Operative Dentistry

Direct pulp capping with a dentinal adhesive resin system:A pilot study

Thomas Heitmann*/Gary Utiterbrink*

The chnical and histoiogic responses of exposed pulpal tissue after direct capping appear to bemore closely related to bacterial infiltration than to direct material toxicity. Dentinalbonding agents have been suggested as a replacement for calcium hydroxide for pulpalprotection. In this pilot study, direct pulp capping with a glutaraldehyde-containing dentinaladhesive was performed on eight permanent premolars and molars. The teeth wereimmediately restored with a resin composite restoration. The chnieal technique includedthe use ofa calcium hydroxide paste to cover the exposure site during completion of thepreparation. Enamel and dentin were etched with phosphoric acid. All teeth remained vitaland without symptoms during the initial observation period of 2 to 6 months.(Quintessence Int 1995:26:765-770.)

Introduction

Direct pulp capping is traditionally performed withcalcium hydroxide [Ca(OH),] formulations, whichhave a bactericidal effect because of their high pH. Inhistoiogic investigations, an outer necrotic zone hasbeen reported. Beneath this zone, or occasionally indirect contact with the Ca(OH)j, reparative dentin isformed and dentinal bridging occurs, macroscopicallyclosing the perforation over the pulp.' Nevertheless, ithas been shown that the macroscopic dentinal bridgeformed does not constitute a continuous sea!, but mayallow bacterial leakage through numerous turmeldefects.' Pulpal necrosis can occur despite the pres-ence of an apparently complete dentinal bridge. '̂̂

It has been documented that the formation of adentinal bridge is not uniquely caused by Ca(OH)jbutcan also occur under many other materials. Somematerials considered toxic to the tissue, such as thesilicate cements or resin composites, elicit little or no

* Research and Development, Clinical Departmenl, Ivoeoiar, Schaan.Liechtenstein.

Reprint requests: Dr Tilomas Heitniann, Mllemoesgade 91, 1 TVDK-2100 Copenhagen 0, Denmark.

pulpal inflammation after direct pulp capping, pro-vided that the restoration is adequately sealed.^ Heal-ing potential is inherent to the pulpal tissue if bacterialirritants are excluded from the dentinopulpal com-plex.''' However, material-speciflc effects cannot beeliminated, as demonstrated with direct application ofzinc oxide-eugenol cement to pulpal tissue.'

The restoration plays an important role in prevent-ing the ingress of pathogenic bacteria and recurrentinfiammation of the pulp, and any provisional restora-tion should also provide a bacterial seal. Placement ofthe final restoration at a later appointment has beensuggested, to permit a visual examination of secondarydentin formation. This second intervention carries arisk of reinfection, adds additional mechanical trauma,and requires additional time and expense.

Recently, it has been suggested that dentinal adhe-sives might be utilized for pulpal protection,'' Many ofthe new dentinal adhesives can seal effectively byhybridizing the superficial dentin,* and some possessan antibacterial effect.'"' High long-term bond strengthsand reduced microleakage have been achieved.'" Pulpa!healing has been demonstrated for some dentinaladhesives in teeth with minimal dentina! thiickness."''-'Aiso, direct capping of pu!pa! tissue with resin haseücited good results cMcaUy" and histo!ogicai!y"'

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Fig 1 Preopetatively, toofh 16 is asymptomatic (patient F).although the mesio-occluscdistolingual amalgam rastOfa-tion has a central fracture.

Fig 2 Secondary canes is excavated, exposing a pulphorn corresponding to the location of the amalgam fracture.Moderate, light red bleeding.

The purpose ofthis pilot study was to evaluate directpulp capping performed with a dentinal adhesive resinsystem (Syntac, Vivadent) on human teeth in vivo.

Method and materials

Teeth to be included in this study were selectedaccording to the following criteria: (I) there wereneither preoperative symptoms nor mild transientsensitivity to thermal or osmotic stimulus, (2) theexposure was localized and did not exceed 1 mm indiameter, and (3) there was no dark or suppuratingbleeding.

