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The Dimensions of the iHumanDentogingivai Junction

Jomes S. Vacek, DOS'Mariin E. Gher, DDS. MEd'Daniel A. Assad. DDS'A. Charles Richardson, DDS'Leo i. Giambarresi, Pt¡D'

This study examined the naturally occurring dimensions of the denfoglngi-vai ¡unction In 10 adult human cadaver jaws. The connective tissueattachment, epitheliai attachment, ioss of attachment, and sulcus depthwere measured tiistomorphometricaliy for 171 tooth surfaces. iVIean mea-surements were 1.34 ± 0.84 mm for sutcus depth: hl4 ±0.49 mm for epithe-liai attachment: 0.77 ± 0.32 mm for connective tissue atfachment; and2 92 + 1 69 mm tor lass Of attachment. These dimensions, os measured inthis study, support the concept that the connective tissue attachment is avariabie widtf^ within a more narrow distribution and ronge than theepitheiioi attachment, sulcus depth, or toss of attachment. The ievei ot theioss ot attachment was not predictive ot the connecfive tissue attachmentiength (IntJ Periodont Rest Dent 1994;14:155-ló5.)

*Penodantics DeporTmenf. Navol Dental School, NofionolNaval Dental Center, Bethesda. Mary [ond

Correspondence fa: CAPT iviorlin E. Gner, DC, USN. 2014Subida Terrace, Carlsbod. Calitornio 92009.

Reprinf requesfs to: Lbrorion, Naval Dental School, NafionolNoval Denfol Center, Befnesda. Maryland 20889-5077.

Ttiis article is a work ot the US government and may be repiinteö with-out peimissioh The opinions or assertions contained tierein are the pri-vate views of the authors ond ore not to be construed as official ar asreflecting the views ot the Department of the r̂ Iavy or any ottierdepartment or agency ot the US government

The dentogingivai junction hasbeen described as a functionalunit composed oi the connec-tive tissue attachment of thegingiva and the epifheliaiattachment.' Gargiuio et ai^reported that the connectivetissue attachment varied iniength from 0,0 to 6,84 mm witha mean of 1,07 mm; this mea-surement combined with themean length ot the epitheiialattachment (0.97 mm) hasbeen called the physiologicdentogingivai junction,^ or bio-logic width.3" Aithough theseindividuai measurements werefound fo vary greatly fromtooth to tooth, the combinedmean dimension has beenused as a guideiine for reestab-iishing the ideai attachmentdimensions when performingclinicoi crown iengtheningsurgery.^"" The need to con-sider a variable supracrestalattachment area to aliow forthe range of epitheiiai andconnective tissue attachmentshas also been discussed.'^''^

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The importance of the bio-logic width in relation to gingi-vai health and as a guide forplacing dentai restorations hasbeen studied.' ' ' -" Clinicaiiy,Newcomb'' ' found that thegreatest degree of gingivaiinflammation was seen whensubgingival crown marginswere placed near the base ofthe gingivai crevice, whileRichter and Ueno'^ noted noditferenoe in gingivai healthwhen crown margins wereplaced subgingivally. From his-tologie observations on dogand human autopsy moteriai,Waerhaug'* concluded thatpocket deepening in responseto artificial crowns did notoccur when the margin did notcome cioser than 0.4 mm tothe bottom of the pocket andattached fibers were nof sev-ered. Than et ai'^ found, how-ever, that when the bioiogicwidth was vioiated by dentalrestorations there was agreater mean ioss of connec-tive tissue attachment adja-cent ta surfaces with a dentalrestoration than adjacent tothose without.

In a clinical investigation,Tarnow et al'^ concluded thatsubgingival crown marginplacement combined withinjury to the gingivai attach-ment resulted in rapid gingivalrepair in the form of recessionwith limited gingivai inflamma-tion, in a study in dogs. Tal etal'^ faund that when amaigamrestorations were piaced at the

osseaus crest a bioiogic widthwas reestablished at 1 year,and that its dimension was 0,90mm, compared to 4,47 mm onsurgically operated controlteeth without restorations. Thisfinding suggests that the bio-logic width, if violated, may bereestabiished at a minimaiacceptabie dimension forhealth. In humans the minimumdimension ot biologic width forthe maintenance ot gingivaihealth has not been estab-iished.

