Direct Posterior Composite Restorationswith a New Adiiesive System:

One-Year Resuits

Martin Schoch^/Norbert Kramers/Roland FrankenbergerVAnselm Petschelf^

Purpose: Syntac Sprint is a new one-bottie adhesive based on the total-etch and total-bond technique. Theaim of this study was to compare the new restorative system consisting of Syntac Sprint and the resincomposite Tetric Ceram with the clinically proven combination of the dentin adhesive Syntac Ciassic andthe resin composite Tetric.

Materials and Methods: In a controiied prospective clinical study, 47 cavities (36 premoiars, 11 molars;29 maxillary, 17 mandibular; 6 occlusal, 33 occluso-approximal, 7 MOD, 1 > 3 surfaces) in 33 patients (17female, 16 maie) were filled. Twenty-five fiiiings were placed with tlie combination Syntac Sprint/TetricCeram under totai etching and totai bonding conditions, in thirteen restorations, Syntac Sprint was pre-cured prior to tbe application of the resin composite; in the other twelve cases, restoration and adhesivewere cured simultaneously. The control group consisted of 22 cavities restored with Syntac Classic piusthe composite Tetric, At baseline and after 6 and 12 months, two calibrated investigators examined therestorations with modified USPHS codes and criteria.

Results: The criteria marginal integrity and integrity ofthe tootb deteriorated significantiy between thebaseline and the 6- and 12- month investigations (Friedman 2-way ANOVA; p < 0.05). Mo differences werefound in the criteria surface rougbness, coior matching, anatcmic form, step forrnation, integrity of the fill-ing, proximal contact, hypersensitivity, or satisfaction. After one year, aii fillings were in good condition.There was no significant difference between the Syntac Sprint/Tetric Ceram and Syntac Classic/Tetricgroups for any criteNon ¡Kruskai-Wallis; p > 0.05¡.

Conclusion: Within the limits of this study, Tetric Ceram fiiiings in combination with Syntac Sprint were

ciinicaiiy successfui after one year.

J Adhesive Dent 1999:2:167-173. Submitted for pubiication.23.02.99: accepted for pubiication: 25.03.99.

Research Associate, Clinic ¡or Operative Dentistry ana Periodontol-ngy, University of Eriangen-Nuremberg, Germany

Lecturer, Ciinic for Operative Dentistry and Periodontoiogy, Univer-sity of Eriangen-Nuremberg, Gerrnany

Research Associate, Ciinic for Operative Dentistry and Periodonto-iogy, University of Eriangen-Nuremberg, Germany

Professof, CIIDJC for Operative Dentistry and Periodontoiogy, Uni-"ersity of Eriangen-Nuremberg, Germany

Reprint requests: Dr. Martin Schoch, DMD, Clinic for Operative Den-tistry and Periodontoiogy, University of Eriangen-Nuremberg, GluecH-strasse I I , D-91054 Erlangen, Germany. Tei: +49-9131-853-4203.Faj; +49-9131-853-3603, email;schocit@clent.uni-eriangen.de

Direct resin composite fillings are becoming morecommon as an aiternative to amaigam restora-

tions, ̂ s:"-' Despite reservations about using resincomposites in the posterior region, promising long-term ciinicai resuits have been reported, even witholder materiais.I'lois-^^

While effective adhesion to enamel using theacid-etch technique has been known to dentistry fordecades, effective bonding to dentin has been de-veioped oniy in recent years. To become a standardin dental practice, the dentin bonding procedureshould not require lengthy application times or sev-

Vol 1, No 2, 1999 167

Schoch et ai

erai different application steps. Therefore, the trendtoward easy handiing and growing user-friendlinessin developing dentin bonding agents (DA) is enor-mous. The latest generation of tiiese agents, con-sisting of only one materiai, can be subsumedunder the catchword "one-bottle adhesives." In ad-dition to the time-consuming application procedure,anotiier problem is dentin moisture controi as acruciai factor in dentinal adhesion,

Syntac Sprint (Vivadent, Schaan, Liechtenstein)is a new one-bottle adhesive, which can be appliedin oniy one layer and need not be light-cured priorto the application of the resin composite. Addition-ally, the manufacturer promises the adhesive's tol-erance of different ciinical moisture conditions ofthe dentin, including contamination with saliva, aspreviously reported for other dentin bonding

The predictive value of in vitro studies is oftenlimited; therefore, controlied prospective clinicalstudies are necessary for definitive assessment ofdental materials,^'^

The aim of the present study was to evaiuate theciinical behavior of the one-bottle adhesive SyntacSprint in combination with the resin composite ma-terial Tetric Ceram (Vivadent), To draw a compari-son to a more estabiished DA,^ the dentin adhesiveSyntac Classic (Vivadent) was used with the resincomposite Tetric (Vivadent). In supplementary tests,Syntac Sprint was precured with light (contrary tomanufacturer's recommendations) to determinewhether this improved the clinical performance ofthe restorations.