If exposure was anticipated on the basis of preope-rative radiographs, the technique was briefiy explainedto the patient and informed consent was obtained.Implementation of these criteria resulted in selectionof eight teeth in six patietits to receive direct pulpcapping.

After administration of local anesthesia, caries wasexcavated with a slowly rotating round bur. A rubberdam was generally placed prior to initiation of treatmentor ahematively placed on removal of the defectiverestoration. Because tooth preparation was nevercompleted at the time of exposure, the site wasprovisionally covered with a nonsetting Ca(OH)paste (Reogan Rapid, Vivadent) during completion ofexcavation and enamel margin finishing. Completecaries removal was performed in all cases, and a matrixwas adapted if required.

Enamel and dentin were etched with 37% phos-phoric acid gel for approximately 30 seconds and 10

seconds respectively. The acid and Ca(0H)2 wererinsed on" and the cavity was briefiy dried. Theexposure site was then observed to ensure hemostasis.The entire preparation, including enamel, dentin, andpnlpal tissue, was treated with the dentinal adhesivesystem (Syntac). The primer was applied liberally forapproximately 5 seconds, followed by a short blast ofair. The adhesive was applied and thoroughly air dried.An unfilled resin (Heliobond, Vivadent) was dis-persed to a thin layer and activated with a curing light(Vivalux, Vivadent) for 20 seconds. To mechanicallyprotect the perforation from intrusion of materialduring further manipulation, another layer of unfilledresin was applied, and a thin layer of resin composite(Tetric, Vivadent) was gently adapted around theexposure and cured. The restoration was completedusing the same resin composite and a vertical layeringtechnique. The treatment is shown in Figs 1 to 8.

The patients were requested to report any symptomsfollowing treatment and scheduled for a controlexamination after 3 to 7 days and again after 2 to 6months. At the recalls, patients were first asked aboutsymptoms (arising from temperature extremes, sweetor sour food, occlusal loading), and responses wererecorded. Vitality testing was performed with carbóndioxide ice and an electronic vitality scanner (Odonto-nieter, GOOF). The teeth receiving treatment werecompared to adjacent and/or contralateral teeth. Thereactions were recorded as normal, hypersensitive ornone. A periapical radiograph was taken, and anychanges were recorded.

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Fig 3 The pulpal exposure is provisionally covered with anonsetting calcium hydroxide paste.

Fig 4 Enamel and dentin are acid etched. The calciumhydroxide has been discolored by the bleeding

Fig 5 After rinsing, no further bleeding is observed. Fig 6 The pulpal exposure is closed with adhesive andunfilled resin. No infiltration of blood is visible at theadhesive interface.

Fig 7 The iirst, thin layer ot resin composite is gentlyadapted to improve mechanical protection prior to furthermanipulation.

Fig 8 The finished and polished direct resin compositerestoration is shown 2 weeks after placement

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Table I Direct pulp capping perfonned with a dentinal adhesive and resin composite in direct contactwith pulpal tissue

Patient

ABBCCDEF

Age (y)

3626262727253930

Sex

MMMFFMMF

ToothNo.

4738282425163616

Caries*

SecPrimPrimSecSecSecSecSec

Follow-up(mo)

66455232

Posto psymptoms

NoNoNoNoNoNoNoNo

Radiographiefindings

NoNoNoNoNoNoNoNo

CO,testing

NormalNormalNormalNormalNormalNormalNormalNormal

Electricaltesting

NormalNormalNormalNormalNormalNormalNormalNormal

• Sec - secondary; Prim - primary.

Results

All teeth demonstrated normal clinical and radiologiefindings (Table 1 ), No patients reported postoperativesymptoms, except for mild, nonspecific discomfort onthe day of treatment.

