The Dual Bonding Technique [PDF]

Zitiervorschau

The internotionol Journal of Periodontics S Restorative Dentistry

537

The Dual Bonding Technique: A Modified Method to improve Adhesive Luting Procedures

Stefan J. Paul. DMD' Peter Schörer, DMD, MS, PhD'*

indirect restorative prooedures usually require temporary restorations for protection of the puip and for restoring the patients esthetic and functianai needs. The use af temporary cements, either with or without eugenoi, however considerably decreases the adhesion of the bond on dentin if— according to the conventionai teohnique—suoh dentin bonding systems are applied onoe ot the moment ot finoi cementation. With a duai application af the dentin bonding agents a considerable Increase in bond strength values was discovered. This orticie presents o modified iuting procedure caited the "dual bonding technique." (int J Periodont Rest Dent 1997:17:537-545.)

•Research Assooiote. Department cf Advanced Prosthodontics, Center for tne Heolth Sciences, University of California, Los Angeles: and formerly Senior Lecfurer, University of Zurich Center for Dentai and Orai Medicine. Zurich, Switzerland. "'Professor and Chairman, Deportment of Fixed and Removable Prosthodontics and Dentai Materiai Sciences, universify of Zurich, Center tor Dentai and Orai Medicine, Zurich, Switzerland. Reprint requests: Dr Stefan Paul, Deportmenf ot Advanced Prosthodonfics, Center for the Healfh Sciences, University of Caiifornia. Los Angeles. 10833 Le Conte Avenue, Los Angeles, California 90024-1668. e-mail: [email protected]

Indirect restorations usualiy require a provisional restorotion that is iuted to the obutment tooth with a temporary oement. Very discouraging and sometimes very contusing results have been reported when the shear bond strength of dentin bonding agents was meosured on dentin thot hod been contominated with provisionai cements prior to the bonding procedure,^ In some cases the bond strength vaiues were increosed, in other cases they were deoreased. An explanation for such varying resuits was diffioult and led fo disagreement. An ottempt to improve the cieaning of fhe dentinai surface after application of temporary cements was undertaken with the use of soaps,^ The results were again discouraging, probably becouse cleaning the dentin with soap resuited in the subsequent inability of the dentin bonding agents to wel the dentinai surface.

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Fig Ja A 27-yeqr-old woman, presentIng no periodantai prqbiems, wanted repiacement of her amalgam ñitings in the mandibuiar ieft first ond second molars.

Fig Ib A rubber dam is placed, the amalgam is removed, secondary caries is eiiminated, and a composite build-up is piaoed with ART Bond and a selfcuring hybrid composite (Briiiiant MM).

Fig Ic The fínai preparation of the iniay cavities is completed.

However, a considerable increese in bond strength volues at the moment of finol adhesive luting was diseovered when the dentin bonding agents were applied twice,^ In a first step of the "duoi bonding technique," the dentin bonding agent was applied and cured right after tooth preparation in adaptation of the conventionai composite filling method. After sealing the dentinai surfoce, a provisionai restoration using a temporory cement was placed. At the time of the compietion of the definitive restoration, the provisionai restoration was removed, and the dentinai surface was cleaned with pumice. For the second step of the duai bonding technique, the same dentin bonding agent was applied again, and the bonding resin was cured oniy after seating the definitive restoration with composite cement. With this technique a doubling of the bond

strength values was observed, even though a provisional cement containing eugenol was used intermedidtely^ The first seaiing of the dentinai surface immediately after preparation had no influence on the quality of the impression when polyether or hydrophobio poly(vinyi siioxanes) were used," After a preliminary clinical evaluation ot the duai bonding technique (34 restorations), the foiiowing clinical protocol was proposed using ART Bond (Coitène-Whoiedent), which had performed as the best commercioily availabie material in a previous study^

requested the repiocement of her amaigem fiilings in the mandibular left first and second molars for esthetic reasons (Fig la). After rubber dam piacement, amaigam removal, and elimination of seoondory caries, a composite build-up (Fig lb) was placed to correct possible internol surface defects. The following materials were used strictiy according to manufacturers' instructions during ail steps of the treatment described: (1) ART Bond, which is a two-step dentin bonding agent with selfetching primer: (2) Briilicnt MH (Coltène-Whaledent), a seif-curing hybrid composite filiing material; and (3) Porceiite U (Kerr), o duai-cured composite luting resin.

Clinical protocol for ttie dual bonding fectinique Cavity preparation A 27-year-oid woman, presenting no periodontal problems.

The International Journai at Periodcntics S Restorative Dentistry

539

Fig 2a ART Bond primer A and B are mixed 1:1 in o plastic dish.

