dental plaque the oral micro-ecological...

DENTAL PLAQUE The oral micro-ecological system


PLAQUE FORMATION PLAQUE FORMATION The organism enharbour many billions of bacteria on its surfaces. Nevertheless the desquamation of the epithelial cells anticipates the long lasting bacterial coexistence in the body.

In the oral cavity the non shedding surfaces, like enamel, root cementum, restorations can promote permanent, long lasting bacterial adhesion and survival on the surfaces.

PLAQUE FORMATIONPLAQUE FORMATION

dental plaque is a bacterial aggregation that are teanaciously attached to the teeth and other non seddign features One mm -dental plaque contains more than 10 microrganisms.

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Löe - experimental gingivitis model (1965), proved that plaque accumulation can lead to gingivitis, and its removal can reverse the disease.

Similarly experimentally was proven that plaque accumulation can cause peri-implantalis kifejlődése (Pontoriero 1994).

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ii

Pontoriero R, Tonelli MP, Carnevale G, Mombelli A, Nyman SR Land NP. Experimentally induced periimplantmucositis. A clinical study in humans. Clinical Oral Implants Research 5 254-259. 1994.


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Non-specific plaque theory (Theilade 1986)

Only the quantity of bacteria mass is important, and the abundant amount of plaque cab cause disease. There are no individual differences between plaques and the healthy and diseased sites show only differences in the quantity of the plaque and not in its composition.

Theilade E. The non-specific theory in microbial etiology of inflammatory periodontal disease. J Clin Periodontol 1986;13: 905-911.

PLAQUE FORMATIONPLAQUE FORMATIONIt was difficult to explain:

Why some patients have plaque and calculus accumulation for several years, but they develop only gingivitis without any attachment loss? Others show severe attachment loss with relatively good oral hygiene.

Why the severity and speed of progression differ from tooth to tooth in the same individual or even show different pattern around different surface at the same tooth?


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Longitudinal studies showed that the presence of certain bacterial strains in the dental plaque show good correlation with the disease activity and the magnitude of attachment loss. The total eradication of those bacteria can ensure long lasting therapeutic results.

The massive mixed bacterial colony has minimal pathogenic potential to initiate attachment loss.Only certain members of those colony should be eradicate to anticipate the attachment loss.

Those early studies established a base of the so called specific plaque

theory (Loesche 1979).

Those early studies established a base of the so called specific plaque

theory (Loesche 1979). Gingivitis/periodonitis are true infections

But this infection is not a classic infection in terms of the Koch's postulates

Loesche WJ, Clinical and microbiological aspects of chemotherapeutical agents used according to the specific plaque theory . J. Dentr Res. 56: 2404- 2414. 1979.


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Gingivitis/periodontitis are hardly exogenous infections

The normal indigenous bacterial flora is the source of the "endogenous " infection.

It is a true opportunistic infection


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To day only a couple of bacterial strains are known that are not detectable in healthy oral environment or they only occur in a very-very low rate. (ie. Porphyromonas gingivalis, Actinobacillus Actinomycetemcomitans)

They are very numerous in diseased periodontal pockets.

Those so called "periodonto-pathogenic microorganisms" can only be considered and true exogenous agents.


Dental plaque accumulation starts supragingivally but later the bacteria spread into the gingival sulcus and into the pathologically deepened sulcus - ie. periodontal pocket.

The composition and morphology of the subgingival plaque are totally different from the supragingival one.


SUPRAGINGIVAL PLAQUE

SUBGINGIVAL PLAQUE

HARD TISSUE ASSOCIATED EPITHELIAL ASSOCIATED DISPERSED INVASIVE

THE MECHANISM OF PLAQUE ACCUMULATION


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Dental plaque or certain specific bacterial components are necessary but not sufficient etiologic factors for the development of destructive periodontitis.

The complex equilibrium between the oral bacterial ecosystem and the host defensive mechanisms will determine the nature of the disease and the character of its progression.