The purpose of this study isto provide additional informa-tion on the dimensions of thedentogingivai junction andreiafed structures using nonde-calcif ied human block sec-fions.

Method and materials

A piiot study wos conducted toestabiish appropriate process-ing methods and sample sizefor the study, Biock sections ofdentulous mandibles wereobtained from human cadav-ers preserved wifh phenoi-formaldehyde, glycerin, andaicohol; one denfulous man-dibie was aiso obfained from ahuman fresh frozen cadaver,Resuits of the piiot study indi-cated that tissues from fhefresh frozen cadavers were nofsuitable for histologie exomino-tion, because of the destruc-tion of the epithelial layerresulting from the freezing

process. The preserved cadov-er tissues yieided sections withreodily identifiable structureswhen stained histaiogically.Measurements from these sec-tions were used to estimate thestudy sample size.

in the principal study, eachof 10 jaws, from cadavers rang-ing in age from 54 to 78 years,were used fa prepare sevenbiock segmenfs of two or threeteeth each (Fig 1). These noh-decalci f ied segments weresectioned first in a mesiodistaidirection along the long axisand contacts of the teeth (Fig2), The remaining faoiai and lin-gual portions were fhen sec-tioned buccoiinguaily alongthe iang axis of the feeth (Fig3), All secfioning was done wifhan EXAKT i cutting/grindingdevice (Exakt) according tothe manufacturer's instructions.The cutting/grinding device iscapabie of making 10- to 30-pm-thick serial sections of non-decalci f ied tissue approxi-mately every 0,75 mm. Theresulting thin nondecaicifiedsecfions confained structures,such as the enamel and dentalrestorotions. for observationand reference. Figures 4a to4d. a ciinicai series, demon-strate the sectioning of thespecimens in preparation forhistoiogic measurements.

The mesial (M), distal (D),facial (F), and lingual (L) sur-faces of every tooth wereeach considered as individualsurfaces for measurement of

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Fig 1 Schematic representation of ahuman mandible Dashed lines repre-sent the approximate initial sectioningplanes. A = typical twa- to three-toothsegment.

• Nandecalcified segment A was first sectioned in a mesiodistal directiong the lang axis and contacts of the teeth to produce black 8. Block B ' was thenlogically prepored to visualize the mesial and distal surfaces ot the teeth farsurements. C = lingual partían that remained after sectioning.

Fig 3 The tacial and lingual partions(A and C from Fig 2) were sectionedbuccotingually alang the lang axis ofthe teeth (dashed lines). Portion A ' washistalogically prepared to visualize thebuccal and lingual surfaces.

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Fig 4a Nondecolcitied sections are prepared for histologieanolysis: posterior mondibular blook segment is shown afterinitiol sectioning.

Fig 4b Mesial-to-distol block seotions were removed ondused to prepare thin histologie seotiohs, Residuol buocol ondlingual sections were then sectioned to permit meosure-ments trom those surfaces.

fig dc Mesiol-to-distol seotions were then ground to o 10-to 30-ijm thickness in preparoticn for stoining.

Fig 4d Thin section stoined to enhonce identification ofanatomic structures for meosurement.

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Fig Sa (left) Stained thin sectian per-mits exominotion ot dental restorations,enamel, and hard tissues in relation tosoft tissues without distortion. Nofe thepresence of calculus, which bridgesthe interproximal space immediatelycoronal to the gingivai soft tissues.

Fig Sb (right) Photomicragrabh ofinterproximai space demonstratesfransepfal collagen fibers, epithelialattachment, which extends to the levelof the transepfai fibers, ond bacterialplaque ond debris on the enamel sur-face of the teeth coronal ta the inter-proximaisaft tissues Vacuoles notedwithin the gingivai tissues ore process-ing artifacts.

the dentogingival junction.Each surface yielded two tofour secfions for hisfomorpho-metric measurement, depend-ing on the width of the toothand its location within the arch.Sections were stained withMasson's triohrome or hema-toxylin and eosin stain andmeasured histomorphometri-caliy by the same examinerwith a Zeiss Interactive DigitalAnalysis System (ZIDAS; Zeiss)(Figs 5a and 5b). Each fissuesection was viewed and mea-sured through o Zeiss lightmicroscope (Zeiss) at x 40 mag-nification, which was fitted with

a drawing tube. iVleosure-ments of the foiiowing struc-tures were recorded:

