Preventive Dentistry

 decision tree for the treatment of caries in posterior teethPaul Surmont* / Luc Martens** / Roland D'Hauwers**

Because ofa better understanding of the earies process, a decrease in the prevalence ofcaries, and the rapid development of dental materials, a renewed approach to the treat-ment of dental caries in the posterior region is possible. A decision tree for the treat-ment of caries in posterior teeth, taking into account some of the most recent toothsubstance-saving treatment options, is presented. These possibilities gradually evolvefrom nondestructive to conventional cavity preparations. In addition, the ''preventiveClass ¡I restoration" is introduced. The application of this conservative attitude towardinvasive techniques offers great advantages for both the patient and the dentist. Unfor-tunately, this approach is time-consuming. Long-term clinical evaluation of the applica-tion of the propo.fed decision tree on a wide scale is needed to confirm its potentialbenefits or to modify and improve treatment options. (Quintessence Int 1990,21:239-246.)

Introduction

During the last decade, caries prevalence has deelinedsharply among ehildren in Western Furope and theUnited States.'- A review article' states that more than25% of 12-year-old children are caries free. This de-crease is generally attnbuted to a decrease of carieson the smooth surfaces caused by the daily use offluorides. Local as well as internal (by ingestion) ef-feets may be attributed to the use of fluoride-contain-ing toothpaste.- In contrast to caries on the smoothsurfaces, the development of fissure caries is preventedto a lesser extent by fluoride applications.'

In the onter layer of the dental enamel of adults,over the years, physicochemical maturation takesplace.'' This yields a decrease in solubility of the en-amel. A recent epidemiologic survey by Helöe et aFindicates that, since the introduction of fluoride-con-taining toothpaste, the oral health of adults also isunproving. Several authors*-' have reported that, be-

' Assistant Professor, Departtnent of Conservative Dentistry,State University of Gent. De Pintelaan 185. B-9000 Geni. Bel-gium.

" Assistant Chairman, Department of Conservative Denlistry.State University of Gent.

cause of the decline of dental caries and the regularuse of bite-wing radiographs, interproximal cariouslesions will become smaller and possibly be diagnosedearlier. However, as a result of the frequent use offluorides, which helps to maintain the integrity of theenamel overlying dentinal lesions, occlusal caries hasactually become more difficult to diagnose.* T hereforebite-wing radiography should also be used as an aidin the diagnosis of oeelusal earies."

Bearing in mind the accepted knowledge of the ini-tiation, progression, and possible reversal of the canesattack, a greater responsibility should be assigned tothe patient for controlhng this process by improve-ment of oral hygiene (including daily use of fluoride)and by control of dietary habits.'

Additionally, the new dental restorative materialsthat have been developed for restoring (posterior)teeth during the last few years have made this newapproach possible. The great advantage of these ma-terials, eompared to amalgam, is their ability to adhereto tooth tissues, either mechanically to etched enamelor chemically to dentin and enamel.'"

Cavity preparation

Because the recently developed restorative materialsadhere to enamel, the principles laid down by Blackmay be reassessed." To be consistent with Black, the

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Preventive Dentistry

basic cavity outline should be prepared according tothe following five principles'':

1. The required outline form is obtained by "the ex-tension for prevention of the recurrence of decay."A prophylactic elimination of all occlusal pits andgrooves is performed, even In cases of local decay."This will often require that a little sound enameland dentin be cut away to obtain the correct outlineform."

2. The required retention and resistance form is ob-tained. This resistance form, necessary to provideenough strength for the restorative material, is re-alized by preparation of a minimal depth (at leastthrough the enamel) and butt joint cavity walls witha minimal loss of sound tooth structure, "resultingin a box-form of cavities." This yields stabihty forboth the restoration and the tooth against bitingforces,

3. The required convenience form is obtained. "Insome instances modifications are to be made thatwill render the form more convenient for placingthe restoration."

4. Any remaining carious dentin is removed. This islargely realized by extension for prevention and thebox form of cavities. If some carious tissue remainslocally, it must be removed carefully and completely.