MATERIALS AND METHODS

Study Design

From iWarch to August 1997, six experienced den-tists piaced 46 restorations (36 premoiars, 11 mo-lars; 30 maxillary, 17 mandibular; 6 occlusal, 33occluso-approximal, 7 iViOD, 1 > 3 surfaces: seeTable 1) in 33 patients (17 female, 16 maie; aver-age age 29 years, range 19 - 41 years).

After wooden wedges were placed, the cavitieswere prepared as conservatively as possible, unlessthe repiaced restorations—as in the majority ofcases—had been prepared according to Biack'srules. Inner angies o f the cavities were rounded,but the enamel margins were not beveied. All cavi-ties were isolated with a rubber dam.

Only presumed caries profunda areas close tothe pulp were covered with a calcium hydroxide ma-terial (Reocap, Vivadent), followed by a zinc phos-phate cement (Harvard, Richter & Hoffmann Har-vard, Beriin),

In order to protect the neighboring teeth and toform the proximal areas, transparent plastic matrixbands (Moiarbands Transparent, Hawe-Neos, Biog-gio, Switzerland) were cervicaily adapted witinwedges (Sycamore interdental wedges, Hawe-Neos),

Twenty-two filiings were placed using the resincomposite Tetric in combination with the DA SyntacCiassic. Therefore, the enamei was selectivelyetched with 37% phosphoric acid gei (Email Pre-parator GS, Vivadent) for 60 s, rinsed for 60 s, anddried with compressed air. After applying with abrush, Syntac Ciassic Primer was left for 15 s onthe dentin before it was dried thoroughly with com-pressed air. The second layer on the primed dentinconsisted of Syntac Classic Adhesive, which wasdried after 10 s. Finally, Heliobond was painted onboth enamel and dentin, and iight-cured for 40 safter excess resin had been blown thin with com-pressed air.

Twenty-five cavities were filled with the resincomposite Tetric Ceram bonded with the DA SyntacSprint. Foiiowing the principies of totai etching andtotai bonding. Email Preparator GS was applied toenamel and dentin from the peripheral to centralparts of the cavity and left on for 15 to 20 s. Subse-quentiy, the surface was washed for 30 s and care-fully dried according to the wet bonding technique.Syntac Sprint was gently brushed into the condi-tioned dentin for 10 s. After a waiting period of 20s, the excess was blown off. In 13 of these 25restorations, Syntac Sprint was precured for 40 sprior to the application of the resin composite. Inthe other 12 cavities, the DA was light-cured simul-taneously with the first layer of resin composite.

In five patients, it was possibie to use both pro-cedures in a split-mouth design. No split-mouth de-sign was used for the two different dentin bondingagents.

The resin composite was incrementally appliedwith a syringe, starting in the proximal boxes. Eachiayer, with a maximum thickness of 2 mm, wasiight-cured for 40 s. After appiying and modeiiingthe last layer, the resin composite was covered witha glycerine gel, Finaiiy, each fi l l ing surface wasiight-cured for 60 s.

The finishing was carried out with diamond burs,poiishing disks (Sof-Lex, 3M-Dental, St. Paui, MN,

168 The Journal of Adhesive Dentistry

Tabie 1 Number of evaiuated restorations by iocation and extensiondivided into the different dentin adhesive systems

Syntac Classic

Cavities 22Premolars 18Molars 4One surface oTwo surfaces 18Three surfaces 3> Three surfaces 1Caries profunda 9Dentinal margin 1

Dentin adhpiivoSyntac Sprint

light-curedseparate y

13

g

4

3

0

5

0

not liglit-cured

1

USA] and strips (Compostrip, Premier, King of Prus-sia, PA, USA), and the Occlu-Brush (Hawe-Neos).

