Journal of Clinical Periodontology: 1981: 8: 98-106.

Key words: Experimental inflammaUon - probe peneiraiion - probe perforation.

Accepted for pubiication May 4, i9S0

Histologic evaluation of probe penetrationduring clinical assessment of periodontal

attachment levelsAn investigation of experimentaiiy induced periodontai

iesions in beagie dogs

JAN JANSEN, TACO PILOT AND NICO CORBA

Department of Periodontology, Faculty of Dentistry, University of Groningen, Groningen, The Netherlands

Abstract. The purpose of this study was to evaluate histologically the extent and characteristics of thepenetration of a periodontal probe during clinical assessment of loss of periodontal attachment in threedifferent situations:

(1) experimental mild gingivitis, (2) experimental severe periodontal inflammation and (3) experi-mental moderate periodontal inflammation.

Mild gingivitis was obtained by mereiy allowing plaque to accumulate on the teeth. Severe periodontalinflammation was created using copper bands for a period of 3 weeks followed by placement of cottonligatures for another 11 weeks. Moderate periodontal inflammation group was obtained by allowing theexperimental defects to recover for a period of 3 to 31 weeks.

At different times gutta percha imitations of a thin periodontai probe were inserted into the pocketsusing a gentle but unknown force. Histologic observation in 30 specimens showed that epithelium wasalways present around the probe tip, in most instances forming a continuous layer of epithelial cells.Histometrical analysis showed that in mild gingivitis the probe tip failed to reach the apical terminationof the junctional epithelium {x= —0.84 mm).

In severe periodonta! inflammation the tip of the probe went past this point (x= +0.50 mm), while inmoderate periodontal inflammation the probe tip came closest to the apical termination of thejunctional epithelium (x=—0.05 mm).

It is concluded that the epithelial lining of a pocket stays intact, even in severe periodontaiinflammation where the probe tip is situated apical to the apical termination of the junctionalepithelium, indicating that during clinical probing the periodontal tissues are compressed and displacedbut not perforated. It is also concluded that in beagle dogs the extent of probe penetration inexperimentally inflamed periodontal tissues is dependent upon the degree of inflammation.

The periodontal probe, inserted with a gentle penetration into a pocketandthereaction of the

force into a pocket, is the most widely used tool periodonta] soft tissues on the presence of the

in the clinicai assessment of the periodontal probe in the pocket.

attachmentlevel.Thevalidityofsuchanassess- The extent of probe penetration has been

ment has been questioned during the last few shown to be influenced by the degree of in-

years (Listgarten 1972, Armitage et al. 1977). flammation of the periodontal tissues (Armi-

At least two aspects seem to be of special tage et al. 1977, Spray & Garnick 1979, Robin-

importance in this respect: the extent of probe son & Vitek 1979) and by the probing pressure

0303-6979/81/020098-09 $02.50/0 ©1981 Munksgaard, Copenhagen

EVALUATION OF PROBE PENETRATION

applied on the probe tip {van der Velden 1979,van der Velden & Jansen 1980).

Inconsistent results have been reported withrespect to the ability of pocket epithelium towithstand the forces induced by a periodontaiprobe. Armitage et al. (1977) evaluated micros-copically the probing error in beagle dogs andreported that in several specimens of the pe-riodontitis group the probe went through thepocket epithelium and was in direct contactwith the connective tissue. Similar results werereported by Spray et al. (1978).

On the other hand it was recently suggestedthat the epithelial lining of an experimentalperiodonta! defect was not perforated by aprobe, even when high probing pressures (1.25N) were applied (van der Velden & Jansen1980).

The purpose of this study was to evaluate thepresence of epithelium around a probe tipinserted with gentle but not standardized forceinto three different types of experimental perio-dontal defects.

Material and Methods

Method of creating defects. In 12 beagle dogsapproximately 18 months of age and weighing12-15 kg, periodontal defects were createdaround three upper right premolars P', P', P̂using the method described by Lindhe & Svan-berg (1974) and modified by van Dijk (1979),The dentogingival fibers around the teeth weresevered down to the level of the alveolar bone.Copper bands were adapted as closely as pos-sible to the teeth and then cemented. After 3weeks the copper bands were replaced by cottonligatures, tied around the teeth and secured asdeeply as possible into the defect. Eleven weekslater the ligatures were removed (end of theactive phase of creating defects). In two dogs thesulci of the premolars of the contraiateral sides,where no periodontal defects were created, werealso used. Only plaque was allowed to accumu-late.

