Restorative decision-making behavior with magnification

operative Dentistry

Restorative decision-making behavior with magnificationS, A, Whitehcad* / N, H, F, Wilson*

Assessment of occlusal fissure systems and restorations of amalgam in 100 extractedteeth were carried out by four examiners. An initial assessment, made with the nakedeye, was repeated with binocular magnification (X 3). The data indicated that restorativedecision-making behavior was modified when magnification was used, with an in-crease in the number of restorations planned for replacement and an increase in thenumber of tooth surfaces planned for restoration. Statistical analysis indicated that oneof the examiners was particularly sensitive to the use of magnification and modifiedhis treatment planning behavior considerably. As part of the process of adapting to tiieuse of magnification, clinicians should review their decision-making behavior.{Quintessence Int 1992;23.-667-671.)

Introduction

The treatment planning strategies of individual dentalpractitioners have been showti to have a significant im-pact on the number of restorations placed and the costof restorative care, Elderton and Nuttali' have shownthat the number of tooth surfaces planned for restora-tion by a group of 15 dentists ranged from 20 to 153surfaces. This represented a disparity in treatment costbetween £92,55 and £47S,60, calculated from theUnited Kingdom National Health Service fees of theday. This study also showed that many of the restora-tions (59%) were plantied with a minority consensusof the practitioners. Richardson and Boyd" have indi-cated that the perceived reasons for amaigam restora-tion replacement have changed, possibly reflecting thedecline in the reported incidence of caries in the de-veloped world. They found that secondary caries, as areason for replacement of existing restorations, de-creased by 33% over the f2-year period of their study,while marginal breakdown as a reason for replacementincreased by 400%,

Lecliirer, Department of Restorative Denlistry, tjniversiiy ofManchester Dentüi Hospilal, tiíigiier Cambridge Street,Manchester MIS 6FH, Engiand.Professor and Dean, university of Manchester, DentalSchool.

Given these changes in the reasons for restorationreplacement, improved longevity of restorations mustbe brought about by an improvement in the quality ofrestorations and by research to provide clinical markersto indentify those restorations in which marginalbreakdown may not be associated with secondarycaries,

fn the search for a more prevention-orientated andcost-effective dental care service, evaluation and re-storative decision-making behavior regarding restora-tions and unrestored tooth surfaces are of paramountimportance if clinicians arc to treat only those restora-tions and susceptible tooth surfaces that dematidoperative intervention.

Several authors have recommended the use of binocu-lar magnification for detital procedures. McLean,"** forexample, has alluded to the terms nmcrocutting whenperforming an operative procedure with the naked eyeand microcurting when performing procedures withmagnification. These terms, however, relate to oper-ative intervention rather than to assessment and diag-nosis, A review of the literature reveals that there issome anecdotal evidence that the use of magnificationimproves restorative decision-making behavior,^ How-ever, it has been suggested that the advantage of mag-nification may be offset by a tendency to overtreat,particularly in relation to the replacement of existitigrestorations.

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Operative Dentistry

Fig 1 The binocular magnification (x 3) loupes employedin this investigation. The spectacle frames supporting theloupes use optically clear giass lenses.

The aim of this in vitro study was to investigate theinfluence of the use of a x 3 magnification aid on deci-sion-making behavior regarding intact and resioredpremolar and permanent molar teeth.

Method and materials

Selection of the teeth

One hundred extracted premolar and permanent moiarteeth, stored in an aqueous medium, were selected forthe investigation. Fifty of the teeth selected containedm oderate-to-large'' dental amalgam restorations placedprior to extraction. The remaining 50 teeth were unre-stored but displayed staining of the fissure systems.Any teeth that had been damaged during extraction, orthat had overt pit and fissure caries or fractured resto-rations were excluded. The teeth were mounted inplaster blocks, numbered 1 to 100 at random by usinga computer-generated table, and stored moist. Softdebris and excess plaster was removed from the crownsof teeth with a nailbrush and soap under runningwater.