CoHection of Data

After 24 h, a clinical check limited to the parameter"postoperative sensitivity" was performed as part ofmodified USPHS codes and criteria.•^•^•ii-is The pa-tients were asked whether they felt "no pain," "oc-casional," "constant but tolerable," or "unbearable"paih from the new restorations.

After approximately 2 weeks (baseline), 6 months,ahd 12 months, two calibrated investigators evalu-ated the restorations Independently of each otheraccording to modified USPHS codes and crite-ria7,9,ii-i3 as follows; surface roughness, colormatching, anatomic form, step formation, marginaladaptation, integrity of the tooth, integrity of the fill-ing, proximal contact, sehsitivity, hypersensitivity,and satisfaction. These parameters were scoredwith the following ratings: excellent/good ("alpha"),sufficient ("bravo"), insufficient ("chariie"), and poor("delta"]. In the event of a disagreement in evalua-tion, the ultimate decision was made by consensusofthe two examiners.

Replicas (Epoxy Die, Vivadent) of the preparedcavities ahd the restored teeth and their antago-nists were made with a polyether impression mater-ial (Impregum, Espe, Seefeld, Germany] at baselineand after six and twelve months. These replicas willbe used for a future study quantitatively measuringwear and marginal adaptation.

Color photographs were taken of the initial situa-tion and of the prepared cavities. At the recall ap-pointments, photos were taken of the restorationsand the antagonists with and without marked oc-clusal contact points.

Statisticai Analysis

The consensus scores regarding the modifiedUSPHS criteria were analyzed using the softwarepackage SPSS for Windows 95 (version 7.5.2). Tocompare the different DA groups at a certain inves-tigation, the Kruskal-Wallis test was applied. Chan-ges over time within an individual DA group couldbe verified using the Friedman 2-way ANOVA test.

RESULTS

All patients were very content ¡"alpha") with allrestorations at the recall appointments, with the ex-ception of one patient who suffered from "occa-sional" (category "2", ie, "alpha") hypersensitivity24 hours postoperatively. This occurred in the Syn-tac Sprint group when the adhesive was cured sep-arately. Within the next twelve months of clinicalservice, no complaints were registered. After oneyear, all restorations were still in place. None ofthem needed replacement, and ho tooth requiredendodohtic treatment.

All composite fillings were rated not worse than"bravo" in all modified USPHS criteria. Conse-

Vol 1, No 2 , 1 9 9 9 169

Schoch etal

Tabie 2 Percentage of the "aipiia"criteria

CriteriaSurface roughhessColor matchihgAnatomic formStep formationIVlarginal integrityIntegrity toothIntegrity fiiiingProsimai contactSensitivity24h-checkupSatisfaction

Syntac Classic

Baseline100

100

100

100

95

100

100

95

100

100

100

lYear100

100

100

100

82

95

100

95

100

100

100

ratings for the modified USPHS

Dentih adhesiveSyntao SprintLight-curedseparsteiy

Baseline100

100

100

100

100

100

100

100

100

100

100

lYear100

100

100

100

92

100

100

100

100

100

100

Syhtac Sprintnot iight-cured

separately

Baseiine100

100

100

100

100

100

100

100

100

100

100

lYear100

100

100

100

92

100

100

100

100

100

100

quently, all restorations were in "exceiient/good" orat ieast "sufficient" condition. Table 2 shows thepercentage of "aipha" ratings in the different crite-ria. Some fiiiings received "bravo" scores for the in-tegrity of the tooth (only Syntac Classic/Tetric),proximal contact (oniy Syntac Classic/Tetric), andmarginai integrity (all groups). There were no statis-tically significant differences for any criterion be-tween the three DA groups. There were also noobvious differences between the various filling loca-tions, or margins located above or below the ce-mento-enamel junction.

One restoration (Syntac Classic/Tetric) showed aproximal distance wider than 100 pm and wastherefore rated "bravo" for the oriterion proximaicontact. Four proximal contacts were rated tooweak ("good"/"alpha") and two were slightly toostrong in this group ("good"/"alpha"). Within theTetric Ceram fiiiings, six contacts received oniy a"good" score, because three cases were rated assiightiy too weak and three as somewhat too strong.

