Quintessence Int 1989:20:249-255 Penodontics

Interproximal tooth morphology and its effect on plaque removalHyman Stnukier, BDS, DMD. HDD* / Martin C. Nager, DMD* / Paul C. Tolmie. DDS*

Introduction

The role of bacterial plaque in tbe initiation and pro-motion of inflammatory periodonta! disease has beenwell established by bacterial sampling procedures andin data obtained from controlled clinical studies.'"'From a therapeutic perspective, mechanical removalof bacterial plaque has been shown to be effective inreducing gingivitis,'"' maintaining periodontal heaithin humans/ and controlling periodontitis in animals.^Becanse the greatest incidence and severity of peri-odontal disease is found interproximally, effective tne-chanical control of bacterial plaque in these areas isof paramount importance.*' Since toothbrushingalone has not been an effective measure of controlingbacterial plaque interproximally,*"'- other aids havebeen recomrnended specifically for interproximalplaque removal.'-' -"

The effectiveness of dental tloss as an interproximalplaque remover and its relationship to the mainte-nance of interdental tissue health have been exhaus-tively investigated.''^ - '^"-^ Other chnical studies-^'^"'have not been able to demonstrate the superiority ofany one type of dental floss in removing dental plaquefrom interproximal tooth surfaces.

When the phystcal and morphologic characteristicsof toothpicks and their effectiveness on interproximalplaque removal were compared, it was noted'*"" thatthe triangular-shaped toothpick was the most effectiveplaque remover. However, when this type of toothpickwas compared to dental floss, the latter was found tobe more efflcient, particularly on the linguoaxial sur-faces."^

In evaluating the efficiency of the single tufted in-terspace toothbrush, wooden toothpicks, and waxeddental oss in cleansing of proximal tooth surfaces,

noted no significant differences among the

Department of Periodontology, School of Graduate Dentistry.Boston tjniversity, Boston, Massachusetts 2tl8.

devices. Nayak and Wade'^ compared an interproxi-mal brush with a rubber cone stimulator and the ef-fectiveness of each in removing proximal plaque. Theyfound that the interproximal brush was more effective,but that neither device achieved complete retnoval ofplaque.

The morphology of the interproxirnal root surfaceand its influence on proximal cleansing have been dis-cussed by Gher and Vernino'" and Fox and Bos-worth." The former concluded that proximal surfacesare inaccessible to cleansing by routine oral hygienemeasures, while the latter demonstrated that even tnin-imal attachment loss would nearly always expose con-cavities on the proximal surfaces, and special meanswould be required to cleanse such areas.

The present study was designed to observe tbe re-lationship between interproximal root morphoiogyand its effect on the cleansing ability of various ora!hygiene measures and devices.

IVlethod and materials

One representative extracted tooth from the incisor,c;mine, premolar, and molar groups of maxillary andmandibular teeth was randomly collected for this in-vestigation.

The selected ieeth were hghtly scaled by hand; ap-propriate care was taken to prevent alteration of theexisting root surface anatomy. A thin coat of petro-leum jelly was evenly applied to the proximal surfacesin question. Ground coffee was carefully dusted ontothe coated surface to color the petroleum, so thatchanges could easily be seen and photographed duringthe study (Figs 1 and 2).

U si tig generally accepted methods, unwaxed dentalfloss was used to retnove the coated adherent jellyfrom the proximal surfaces. After the flossing methodhad removed all tbe adherent material it could reach,the interproximal brush was used to attempt furtherremoval ofthe artificial coating from the tooth (Figs1 and 2).

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Figs la to 1e Cleansing ot a coated maxiliary first premoiar.

Fig la Coated tooth. Fig Ib Fiossing activity. Fig Ic Tooth surface after flossing.

Fjg "id Interproximal brush activity. Fig Ie Tooth surface after brushing.

Color transparencies (1:2 magnification) were rnadcof the relevant proximal surfaces before the applica-tion of the coating matertal, irnmediately after coating,and following the use of dental tloss and interproximaltoothbrush.

The teelh were cleaned thoroughly to remove anyadherent coating and horizontally sectioned 3 to 4 mmapical to the interproxirnal cementoenamel junction{CEJ) of each looth, using a diamond disk (Figs 3and 4), This arbitrary distance was selected to simulatethe attachment level that could be expected with anattachment loss of approximately 25%. About threefourths of the remaining apical portion of each cuttooth was embedded vertically, apex down, into red(maxillary teeth) or blue (mandibular teeth) modelingclay. A color transparency was made of eaeh cut sur-

face at a 1;1 magnification, Unwaxed dental fioss, Su-perfioss (Educational Heath Products Inc), triangu-iars toothpicks, and interproximal brushes were ap-posed to the proximal surfaces to simulate, in vitro,accepted cleansing methodology; these were photo-graphed.