The dogs were sacrificed after a period of 0, 3,

7, ] 5 or 31 weeks. This approach would result inthree distinguishable degrees of inflammationin the periodontal tissues:

Mild gingivitis, without loss of attachment (nodefects created but only plaque accumulation).

Severe periodontal inflammation, with loss ofattachment (defects at the end of the activephase plus the weeks immediately thereafter, 0-3 weeks).

ATJE

Fig. 1. Schematic representation of the distance (a)from the probe tip to the most apical termination ofthe junctional epithelium (ATJE) and the distance (b)from the middle of the probe tip to the root surface.

Schematische Darslellung des Abstandes (a) von derSondenspitze zum apikalen Fpithelansatz (ATJF) unddes Abstandes (b) von der Mitte der Sondenspitze zurWurzelo h erflac he.

Sehema representant la distance (a) mesuree entreI'extremite de la sonde et la Umite la plus apicale derepithelium de jonction (ATJE) ei la distance (b) entrele milieu de I'extremite de la sonde et la surface de la

100 JANSEN, PILOT AND CORBA

4bEig. 2a. Representative section of the mild gingivitis group with the "probe" (P) in situ. The probe tip rests at thetransition from sulcular epithelium (S.E.) to junctional epithelium (J.E.) and fails to reach the apicaltermination of junctionai epithelium (arrow). 75 X.

Typisches Priiparat der "leichten Gingivitis" Gruppe mit der Sonde (P) in situ. Die Sondenspitze befindet sich amObergang vom Saumepithel (SE) zum Epitheiansatz (J.E.). koronal des apikalen Epithelansatzes (Pfeil). 75-facheVergrosserung.

Coupe representative du groupe de gingivite legere. avee la "sonde" (P) in situ. L'extremite de la sonde reste a latransition entre I'epithelium du .silion fSE) et /'epithelium de jonetion (JE). et ne reussit pas a atteindre la limiteapicale de I'epithe/ium de Jonction (fleche). Grossissement 75 X.

Eig. 2b. Higher magnification oi the area around the probe tip. Score+ was given for the presence of epitheliumin this area, because of lack of continuity in the indicated area (arrow). 180X.

Starkere Vergrosserung der Umgebung der Sondenspitze. In diesem Falle wurde die Bewertungseinhei! (seore) Terteilt, da die Epithelschicht dieser Region (Pfeil) nicht zusammenhangend war. 180-fache Vergrosserung.Grossissement plus fort de la region autour de l'extremite de la sonde. On a donne le score + pour indiquer querepithelium dans ceiie region n'etait pas continu (fleche). Grossissement ISOX.

Fig. 3a. Section of the severe periodontal inflammation group. The probe tip is located apical to the apicaltermination of the junctional epithelium (arrow) and situated at a certain distance from the root surface. 75 X.Prdparat der experimentell hervorgerufenen. sclweren parodontalen Entzundung. Die Sondenspitze befindei sichapikal des apikalen Epithelansatzes (Pfeil) und in gewissem Abstand von der Wurzeloberfldche. 75-faeheVergrosserung.

Coupe d'une inflammation parodontale grave. L' extremite de la sonde est placee d un niveau plus apical que la limiteapicale de I'epithelium de jonction (fleche) et situee a une certaine distance de la surface de la racine. Grossissement75X.

Fig. 3b. Higher magnification of the probe tip area of Fig. 3a showing clearly the presence of acontinuous layerof epithehum around the probe (score + + ) . ISOX.

EVALUATION OF PROBE PENETRATION 101

Moderate periodontal inflammation, with loss ofattachment (defects in the healing phase, 3-31weeks).

Method of probe placement. Since the evaluationwas meant to be a check on clinical probingwithout standardized pressure, only a gentleunknown pressure was used in the experiment.