Significant changes over time within individuaiDA groups were oniy obvious among the criteriamarginai integrity (Figs 1 and 3) and integrity ofthetooth (Figs 2 and 3),

At baseline, only two teeth within the SyntacClassic group showed an enamel crack which wasvisible but could not be probed ("alpha"). The oth-ers exhibited no enamel cracks whatsoever. After 6months, enamel cracks occurred in more than half

of all restored teeth, and one was even detectablewith a probe ("bravo"). This situation remained sta-ble up to the one-year recall at the end of the study.

A simiiar deterioration in tooth integrity was obvi-ous in both Syntac Sprint groups, although no toothhad to be scored "bravo." Slight chipping was de-tected in one oase, leaving a defect which could beeiiminated by polishing ("alpha"). The lower fre-quency of enamel cracks in these two groups wasnot found to be statistioally significant (p < 0.05).

The restorations' marginal integrity not onlyshowed deterioration overtime but also a change inthe quality of fiaws. In only two restorations (oneSyntac Classic, one Syntac Sprint "polymerized") atbaseline was gap formation (< 100 pm = "alpha")detectable. Another filling of the Syntac Classicgroup showed a discoloration of the margin whichwas not removable by polishing ("bravo"). In a totalof 29 restorations, marginal overhangs scored as"good" ("alpha") were observed.

After one year, the number of restorations with-out any detectable deficiencies ("excellent*') de-clined from 14 to 8. This was chiefly due to moregap formation and marginal discolorations. Fourcases of gap formation exhibited widths of morethan 100 |jm (3 Syntac Classic, 1 Syntac Sprint "notpolymerized") resulting in "bravo" scores. The domi-nant baseline probiem of marginal overhangs wasthus pushed into the background somewhat.

The color matching was "excellent" in almost all

170 The Journal of Adhesive Dentistry

Schoch et ai

restorations. In only one Tetric and two TetrJc Ce-ram fillings was a minor oolor deviation obvious

While the polish of seven Tetric fillings was ratedas "good" after one year, only two Tetric Ceramrestorations had to be scored as "good" because ofslight surface roughness.

The assessment of filling integrity revealed minorwear on two restorations in each DA group (2 Tetric,4Teric Ceram) after 12 months, mainly located onlateral ridges.

Concerning the anatomical form of the surface ofthe fillings, some differences between the two com-posites were observed. In both groups, four restora-tions were considered "overcontoured," whiletwelve Tetric, but only four Tetric Ceram fillings wererated as slightly "undercontoured," There were noobvious changes over time.

Step formation was rated quite similarly in bothcomposite groups. In 50% of all restorations, a posi-tive step formation was detected, but only fourrestorations within the Tetrio group and two withinthe Tetric Ceram group showed a negative step for-mation.

DISCUSSION

All fillings were still in place after one year, and re-ceived exclusively "alpha" and "bravo" scores for allmodified USPHS codes and criteria. This indicatesan acceptable in vivo performance. The high inci-dence of "alpha" scores is comparable to most ofthe studies using USPHS codes and criteria.i-2.i3Compared with Scheibenbogen's results of up to84% "bravo" after one year for the anatomical formof restorations placed by student operators.i'^ thehigh percentage of "alpha" scores in the presentstudy must be ascribed to the greater experience ofthe research assistants placing the adhesive resto-rations.

Within the course ofthe first year, there were nostatistically significant differences between thethree DA groups and the two resin compositegroups for any of the criteria. The question musttherefore be posed as to the advantages and disad-vantages of Syntac Sprint in combination with theresin composite Tetric Ceram,

The application of Syntac Sprint in only one layeris fast and easy. Only one material and no interme-diary steps are necessary, so that the user-friendli-ness is increased and technique sensitivity may be

100%

75%

50%

25%

Base 6 M 12 M Base 6 M 12 M Base 6 M 12 M

Synlac Sprint Syntac SprintSyntac Classic light-cured not light-cured

separately separately

Fig 1 Marginal integrity.

100%'

75%'

50%'

25%'

Base 6 M 12 M Base 6 M 12 M Base 6 M 12 M

Syntac Sprint Syntac SprintSyntac Classic light-cured not light-cured

separately separately

Fig2 integrityoftooth.

Modified USPHS ratings1 alpha- excellent2 alpha- good3 bravo-sufficient I

Fig 3 Key to Figs l a n d 2.