Discussion

In the clinical treatment of patients, it requires a deepconviction to abandon a traditional technique. Thisseems particularly valid in the treatment of vital pulpaltissue. Calcium hydroxide has been established fordecades as the material of choice for pulp capping.

Many Syntac restorations have been placed by theauthors-since 1989 in unlined cavities and since 1992with phosphoric acid etching of the dentin. Theincidence of postoperative sensitivity has been ex-tremely low. In a clinical investigation of 39 directposterior restorations placed without base materials,Krejci et al'^ reported only one case of postoperativesensitivity (which disappeared tbilowing occlusal ad-justment), despite the fact that many ofthe prepara-tions were extensive.

The rapidly increasing dentinai permeability withreduced distance to the pulp, as reported by Pash-ley,"*" means that physiologically there is little difference between direct puip capping and deep prepara-tions (minima! remaining dentjnal thickness) in termsof direct toxic effects. This concept is supported byhistologie findings with this adhesive; direct contact

with pulpal tissue was found to be a biologicallyacceptable treatment modality."

On this basis, the present results do not seemastonishing. Although electric pulp testers can providefalse positives through periodontal receptors,'^" thisrisk was minimized as far as possible by the clinicalexamination procedures and radiographie examina-tion of periapical structures.

Hybridizing the superficial dentin may provide aneffective seal against bacterial infiltration. A hybridlayer of 4 to 6 |im is formed when Syntac is used withthe described total-etch technique. If the primer isapplied to the smear layer, formation of the hybridlayer depends on the thickness and density of thesmear layer and the application time of the primer.Studies to date have demonstrated significantly reducedmicroleakage following phosphoric acid etching ofdentin with Syntac.^°-' The possibility of hybridizingthe exposed pulpal tissue exists as an analog tohybridizing dentin.

Disinfection of the cavitj' could be important,because the presence or absence of bacteria appears tobe a primary determinant of the outcome of pulpcapping. In this respect, dentinal adhesives containingglutaraldehyde seem favorable because of their bacte-ricidal effect on application. This effect can beexpected to last for an extended period of time.^^"Glutaraldehyde does provide fixation ofthe superficialexposed pulpal tissue, but does not penetrate deeplyinto tissue because of its high reactivity.-''-^^ This"fixed" superficial pulpal tissue could have an effect on

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pulpal healing similar to the effect ofthe necrotic zoneunder Ca(OH),.

The favorable histologie results obtained witb IRM(Dentsply De Trey) as a surface-sealing materialdemonstrate the concept of a biologic seal.''' ie. arestorative material that prevents bacterial ingress,despite permitting microleakage. Ideally, the bondedrestoration provides a mechanical seal, but the capabil-ity of dentinal bonding agents to provide this seal alsodepends on the application technique and cavity geom-etry. Should the mechanical seal fail, either duringresin shrinkage or over time, a restorative system tbatprovides a biologic seal may prove valuable.

In this study, the established dentinal bond shouldprovide a mechanical seal at the periphery ofthe pulpalexposure. In addition, the antibacterial adhesive sys-tem may contribute to a biologically sealed restoration.The short-term application of Ca(OH)., perhaps con-tributed to hemostasis and disinfection.

Pulpal heaiing can be influenced by physiologicfactors and antecedent pathosis. The mean age ofthepatients (range of 25 to 39 years) was relatively high,and previous restorative therapy ofthe involved teethwas generally extensive, but this apparently did notcompromise the resuits.

The effects ofthe heat generated by the light and theexotherm of the resin composite could potentiallyendanger pulpal vitality.-' The application oían initialthin first layer and polymerization with a relativelylow-intensity light (Vivalux, registering 250 mW/cm'with the Demetron Radiometer) may have heipedminimize this risk.

As can be seen in long-term clinical studies,apparent early success is no guarantee for long-termresults.-*-' Some failures with Ca{OH), become evi-dent fairly quickly after treatment, and a substantialpercentage of teeth remain sensitive for considerabletime.-' Apparently, calcium hydroxide loses its anti-microbial properties.^" It is also known that Ca(OH),under restorations may "disappear" with time."