5. The enamel wall is finished by elimination of allunsupported enamel prisms, to prevent them frombreaking down, which would result in poor mar-ginal adaptation and eventually recurrent canes.

No direct filling material that adhered to toothstructures was available when Black'- eoneeived theseprinciples. Nevertheless, they proved, for a long peri-od, to be excellent guidehnes. In fact, even with thenew adhesive materials, they remain a standard forrestorative dentistry.

Thylstrup et al'̂ concluded that, up to now. the "drilland fill ideology'" is still considered by most dentiststo be the way to treat dental caries. Elderton" andMacchi,'* however, have stated that present-day res-torative dentistry should become a set of therapeuticmeasures with the ultimate goal of fighting an infec-tion and providing protection against reinfection.

Silverstone''' and Primosch'^ reported that, becauseof a better understanding of the caries process, somelesions that would previously have been treated by acavity preparation and a subsequent restoration, maynow be treated by an application of fluoride, whichenhances remineralization. Fluoride has a lesser effect

on preventing fissure caries than it does en the smoothsurfaces. Nevertheless, Svanberg nnd l.ocsche havepointed out that a well-directed lluoride applicationimmediately after tooth eruption can prevent the de-velopment of fissure caries.

Acid etching of the enamel can be considered a wayof performing extension for prevention. Undercuts areunnecessary for obtaining the retention form, becauseretention is actually gained by means of the acid-etchtechnique. When pit and fissure sealant is being used,the minimal depth is limited to the length of the resintags penetrating the enamel. If a bulk of (compositeresin) restorative material is needed, only the conven-ience form is prepared, mostly hmited to the size ofthe bur. Because lesions are becoming smaller, prep-aration of the convenience form generally yields theremoval of all carious tissue. Taking into account theseconsiderations, when posterior composite resins areused as restorative materials, the principles put for-ward by Black'- are still fully apphed. Several authorshave stated that the outline form in these cases shouldbe restricted to the extent of the carious lesion, com-bined with an appropriate fissure treatment.'*--' Theoption of a limited cavity outline was already sug-gested by Black'" for the treatment of small occlusallesions.

For the treatment of small interproximal cariouslesions, Kennedy- and McLean'' have propagated the"tunnel preparation" or "internal preparation." Usingthis technique, access to the approximal carious tissueis gained from the occlusal surface, while the marginalridge is kept intact. Recently, however, it was foundthat with use of the tunnel preparation, in most casesthe carious tissue was not totally removed.'"-' Therestorations also displayed a relatively high degree ofleakage at the interproximal margins.-^ These disad-vantages are caused by a limited visibility of the den-tinoenamel junction at the interproximal level. Ae-cording to the same authors,-'*'-^ low visibility at theinterproximal level can be improved by enlargementof the occlusal aspect of the preparation. This is incontradiction, however, with the basic philosophy ofthe tunnel preparation.

These developments have been the focus of severalrecent papers and congresses.''"-'"'-'' It was our inten-tion to translate this new preventive approach intoguidelines that arc applicable in daily conservativepractice. In addition, an alternative for the tuntielpreparation, which we define as the preventive Classa restoration, is presented. The treatment of extensivelesions will not be discussed in this paper.

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Preventive Dentistrv

Treatment options

A weighted thought process leads to the decisionwhether a treatment is needed or not. The most im-porlant factor in this matter is to know whether thispatient belongs to a high-risk group, or if a tooth iscaries active, and if this activity can be arrested solelyby improvement of the patient's oral hygiene and nu-tritional habits,"-'' In this respect, there is a need fortechniques that allow preeise identification of caries-active sites and that are applicable in datly practice,-*Up to now, dentists mostly have had to rely on thecaries history, plaque scores, and age of the patient,'

If intervention by tbe practitioner is required, thefollowing can serve as a guideline toward a more pre-ventive approach to dental caries in tbe posteriorteeth, A deeision tree of all treatment options is shownin Fig 1.

