluation of three methods ofbonding resin composite to stainiess sleel. tnt J Prosthodont1993;8:502-5Ü5.Chang I, Powers JM, Hart D. Bond strength of composite to alioytreated with bonding .systems. J Prosthodont 1993:2:110-114.Pfeiffer P. Spezifische adhärente Klebung abge.îtrahiterLegiemngsoberflächen. Dtsch Zahnärztl Z 1989:44:936-937.Schmid M, Fischer J, Hoffmann Ch, Strub JR. Chemische undthermische Kompatibilität voll keramischer Verbundsysteme. DtschZahnärztl Z 1990:45:505-508.

Hansson O, Moberg L. Evaluation of three silicoating methods forresin-bonded prosthesis. Scan JDentRes l993;10t:243-25i.Musil R. Häselbarth M. Anliegen, Organization and Ergebnisseeiner 10-Jahres-Studie zur klinischen Bewährung des Silicoater-Verfahrens am Ende des 5. Jahres, tn: Hofmann M (ed). Siiicoater-Symposium: Klinische Erfahrungen und experimentelieErgebnisse. Heidelberg: Hüthig, i990:3-9.Wöstman B. Das Siiicoater-Verfabren im Vergleicb mit ber-kömmlichen Verblenmethoden-Ergebnisse eines Recallprogramms.In: Hofmann (ed). Silicoater-Symposium' Klinische Erfahrungenund experimente lie Ergebnisse. Heideiberg: Hüthig, 1990:10-17.Bruhn L, Buchholz G, Curth K. 3-Jahres-Studie zur klinischenBewertung des Silicoater-Dentacoior-Verfahren.s im Vergleich zuanderen Verbiendsystemen. In: Hofmann (ed). Siiicoater-Symposium: Kiinische Erfahrungen und experimenteiieErgebnisse. Heidelberg: HUthig, i990:l8-25.


Ozean et ai

67, Heidi K, Klinische Etfahiuiigen de,í Silicoter-Vetfülirciis bei derAtiwendung protetisclier Therapiemittel aus edemetall-freienLegierungen, In: Hofmaiiii (ed), Silicoaler-Symposium:Klitiisciie Erfahrungen und experimentelle Ergebnisse,Heidelberg: Hülhig, 1990:44-48,

68, Van der Veen JH, Klinischer und expei'imenteller Vergleich desSilicoater-Verfahrens tnit anderen Verbundsystemen, In:Hofmann (ed), Silicoater-Symposium: Klinische Erfahrungenund expetitnentelle Ergebnisse, Heidelberg: Hüthig. 1990:128-132,

69, Kerschhauni T, Das Silicoter-Verführeti- Daten aus dem Adhasiv-brückenregister, in: Hofmann (ed), Silicüater-Symposium:Klinische Erfahrungen und experimentelle Ergebnisse.Heidelberg: Hiithig, l'i90:6ÇI-74,

70, Kellet M, Verdijden CWGJM, Smith GA, Creugers NHJ. Amulticentered clinical study on posterior resin-bonded bridges'Tbe Maiicbester trial, J Dent t994;22:208-212,

71, Verzijden C, Creugers NHJ, Van't Hof MAA. Meta-analysis oftwo different trial.s on posterior resin-bonded bridges, J Dent1994;22:29-32,

72, Verzijden C. Creugers NHJ, Mulder J, A mu Iti-practice clinicalstudy of posterior resin-bonded bridges. A 2,5-year interimreport. J Dent Res l994;73:529-535,

73, Mayer K, Drei Jahre klinische Erfahrung mil dem Rocatec-Vcrbundsystem, Dent Lubor I994;42:1787-1790,

74, BoEning KW. Clinicai performance of re s in-bonded fixed partialdentures, J Prosthet Dent 1996;75:39-44,

75, Scliott HJ. Zahnfarbene Verblendung von Modellgussklammem,Quintessenz Zahntech I989;l5:n33-1136.

76, Wichmann M. Die verblendete Modellgussklammer. DtschZahnarztl Z l990;45:77t)-772

77, Vietor K, Freesmeyer WB, Die kunsts toff verblendete Model-gussklammer-Ergebnisse einer In-vivo-Studie, Quintessenzl992;43:1935-¡943.

mimm • Answers to Ql 8/98 Questions =

^ i»r^^ 1. D

2. A3. D4. A

5. B6, D7, C8, D

9, D10. B11. A12, B

13.14.15.16.

CDDA

724 Voiume 29, Number 11

a brief history and current status of metal-and ceramic

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