The effect of cavity pretreatment procedures bonding: A four-year clinical evaluation Jan W. V. van Dijken,

D.D.S.,

on dentin

Ph.D.

Umel University, Faculty of Odontology, Umei, Sweden Cervical abrasion and erosion lesions were restored with composite resin restorations bonded with four different dentin-bonding resins, an enamel-bonding resin, or restorations of a glass ionomer cement. The long-term clinical retention of the restorations were evaluated during a 4-year period. The surrounding enamel was not acid-etched. Four cleaning methods for dentin pretreatment were used to study their effects on the bonding between dentin and the restorative materials. The dentin was treated with either (1) etching for 60 seconds or (2) 16 seconds with 37% phosphoric acid, (3) cleaning with 6% sodium hypochlorite (NaOCL) for 20 seconds, or (4) cleaning with Tubulicid etchant for $0 seconds. None of the composite resin restorations, regardless of pretreatment or bonding method, showed acceptable retention rates. All glass ionomer cement restorations were retained after pretreatment with Tubulicid etchant and 5% NaOCL after a B-month period. Full acceptance, in other words, 3 years retention, was reached only after pretreatment with NaOCL. (J PROSTHET DENT 1990;64:148-62.)

T

he acid-etch technique is now widely used to achieve mechanical attachment between enamel and composite resin restorations. The success with bonding composite resin to enamel has stimulated studies of similar bondings to dentin. Mechanical bonding to dentin, however, is hampered by the structural feature of the dentin. Other methods based on other principles have been evaluated. Recently some dentin bonding resins were introduced, and it was claimed that they were effective in mediating a strong chemical bond with the dentinal tissue. Although bond strength values vary widely in in vitro studies, some of the commercial dentin bonding agents seem to have properties that could make them useful in clinical practice.lm4 Controversy exists about the role of the smear layer for the effectiveness of the bonding agents. The smear layer, which is composed of dentinal debris, covers the cut surface and is only loosely attached to the underlying dentin. It seems logical to assume that in cavities where the smear layer is removed a direct contact is achieved between the dentin and the bonding agent forming adhesion.596 A variety of chemical cleaning procedures, including the use of acids, have been recommended by manufacturers of dentin-bonding agents.2r3*7-gCleaning the dentin with acids removes the smear layer and improves the bond strength in vitro,‘O but also results in widening of the tubule orifices and increased wetness of the exposed dentin surface in vivo.11-14Etching with strong acids gives pronounced changes in the topography of dentin surfaces that

*AssociateProfessor,Department of Cariology. 10/l/18647

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could be used for mechanical retention.14 However, etching also reduces the number of adhesive bonding sites on the dentin surfaces. Therefore, it is desirable to find an agent that can remove most of the smear layer, but leaves the dentinal tubules blocked so that the pulpal fluid will not contaminate the surface. In a laboratory investigation, Newman and PorterlO found that a X-second application with a 6% sodium hypochloritesolution appeared to remove a significant amount of the smear layer without removing the dentinal plugs. Briinnstriim et al.lls l2 showed that a 0.2% EDTA-containing commercial cavity cleaner produced a clean dentin surface. This study evaluated the effect of four pretreatments of dentin on the retention of five dentin-bonding agents and one enamel-bonding agent in cervical erosion and abrasion lesions where no mechanical cavity preparation was done and where the restorations were not bonded to acid-etched enamel.

MATERIAL

AND METHODS

Materials tested. The six systems investigated, one enamel-bonding resin, four dentin-bonding resin systems, and one glass ionomer cement are listed in Table I. All of the systems are commercially available and were, except for the enamel-bonding agent, recommended for the restoration of abrasion and erosion lesions. Clinical group. The patients selected for the study, 52 men and 61 women, had at least four cervical noncarious abrasion and erosion lesions each. The mean age of the patients was 50.4 years (range 33 to ‘77 years) at the start of the study. There were 728 lesions selected for the study (Table II). Treatment proceduree. All of the lesions were filled

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Restorative materials investigated Code

Bonding agent type

Concise Enamel Bond/ Concise

CEB

Enamel bonding

Scotchbond/ Silar

SB

Dentin bonding

Clearfil bonding system

CL

Dentin bonding

Cervident adhesion promotor/Cervident

C

Dentin bonding

Dentin bonding agent/ Miradapt

DBA

Dentin bonding

Fuji

F

Glass ionomer cement

Restorative

without

system

prior cavity preparation.