The first evaluation that has to be made is whetheror not the tooth displays an interproximal (initial) le-sion. This can be checked by either visual or tactileinspection, by bite-wing radiography, or by transillu-mination.*'

If the interproximal surface is intact, then the treat-ment options suggested below the first subbeadingshould be followed,'' while the treatment options sug-gested under the second subheading should be fol-lowed when the proximal surface displays a lesion.

Pit and fissure earies: prevention and treatment

Dental caries can be considered an infection, causedby colonization by Streptococcus mutans. Coloniza-tion in the fissures can be prevented by fiuoridation(eg, with fluoride varnish) immediately after tootheruption. Thus, the fissures will be colonized by non-cariogenic bacteria and will not become carious,''

In patients belonging to a high-risk group-* (eg. car-ies-aetive patients with an elevated level of S mutans.patients witb high sugar intake, some pédiatrie pa-tients, mentally handicapped patients, physicallyhandicapped pafients who cannot brush their teethadequately, patients treated under general anesthesia,etc) sound teeth can in some instances be sealed,-' Tbistreatment option, in which sound fissures without thepresence of any (initial) lesion are sealed, is designedfor the high-risk groups and is not featured in thedecision tree, A sealant itself does not protect the in-terproximal surface from carious attack, although itmay increase the age at which a patient needs resto-

ration. In this way, the survival of any future resto-ration tnay be increased considerably,'"

Fissures that need to be scaled and that are openand not suspected of caries are sealed using the non-invasive pit and fissure seaiing technique. From a re-view of tbe different procedures used for the treattnentofocclusal fissures. De Craene et al'' concluded thatnarrow sticky fissures or fissure slopes that are sus-pected to bave caries and tbat show a white spot areto be treated with tbe invasive pit and fhsure sealingtechnique described by Simonsen, '̂ With this tech-nique, the narrow, sticky fissures are prophylactieallyenlarged with small burs, ehminating all suspeetedcarious tissue, Silverstone'̂ demonstrated that, in mostcases, fissure caries initiates on the fissure slopes, rath-er than in the deepest point of the fissure, A fissurecan therefore be sealed without any further elimina-tion of tooth substance if, during preparation, the areaof discoloration decreases, Theilade" found that, withacid etching, more than 75% of the cariogenic bacteriaare eliminated. Moreover, Mertz-Fairhurst et nP dem-onstrated that these fissures may ultimately becomesterile.

If the carious lesion penetrates into the dentin inone small spot, this area is locally prepared with acylindrical bur. This local, small cavity is filled with aposterior composite resin, while the remaining fissureis covered with a sealant,'̂ "-' This is called ihs preven-tive resin restoration by Simonsen,'' Since the termspreventive resin restoration and preventive glass io-nomer restoration may imply that only such materialscan be used for restoring this type of lesion, and toconform with the preventive Class II restoration thatwill be introduced later, we prefer tbe term preventiveClass 1 restoration.

A conventional Class I restoration, according toBlack,'- is performed in cases in which the cariouslesion penetrates the dentin in different spots or thewhole fissure appears to be carious. This can be re-stored with either amalgam or a posterior compositeresin.

Again, tbe only differences from Black's principlesare the adhesive restorative materials being used.

Interproximal caries: prevention and treatment

If an incipient lesion is diagnosed, visually as a whitespot without any surface defect, or radiographicallyas a triangular radiolucency limited to the enamel, thissubsurface lesion is to be treated by local interproxi-

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Preventive Dentistry

Erupting teeth Erupted teethI

Weighted thought process

No treatment need

No interproximal lesion

Oeclusal fissurewith an initiai lesion

Occlusal fissurewith dentinal earies

Openfissure

Narrowstiekyfissure

Loeaioeelusaldentinallesion

Largeocclusaidentinallesion

Soundoeclusaltissure

Fig 1 Decision free ofthe treatment ot cariesin the posterior region.