Fig 2b A brush tip is used for 30 seconds for the first application of ART Bond primer A and B on dentin and enamel. Enamel is not etched at this time with a 37% phosphoric acid gei.

Fig 2c Primed tooth surfaces ore oir dried for ¡5 seconds.

Fig 2ci One drop at the unñiied ART Bonding resin is reieased.

Fig 2e Eirsf oppiicotion ofARJ Bonding resin on dentin and enamel using a brush tip for 30 seconds.

Fig 2f Bonding resin is air thihned with gentie biasting from o dental syringe.

Part i of the duai bonding technique The dentin bonding agent is first applied immediately after finai preparafion in fhe following manner (Fig Ic): 1, Mix the ART Primer A and B in o 1:1 ratio (Fig 2a).

Brush ART Primer A ond B onto denfin and enamei for 30 seconds (Fig 2b), Do not efch enamei af fhis time wifh 37% phosphoric acid gel fo avoid a micromechanicai inferiock befween enamel and fhe subsequehfly added bonding resin. Air dry primed toofh surfaces for 15 seconds (Fig 2c).

4. Release one drop of ART Bonding resin (Fig 2d). 5. Brush one layer ot ART Bonding resin onto the primed tooth surfoces tor 30 seconds (Fig 2e). Ó. Air thin fhe bonding resin with gentle blasting from fhe denfci syringe (Fig 20.

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fig 2g Brush tip in Fig 2e is used again for a second brush-in without picking up new bonding resin to recover eventuai ix>nding voids after air thinning.

Fig 2h Preparation is iight cured for 60 seconds.

Fig 2i The first oppiiootian of the dentin bonding agent (Port i of the duai bonding technique) is occompiisiied.

Fig 2j After removai of the ruPPer dam. an impression is made with poiyether.

Fig 2k A pravisional is luted with eugenat-oantaining Temp Bond.

7. Perform a second brush-in of the Bonding resin using fhe some brush fip without picking up new bonding resin fo recover possible bonding voids after air fhinning (Fig 2g). 8. Light cure for 60 seconds (Fig 2h). Parf i of fhe dual bonding technique is accompiished (Fig 21). 9. Make the impression with either polyether (eg, Permadyne, ESPE) or poiy(vinyi siloxane) (eg. President. Coifène-Whaiedent) (Fig 2j). 10. Lufe fhe provisional wifh eugenol-confaining femporcry cement (Temp Bond. Kerr) (Fig 2k). Part ii of the duai bonding technique The second parf of the dual bonding technique is performed af final cementotion (Fig 3a). Following is fhe procedure for efchable ceramics (eg. Empress, Dicor, or any feldspafhic ceramics): 1. Cieon fhe cavify check the morginai fif and color inatch, ond etch and silanate fhe internal surfoces of the resforotions (Fig 3b). 2. Place rubber dam and ciean cavity wifh pumice (Fig 3c). 3. Etch enamel with 37% phosphoric acid gel for 30 seconds (Fig 3d).

The International Journal of Periodontics & Restordtive Dentistry

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Fig 3o (left) The final ail-ceramic inlays (Empress) are completed.

Fig 3b (righf) The cavities are cieaned with pumice and the ñnai all-ceramic iniays are checked for marginal tit and catar match. Next the inlays are etched and siianized because Empress IS an etchabie ceramic.

4. Rinse ond dry to ciieck for bonding resin remnants on the covity margins. Where no opaque-white etching pattern is visibie, repeot iost two steps (Fig 3e). 5. Brush one ioyer of ART Primer A and B (1:1 mix) onto dentin and enamel for 30 seconds. Air dry primed tooth surfaces for 15 seconds. 6. Brush one layer of ART Bonding resin onto the primed tootii surfoces for 30 seconds. Air thin the bonding resin w'ñU a gentle biast from fhe dentai syringe. 7. Brush in again with the same brush tip without picking up new bonding resin. Do not iight cure fhe bonding resin yet, or the film thickness of the bonding resin couid interfere with the marginai fit of the definitive restorotion. 8. Seat the restorotion with composite luting resin (duoicured Porcelite U, Kerr) and remove excess resin, 9. Light cure the dentin bonding ogent and composite luting resin for 180 seconds (Figs 3f dnd 3g).

Fig 3c Prior to the final cementation. a rubber dam is placed and the cavities are again thoroughly cleaned with pumice, rinsed, and dried.