As soon as the cleaned and polished tooth surface is moisturized by saliva a monomolecular protein layer will cover all the surfaces. It binds to enamel by ionic, hydrophobic and van der Waals forcesThis protein layer is called as " acquired pellicle"

The main component of acquired pellicle is salivary glycoprotein (mucin), and in a lesser extent some salivary immuno globulins Its thickens is less than 1um Early pellicle is bacteria free

Plaque distribution after 12 hours of no Plaque distribution after 12 hours of no oral hygieneoral hygiene

Lang et al. 1973

100%

PL 1 = 0 PL 1 = 1 PL 1 =2

MESIAL

Lower

Upper

0%

100%

Approximal

DISTAL

Lower

Upper

100%

0%

100%

Facial/Oral

Lower

Upper

100%

0%

100%

FACIAL

ORAL

Lower

Upper

100%

0%

100%M P C I C P M



Initially bacteria binds to pellicle by physico-chemical forces ( ionic bonds, Van der Waals force). Later bacteria bind to pellicle by protein-protein and protein - carbohydrate interactions.

Several virulence factors can enhance their adhesion. The natural bacterial glycoprotein coat (glycocalix), contains a great amount of polysaccharides that many times organized in surface fibrils.

Certain bacteria can synthesize extracellular polysaccharides by glycosyl transferase enzyme.

De Jong HP, DeBoer P, Busscher HJ et al.: Surface free energy changes of human enamel during pellicle formation: an in vivo study Caries Res 18: 408-415. 1984.



The non-soluble extracellular polysaccharides form the interbacterial matrix of the dental plaque while the soluble part serves as energy reservoir.

The attached bacterial mass grows very rapidly partly by cell division partly bacterial coagreagation



As the bacterial plaque gets thicker the oxygen cannot reach the deepest bacterial layers partly because of simple physico-chemical rules, partly because of the oxygen consumption of the superficial bacteria

In this way an oxygen gradient is to form from the surface to the depth with decreasing oxygen concentration. This eventually will reorganize the composition of the bacteria in the depth and shifting towards the anaerobes.



In the depth - anaerobes on the surface - aerobe or facultative anaerobes

In the depth bacteria cannot utilize nutrients originating from the saliva they use the sulcular fluid and blood as energy source.

In the depth of the sulcus no saccharolytic bacteria occur.



sterile dental pellicle

Gram+ cocci

Gram+ rods, actinomyces

Gram - bacteria

anaerobes, Gram - majority

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Dental plaque as a biofilmDental plaque as a biofilm

Biofilm is a well organized bacterial coating on the non- shedding hard surfaces In the depth of the biofilm the microorganisms are densely packed embedded into sticky polysaccharide matrix.

��Periodontal diseases Periodontal diseases are bacterial infections are bacterial infections

��Specific bacterial Specific bacterial pathogens are the pathogens are the

primary etiologic agentsprimary etiologic agents

��These bacteria form a These bacteria form a biofilm above and biofilm above and

below gingival marginbelow gingival margin

��

Plaque is natural and might exist in harmony with the host

•NO OVERT INFLAMMATORY REACTION

•OR

•INFLAMMATION

Disease is the consequence of breaking down

this balanced relationship

• The magnitude or nature of the microbial challenge

• Nature of the host response

•(Socransky et al. 1998).

DENTAL PLAQUE IS A NECESSARY BUT NOT SUFFICIENT ETIOLOGIC FACTOR OF DESTRUCTIVE PERIODONTAL DISEASE

DENTAL PLAQUE

GINGIVITIS

PERIODONTITIS

DESTRUCTIVE PERIODONTITIS

RISK FACTORSGENETIC

SYSTEMIC

BEHAVIORAL

RISK FACTORS RISK FACTORS

Oral hygiene Local plaque retentive factorsbacterial specificity systemic immune status Diabetes mellitus Tobbaco smoking OsteoporosisEthnic background Age DietGenetics Stress Socio-economics

��SupragingivalSupragingivalirregularitiesirregularities�� crowdingcrowding,,�� calculuscalculus�� roughrough restorationsrestorations

enhanceenhance thethe retentionretentionofof thethe supragingivalsupragingivalbiofilm biofilm protectprotect organismsorganisms

fromfrom thethe actionaction ofof oraloralhygienehygiene measuresmeasures..