242 Quintessence International Voiume 21, Number 3/1990

Preventive Dentistry

Treatment need

1 ^ Fluoride application

I I Noninvasive pit and fissure sealing

^ ^ Invasive pit and fissure sealing

WE Conventional cavity preparation

Interproximal lesion

Interprcximai lesionlimited to the enamel

Interproximal lesioninto the dentin

Occlusallissurewith aninitiallesion

Occiusaltissure

withdentinalcaries

Soundocciusaitissure

Occlusaltissurewith aninitiallesion

Oeclusatissure

withdentinaicaries

Open Narrowlissure sticky

fissure

Local Largeocclusal occlusaldentinal dentinallésion lesion

Opentissure

Narrowstickyfissure

Loca iocclusaldentinallesion

Largeocclusaldentinallesion

Recall

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Preventive Dentistry

Fig 2 Schematic representation of a preventive Classrestoration.

Preuertive Class II restoralion+

Noninvasive pit and fissure seallrg

Fig 3 Schematic representation ot a preventive Class IIrestoration combined with noninvasive sealing of the oe-elusal pits and tissures.

mal fluoride application. Silverstone" and Primosch'*indicate that, alter intensive fluoride therapy and withadequate oral hygiene and dietary habits, many sub-surface lesions can be remineralized. This concept oftreating caries without the use of surgical treatment,although known to most dentists, has not yet foundits way into daily dental practice."

The proposed treatment options for dealing withfissure caries can be combined with an interproximaltopical fluoride application. This is consistent withactual concepts for a preventive attitude towards deo-ta! caries.

Presently, in daily practice, teeth displaying smallprogressive interproximal lesions with dentinal in-volvement, but without pit or flssure caries, are fre-quently seen. These lesions can be treated by a typeof restoration we call the preventive Class II restora-tion (Fig 2). The interproximal lesion is eliminated bythe preparation of a traditional approximal box.Elderton''' has suggested a new approach to the tra-ditional box cavity. Nevertheless, the contact area stillmust be cleared totally.*''••'* If a posterior compositeresin is chosen as fllling material, the axial wall isprotected by a liner or a base eement. The beveledenamel margins of the box are aeid etched, and thecavity is fllled with the incremental technique. If amal-gam is preferred, the cavity should display retentionform. Afterward, fluoride application to the fissure isoften less pertinent, because the fissure is already col-onized by oral bacteria. The fact that a progressiveinterproximal lesion has developed, however, eouldmean that the tooth is caries active. Then, the occlusal

surface is sealed either by ihe noninvasive (Fig 3) orby the invasive sealing teehniqtie (Fig 4) as discussedpreviously. Moreover, application ofa sealant over thepreventive Class II restoration will reduee marginalleakage.'"

In cases in which both the interproximal surface andone occlusal pit are carions, and both lesions extendinto the dentin, a combination of a preventive ClassI restoration (the preparation of one occlusal pit), apreventive Class II restoration (the preparation of anapproximal box) and invasive sealing of the remainingocclusal flssure is the therapy of choice (Fig 5).

Finally, when both the interproximal surface and theocclusal fissure are carious, and both lesions penetratewell into the dentin, a Class II restoration as deserihedby Black'- is prepared, taking into account the latestinsights into cavity design. '̂' This can be filled witheither amalgam or posterior composite resin.

After the initial treatment, individually determinedreview appointments should be planned according tothe patienfs needs and the possibilities of an adequatefollowup of diagnosed initial lesions.-''

Disadvantages

Some disadvantages are hnked to the application ofthe described decision tree with its respective treat-ment options:

1. A refined diagnosis of the lesions is reqtiired, '̂whieh sometimes is quite time-consuming. For theprivate praetioner, time spent on performing this

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Preventive Dentistry

Preventive Glass II restoration-̂

Invasive pit and lissiiie sealing

Fig 4 Schematic representation ot a preventive Class IIrestoration combined with invasive sealing ot the occlusalpits and fissures.