Only a slight polishing

with pumice was done to remove dental plaque. The teeth were isolated from contamination by moisture with cotton rolls and a saliva ejector. No rubber dam was used. Where the operation field could not be kept dry at the subgingival margins, these margins were exposed with electrosurgery. The dentin surfaces were subjected to one of the following treatments: (1) etching with 37 % phosphoric acid (etch gel) for 60 seconds, (2) etching with 37% phosphoric acid for 15 seconds, (3) scrubbing with 5% NaOCL (University Hospital Chemist, Umei, Sweden) for 20 seconds, or (4) scrubbing with a surface active cavity cleanser (Tubulicidblue, Dental Therapeutics Ltd., Ektorp, Sweden) for 60 seconds. The surrounding enamel was neither beveled nor acid-etched, a procedure that would increase the retention of the materials by mechanical bonding to the enamel. After application of the conditioning agents, the surfaces were washed thoroughly with a water spray for 30 seconds. The cotton rolls were replaced and the lesions were dried with a gentle blast of compressed air. The bonding resins were then immediately applied. Excesswas removed with a gentle blast of compressed air immediately after placement. For the chemically cured Scotchbond resin, two thin coats were applied, each gently air dried. The composite resins and the glass ionomer cement were inserted with a syringe by use of a bulk placement technique. The defects were slightly overfilled and covered by a previously contoured matrix (Hawe Neos, Gentilino, Switzerland) held in place for 5 minutes. The glass ionomer cement restorations were protected with two thin coats of varnish and a coat of varnish, Each coat of varnish was gently air dried for 15 seconds. Finishing of the restorations was delayed for at least a week. Evaluation. The restorations were evaluated when

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Batch No.

3M Dental Prod. St. Paul, Mimi. 3M Dental Prod.

1422 L 7422 R 8601 B 869A 40014 6843-17445 6843-17441 6843-17443 051684 C 110883 D 35 908 14011

Table

II.

Manufacturer

Kurary Co. Ltd. Osaka, Japan SS White Philadelphia, Pa. Johnson and Johnson East Windsor, N.J. G-C Dental Industrial Corp. Tokyo, Japan

Pretreatment methods investigated

Material

ConciselCEB SiladSB

Clearfil system

Cervident

MiradapVDBA

Fuji

Dentin pretreatment

HsP04 37% HsP04 37% HsP04 37 % NaClO 5% Tubulicid Hap04 37 % H3P04 37 % NaClO 5% H3P04 37 % H3P04 37 % NaClO 5% HsP04 37 % NaClO 5% Tubulicid H3P04 37 % H3P04 37 % NaClO 5% Tubulicid

Pretreatment time (eec)

60 15 15 20 60 60 15 20 60 15 20 15 20 60 60 15 20 60

No. of restorations

22 24 46 64 78 38 50 48 22 40 54 34 34 37 20 52 44 36

polished (baseline) and every 6 months thereafter during a 4-year period by use of a slight modification of the USPHS criteria.15 Color slides were made at the evaluation visits and were used at the end of the study to verify the evaluation scores. The retention and secondary caries evaluations are reported in this article. All of the restorations were placed and evaluated by the same individual.