Examination ofthe teeth with the naked eye

The teeth were examined by four full-time teachers ofconservative dentistry recruited to take part in this in-vestigation. Under controlled lighting conditions, eachof the four clinicians examined the teeth indepen-dently using the naked eye at a fixed eye-tooth dis-tance of 32 cm at 90 degrees to the occlusal surface ofthe tooth. Immediately prior to the evaluation, the

teeth were dried using oil- and water-free compressedair. Specimens were subsequently rehydrated aftereach examination session. The use of dental explorersor other aids was not permitled, because changes inthe surfaces of the teeth and in and around the mar-gins of the restorations might have influenced sub-sequent examinations. Only the occlusal surfaces ofeach tooth, as seen from the viewing angle of 90 de-grees, was inspected. A dental mirror was available toreflect light onto the tooth if the examiner wished.

The examiners were asked to decide on the treat-ment that they thought appropriate for each tooth, as-suming that the teeth were those of an adult patientwith a well-maintained dentition who was being seenfor a routine recall appointment. The examiners usedtheir own judgment as to the need for operative inter-vention, but within a framework of criteria mutuallyagreed on by the participating examiners within thisstudy. It was a generally accepted principle by theparticipating examiners that operative interventionshould be undertaken when the examiner consideredthere to be active primary or secondary dentinal cariesthat couid not reasonably be expected to arrest or re-mineralize.

The examiners were required to reach one of the fol-lowing decisions in each case: 1 — operative interven-tion with restoration of the intact tooth or replace-ment of the existing restoration ('•restore'"): 2 = toothsurface or restoration acceptable ('"leave"); 3 = nooperative intervention required at this recall but spe-eial attention to be paid to this surface at subsequentrecall visits ("defer"). Radiographs of the teeth werenot provided. The data were entered directly into amicrocomputer by the examiners using a dedicateddata-capture program.

Examination of the teeth with magnification

After 1 week, but within 1 month, the assessments ofthe selected teeth were repeated by the same examin-ers under identical conditions. However, on this ocea-sion, the examiners were asked to carry out the proce-dure while wearing a binocular magnification aid (x 3).The magnification aid chosen for this investigation wasthe Keeler binocular loupe magnification system(Keeler Ltd) (Fig 1). The loupes were adjusted to theoptical needs of each examiner with respect to inter-pupillary distance, individual eye focus compensation,and loupe size. At the time of the study, all theexaminers had had the opportunity to gain severalweeks experience in their use. The same eye-tooth dis-tance of 32 cm was maintained to ensure that the

668 Quintessence International Volume 23, Number 10/1993

Operative Dentistry

examiners visualized the tooth at a constant magnifica-tion of X 3, The 32 cm also corresponded to the focallength of the magnification system that allowed thelens system of the eye to focus the image from infinity.As described previously, the examiners entered thedecision codes directly into a microcomputer.

Artalysis of the data

The data were analyzed to assess the intraexaminervariability in treatment planning behavior when x 3binocular magnification was used. For descriptive pur-poses, data were expressed in percentages of decisionsmade with regard to overall changes in decision be-havior, particularly with regard to decisions to defer,and the number of decisions that were made by aminority consensus. For the purposes of the statisticalanalysis of the consistency of the examiners, when adecision to defer was recorded, it was interpreted as adecision to leave the tooth, because no operative inter-vention was intended. Thus the judgment was essen-tially dichotomous and allowed the use of the Kappastatistic as recommanded by Fleiss and Chiltern. TheKappa statistic was calculated using the methoddescribed by Fleiss et al" and the results were inter-preted according to guidelines suggested by Landisand Koch." For most purposes, values of Kappa below0.40 may be taken to represent poor consistency,values between 0.41 and 0.60 moderate consistency,values between 0.61 and 0.80 substantial consistency,and values between O.Sl and 1.00 good consistency.

Kesults

The decisions made by the examiners are summarizedin Fig 2. All of the clinicians recruited to take part inthis study made more decisions to intervene opeia-tively when they examined the teeth with binocularmagnification. Where there was a group of decisionsto defer recorded with the naked eye, an increase indecisions to restore recorded with magnificationtended to be associated with a decrease of decisions todefer. From calculations of observed percentages, thepercentage of intervention decisions that were madeincreased by 56% when unrestored occiusal surfaceswere examined with magnification and by 55% whenrestored ocelusal surfaces were observed. For exam-ple, one examiner's decision to intervene rose by122% in unrestored teeth and 50% in restored teethwhen magnification was used.