Fig 5 Schematic representation of a preventive Class Irestoration combined with a preventive Class II restoration.

refined diagnosis is not rewarded, which could eas-ily lead to overtreatment.^

2, The use of composite resin restorative materials inthe posterior region is technique sensitive and time-consuming." Complete isolation of the operativefield is mandatory. Isolation is sometimes difficultto obtain in young patients.-"

Advantages

1. Treatment is conservative, limited to the extent ofthe lesion."-'

2. Less sound tooth structure is removed than is re-moved in traditional cavity outlines.-"

3. During the treatment session, preparation can beswitched easily from the least destructive to themore radical removal of tooth tissue.''

4. With hoth watchful waiting and the fluoridationtherapy, some responsibility is assigned to the pa-tient in preventing further destruction. This indi-rectly could promote better oral health.'

5. If the preventive attitude is applied to carious le-sions in the posterior region, the drill and fill ide-ology will be eliminated and use of a weightedthought process before the bur is handled will bepromoted.-'

CoDclusion

This method of decision making is a delicate processthat demands trained diagnostic skills and consider-able working time. Therefore, establishing a refmed

Quintessence InternationalVolume 21, Number 3/1990

diagnosis will take more and more time in daily prac-tice. Mechanisms should be installed within the healthinsurance services to remunerate the time spent by thepractitioner. Olherwise, this will lead to a higher de-gree of overtreatment. In this context, the develop-ment of practical additional tools for the objectiveidentification of particular sites or patients at riskwould be useful.

Review appointments, in which the progression rateor arrest of initial lesions is monitored, are mandatory.Recall should be followed meticulously by the patient.Additionally, patients should continue to use fluoridedaily to follow strictly all dietary counseling, and toadopt proper oral hygiene measures. Compliance willyield better oral health. Only long-term clinical trialswill ultimately reveal all the potential benefits linkedto this preventive approach to dental caries.

References

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2. Fédération Dentaire Inlcrnalionale, World Health Organiza-iion: Changing patterns of oral health and implications foi oralheatth manpower. Int Dent J 1985;35:2.15-25I.

3. Nikoforuk G: Demd Carm: Etiology and Medmnbm.s. BaselKarger Verlag, 1985.

4. Hoppenbrouwets P. Sd.olberg H, Borggreven J: Measurementol the permeabihly of dental enamel and its vaiiaiion wiih dcpihusing an eleclrochemical methoJ. J Dent Re.s 1986-65154-157

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13, Thylstrup A, Bille J, Qvist V: Radiographie and observed tissuechanges in approximal carious lesions al the lime of operativetreatment. Caries Res 1986:20:75-84,

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17, Svanberg M, Loesche W: The salivary concentration of strep-tococci mutans and streptococci .vangnis and their colonizationof artificial tooth fissures in man. Arch Oral Biol 1977;22:441^147.

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28. Krasse B: Carles Ri.sk. Chicago. Quintessence Publ Co, 1982.29. Martens L: The treatment of fissure caries - a preventive ap-

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31. Simonsen R: Clinical Applications of the Acid Etch Technique.Chicago, Quintessence Publ Co, 1978, pp 19-42.

32. Theilade E: Effecl of fissure sealing on the microflora in oeelusalfissures of human teeth. Arch Oral Biol 1977;22:251-259.

33. Merli-Fairhursl EJ, Schuster GS. Fairhurst CW: Arresting car-ies by sealants: result of a clinical study. J Am Dent AssocI986;112:194-197.

34. Elderton RJ: New approaches to cavity design. With specialreference to the Class II lesion, Br Dent J 1984:157:421^27.

35. Otto P, Rule J: Relationship between proximal cavity designand recurrent caries, J Am Dem A.tsoc 1988:116:867-870.

36. Fuks A, Grajower R. Eidelman E: Assessment of marginal leak-age of Class 11 amalgam-sealant restorations, J Dent Child1986:53:343-345,

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20th International Meetingon Dental Implants and Transplants

Bologna (Italy), May 18-20, 1990

Information: G,I.S,I. c/o Prof. G. Muratori1, Via S, Gervasio, 40121 Bologna (Italy), Tel, 051/227505-237516

246 Quintessence International Volume 21, Number 3/1990