RESULTS Three patients with a total of 15 restorations were not available for recall evaluations. The remaining 713 cervical

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Fig. 1. Etching for 60 seconds with 31% phosphoric acid. CEB, Concise enamel bond; C, Cervident adhesion; CL, Clearfil bonding system; F, Fuji cement.

restorations were examined during the $-year period. Secondary caries had developed at the margins of eight of the resin restorations. The cumulative loss rates of the restorations after the different pretreatment methods are shown in Figs. 1 through 4. A total of eight partially lost restorations, four resin and four glass ionomer cement, were scored as lost. The enamel-bonding system showed the highest loss rate. After 6 months the loss rates were 41.7% and 72.7% and after 4 years 66.7% and 90.9% when the lesions had been treated with phosphoric acid for 15 seconds and 60 seconds, respectively. Cumulative loss rates of the dentin-bonding resin systems after 6 months varied between 5.9% to 54.5%) after 3 years between 43.3% and 88%) and after 4 years between 47 % and 90.9 % , dependent on the pretreatment method used (Table II). Most losses of restorations retained with dentin-bonding agents occurred during the first year. The glass ionomer cement was the material that showed the best retention rate. None of the restorations in the NaOCL group and Tubulicid etchant group were lost after 6 months. The pretreatment method had a profound effect on the retention of the glass ionomer cement restorations. Eighty percent of the restorations with a go-second pretreatment and 50% of restorations with a 15-second pretreatment with phosphoric acid were lost after the 4-year period. Tubulicid pretreatment etchant gave a 24% loss rate. The best retention was found after treatment with 5% NaOCL, where only 14% of the restorations were lost.

DISCUSSION The methods for in vitro evaluation of the bond strength between dentin and composite resin restorations combined with dentin-bonding systems vary widely,2 and their interpretations are complex. The minimum in vitro bond 150

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Fig. 2. Etching for 15 seconds with 37 % phosphoric acid. C, Cervident adhesion; SB, Scotchbond resin; CEB, Concise enamel bond resin; CL, Clearfil bonding system; DBA, dentin bonding agent.

strength value valid in clinical use has not been established, and quantitative data from in vitro tests alone are not sufficient to predict the clinical effectiveness of dentin-bonding systems. The new acceptance program for dentinadhesive materials established by the American Dental Association (ADA) requires that the bonding systems are tested in clinical situations. Further there should be no dependence on cavity preparation or retention form, and the restorations preferably should be tested in class V erosion lesions. In many of the earlier clinical investigations of dentin bonding resins, the surrounding enamel was also acid etched, and good retention rates were therefore reported.16‘1gLimited clinical results have been reported of dentin-bonding resins placed in cavities without acid etching of the ename1.20-22 For provisional acceptance according to ADA’s acceptance program, two independent clinical studies should show a minimum of 95 % retention after 6 months. For full acceptance at least 60% of the restorations should demonstrate adequate retention and sealing after 3 years. Presently none of the marketed dentinbonding resins have ADA acceptance. The result8 of studies aiming at ADA’s requirements vary, but are as a whole discouraging. Six-month studies of some dentin-bonding resins, which were al80 investigated in this study, showed cumulative losses of restorations between 13% and 100% .17W23 Between 23% and 50% loss of restorations has been reported for Cervident resin 3 years after placement.24-26 The tested dentin-bonding systems in the present study showed more than 5% lost restorations after 6 months. After 1 month nine of the 12 test groups showed an acceptably high failure rate (>5%) independent of the pretreatment method used. Only Miradapt/DBA resin, after a 15-

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Fig. 3. Cleaning for 20 seconds with 5% NaOCL. C, Cervident adhesion promoter; CL, Clearfil bonding system; DBA, dentin bonding agent material; SB, Scotchbond resin; F, Fuji cement.