Because of the striking similarity and easinessin histological processing, guttapercha pointsnr. 70 (Produils Dentaires S. A. Vevey, Switzer-land) were used as immitations of a Universityof Michigan probe (terminal diameter of 0.35mm) (Hu Friedy, Chicago, 111. U.S.A.).

Care was taken to insert the "probes" parallelto the long axis of the root and to keep the tip ofthe guttapercha point in contact with the Eoothsurface. The probes were inserted with careuntil a definite resistance was felt. They werethen held in place and fused to the teeth using adroplet of Histacryi (Histoacryl® blau, B,Braun, Melsungen A.G., Germany).

Only interproximal measurements were per-formed and only one guttapercha point wasplaced between two premoiars. This resulted ina maximum of four probes per dog. Two days

before placement of the guttapercha probes andsacrifice of the animals, clinical probing depthswere performed on the same sites so that thethree histoiogical levels of inflammation couldbe correlated with the clinical measurements.

Hisloiogic preparation. The dogs were killed bya perfusion technique. The sequence was asfollows: Nembutal anesthesia, intravenous he-parin injection, opening of the thorax, position-ing of canula in the left atrium, clamping of theaorta descendens, opening of the right atrium,perfusion with 3 1 saline followed by 3 1 10%neutral formalin.

The head was dissected and small blocks weresawed containing two neighboring halves ofteeth together with the interdental periodon-tium. These small blocks were then decalcifiedin a solution of 25% formic acid, containing10% sodium citrate, dehydrated and embeddedin paraffin, Mesiodistal sections of 8/; thicknesswere cut and stained with hematoxylin - eosin.Only those sections judged to have been correct-ly orientated and containing the midsection ofthe guttapercha points were used.

Die starkere Vergrossermg des Sondenspitzengebieies der Fig. 3a zeigt das Vorhandensein einer zusammenhdngen-den Epiihelschicht um die Sonde herum (Beweriungseinheit + +;. 180-fache Vergrosserung.

Grossissement plus fort de la region autour de lexiremite de la sonde de la Fig. 3a. montrant tres clairement lapresence d'une couehe ininterrompue d'epiihelium autour de la sonde (score 4- +). Grossissement J80X.

Fig. 4a. Representative section of the moderate periodontai infiammation group. The probe tip is situated at theapical termination of ihe junctionai epithelium (arrow). The probe (P) is in contact with the root surface. 75 X.

Typisches Frdparai der "massigen parodontalen Fntzilndungsgruppe". Die Sondenspiize befindet sich in der Naheder apikaten Grenze des Fpithelansalzes (Ffeil). Die Sonde (F) ist in Konrakt mit der Wurzeloberflache. 75-fache

Vergrosserung.Coupe representative du groupe de finflammalion parodontale moderee. L'extremite de la sonde est situee a lalimite apicale de I'epithelium de jonction (fleche). La sonde (F) est en contact avec la surface de la racine.Grossissement 75 X.

Fig. 4b. Higher magnification of the probe tip area of Fig. 4a showing a very thin flattened layer of epitheliumlining the probe tip (score + + ) , 180X.Stiirkere Vergrosserung des Sondenspitzengebietes der Fig. 4a. die eine schrdiinneabgeftachteEpitheischicht ringsum die Sondenspitze herum zeigt. 180-fache Vergrosserung.

Grossissement plus fort de la region autour de l'extremite de la sonde de la Fig 4a, montrant une couehe comprimietres mince d'epithelium entourant I'extremite de la sonde (score + +). Grossissement 180X.

102 JANSEN, PILOT AND CORBA

Analysis of sample. Thirthy different sectionsout of 40 proved to be suitable and were used foranalysis: four in the mild gingivitis group, 11 inthe severe periodonta! inflammation group and15 in the moderate periodontal inflammationgroup.

From black and white photographs of theselected sections (magnification 35 X), the dis-tance from the tip of the probe to the mostapical termination of the junctionai epithelium(ATJE) and the distance from the middle oftheprobe tip to the root surface were measured(Fig. 1).

Furthermore, the presence of epitheliumaround the probe tip was independently evalu-ated by two investigators (H.W.B.J. and R.L.)using a light microscope at a magnification of250 X.( + -r) Continuous layer of epithelium present

around the probe tip,( + ) Epithehal cells present around the probe

tip but there are one or more sites wherethese cells do not form a distinct con-tinuous layer.