The Kappa statistic indicated that, for three of thefour examiners, there was substantial consistency be-

DD

•

DEter

Leavs

Restore

Oi/eiall decision behavior

Eye Magnily &ye Maynify Eye Maynily Eyt Magnify

Four Three Two One

Decision beliavior for uniestored teeth

Eye Magnify Eye Magn'fy Eye Magnily Eye Magnily

Four Three Two One

Decision beiiavior for reslored teeth

Eye Magnify Eye ftflagnify Eye Magnily Eye Magnify

Four Three Two One

Fig 2 Decision-making behavior of the four examinerswith the naked eye and with x 3 magnification.

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Tíiblf I Values of Kappa Cor intraexaminer consistencywith and without magnification for the surfacesexamined

Examiner

Surface One Two Three Four

All surfacesRestorationsUnrestoredsurfaces

0.50 0.81 0.96 0,740.64 0.71 0.67 O.fil0.52 0.77 0.64 0.92

tween the decision-making behavior when the nakedeye and magnification were used (Table 1). This con-sistency was maititained for restored and non-restoredtooth surfaces. The Kappa statistic for the fourthexaminer was low (mean < 0.6Ü). indicating that, forthis examiner, the use of magnification modified thedecision-making process beyond that which couldhave been expected by chance alone.

There was a consensus in 62% of decisions madewith the naked eye, but in only 43% of decisionsmade with magnification. The percentage of minoritydecisions for evaluations with the naked eye and mag-nification were 26% and 38%, respectively. Thesechanges were considered to be related to the decision-making behavior of the fourth examiner when mag-nification was used.

Discussion

Previous studies have shown that there is ponr agree-ment among clinicians as to the presence of caries andthe correctness of their judgment,'" Elderton and Nut-tall" have shown that there is considerable variabilityin the prescribing patterns within a group of dentists.They also reported that small changes in the perceivedlevel of quality of existing restorations may lead to sig-nificant changes in prescribing behavior, leading to aconsiderable loss of tooth structure and a concomitantincrease in health care costs. Treatment recommen-dations varied among the clinicians"; this is in agree-ment with other studies on the variation of treatmentplanning among dentists.'

In this study, when there was a decision to replace arestoration or restore a fissure system, there was nofurther examination of the tooth for caries to see ifthat decision had been correct. In support of thisapproach, several studies have indicated that there is

little correlation as to the state of the margin of anamalgam restoration and the likely presence of recur-rent caries.'^"" One study included contouring andpolishing of defective margins as a treatment planningoption."* This strategy was not adopted in this presentinvestigation because contouring and polishing defec-tive tnargins of amalgam restorations usually increasesthe amalgam marginal angle and may predispose therestoration to accelerated marginal failure.

Treatment planning decisions to restore intact teethand to replace existing amalgam restorations changedsignificantly when decisions were made with magnifi-cation; more decisions were made to intervene opera-tively. This suggests a decrease in the acceptability ofa restoration or lo a perceived ittcrease in the likeli-hood of primary fissure caries when a x 3 magnifica-tion aid was used.

When the naked eye was used, about 26% of thedecisions were minority decisions (ie, two or noexaminers reaching a consensus). This result is inbroad agreement with data recorded by Merrett andElderton," who found 29% of decisions to be minor-ity ones. However, with magnification, the number ofminority decisions rose to 38%, with a correspondingfall in the number of cases of total agreement. Thissuggests that, despite agreed criteria for intervention,in approximately one third of the teeth examined, oneclinician was applying replacement or restorationcriteria different from those being used by the others.There was also a decrease in the number of defer deci-sions when magnification was used, fulfilling the ex-pectation that magnification would reduce the uncer-tainty of decision making.

The increase in operative intervention decisions forselected individuals may have been due to their lack offamiliarity with the effects of the magnification sys-tem. Defects in fissure morphology and restorationmargin defects that may have been unresolved withthe naked eye could now be visualized. It is not sur-prising, therefore, that there was an increase in thenumber of such defects observed and considered towarrant operative intervention. This increase in vi-sualization may not, however, fully explain thechanges in decision-making behavior, particularlygiven the wide variation between one examiner,whose behavior was markedly changed by the use ofmagnification, and the others, whose decision-makingbehavior was not so affected.