O) Suicus depth (SUL): thedistónos from the crest of thefree gingiva to the most coro-nal extent of fhe epifheliaiattachment

(2) Epitheliai ottachment(EA): the distonce from themost coronal extent of fhe epi-fheliai aftachment to the mostcoronai extent of fhe connec-five fissue attachment

(3) Connective tissue at-tachment (CTA): the distancefrom the most coronai extent ofthe connective tissue attach-

ment to the most coronal ex-tent of the periodontal liga-ment (The coronoi extent offhe periodonfai iigoment wasdefined os the levei at whichthe PDL was first found to be ofuniform thickness when com-pared with other areas of thePDL on the tooth being exam-ined.)

(4) Loss of affachment(LOA): the distance from thecementoenomel junction (CEJ)to the most coronol extent ofthe connective tissue attach-ment

Also recorded were thesubject's identification number.

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age, sex, tooth number, toothsurtace (M = mesial; D = distai;B - buccoi; L = iingual), thetype of restoration present, itany, and the distance from theapicai margin of the restorationto the coronai extent af theconnective tissue attachment.Only teeth with subgingivalrestoration margins and amicroscopicaliy visibie CEJwere inciuded in the measure-ments for subgingival restoro-tions. The mean dimensions otthe dentogingivai junction foreach tooth surface were deter-mined on 171 surtaces. Mea-surement error wos calculatedby making 124 replicate mea-surements on a total ot 31 ran-domly selected sites. A periodof ot ieast 24 hours eiapsedbetween repiicate measure-ments. The two measurementswere compared to determinethe precision of the measure-ment technique.

Every eftort was made fosection the teeth parallel to thelong axis ot the tooth. How-ever, due to variations in rootcontours, sectioning aiong theiong axis resuited in tangentialcuts across some isolated areas,such as furcation entrances,because of curvature of theroot at fhe entrance into thefurcation.2'^"^^ This precludedaccurate dimensional measure-ments in these areas. These fewareas were excluded from thedata set.

The mean, standard devia-tion, range, and frequency dis-tribution of the measurementsof the EA, CTA, LOA, and SULwere determined. A one-wayanalysis of varionce was usedto compare measurementsbetween surface locations (B,L, M, D), orch position (anterior,posterior), and surfaces with orwithout a subgingivai dentairestoration. Scheffe's methodfor muitipie comparisons wasused tor discrimination,i?egression analysis was used tocorrelate the CTA dimension tothe corresponding LOA.

Results

Medn dentogingivai dimen-sions for ail surfaces are shownin Tabie 1. There were no signifi-cant differences between themeosurements for fhe foofhsurfaces (B, L, M, or D) for SUL,LOA, EA, or CTA (Fig 6).Regression analysis showedthere was no significant corre-iation between the LOA andthe CTA, EA-i-CTA (biologicwidth), or SUL-̂ EA-hCTA.

When tissue dimensions forthe anterior and posterior teethwere compared, both the CTAand EA were significantiygreater in fhe posterior sex-tants. When moiars and premo-iars were analyzed separately,only fhe CTA was signiticantiygreater in the posterior teeth

{Tabie 2), When the dimensionsof the EA and the correspond-ing CTA for that surface werecombined (bioiogic width) theposterior teeth showed a sig-nificantiy greater (P < .004) bio-logic widfh than the anteriorteeth. When moiars and pre-moiars were analyzed sepa-rateiy, the bioiogic width of themoiars was significantiy greater(P < ,02) than that of the anteri-or teeth, whiie the bioiogicwidth of the premoiars was notsignificantiy different from thatof the moiars or the anteriorteeth (Tabie 3).

Tooth surfaces wifh subgin-givai restorations were found tohave a significantly longer EA(P < .04) than nonrestoredteeth, but no significant differ-ences were found for the CTA,SUL, or LOA (Tabie 4), When themean measurements for thecombined dimensions of theEA and OTA (bioiogic width) forteeth that had restorationswere compared to the bioiogicwidth for teeth without restora-tions there was a significantiygreater (P < .02) bioiogic widthin restored teeth. There was nosignificant difference in any offhese dimensions when com-paring fypes of restoration.

