Measurement of Changesin Complete MandibularDenture Security UsingVisual Analogue Scales

OavidJ. lamb. BUS, .V.DS, FDSSenior Lecturer and Honorary ConsultantDepartment of ResWradVe Dentislry

Bryan Ellis, BSc, MScSenior LecturerSchool oí Materials

Gerry Kent, BSc, PhDSenior LecturerDepartment of Psychiatric Medicine

University of Sheffield

United Kingdom

The security of mandibular dentures for edentulous patients has beenquantified using a visual analoguG scale, Relining "loose" dentures wasshown to produce an increase in the patients' assessments of denturesecurity for 21 outot23 patients. The security of a denture after reliningwas found to correlate with the form of the residual mandibular ridge asmeasured by the mean anterior ridge height, Int i Prosthodont 1994:7:30-34.

Q uality of life for the edentulous patient is sig-nificantly affected by denture wearing,' and

patient satisfaction with complete dentures is animportant research topic. However, few clinicallyuseful factors have been found to correlate withpatient satisfaction, A patient's history providesthose that are the most reliable, ie. previous prob-lems with dentures,-''the number of previous den-tures,' and the frequency with which they havebeen replaced.' In general, the oral anatomy can-not be used to predict success,' Thus, althoughweak correlations have been established betweenmaxillary residual ridge quality and patient satisfac-tion, the size of the mandibular ridge has not beenshown to be of significance,''

Correlations between patient satisfaction andfactors in the patient history and clinical examina-tion allowdifficult patients to be identified; they donot help prescribe clinical techniques that mightimprove satisfaction.

Although definite relationships between patientsatisfaction and variations in clinical techniquewould be useful, even attempts to relate a patient'sown assessment of denture quality with a clinicalassessment of their dentures have been inconclu-sive,'" possibly because denture satisfaction is acomplex, subjective feeling and desirable qualitiessuch as stability may sometimes be incompatiblewith good appearance.

Reprint requests: Dr Lamb, Department of Re5torati\je DenlislrySchool of Clinics! Dentistry, Ti^e University of Si^effield, Welles-ley Road, Sheffield .SIO 2S1, United Kingdom.

As an alternative, some workers have chosen toisolate those factors identified as being responsiblefor patient satisfaction, ie, good retention, pain-free function, and good appearance,' and relatethem individually to aspects of clinical technique.Reductions in postplacement pain have thus beenrelated to provision of balanced occlusion af thetime of placement,'" and denture base extensionsinto the retromylohyoid fossa have been shown bycineradiography to be associated with greater sta-bility of the mandibular denture."

That, in a patient's judgment, such improve-ments are associated with better dentures can onlybe confirmed by measurement of their own per-ception. This can be done by assessment on a visualanalogue scale (VAS), which is a technique com-monly used for quantifying feelings," In compari-son with others, these methods have been provedreliable in dentistry for the assessment of pain,"The purpose of this study was to use a VAS toquantify the changes in denture security producedby relining mandibular complete dentures.

Materials and Methods

Selection oí Subjects

Twenty-eight edentulous patients were selectedfrom those attending Sheffield Dentai Hospitalcomplaining of looseness of their dentures. Allwere experienced complete denture wearers, andall had had their present dentures made at least 3years previously. Two were later excluded from thestudy because the dimensions of their residual

I ol Prosthodoniii 30 Voljme7,Niiniber1,

Denture iooseand insecureat all tiirea

Oenture lirmand secure atall titres

Measurement of Complete Mandibular Denture Security

Fig 1 VAS used in the study (notto scale); score (S) == distance inmm from leff extremity.

mandibular ridge could not be measured by thetechnique used, and one because of poor literacyskills that precluded understanding of the VASmethod of measurement. Two were excluded be-cause they failed to attend several of their sched-uled visits and their treatment was excessively pro-longed. Twelve men and eleven women completedthe study.