The developed transparencies were projected ontoa screen to examine the relative removal of the petro-leum and coffee coating and the intirnate relationshipof each device with the interproximal surface of theindividual teeth. !n this purely ohservattonal study, noatternpt was made to quantify the cleansing ability ofthe various devices. On the projected slides, the exactrelationship of the cleansing devices to the proximalsurface of each tooth and the abihty of each to reachthe bottom of surface concavities were observed.

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Figs 2a to 2e Cleansing ot a coated mandibular first premolar

Fig 2a Coated tooth. Fig 2b Flossing aclivity. Fig 2c Tooth surtace after flossing.

Fig 2d Interproximal brush activity. Fig 2e Tooth surface after brushing.

Results

Use of unwaxed dental fioss ibr removal of the coatedpetroleum from the proximal surfaces resulted in sat-isfactory cleansing of only convex or flat root surfaces.The vicinity of the line angles was adequately managedwith this method (see Figs 1 and 2). The concavitiesof the proximal root surfaces were adequately cleansedhy the interproximal toothbrush after the fioss hadfailed to clean these areas (see Figs 1 and 2).

Examination of the projected images of the clean-sing devices applied to the proximal root surfaces re-vealed that only the interproximal toothbrush couldreliably reach the depths of the concavities. In veryshallow concavities, the Superfioss did come close tothe fioor of some concavities. The toothpick could

reach the deeper parts of the eoncavities when it wasproperly angulated horizontally (see Figs 3 and 4).

Discussion

Wherever the interproximal surface curvature of thetooth was convex, all the devices were adequately ap-plied to the interproximai surfaces and could be ex-pected to cleanse these areas in vivo. However, as mostteeth do not have uniformly convex or flat surfacesbelow the CEJ, the ability of dental fioss, Superfioss,and possibly even toothpicks to cleanse these predom-inantly concave areas must be seriously questioned. Inthe absence of disease, or in early periodontal disease,where the gingival tissues are still attached at or nearthe CEJ and where tooth surfaces are more likely to

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Figs 3a to 3e Application of oral hygiene devices to the mesioproximal surface of a maxillary first premolar

Fig 3a Tooth exhibiting level of Fig 3b Fioss on proximal surface. Fig 3c Superfioss appiication.section.

Fig 3d interprcximai brush m position. Fig 3e Tooffipici< apposed to tooth surface.

be convex or flat, these deviees appear to be effectivein the removal of interproximal plaque and debris.Thus they can still play a role in prevention and treat-ment of incipient periodontal changes.

When periodontal disease progresses apically, thegingival tissues are hkely to be apposed to more con-cave or convoluted interproximal root surfaces. Thesame holds true in instances of treated periodontaldisease, where the tissues are more apically situatedon concave root surfaces. In such instances, based onthese observations, it would appear that the inter-proximal brush is the only device that reliably canreach concave surfaces. When the interproximal brushis apposed to the proximal tooth surfaces, the bristlesin the line angle areas are compressed, while the re-maining bristles, noncompressed in the interproximalareas, reach and cleanse the concavities (Figs 3 to 5).

The toothpick, by careful manipulation and angu-lation, can also be made to reach most concavities. Invivo this may not always be possible because of prox-imity of adjacent teeth and questionable dexterity ofmany patients. Only the most shallow concavities canbe cleansed with Superfioss.

Further investigations are now under way to quan-tify, in clinical situations, the observations made inthis study.

Conclusions

Within the parameters of this study it can be con-cluded that (1) concave proximal root surfaces eanbe rehably reached and cleansed by interproximalbrushes; (2) with very careful horizontal angulation.

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Figs 4a to 4e Application of oral hygiene devices to the mesioproximal surface of a mandibuiar central incisor.

Fig 4a Tooth exhibiting level of Fig 4b Floss on proximal surface. Fig 4c Superfloss application,section.

Fig 4d Interproxitnal brush applica- Fig 4e Toothpick apposed fo foothtjon. surface.

Figs 5a to 5e Clinical use of oral hygiene devices on maxillary first premolar.

Fig 5a Stained to disclose proximal plaque accumulation. Fig 5b Plaque at line angle during flossing.

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Fig 5c Plaque remaining n concavity after tlossing. Fig 5d Cleansing with interproxtmal brush.

Fig 5e Results after use ot interproximal brush.

toothpicks can negotiate sotnc concavities; (3) dentalfloss appears to reach only flat or convex surfaces neartbe line angles of the teeth: (4) Superfloss may reachthe fioor or some ofthe most shallow concavities; (5)the effectiveness of some oral hygiene devices currentlybeing used should be questioned when proximal sur-faces are concave; (6) further studies are necessary toevaluate tnore properly the effect of traditional homecare devices and methods.

Analysis of tbe material examined in this study leadsthe authors to conclude tbat the interproximal brushappears to be the most effective device tested in thisstudy for the removal of plaque and debris from con-cave proximal tootb surfaces. Further research is need-ed to determine the effectiveness of interdental clean-sing devices in vivo.

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