( —) Distinct area where no epithelial cells arepresent but where the probe is in directcontact with connective tissue.

Epithelial cells were differentiated from connec-tive tissue cells or inflammatory cells on thebasis of difference in staining and the presenceof continuity of neighboring cells, constitutingthin cell layers. The typical form of epithelialcells could not be used as a criterion because thecells underneath the probe tip were often ex-tremely compressed.

Results

MiU gingivitis group. Mean probing depth in thefour selected sites was 2.00 mm (s.d.—0.40mm).

Histologic characteristics; few inflammatorycells were present in the connective tissuebeneath the sulcular and junctionai epithelium.This epithelium showed virtually no rete peg

formation. Well-organized collagen bundles inthe connective tissue beneath the junctionaiepithelium could be identified. There were fewblood vessels of normal width present and noapicai migration of junctionai epithelium hadtaken place (Fig. 2a).

Epithelium was present around the probe tipin all four cases observed. In one section bothexaminers had some doubt about the continuityof the present epithelial cells (score + , Fig. 2b),the remaining three sections were found to bepositive (score + + ) . In all specimens, theprobe tip failed to reach ATJE. The meandistance from probe tip to ATJE was x = —0.84mm (s.d.—0.37). Fig. 2a shows the characte-ristic relationship. In all four cases the probe tipended at the transition from sulcuiar to junc-tionai epithelium.

Severe periodontal inflammation group. Meanprobing depth in the selected sites was 3.09 mm(s.d.^0.91 mm).

Histologic characteristics: cell-rich, collagen-poor connective tissue, abundance of inflam-matory cell infiltrate beneath and in the sulcularand junctionai epithelium, many extensive retepegs, many dilated blood vessels, and an apicalmigration of junctionai epithelium along thecementum. In no instance was the probe tip indirect contact with the underlying connectivetissue. There was always an epithelial liningpresent around the probe tip, although thisepithelium was streched, often resulting in verythin, flattened cell (Fig. 3b).

While one examiner had doubt about thecontinuity of the epithelial lining in two sections(score -I-), all other sections were found positive(score + + ) by both examiners.

In this group the probe tip was generallysituated apically to ATJE (x=+0.50 mm,s.d. —0.43 mm). In only one specimen out of the11 the tip failed to reach ATJE.

The probe tip was in most instances situatedat a distance from the root surface (b = 0.97mm, s.d.=0.58 mm) and some tissue wasalways found between the probe tip and the root

EVALUATION OF PROBE PENETRATION 303

surface. Junctional epithelium was present onthe root surface, not detached from it by thepenetrating probe (Fig. 3a).

Moderate periodontal inflammation group. Meanprobing depth in the 15 selected sites was 3.40mm, s.d. —0.50 mm.

Histologic characteristics: more inflamma-tory cells were present than in the gingivitisgroup, but less than in the severe inflammationgroup. There were few partially organized coi-lagen bundles in the cell-rich connective tissue.Rete peg formation of the sulcular epitheliumwas less pronounced than in the severe inflam-matory group. There was an apical migration ofthe junctional epithelium and a few enlargedblood vessels, but not as many as in the severeinflammation group (Figs. 4ab). As in theformer two groups, in this group again no probetip was in direct contact with connective tissuebut a thin layer of stretched epithelium wasalways present in between. This epitheliumformed in the majority of cases a continuouslayer (score +-|-). In only three out of 30observations in this group was a score (-i-) givenby one examiner.

In this inflammation group the extent of thepenetration of the probe tip indicated ATJEmore closely than in the two other groups. Themean deviation from this point was x —0.05mm, s.d. =0.34 mm. In nine cases the tip failedto reach ATJE, in the remaining six specimensthe tip was situated apical to ATJE. Theterminal part of the probe was in contact withthe root surface in almost all specimens (b =0.49 mm, s.d.-0.28 mm).