Clinical Technique

At the first visit, the purpose of the study wasexplained to the subject, and the occlusion waschecked for any interferences that might have af-fected denture security. Next, if a subject com-plained of looseness of the maxillary denture, topreclude the insecurity of that denture inttjrferingwith later clinical procedures and measurements,its retention was improved by providing peripheraladditions or a functional posterior palatal seal untilthe complaint was resolved. At the next visit, man-dibular denture security was scored on a VAS, andthat denture was relined using a chairside relinematerial (Total E^ard, Stafford Cookson, WestHempstead, NY) before the patient was dismissedfor review in 2 weeks. The occlusion was preservedby contact between tbe maxillary and mandibularteeth, but, to ensure a consistent lingual extensionat intervals during tbe setting of the reline material,the subject was requested to open and protrudethe tongue to contact the lower lip.

If, at the review visit, the patient had been pain-free, the security of the mandibular denture wasagain scored on the VAS. For the eight patients whofound that the relined denture was not comfort-able, any necessary adjustment of the fitting sur-face was completed and the pafient reappoinfed for1 week later. Only when the patient was pain-free(all subjects in the study were free of pain by thesecond review) was denture security scored. Whenmaking the postreline score, the patient was notallowed to refer to the earlier score. Because thechairside reline material had a limited period offunction (some relines deteriorated rapidly andwere found to require replacement after 3 to 4months), arrangements were made to fabricatenew dentures at a later date.

Measurement of Functional Defect

The subjects' subjective assessment of tbe"looseness" of tbeir mandibular denture was mea-sured by a visual analogue method in the followingmanner;

A horizontal IQO-mm line was drawn, as advisedby earlier workers." The left extremity of the linewas labeled "denture loose and insecure at alltimes" and the right "denture firm and secure at alltimes" (Fig 1). Divisions or numbers can interferewith the distribution of the results and were omit-ted." After receiving an explanation of the method,subjects were asked to mark the line between thetwo extremities at a point corresponding in theirjudgment to the current security of their mandibu-lar denture. The score was recorded as the distancein mm from the leff, such that a high score indi-cated security of fif. All subjects were given thesame explanation, were encouraged to score truth-fully, and were reassured that their response wouldnot alter their future treatment in any way. Subjectswere asked to use their experience of denturewearing to determine their estimate. To ensurecomprehension of the right-side phrase it was de-scribed to each subject as being "like having yournatural teeth."

Measurement of Mean Anterior Ridge Height

When the relined denture was comfortable,addition-reaction silicone putty (Provil, Bayer,Leverkusen, Germany} was placed on the fittingsurface and trimmed level wifh fhe lingual, buccal,and labial periphery using a spatula. This provideda replica of that part of the residual ridge uponwhich the denture was supported. The set puttyreplica was removed and stored.

The replica was later used to assess the height ofthe anterior residual ridge. Vernier calipers wereused to measure at the crest in the midline andbilaterally at points 3 cm distal. Readings werefound to be reproducible. For a representative setof 10 successive measurements at the same site,with a mean of 3.14 mm and standard deviation (n-1) 0.057, the coefficient of variation was 1,8%. Themean of the three measurements was recorded as

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the mean anterior ridge height. More po^^teriorparts of the residual ridge not oriented in the occlu-sal plane were considered less likely to provideresistance to displacing forces arising from func-tional movement.

Results

Figure 2 presents tbe VAS scores for the subjects'assessments of mandibular denture security before(S,) and after relining (S,). All but two lie above thereference line A {S, = S,l, showing that reliningdentures gives a significant increase in tbe patients'perception of denture security (mean S, = 30.9,mean S, = 59.0, t = 3.73, P - -0006). The referencelineB(S, = S, -t- 12) gives an indication of the pointabove which significant increases in denture secu-rity are likely to occur.

The improvements in mandibular denture secu-rity (S:-S,) are presented in Fig 3. Tbe range is widewith two showing a negative increase.