LOCAL PLAQUE RETENTIVE LOCAL PLAQUE RETENTIVE FACTORSFACTORS

�� 1 ANATOMICAL 1 ANATOMICAL ETIOLOGIC ETIOLOGIC FACTORSFACTORS

�� 2 IATROGENIC 2 IATROGENIC ETIOLOGIC ETIOLOGIC FACTORSFACTORS

1 1 ANATOMICAL ETIOLOGIC ANATOMICAL ETIOLOGIC FACTORSFACTORS

�� a) a) Palatine sulcus of upper incisors.Palatine sulcus of upper incisors.�� b) b) FurcationFurcation areas. areas. �� c) c) CervicalCervical enamelenamel projectionsprojections�� d) d) EnamelEnamel pearlspearls�� ee) Crowding of the teeth in the dental arch.) Crowding of the teeth in the dental arch.�� f) f) Mucogingival deformities . Mucogingival deformities . �� gg) Occlusal anomalies.) Occlusal anomalies.

a) Palatine sulcus of upper incisors.a) Palatine sulcus of upper incisors.

�� palatine sulcuspalatine sulcus which which starts from the palatine starts from the palatine tubercle of the lingual tubercle of the lingual surface surface accumulataccumulatesesdental plaque, and dental plaque, and enhances the pocket enhances the pocket formation.formation.

Lee K. et al.: Palato-gingival grooves in maxillary incisors. Br. Dent. J. 124:14, 1968.

b) b) FurcationFurcation areasareas�� The The anatomyanatomy ofof thethe

furcationfurcation ::

�� favorsfavors retentionretention ofofbacterialbacterial depositdeposit

�� makesmakes periodontalperiodontaldebridementdebridement, ,

�� oraloral hygienehygieneproceduresprocedures difficultdifficult. .

Hirschfeld L, Wasserman B. A long-term survey of tooth loss in 600 treated periodontal patients. J Periodontol 1978: 49: 225–237

b) b) FurcationFurcation areasareas

�� FurcationsFurcations are are difficult difficult to to instrument instrument because of their because of their gothic arch gothic arch configuration configuration

b) b) FurcationFurcation areasareas

�� The dental plaque The dental plaque accumulates in that accumulates in that region and causes region and causes faster periodontal faster periodontal destruction of the destruction of the molars and molars and premolars, premolars,

PSEUDOFURCATION

(BUCCAL GROOVES) ON THE ROOTS OF CENTRAL INCISIORS

FURCATION LESIONS ARE ALSO THE CONSEQUENCE OF PERIODONTAL ATTACHMENT LOSS AND PERIODONTAL RESECTIVE SURGERY

c) c) CervicalCervical enamelenamel projectionsprojections

�� EctopicEctopic depositsdeposits ofofenamelenamel apicalapical toto thethelevellevel ofof thethe normalnormalcementoenamelcementoenameljunctionjunction

�� ConnectiveConnective tissuetissuedoesdoes notnot attachattach totocervicalcervical enamelenamelprojectionsprojections

�� theythey cancan lead lead totofurcationfurcation defectsdefects. .

c) c) CervicalCervical enamelenamel projectionsprojections�� 82.5% 82.5% ofof molarsmolars withwith cervicalcervical enamelenamel

projectionsprojections, , exhibitedexhibited furcationfurcation involvementinvolvement,,

�� whilewhile onlyonly 17.5% 17.5% ofof molarsmolars withoutwithout cervicalcervicalenamelenamel projectionsprojections had had furcationfurcation involvementinvolvement

Hou G-L, Tsai C-C. Relationship between periodontal furcation involvement andmolar cervical enamel projections. J Periodontol 1987: 58: 715–721

d) d) EnamelEnamel pearlspearls

�� EnamelEnamel pearlspearls cancan lead lead toto furcationfurcation involvementsinvolvements

�� The The prevalenceprevalence ofofenamelenamel pearlspearls arearereportedreported betweenbetween 1.11.1––9.7%. 9.7%.

�� NearlyNearly threethree--quartersquarters ofofenamelenamel pearlspearls areare foundfoundonon maxillarymaxillary thirdthird molarsmolars. .

Moskow BS, Canut PM. Studies on rootenamel. (2) Enamel pearls. A review of theirmorphology, localization, nomenclature, occurrence, classification, histogenesis andincidence. J Clin Periodontol 1990: 17:

Cervical enamel pearl onthe maxillary first molarAlveolar bone lossassociated with thisanomaly

That is not present in thecontralateral tooth and no bone loss either

e) e) CrowdingCrowding ofof thethe teethteeth inin thethedentaldental archarch..