The decision to initiate restoration of a tooth sur-face or restoration replacement is essentially an exer-cise in problem solving. As with many dental prob-

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lems. the respotise of the clinician is influeiicetl consid-erably hy past experiences. The clinician develops hisor her own criteria for problem solving, in this case foroperative intervention, based on his or her owtiunique experiences. For example, a clinician's exper-iences in ati era of high caries activity or poor restora-tion longevity might influence the cognitive networkto operate on a more intervention-orientated criteriafor restoration evaluation.

Improvements in restoration quality that depend onthe resources of the operator are more difficult toqtjantify, because many factors are involved: thesemay include the skill of the operator, his or her educa-tional standard and educational background, patientcompliance, and the system of retnuneration of theoperator within the prevailing health eare framework.Changes in these types of behavior patterns are usu-ally brought about by educational means. To this end,consensus views, such as the summary statements ofthe International Symposium on Criteria for Place-ment and Replacement of Dental Restorations,"* mayaid in educating chnicians and clarify the definition ofcriteria for restoration replacement.

S. Fleiss JL, Fisehman SL. Chilton NW. et al: Reliability of dis-ercte measurements in caries ttials. Caries Res 1979;13:23-3t.

9. Landis JR, Koch GG: The measttrment of observer agree-ment for categorieal data. Biometrics 1977 ;33:159-174,

10. Eldeilon RJ: Variability in the decision-makitig process andimplications for ehange toward a preventive philosophy, inAnusavice KJ (ed): Quality Evaluation of Denial Rexloralions:Criletia for Pliicemem and Replacement. Chicago, Qtiintes-sence Publ Co, 1989, pp 211--219.

11. Elderton RJ, Nttttall NM: The nature of restorative dentaltreatment decisions. Br Dam I 1983; 154:363-365.

12. Maryniuk GA: Replacement of amalgam restorations thathave marginal defects: variatiotis and cost implication^;. Qain-

13. Letzel FiF, Vrijhoef MM: The influenee of polishing on themarginal integrity of amalgatvi restorationü. / Orai Rehabill984;U:89-94.

14. Letïel HF, Aardening CJM. Fick JM:Tat:iish, ciirrosion. mar-ginal fracture and creep of dental restorations: a two-yearelinieal study. Oper Dem 1978:3-,82-92.

15. Bryant RW, Collins CJ: The finishitig and early marginal frac-ture of clinical amalgam restorations. J Dem 1987; 17:111-116.

16. Thornton R Linden GJ: The assesstnent of restorations bydental sliidetits ard their teachers. / Deiir 1987;I5:19-29.

17. Merrett MCW. Elderton RJ: An in vitro stndy of restorativedental treatment decisions, Br Dent 3 1984;157:128-135.

18. Symposium summary statements, eriteria, and reeommenda-tions, in Anusaviee KJ (ed): Quality Evatuatiou of Dental Re-slorations: Criteria fir Placement and Replaeement. Chicago,Qtiintessenee Ptibl Co, 1989, pp 411^15. n

Summary

The results of this study indicated that the use ofmagnification may exert a considerable influence onrestorative decision-making behavior. As part of theprocess of adapting to the use of magnification, it isdesirable for clinicians to review their decision-makingbehavior with regard lo the assessment of restorationsand oeelusal fissure systems.

References

1 Elderlon KJ, Ntittall NM: Variation among dentists in plan-ning treatment, Br Dem J 1983:154:201-206.

2. Richardson AS, Boyd MA: Replacement of silver amalgamrestorations by 50 dentists in 246 working days. J Can DemAssoc 1973;8:556-559.

3. McLean JW: Limitations of posterior composite resins andextending their tise witb glass ionomer eements. Qt:mtessençelnt 1987; 18:517-529.

4 McLean JW, Gasser O: Glass-cermet cements. (2""i'<'"c""'¡m 1985; 16:333-342.

5. Simonsen RJ: The use of field magnification, editorial. Qxm-

tessence tnt 1985:16:44.S.6 Wilson NHF, Wilson MA, Wastell DC, et al: A elinical trial of

a visible li^tit cured posterior eomposite restn restorativematerial: fiv°e-year results. Quintessence Inl 1988:19:675-681,

7 Fleiss JL Chiltern NW: The measurement of interexaminer• agreement in periodontai disease, I Periodom Res

19S3; 18:601-606,

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