Fig 3d Only the enamel is etched with 37% phosphoric acid for 30 seconds. (ART Band contains a seif-etching primer Therefore, when using ART Bond. acid etching the denfin as o separate step is not needed)

Fig 3e The acid gel is removed, and the teeth are rinsed with water spray ana completely air dried to check for banding resin remnants on the cavity margins m enamel. Where no opaquewhite etching pattern is visible, repeot Steps in Figs 3c and 3d

Fig 31 Dentin bonding agent is applied a second time, as described in the teat.

Fig 3g Finai dinicat resuit oner repiacement af two amalgam fiiiings with two Empress inlays. The occlusion is checked oniy after the ñnai cementation.

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Nonetchable ceramics iike in-Ceram Aiumina, In-Cerom Spineii, or Zirconia have a core fhaf is usually less translucent than thot of etchoble ceramics (eg. Empress. Dicor. or any feldspothic ceramics). Therefore, fhe outhors recommend a slightly different procedure that uses only the ART Primer (nof the ART Bonding resin) ond self-curing Panavia TC (Kuraray) fcr the second oppiication. The selfcuring cemenf omits ony probiems that might result from improper curing of the luting materiais because of insufficienf iight penetration, 1. Cieon cavity, check marginal fif and coior motch. and only sandbiosf the internai surfaces of fhe restorafions, Silane is nof needed. 2. PiGce rubber dam and clean cavity with pumice. 3. Etch enamel with 37% phosphoric acid gei for 30 seconds. 4. Rinse and dry to checi< for bonding resin remnants on fhe cavity margins. Where no opaque-white etching pati-ern is visibie, repeat iast two steps, 5. Brush one iayer ART Primer A ond B (1:1 mix) onto dentin and enamei for 30 seconds. Air dry primed tooth surfaces for 15 seconds. Do not use ART Bonding resin. Nonetchable ceramics may

The International Journal of Periadontics & Restorotive Dentistry

have a core thaf is too opaque for the penetration of the poiymerizing iight. As o consequence, the ART Bonding resin may not be fully cured, 6. Seot restorotion with seltcuring composite iuting resin (Panavia TC, Kuraray) directly on surface that is oniy primed, 7. Remove excess resin. 8. Appiy air biock (Oxygard) onfo margins.

Discussion On dentin. bond strength vaiues up to approximately 30 MPo have been reported; however, a very recent evaluation of the newest adhesive systems resuited in bond strength voiues that seem more reolistic. They were in the ronge of 10.9 fo 7.5 MPa^ after a single applicotion of the dentin bonding agent (DBA). In an in vitro set-up that integrated multiple ciinically reievonf porameters. maximum bend strength values were found to be ot a similarly low ievei (around 8 MPa),^"^ It is clinicaiiy questionable if such bond strength vaiues oround 10 MPa are reolly high enough fo resist the contraction forces generated during the polymerizoticn of composite resins (up to 17 MPo').

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With the duoi bonding technique, bond strength vaiues can be doubied (mean values between 13 and 19 MPa) using either ART Bond, Syntac, or the expérimentai P-Bond, even when a eugenol-containing temporary cement is used for the provisional restorations,' Such bond strength vaiues might be strong enough to resist contraction forces during the polymerization shrinkage of composites (up to 17 MPa'). Four major questions arise with the dual bonding technique described:

Why use ART Bond?

in a previous study^ an experimental dentin bonding agent (P-Bond) ochieved the highest bond strength values (approximately 19 MPa) after contamination of the dentin with eugenol-containing temporary cement (Temp Bond), Unfortunoteiy, this product is not yet commercioily ovailabie, ART Bond performed second best in the same study^ In addition, ART Bond is a so-oalled "two-step" dentin bonding agent that does not require a separate etching step for the dentin because it contains a self-etching primer and saves vaiuable clinicai time.

is it possibie to remove the bonding resin from the enamei margins after the ^rst appiication of the dentin bonding resin? if enamel is not acid etched during the first application of the dentin bonding agent, no etch pattern will be generated, Enomei, as a pureiy inorganic material, and unfilled bonding resins, as pureiy organic substances, are incapable of a chemical reaction between each other. Because no etch pattern is created on the enamel surfaee, no micromechanicoi bond can deveiop between the two materiais at the first appiieation. Therefore, removing the bonding resin from the unetched enamel margins prior to the second opplicotion by rubbing with pumice is possible.