4. Cleaning for 60 seconds with Tubulicid etchant. SB, Scotchbond resin; DBA, dental bonding agent; F, Fuji cement.

set phosphoric acid pretreatment, was close to the 5% acceptance level, with a 5.9 % rate of loss. Nevertheless, after 1 year the number of lost restorations increased to 29.4%. None of the tested pretreatment methods seemed to be superior to any of the others to increase the clinical bond strength of the resins. In the present study the glass ionomer cement generally showed the best retentive properties. Brandau et al.,s using citric acid as a cleaning agent, showed a 25% loss of cement restorations after 54 months. Using pumice pretreatment, Beech and Tyasz3 reported a 3 % loss of Fuji II restorations after 6 months, and Mounts7 reported a 4% loss of Fuji II restorations after 3 to 4 years. Horstedt et a1.28 with only a water spray pretreatment showed no loss of restorations after 6 months. The findings in this study show that a strong acid, independent of treatment time, is not the pretreatment method of choice, Less aggressive cleaning methods, such as treatment with NaOCL or Tubulicid etchant, reduce the marginal gaps4and promote the retention of the glass ionomer cement fillings. With these two pretreatment methods, acceptable retention rates for the glass ionomer cement fillings were recorded after 6 months. However, only the NaOCL group showed fully acceptable retention rates (>80 % ) after 3 years. This finding is in accord with the in vitro results of Negm et al.2s who showed that conditioning with 5% sodium hypochlorite solution gave a better bond of glass ionomer cements to dentin than did a treatment with a strong acid solution. The pretreatment effects in this study relate to cervical abrasion and erosion defects that are covered with an organic pellicle or a smear layer produced by polishing with pumice. The reported results therefore cannot be directly related to cut surfaces covered with smear layers of vary-

ing depth and density. In previous studies41l4 we demonstrated that the smear layers of cut surfaces were removed by phosphoric acid with application times used in this study. Tubulicid etchant removed most of the smear layer without removing the smear debris that had fallen into the orifices of the tubules, and 5 % NaOCL removed the smear debris out of parts of the tubules. It can be assumed that the thinner smear layers on cervical defects will be removed entirely by NaOCL and Tubulicid etchant pretreatment. This objective is more difficult to achieve clinically on cut surfaces because of the thicker smear layer, the complex geometry of many cavities, and the difficulty of obtaining adequate access.

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CONCLUSIONS 1. None of the tested dentin-bonding resin materials showed retention rates that complied with the provisional acceptance program set up by the ADA, regardless of dentin pretreatments tested. 2. The 6-month observation of the glass ionomer cement complied with the ADA criteria after both 5 % NaOCL and Tubulicid etchant pretreatment. However, based on the 36-month evaluation, full acceptance was achieved only after NaOCL pretreatment. 3. Recurrent caries were not observed in the glass-ionomer cement group and only in low frequenqy in the dentinbonding resin groups.

REFERENCES 1. Powis DR, Folkis T, Merson SA, Wilson AD. Improved adhesion of a glass ionomer cement to dentin and enamel. J Dent Res 1982;61:141622. 2. Council on Dental Materials, Instruments, and Equipment. Dentin bonding systems: an update. J Am Dent Assoc 1987;114:91-5.