Discussion

Three different inflammatory conditions wereidentified in this experiment and were histo-logicaliy classified as: a) mild gingivitis withoutapical migration of junctionai epithelium, b)severe periodonta! inflammation and c) mode-rate periodontal inflammation, the latter two

accompanied by Joss of connective tissue at-tachment.

The presence of leucocytes just beneath thesuicuiar epithelium in the miid gingivitis groupindicated that the tissues could not be classifiedas absolutely healthy (Lindhe & Ryiander1975), although in other studies on dogs thepresence of a few leucocytes was considerednorma] (Hamp & Lindberg J977, Attstrom1970),

In the severe periodonta] inflammationgroup all histologicai symptoms of severe perio-dontitis as shown in dogs by Hamp & Lindberg(1977) and Armitage et al. (J 977) and in man byZachrisson & Schultz-Haudt (1968) were pre-sent: extensive anastomosing epithelial proli-ferations into the connective tissue, dense in-flammatory cell infiltrate and loss of collagenstructure. On this basis this group was termed"severe periodontal inflammation group" ac-cording to Zachrisson & Schultz-Haudt (1968).The moderate periodontal inflammation groupwas obtained by allowing a created defect torecover from the presence of a plaque-loadedJigature for different periods of time (3-31weeks). Histologically, all symptoms presentwere less pronounced than in the severe inflam-mation group.

In no specimen had the probe tip clearlyperforated the epithelial lining of the perio-dontal defect. The probe was thus never indirect contact with the underlying connectivetissue, not even when severe inflammation waspresent and the probe tip was located apical toATJE. This means that even in the case ofsevere periodontal inflammation not oniy is anepithelial lining of the defect present, but thisepithelium resists forces induced by gentleprobing.

This finding is in agreement with van derVelden & Jansen (1980) who under experi-mental conditions similar to the severe inflam-mation group in the present study, but using aprobe twice as thick, also reported that perfora-tion of the epithelium rarely occured, even whenvery strong probing forces were used. However,

104 JANSEN, PILOT AND CORBA

Armitage et al. (1977) as well as Spray &Garnick (1979) suggested frequent perforationof the epithelial lining of the pocket wall innaturally occurring periodontitis, using a probeof the same size as the one used in the presentexperiment. Weaker probing forces in thisexperiment as a possible explanation for thediscrepancy is not very likely because in thisstudy the probe tip extends on average moreapically than in the afore-mentioned studies, soone would expect even more cases of epithelialperforation. Differences in severity of inflam-mation of pocket walls (e.g. ulceration), assuggested by van der Velden & Jansen (1980),ismore likely.

In the present study a distinct relationshipwas found between the degree of inflammationand the extent of probe penetration. In slightlyinflamed gingiva the probe tip failed to reachATJE, while in severe periodontal inflamma-tion the probe tip was located apical to ATJE.

A number of other studies confirm thisfinding (Armitage et al. 1977, Robinson & Vitek1979, Spray et al. 1978, Spray & Garnick 1979).This indicates that healthy or slightly inflamedperiodontal tissues seem to offer too muchresistance to a probe inserted with a gentleforce, to correctly indicate the connective tissueattachment level or ATJE. Severely inflamedtissues, on the other hand, seem to be too loose-ly arranged to stop the probe at ATJE. Prob-ably some loss of integrity of the inflamedtissues, as was the case in the moderate perio-dontal inflammation group in the present studyor the experimental gingivitis group in theexperiment of Armitage et al. (1977), providesthe best condition for more ciosely measuringconnective tissue attachment levet through cli-nical probing.

In the present experiment a gentle but un-known probing force was used. According toGabathuler & Hassel (1971) probing forces thatrepresent "gentle probing" will only rarelyexceed 40 ponds ( = 0.40 N). Therefore it isassumed that in our experiment no forcesexceeding 40 ponds were used.

It has recently been suggested by van derVelden & Jansen (1980) that with the use of athin probe, the probing force per unit area at theend of the probe tip is much greater than withthe use of a thick probe. In evaluating probingforces in relation to probe penetration in experi-mentally induced periodonta! defects, theyfound that with the use of their probe (terminaldiameter of 0.63 mm) it took forces over 0.75 Nto consistently pass ATJE. In the severe perio-dontal inflammation group of the presentstudy, which corresponds closely to van derVelden & Jansen's experimental pockets, agentle probing force, probably not exceeding0.40 N, was sufficient to consistently pass theATJE, using a probe 0.35 mm in diameter.