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Wt^y does ttie eugenalcantaining Temp Bond nat interfere with the paiymerizatian of tiie resin ftiat is applied after ttie removai of fhe provisional cement? Eugenoi is commoniy known to be a potenfiai inhibitor of the poiymerization of any resinous material. However, an increase in the shear bond strength values after serial applicafion of a denfin bonding agent^ despite fhe use of a eugenol-confaining provisional cemenf is possible, because after the first appiication of fhe denfin bonding agenf the denfin will be seoied against fhe penetration ot the eugenoi molecules. When fhe final resforations are ready for cemenfation—after a period of severai weeks—the eugenolcontaining temporary cement (Temp Bond) can be removed easily from fhe resin-sealed dentinal surface fo such o degree fhat any eugenoi remnanfs no longer disfurb fhe second poiymerizafion of fhe DBA, whioh fhen is applied for a second time. This explains fhe aimost doubied bond strength vaiues.' in oddition, the temporory cement (Temp Bond) can be removed much more easily and quickiy trom fhe seoied tooth surface prior to the finai cemenfation, saving vaiuable ciiniooi time.

The internofional Journal af Periadantics & Restarative Dentistry

Why is tfie risk of postoperative sensitivity aimosf reduced to zero? Air thinning the banded footh surtoces after the appiication of the bonding resin prior to cemenfation is porf of fhe recommendafions ot aimosf every manufacturer's bonding insfructions fo minimize the risi< of an exaggerafed film fhickness of fhe bonding agehf.^'' On the other hand, air-fhinning fhe bonded dehtinal surfaces wifh o "gentle" air-blast runs the risk of dentinoi tubules not covered with bonding resin,'° Such uncovered tubules are voids which, in vivo, might be refilled wifh dentinoi liquid offer fhe anesfhesia is gone. Perhaps such liquid-fiiled spaces are one cause of postoperative sensitivity because every time pressure is opplied on such an adhesive denfin inferface during biting, fhe iiquid in these voids might be compressed and cause a pressure change within the iiquid-fiiled tubuiar system fhof is connecfed fo fhis space. The aspiration of odonfoblasfic cell bodies into the opening of the fubuies mighf then cause pain. For fhis reason, using the brush twice when applying the bonding resin is recommended (see Figs 2e fo 2g),This parficuiar procedure should close dentinal tubules, prevent void iumina, and controi film thickness.

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Conclusion The dual bonding fechnigue pracfioally doubied the in vlfro bond sfrengfh values of several dentin bonding ogents.^ A preliminary clinical evaluafion showed the following advantages of fhis technique for adhesive luting procedures of all-ceromic resforotions; 1. The bond sfrengfh to denfin is capable ot resisting shrinkage forces during polymerization of composites. 2. There is a reduction of postoperotive sensitivity. 3. The use of eugenoi-containing temporary cements provides better retention of the provisional when combined wifh dentin bonding agents. Removal ot eugenoi remnants prior to finai cemenfotion is more easiiy aohieved through quick conventional cavity cieaning. 4. Minimal odditionai ciinicai working time is necessory.

Acknowledgments The outhors wouid like to thonk the following fechnicions for performing fhe very skillfui ail-ceramio resforofions: Nioolo Pietrobon, CDT: Arnoid Wohiwend. CDT: Waiter Gebhord, CDT, Friedrich Schuppisser, CDT; and Anyoung Ngyen, CDT

References 1. Poui SJ, Schärer P Effecf of provisionol oemenfs on the sheor bond strength ot various dentin bonding dgents. J Ordi Rehabii 1997:248-14. 2. Bdchmann M, Paul SJ, Lüthy H. Schärer P Effect of cieoning dentin Viiith soop ond pumice on sheor bond strength of dentin bonding agents. J Orai Rehabii 1997:24: 433-438. 3. Bertschinger C, Poul SJ, Lüthy H, Schórer P Duoi oppiioation of denfin bonding ogents: Effect on bond strength. Am J Dent 1996:9:115-119. 4. Zeilweger U. Der Einfluss der Sduersfott-lnhibitionsschicht von Dentin-ddhosiven ouf die Polymerisation verschiedener Abdruckmdteriaiien. Med Diss Zurich, 1997: 1-47. 5 Chrisfensen G. Clinicdi Reseorch Associotes Newsietter, Moy 1996:20' 1-3. 6 Paul SJ, Schärer P intropuipai pressure ond thermoi cyciing: Effect on sheor bond strength of eleven modern dentin bonding agents. J Esthet Denf 1993:4:179-185 7, Feilzer AJ, DeGee AJ, Dovidson CL Increosed wail-fo-woil curing controcfion in thin bonded resin loyers J Denf Res 1989:08:48-50 8 Pashiey EL. Oomer RAW. Simpson MD, Horner JA, Pashiey DH, Caughman WF Dentin permeobiiity: Sealing the dentin in crown preparotions, Oper Dent 1992:17:13-20. 9, Peter A, Paul SJ. Lüthy H, Schärer P Fiim thici