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3. Hots P, McLean JW, Sud I, Wilson AD. The bonding of glass-ionomer cements to metal and tooth substances. Br Dent J 1977;142:41-7. 4. Dijken van, JWV, Horstedt P. Effect of 5% sodium hypochlorite and Tubulicid pretreatment in vivo on the marginal adaptation of dental adhesives and glass ionomer cements. Dent Mater 1987;3:303-6. 5. Prodger TE, Symonds M. ASPA adhesion study. Br Dent J 1977;143: 266-70. 6. Diamond A, Carnell R. The smear layer: a review of restorative progress. Pedodontics 1984;8:219-26. 7. McLean JW, Wilson HD. Sealing of erosion cavities with a glass ionomer cement [Abstract]. J Dent Res 1972;51:1254. 8. Brandau HE, Ziemiecki TL, Charbeneau GT. Restoration of cervical contours on non-prepared teeth using glass ionomer cement: a 4% -year report. J Am Dent Assoc 1984$04:782-3. 9. Fusayama T, Nakamura M, Kurosaki N, et al. Nonpressure adhesion of a new adhesive restorative resin. J Dent Res 1979;58:1364-70. 10. Newman SM, Porter H. Dentin pretreatment effects on dentinal bonding [Abstract]. J Dent Res 1986;65:177. 11. Br&nnstrijm M, Johnson G. Effects of various conditioner and cleaning agents on prepared dentin surfaces: a scanning electron microscope investigation. J PR~~THET DENT 1974;31:422-30. 12. Briinnstrbm M, Nordenvall K-J, Giants PO. The effect of EDTA-contaming surface active solutions on the morphology of prepared dentin: an in viva study. J Dent Res 1980;59:1127-31. 13. Nordenvall KJ. Resin impregnation of enamel and dentin [Thesis]. University of Stockholm, 1981. 14. Dijken van JWV, Hijrstedt P. In vivo adaptation of restorative materials to dentin. J PROSTHET DENT 1986;56:677-81. 15. Dijken van JWV. A clinical evaluation of anterior conventional, microfiller and hybrid composite resin fillings. A six year follow-up study. Acta Odontol Stand 1986;44:357-67. 16. Doering JV, Jensen ME. A new photocuring dentin bonding material: six month clinical results [Abstract]. J Dent Res 198664276. 17. Dennison JB, Ziemicki TL, Charbeneau GT. Retention of unprepared cervical restorations utilizing a dentin bonding agent-two year report [Abstract]. J Dent Res 1986,65:173. 18. Ziemiecki TL, Dennison JB, Charbeneau GT. Clinical evaluation of the

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effect of surface pretreatment on dentin bonding-one year report [Abstract]. J Dent Res 1986;65:314. 19. Vanherle G, Verschueren M, Lanbrechts P, Braem M. Clinical investigation of dental adhesive systems. Part I. an in vivo study. J PROSTHET DENT 1986;55:157-63.

20. Tyas MJ. Dentin bonding agents. Clinical and laboratory investigations [AbstractJ. J Dent Res 1987;66:827. 21. Ziemiecki TL, Dennison JB, Charbeneau GT. Evaluation of Scotchbond: retention of cervical erosion restorations after one year [Abstract]. J Dent Res 1985;64:276. 22. Doering JV, Jensen ME. Clinical evaluation of dentin bonding materials on cervical “abrasion” lesions [Abstract]. J Dent Res 1986;65:173. 23. Beech DR. Bonding of restorative resins to dentin. In: Vanherle G, Smith DC, eds. Posterior composite resin dental restorative materials. The Netherlands: P Ssulc Pub1 Co, 1985;231-7. 24. Flynn M. Clinical evaluation of Cervident and ASPA in restoring teeth with cervical abrasions. Oper Dent 1989,4:118-20. 25. Jendresen MD. Clinical performance of a composite resin for class V erosion [Abstract]. J Dent Res 1978;57:339. 26. Matis BA, Cochran M, Carlson T, Phillips RW. Clinical evaluation and early finishing of glass ionomer restorative materials. Oper Dent 1988;13:74-80. 27. Mount GI. Longevity of glass ionomer cements. J PROSTHETDENT 1986;55:682-5.

28. Nor&d P, Knudsen I, Asmussen E, Munksgaard EC. Clinical study of adhesive materials for restoration of cervical erosions [Abstract]. J Dent Res 1986;65:778. 29. Negm MM, Beech DR, Grant AA. An evaluation of mechanical and adhesive properties of polycarboxylate and glass ionomer cements. J Oral Rehahil 1982;9:161-7. Reprint requests to: DR. JAN W. V. VAN DLIKEN FACULTV OF ODONTOL~GY thEA UNlVJDtSITY S-991 87 UMI!# SWEDEN

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The effect of cavity pretreatment procedures on dentin bonding: a four-year clinical evaluation.

Cervical abrasion and erosion lesions were restored with composite resin restorations bonded with four different dentin-bonding resins, an enamel-bond...
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