Acknowledgments

The authors wish to thank Dr. H. W. B. Jansenand Mr. R. Liem from the Department of OralBioiogy, University of Groningen, for theirassistance in qualifying the histological sec-tions.

Zusammenfassung

Histologische Untersuchung der Sondenpenetrationwdhrend der klinischen Bestimmung des parodontalenAttachmerttniveausMit dieser Studie wird beabsichtigt das Ausmass undden Vorgang bei der Penetration einer Zahnfleisch-tasche mit einer Parodonlaisonde bei den folgendendrei Situationen zu besiimmen:(1) Bei experimentell hervorgerufener, leichter Gin-

givitis,(2) Bei experimenteli hervorgerufener, schwerer pa-

rodontaler Entziindung.(3) Bei experimentell hervorgerufener, massiger pa-

rodontaler Entziindung.Die leichte Gingivitis wurde durch blosse Plaqtiean-sammlung an den Zahnen erreicht. Die schwereparodontale Entziindung wurde durch dreiwochent-liche Applikation von Kupferringen mit daran an-schliessender l]-w6chentiichen Einlage von Baum-wollfaden hervorgerufen. Das Bild einer massigenparodontalen Entzundung wurde durch eine Periodedes Aiisheilens experi men teller Defekte von 3 bis 3 iWochen erzielt. An verschiedenen Zeitpunkten wur-den Guttapercha-Imitationen einer dunnen Parodon-

EVALUATION OF PROBE PENETRATION 105

talsonde mit leicfatem, aber unbekanntem Kraftauf-wand in die Zahnfleischtaschen inseriert. Die an 30Praparaten vorgenommene histologische Auswer-tung zeigte, dass rings um die Sondenspitze herumimmer Epithelzellen vorhanden waren, die in denmeisten Fiillen eine zusammenhangende Schicht vonEpithelzellen gebildet hatten. Eine histometrischeAnalyse dreier Praparate zeigte, dass die Sonden-spitze bei ieichter Gingivitis die apikale Grenze desEpithelansatzes nicht erreichte (K— —0,84 mm).

Bei schwerer parodontaler Entzundung penetriertedie Sonde iiber diesen Punkt hinaus(x— -I-0,50 mm),wahrend bei massiger parodontaler Entzundung dieSondenspitze der apikaien Begrenzung des Epithel-ansatzes am nachsten kam (x—— 0,05 mm).

Als Schlussfolgerungen werden angegeben:Das Saumepilhe! einer Zahnfleischtasche verbleibt

sogar bei schwerer parodontaler Entzundung, bei derdie Sondenspitze apikal des Epithelansatzes zu liegenkommt, intakt. Das bedeutet, dass das parodontaleGewebe wahrend des klinischen Sondierens zusam-mengedruckt und verdrangt, nicht aber perforiert

wird.Fur Beagle Hunde gilt, dass der Grad der Sonden-

penetration bei experimentell hervorgerufener Ent-zundung parodontalen Gewebes, von den Grad derEntzundung abhangig ist.

Resume

Evaluation histologique de la penetration de la sondependant I'examen elinique du niveau de I'attache paro-dontale. Etude sur des lesions parodontales provoqiieesexpenmenlalement chez des chiens briquetsLa preseme etude avait pour but d'evaluer, d'un pointde vue histologique, la mesure et les caracterlstiquesde la penetration d'lme sonde parodontale dans troissituations differentes: (1) une gingivite experimentaleiegere. (2) une inflammation parodontale experimen-tale grave et (3) une inflammation parodontale experi-mentale moderee.

On a obtenu la gingivite Iegere en iaissant la plaques'accumuleT sur les dents. On a cree une inflammationparodontale grave en posant des bagues de cuivre quirestaient en place pendant une periode de troissemaines, apres quoi on a applique des ligatures decoton pendant une autre periode de onze semaines.On a obtenu i'infiammation parodontale moderee enpermettant aux lesions experimentales de se remettrependant une periode de 3 a 31 semaines.