Direct pulp capping with Ca(OH), could be com-bined with a bonded resin composite to reduce the riskof subsequent bacteriai microleakage. This would seemto add the biologic efFect of Ca(OH), to the sealingcapability of some bonding agents, but there are severaldisadvantages to this technique:

1. Mechanical properties of calcium hydroxides areless than ideal.

2. Phosphoric acid etching weakens or dissolves the

calcium hydroxide material (even If only the enamelis etched).

3. Investigations have demonstrated that CalOH)^materiais themselves can prohibit proper polymeri-zation ofthe resin composite.̂ '̂̂ ^

4. Calcium hydroxide occupies some of the area thatcould have been used for dentinal bonding.

5. The bonding agent may infiltrate under the opaquecalcium hydroxide, possibly compromising poly-merization.If the absence of postoperative sensitivity after resin

pulp capping in this study is assumed to indicateadequate seahng, then these short-term results permit aguarded but optimistic prognosis for long-term clinicalsuccess.

Conclusion

The potential advantages of direct pulp capping with adentinal adhesive and resin composite include animproved seal ofthe exposure periphery for preventionof reinfection and the avoidance of the risks of asecond operative procedure. Postoperative sensitivityalso seems to be reduced.

Long-term clinical trials with a larger patient groupwould be necessary before this treatment can berecommended generally, but the initial results appearto be ver>' promising.

References

1. Sclirüder U. Effects of caleiuiti hydroxide-containing pulp-cappingagents on pulp cell migration, proliferation and differentiation,J Dent Res 1985;64:541-54S.

2. Cox CF, S Jbay RK, Suzuki S, Sjzjki S, Ostro E. Healing responseof direct capped denial pulps with various materials: Temporalhealing wilh a biological seal in rhesus monkeys. Int J PeriodontRest Dent. Submitted,

3. Sanlini A. Long-term chnical assessment of pulpolomies withcalcium hydroxide containing ledermlx in human permanent prt-moLits and molars Acta Odontol Pediatr

4, Cox CF. Suzuki S. The re-evalualion ofpulp protection: Biologicalconsideration of CalOHl^ liners versus llie cohesive hybridizationofptepared vital demin J Am Dent Assoc I954;125;823-831.

5, Heys DR. Cox CF. Heys RJ. AveryJK, Histológica! considerationsof direct pulp capping agents. I Dent Res 1981 ;60:1371 -1379.

6. Nakabaj'ashi N. Ashizawa M. Nakamura M. ldentificalion of aresm-dentin hybrid layer in vital human dentin created in vivo;Durablebondingto vital dentm. Quintessence Inl 1992;23; 1.15-141.

7. Prati C. FavaF, Di GioiaD. Selighini M. Pasliley IDH, Antibacterialeffectiveness of dentin bonding systems. Dem Mater 1993:9:338-343,

a. Emilson CG, Bergenholtz G, Antibacterial activity of dentinalbonding agents. Quintessence Int 1993:24'511-515.

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Operative Dentistry

9. Meiers JC. Oriltb TE, Miller CA. Aniimicrobial activity of dentinbonding systems and glass ionnmers labsnact 16391. J Dent ResiyS2;7IJ10,

10. Haller B, E-lofmann N, Blailier B, Pfannkiieli A, Bestandigkeit desKomposit-DenlinverbunJes bei künstlicher Alterung. Dlsch ZEihnÜrztlZ i99Ji4K:IÜU-IO4.

ü . Cox CF, Suïuki S, Farmer JB, cl al. Histological and clinicalevalualion oí Syniae denlin bonding and Helioprogress resincomposile systems. Inl J Periodonl Rcsl Denl, SubmitLcd.