Analysis of the precision ofrepiicate measurements dem-onstrated 95% conf idenceintervais of ± 0,08 mm for theOTA, ± 0.12 mm for the ËA andLOA, and ± 0.14 mm for the sui-cus depth.

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Table 1 Dentogingivai dimensions (mm) for the epithelial attactiment(EA), connective tissue attachment (CTA). loss ot attachment (LOA), ondsulcus depth (SUL) tar all surfaces

Measurement(mean ± SD) Range

EACTALOASUL

1 Id ±0,490,77 ± 0,292,95 ± 1.701 32 - 0,BO

0,32 - 3.270.29-1.840.60-8,730,20 - 6,03

Fia 6 Graph disploys mean fissue dimensions for the epitheliol ottachment (EA).connective tissue attochment (CTA). loss of ottachment (LOA), and sulcus depth(SUL). for distal (0). mesiol (MX llnguai ft), and buccal (B) surfaces.

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Table 2 Tissue dimension (mm) for the epitt iel ial a t tac t iment (EA), con-nective tissue at tachment (CTA). loss of ottachiment (LOA), a n d sulousdeptt i (SUL) for teeth g rouped by arct i position

EAAnteriorPremolarMoiar

CTAAnteriorPremolarMclor

LOAAnteriorPfemolorMolor

SULAnteriorPremolarMoiar

Meo sûrement(meon ± SD)

1.03 + 0 451.20 ± 0.531.22 ± 0.46

0.71 ±0.24"0.77 ±0.310.89 ±0.31"

3.33 ± 1.992.73 ± 1.372.76 ± 1.65

1.19 ±0.891.30±0.6S1.54 + 0.60

Range

0.38-2.4B0.32 - 3.270.44 - 2 30

0.35 - 1.340.29 - 1.840.40-1.77

0.76-8.730.S7-6.580 60-6.50

G.d3 - 6.030 26-3.240.56-4.04

Table 3 Biologic width (epithelial o t taohment plus connect ive tissueat tachment) ( m m ) tor teeth g rouped by arch position

Archpositron

AnteriorPremolarMolar

Meo sûrementCm eon ± SD)

1.75 t 0 56'1.97-0 672.08 ± 0.55-

Range

0.75-3.290.78-4.330.84 - 3.29

'P<.02.

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Tabie 4 Tissue dimensions (mm) for surfaces witti subgingival restora-tions (restored) and without subgingival restorations (nonrestored) for ttieepittieiial attoctin-ient (EA), connective tissue attachment (CTA), loss otattachment (LOA), and suicus deptti (SUL)

EARestoredNonrestored

CTARestoredNonrestored

LOARestoredNonrestored

SULRestoredNan restored

•P< .04.Restored (n = 37); nor

Measurement(mean ± SD)

1.32 ±0.47'1.11 ±0.49*

0.84 ±0.200.76 ±0.29

2 60 ± 1.533.01 ±1.73

1.ÓO + 0 801.27 Í 0 79

irestored (n = 1<14).

Ronge

0.69 - 2.290.32-3.27

0.42 - 1.470.29-1.84

0.60-8.730 74-8.73

0 64 - 4.040 26 - 6 03

Discussion

Nondecalcified secfions wereused in this study to minimizethe error introduced by thedimensionol changes inherentin decoicit icotion ond tissuepreparation. The preservationof fissue with stondard histo-iogic methods has been shownto cause a measurabie change(15% total shrinkage) in thedimension of the soft tissue;therefore, the dimensions of fhesuicus would need fo be adjust-ed for fhis factor.^'i jhg cieooici-fication ot the hard tissue alsocauses a dimensional changein the tissue.^^ These tactorsmust be considered in aii stud-

ies that use decalcitied and his-toiogicolly prepared tissue.