Vol 1, No 2 . 1 9 9 9171

reduced. Aithough none of the dentists in this studyreported considerabie time savings, the describedgood handiing properties could heip to raise the ac-ceptance of dentin bonding agents in gênerai den-tal practices.

Because it is often very difficult to ciinicaiiy mon-itor the moisture content of dentin, a special soi-vent has been deveioped for Syntac Sprint. ' 'According to the manufacturer's descriptions, it toi-erates contamination with saliva and the differentmoisture conditions occurring in vivo because itsaqueous components help to réhydrate the desic-cated collagen network. Since ail of the dentists inthis study appiied rubber dams and used the samewet bonding technique, a smali range of moistureconditions was present, but not contamination withsaliva. Under these conditions, Syntac Sprint's per-formance was similar to Syntac Ciassic after oneyear.

The manufacturer's recommendation to simulta-neously iight-cure the Syntac Sprint layer and thefirst portion of composite wouid signify a furthersimplification of the appiication protocol. Sincethere were no significant differences between thetwo Syntac Sprint groups, this study did not provideany arguments against the shortened applicationmode. On the other hand, it shouid be borne inmind that the layer's thickness will vary from den-tist to dentist, regardless of method.

Sensitivity plays a major role in the subjectivesatisfaction of the patient, and is therefore poten-tially crucial for acceptance of the restoration.^Compared to data from the literature^'' and the con-trol groups, the rate of postoperative discomfort ob-served in this study can be considered acceptable.The moment of photopoiymerization had no influ-ence on the development of hypersensitivity.

The adhesion of Syntac Sprint to dentin andenamel seems to be similar to other dentin bondingagents. In a Syntac Sprint manufacturer's brochure,shear bond strengths of non-precured Syntac Sprintto dentin were given as 23 MPa on extremely desic-cated or contaminated dentin and 24 iViPa on nor-mai or wet dent in . Twenty-four iViPa was alsoachieved on dentin when Syntac Sprint was pre-cured for 10 s. The shear bond strengths of non-precured agent to enamei ranged from 21 MPa ondesiccated enamei, to 22 MPa on contaminated orwet enamei, and on to a maximum of 24 MPa onnormai enamei. Precuring for 10 s provided a shearbond strength on enamel of 22 iViPa. in contrast,Frankenberger et ai^ reported a dentin push-out

bond strength of 27 MPa with precuring for 10 s.Bond strength was significantly inferior without pre-curing (22 MPa) or on contaminated dentin [20MPa). Based on these in vitro results, the use of arubber dam, the wet bonding technique, and pre-curing with iight for at least 10 s are recommended.

Ferrari et al" carried out SEM evaluations of thebonding mechanism of Syntac Sprint, which exhib-ited a hybrid layer of about 3 to 7 ym thickness,resin tags, and adhesive iaterai branch formation.They strongly recommend the use of Syntac Sprintaccording to manufacturer's instructions.''

The two restorations with proximal marginsbelow the cemento-enamei junction did not performdifferentiy from the fillings with all margins locatedin enamel. Differences between premoiars and mo-lars and between large and small cavities could notbe found after tweive months.

The handiing properties of Tetric Ceram do notseem to be inferior to those of conventionai Tetric.Tetric Ceram actually received better ratings forsome criteria, such as surface roughness andanatomicai form at the restoration surface, al-though these differences were not statistically sig-nificant. The results of the present study ciearlyindicate that marginal overhangs of well-matchingfine-hybrid resin composites are a persistant prob-lem, at least within the observed 12 months of ciini-cai service.

CONCLUSIONS

After 12 months of clinical service, aii Tetric/Syntac Ciassic and all Tetric Ceram/Syntac Sprintrestorations were in place and ciinicaiiy acceptable.

In terms of the modified USPiHS codes and crite-ria, there were no significant differences betweenthe different dentin bonding agent systems or be-tween the resin composites.

Light-curing of Syntac Sprint prior to the applica-tion ofthe resin composite did not have any impacton the clinical performance.

Due to its simpiified application protocoi, SyntacSprint may help to increase the acceptance ofdentin bonding agents and lower the technique sen-sitivity.

The future results of this prospective long-termciinicai study will facilitate a final evaluation of thisnew one-bottle adhesive.

172 Tbe Journal of Adhesive Dentistry

Schoch et al

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