12. Cos CF Eireels of adhesive resins and variotis denial cenienls on thepulp. Oper Dent 1992;(sjppl î):165-176.

1.1. Kanca J [II. Replacement ofa fr̂ ictured incisor fragment over pulpalexposure; A case report Quintessence Int 1993i24;8l-84.

14. Co.\CF, KeallCL.KeallHJ.OstroE.BergenlioltiG Biucompati-bilily of surface-sealed dental materials against exposed pulps.J Prosthel Dem I987;S7:1-S.

15, Krejci I, Besek M. Lutz F Clinical and SEM study of Tetric resincomposite in poslerior leelh: 12 tiionth results. Am J Dent 1994;7:27-30.

16. Pashley DH. Dcntin-predetitin complex and its permeability;Physiologic overview. J Dent Re? I985;fi4:6l3-62U.

17, Pashley DH, Pashley EL, Dentin permeability and restorativedentistry; A status report for the American Journal of Dentistry. AmJDent 199l;4;5-9.

IS, Mumford JM, Newton AV Zone of excitation when electricallystimulating human teeth. Arch Oral Biol 1969:14: IJSJ-U8S.

19. Curson I, Diagnosis in endodontics, J Br Endod Soc 1979,12lsiippl):29-3S.

20. Gwinnett AJ, Dickerson WG. Yu S. Dentin bond shear strength andmicroleakage for Syntac/Heliomolar. A comparison between themanufacturer's and total etch technique J Ksthet Dem 1992:4:164-168.

21. Watson TF Wilmot DM. A confocal microscopic evaluation of theinlerface between Syntac adhesive and tooth tissue. J Dent 1992;20;302-31O.

22. Felton D, Bergenholti Q, Co* CF Inhibition of bactenal growthunder composite restorations following GLUMA pretreatmcnl,JDent Res l9S9:6B:491-495.

23. Kanehira M, Yamanaka H, Okuda R. Composite resin fillingrestored by using GLUMA bonding system. Dent Mater J 1987:3U;I588-1599.

24. Dijkman GEHM, Jongebloed WL, de Vries J, Ögaard B, Atends J.Closing of denlinal lubules by giutaraidehyde treatment, a scanningelectron microscope sludy. Scand J Denl Res 1994; 103:144-150.

25. Danken J, s'Gravenmade EJ, Wemes JC, Diffusion of formocresoland giutaraidehyde through demin and cementum. J Endod 1976;2:42-46,

26 Kopel HM. Bernick S, Zaehrisson E, DeRomero SA. The effects ofgiutaraidehyde on primary pulp lissue following coronal amputation;An in vivo histological sludy. ASDC J Dent Child 1980:47:425-430.

27. Goodis HE, White JM, Marshall SJ, Koshrovi P, Watanabe LG,Marshall GWJr. The effect ofglass ionomer liners in lowering pulptemperatures during composite placemeni, in vitro. Denl Maler1993:9:146-150.

28. Baume LJ, Hok J. Long term clinical assessment of direct pulpcapping. Int Dent J 1981:31:251-260.

29. Fitzgerald M, Heys RJ. A clinical and histological evaluation ofconservative pulpal iherapy in human teeth. Oper Dent 1991;16;IOI-I12.

30. Cox CF, Bergenholtz G, Heys DR, Syed SA. Fitzgerald M, Heys RJPulp capping of denial pulp mechanically exposed to oral micro-flora: A I -2 year observation of wound healing in the monkey. JOral Pathol !9a5:14l56-168.

ing Dycal. Br Dent J 1979;31, Barnes IE, ¡Odd EAM. Disappe147:111,

32, Lussi AR, Hotz P, Einfluss verschiedener Unterfuellungsmaterialienaufdie Polymerisation von Komposits. Schweiz Monatsschr Zahn,med 1994:104:854-858.

33, Marshali SJ, Marshail GW, Harcotirt JK.. The influence of variouscavity bases on the microhardness of composites. Aust Dent J1982;27:29l-295. •

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