Because human cadavermaterial was used in this study,the duration ot inflommafionpresent ot the time of tissuepreparotion couid not bedetermined, and previous peri-odontoi therapy on the sampiepopulation was not known.Within this somple popuiationthere was a wide ronge ot iossof attochment. The sampiepopulation in the present studymay represent a group ofpatients that had a iow suscep-tibility to the development otperiodontoi diseose,^* beoouseoniy subjects with few missingfeefh were inciuded in the

study. As tound in fhis study, theconnective tissue attachment(CTA) voried in width, but witha more narrow range ond vari-ance than that for the EA, SUL,or LOA. The hisforioal conceptof allowing 1 mm for the CTAwould adequotely include theCTA dimensions reported here.

When the measurementsfor surfaces with subgingivalrestorations were compored tothe dimensions for surfooeswithout restorations, there wasa significantly longer EA tor therestored teeth thon for the non-restored teeth. No signiticontditterenoe was tound tor theother dimensions. These resultsare not in agreement with stud-ies by Than et oi^' orKeszthelyF'' that have shown agreoter loss of attachmentodjocent to restored surfoces:however, both ot these studiesused extrocted teeth withoutottached odjacent structures.

In this sample populationno correlation was found be-tween the LOA and the corre-sponding length of fhe CTA orbiologic width. This finding sug-gests that ciinicol determina-tion of the LOA wouid not beusetui in predicting the lengthof the CTA (or concomitantbiologic width). Therefore theclinician couid not use theattachment levei as a guide-line to determine the necessoryrequirements for the reestab-iishment ot the EA ond CTA.

The meon dimension of theOTA plus EA (biologic width)

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was 0,33 mm greater on molarteeth thon onterior teeth,Aithough clinicaiiy smoli, thisresult suggests that on molarteeth a greater iength of bio-logic width may have to beallowed when attempting toreestabiish naturaily occurringdimensions of the dentogingi-va[ junction. The range of bio-logic widfh fhaf was observedwos 0,75 mm fo 4.33 mm. Theideal dimensions to use in aparticular clinical situation can-not be determined by examin-ing the results of this study.

The concept of a bioiogicwidth, as currently accepted(0.97 mm for the EA, and 1.07mm for fhe CTA), requires aminimum of 2,04 mm of soundfooth structure above theosseous crest.^"^''° in the pre-sent study, 15% of fhe restora-tions vioiated these dimensions,in these sompies the combinedmeasurement of fhe EA andthe CTA wos less than 2.04 mm,and the restoration margin wasi ess than 2 mm from fheosseous crest. These findingssuggest that o minimum dimen-sion for fhe reestablishment ofthe biologic width may be lessthan previously reported.^•^•'•'°This couid be important whenrestoring teeth thot hove un-dergone root resective proce-dures that create tooth onato-my which does not allow forthe estoblishment of accept-obie dimensions of bioiogicwidth. For exampie, a recentarticle concluded that the bio-

iogic width, as currentiy per-ceived, is violated in 8ó% of dis-tobuccai root resected maxil-iory first molars.^^ Furtherresearch is required to clearlyestablish the minimum dimen-sions of the dentogingival junc-tion compatibie with heolth inhumans.

Conclusion

Within the limitations of thisstudy and the use of individuaiteeth as the experimental unitsthe foiiowing conclusions orepresenfed:

(1) When comporing fhedentogingival tissue dimensionsbefween tooth surfaces (B, L,M, D), fhere were no significantdifferences for any ot the tissuedimensions.

(2) No correlation wasfound between the LOA andthe corresponding length ofthe CTA or bioiogic widfh(CTA+EA).

(3) While significant varia-tion was noted in the length ofthe CTA, it was the least vari-able ot the tissue dimensionsevaluated.

(4) The epithelial attooh-ment wos signiticantly greateron tooth surfoces odjocenf tosubgingival restorations.

(5) Both the CTA and EAwere significantly greater in theposterior sextants.

Aoknowledgments

The authors would like to thank ttieUniformed Services University of fheHealth Services for its help in providingthe specimens and Eskinder Dag-nachew for his valuable ossistonce inthe preparation ond sectioning of fheteeth. We also thank the paftiologydeparfment at the Navol DentalSchool, National Naval Dental Cerifer,Bethesda, Maryland for their assistanceand valuable comments This proiectwos funded by Naval MedicalResearcn and Development Center.Work Unit # 63706N M0095-06-3014

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