Figure 4 plots the subjects' assessments of man-dibular denture security before relining against

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mean anlerior ridge height. There is a weak correla-tion (r- = 0.25, P < .021, The markerl regressioncurve nbeys the equation: VAS score - ^0.08 + 8.3(mean anterior ridge height). The subjecfs' assess-ment.s of denture security after relining are plottedagainst anterior ridge height in Fig 5. There is amore significant correlation (f- = 032, P< .01), Themarked regression curve obeys the equation: VASscore = -13.5 + 12.0 (mean anterior ridge height).

Discussion

Tbe visual analogue metbod has been .shown tobe capable of detecting changes in patients' assess-ments of differences in denture security obtainedby relining (Fig 2). Tbe wide range observable inthis study (including two negative increases) (Fig 3)can have three explanations. First, a reline mightproduce clinically undetectable changes in occlusalrelationships that could cause instability, reducetbe postreline VAS score, and even diminish theamount of detectable improvement. Second, somepatients are intolerant of even very small discrepan-cies between the denture and supporting tissues,as many as 20% reporting dissatisfaction with theretention of their complete mandibular denture 1year after placement.'^ Relining is likely to providesuch patients witb oniy very small increases in den-ture security that will be correspondingly difficult

to measure. Finally, inherent in the study design isthe possibility that when the subject is not allowedto see his or her original score to preclude influenc-ing his or her judgment, a negative increase canresult. For these reasons, a clinically significantincrease in security can only be predicted if the VASincreases by a value of approximately 10 to 12 mm.Although this study showed that five patients hadthis marginal form of improvement (Fig 21, theresults were nevertheless significant and point to atechnique that might be usefully employed in fur-ther studies.

These results also suggest a relationship betweenmandibular ridge height and the stability and satis-factory function of mandibular dentures. Claims fortbe importance of ihis relationship were originallybased on experience" but were later refuted byclinically based studies."" However, recent workhas shown a weak correlation between mandibularridge form and the ability to chew hard foods," andpatients given a relative increase in mandibularridge height by sukus-deepening operations havea better opinion of their dentures than unalteredcontrols.'* The results of this study appear to con-firm a reiationship between residual ridge anatomyand denture security with a similar degree of sig-nificance to these studies,'" The degree of scatterimplies, however, that conventional prosthodonticmethods have a good chance of improving a pa-

Numbei 1,1994 33 The Internationa

Mea5urementot Complete Manditjular Denture Security

tient's perceptioti of the security of a denture andshould always be tried before recommending sur-gical improvement of the ridge form. As a corollary,the regression line for the postreline results showsa positive intersection with the y-axis at mean ridgeheight = 0, showing thai even dentures on very flatridges will have some degree of security. This con-firtns Barbenei's'" conclusions on the importance oíthe fluid film in retention of complete dentures andemphasizes the importance of restoring a thin, in-tact, viscous fluid film between the denture and itssupporting tissues.

This study showed that the VAS method is auseful method for measuring denture security andcould be used in further studies to establish therelative importance of the factors involved. How-ever, the study design does allow alternative expla-nation!^ for the observed changes. The improve-ment might have resulted from reporting bias (ie,patients felt obliged to give a higher rating afterrelining to justify the effort being made by theclinician) or unreliability of the ratings.

The former problem is inherent in much researchconducted in a clinical setting, but the solution, arandomized study in which some patients receivedsham treatment, would be unethical. The lattercould be overcome by a design in which patientswere asked to indicate the stability of their pros-theses on at least two occasions before treatment (soproviding a more reliable baseline) and might justifya more complex design to confirm this aspect.

It should also be noted that other measures be-sides the VAS could have been used. Patients couldhave been asked to indicate the levels of functionalabilities before and after relining, and a further use-ful study might involve comparison of VAS-measu red denture security with functional disability.

Conclusions

Twenty-three patients used a visual analoguescale to evaluate the security of their mandibulardentures before and after relining. Within the limi-tations of the study design the following conclu-sions may be stated:

1. Visual analogue scales are a useful means ofmeasuring complex subjective feelings and canbe used to measure denture security.

2. Using visual analogue scales a moderate correla-tion was established between subjects' assess-

Iheir. after

ments of mandibular denture security ?mean anterior ridge height, the correiatirelining being better than before relimri

References

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