A differents moments, des imitations en guttapercha d'une mince sonde parodontale ont ete intro-duites dans ies cu!s-de-sac avec une force legere nonstandardisee.

Des observations histologiques dans 30 specimensont montre que l'epithelium etait toujours presentautour de I'extremite de la sonde, oii il formait dans la

plupart des cas une couche ininterrompue de cellulesepitheliales.

Des analyses histometriques ont permis de con-stater que, dans le cas d'une gingivite legere, I'extre-mite de la sonde ne reussit pas a atteindre la limiteapicale de l'epithelium de jonction (x = —0,84 mm).

Dans les inflammations parodontales graves, I'ex-tremite de la sonde depassaitce point (x= +0,50 mm)alors que, dans Ies inflammations parodontales mo-derees, I'extremite de la sonde s'approchait le plus dela iimite apicale de Tepithelium de jonction {x =-0,05 mm).

Ceite etude permet de conclure que le revetementepithelial d'un cul-de-sac reste intact, meme dans lesinflammations parodontales graves ou I'extremite dela sonde est situee a un niveau plus apical que la iimiteapicale de l'epithelium de jonction, ce qui indiqueque, pendant les sondages cliniques, les tissus sontcomprimes et deplaces mais non pas perfores.

On peut conclure egalement que, chez les chiensbriquets, le niveau de penetration de la sonde dans destissus parodontaux enflammes experimentalementdepend du degre de I'infiammation.

References

Armitage, G. C , Svanberg, G- K. & Loe, H. (1977)microscopic evaluation of clinical measurements ofconnective tissue attachment level. Journal of Cli-nical Feriodontology 4, 173-190.

Attstrom, R. (1970) Presence of leucocytes in crevicesof healthy and chronically inflamed gingivae. Jour-nal of Periodontal Research 5, 42-47.

Dijk, L. J. van (1979) Surgery and ora! hygiene onartificial periodontal defects in beagle dogs. Thesis,University of Groningen, The Netherlands.

Gabathuler, H. & Hassell, T. (1971) A pressure-sen-sitive periodontai probe. Helvetica OdoniologicaActa 15. U4-117.

Hamp, S. E. & Lindberg, R. (1977) Histopathologyof spontaneous periodontitis in dogs. Journal ofFeriodontal Research 12, 46-54.

Lindhe, J. & Svanberg, G. K. (1974) Influence oftrauma from occlusion on progression of experi-mental periodontitis in the beagle dog. Journal ofClinical Feriodontology 1, 3-14,

Lindhe, J. & Ryiander, H. (1975) Experimental gin-givitis in young dogs. Scandinavian Journal of Den-tal Research S3, 314-326.

Listgarten, M. A. {1972) Normal development, struc-ture physiology and repair of gingivai epithel-ium. Oral Sciences Reviews J, 3-67.

Robinson, P. J. & Vitek, R. M. (1979) The relation-ship between gingivai inflammation and resistanceto probe penetration. Journal of Feriodontal Re-search 14, 239-243.

106 JANSEN, PILOT AND CORBA

Spray, J. R., Garnick, J. J., Doles, L. R, & Kiawitter,J. J. (1978) Microscopic demonstration of theposition of periodontal probes. Journal of Ferio-dontology 49, 148-152,

Spray, J. R. & Garnick, J .J . (1979) Position of probesin human periodontal pockets. Journal of DentalResearch 58, (Special issue A) Abstract no. 331.

Velden, U. van der (1979) Probing force and the rela-tionship of the probe tip to the periodontal tissues.Journal of Clinical Periodontology 6, 106-114,

Velden, U. van der & Jansen, J. (198U) Probing forcein relation to probe penetration into the periodon-tal tissues in dogs, a microscopic evaluation. Jour-nal of Clinical Periodontology.

Zachrisson, B. V, & Schultz-Haudt, S, D. (1968) Acomparative histological study of clihically normaland chronically inflamed gingivae from the sameindividuals, Odontologisk Tidskrift 76, 179-192.

Address:

Jan JansenDepartment of PeriodontologyFaculty of DentistryUniversity of GroningenAnt. Deusinglaan 19713 A V GroningenThe Netherlands