�� the close convergence of the close convergence of the roots of neighboring the roots of neighboring teeth promotes the plaque teeth promotes the plaque accumulation resulting in accumulation resulting in faster periodontal faster periodontal destruction, is important due destruction, is important due to the difficulty of removing to the difficulty of removing dental plaque. dental plaque.

��Ainamo J. Relationship between malalignment of the teeth and periodontal

disease. Scand J Dent Res 1972: 80: 104–110

Geiger AM, Wasserman BH, Turgeon LR. Relationship of occlusion and periodontaldisease. Part VIII. Relationship of crowding and spacing to periodontal destructionand gingival inflammation. J Periodontol 1974: 45: 43–49

f) Mucogingival f) Mucogingival lesionslesions

�� The clinical impression is The clinical impression is that that the attached gingiva the attached gingiva will provide a protective will provide a protective barrier against barrier against inflammation and inflammation and attachment loss. attachment loss.

�� Several studies have Several studies have challenged the view that a challenged the view that a wide zone of attached wide zone of attached gingiva is a more effective gingiva is a more effective barrier against recession barrier against recession

f) Mucogingival f) Mucogingival lesionslesions�� It has been It has been

demonstrated that in demonstrated that in the absence of the absence of attachedattached gingivagingiva, , gingival health and gingival health and attachment levels can attachment levels can be maintainedbe maintained

Dorfman HS, Kennedy JE, Bird WC. Longitudinal evaluation of free autogoneousgingival grafts. J Clin Periodontol 1980: 7: 316–324 Wennström J, Lindhe J. Role of attached gingiva for maintenance of periodontalhealth. Healing following excisional and grafting procedures in dogs. J ClinPeriodontol 1983: 10: 206–211Wennström J, Lindhe J, Nyman S. Role of keratinized gingiva for gingival health.

Clinical and histologic study of normal and regenerated gingival tissues in dogs. . J Clin Periodontol 1981: 8: 311–328


�� HHighigh frenum and frenum and muscle attachments,muscle attachments,

�� can cause the can cause the detachment of the detachment of the free gingiva,free gingiva,

�� promotes the spread promotes the spread of the dental plaque of the dental plaque inside the gingival inside the gingival sulcus sulcus

gg) Occlusal anomalies.) Occlusal anomalies.

�� Occlusal anomalies had been considered as Occlusal anomalies had been considered as causative factor for periodontal disease causative factor for periodontal disease ((RamfjordRamfjord et al. 1966 ).et al. 1966 ).

�� It has been proven by long term animal studies ( It has been proven by long term animal studies ( LindheLindhe & & SvanbergSvanberg 19741974 ), that the traumatic ), that the traumatic occlusion can not be regarded as an etiologic occlusion can not be regarded as an etiologic factor for periodontal disease factor for periodontal disease

�� it does not cause pocket or attachment lossit does not cause pocket or attachment loss

Lindhe J., Svanberg G.: Influence of trauma from occlusion on progression of experimental periodontitis in the beagle dog. J. Clin. Period. 1:3, 1974

gg) Occlusal anomalies.) Occlusal anomalies.�� Occlusal traumatism can cause degenerative changes Occlusal traumatism can cause degenerative changes

in the deep periodontal structuresin the deep periodontal structures

�� Inflammatory process in the gingiva is allowed to Inflammatory process in the gingiva is allowed to spread apically more rapidly and result in more severe spread apically more rapidly and result in more severe periodontal destruction. periodontal destruction.

gg) Occlusal anomalies.) Occlusal anomalies.

�� Missing teeth can Missing teeth can lead to lead to mesialmesial drifting, drifting, tilting and extrusion of tilting and extrusion of teeth. teeth.

�� These alterations These alterations can result in can result in increased plaque increased plaque retention, food retention, food impaction and impaction and vertical bony defectvertical bony defect

2 IATROGENIC ETIOLOGIC 2 IATROGENIC ETIOLOGIC FACTORSFACTORS

�� a) a) Dental Dental ccariesaries�� b) b) DentalDental calculuscalculus�� c) Dental materials and plaque retention.c) Dental materials and plaque retention.�� d) Effect of bad restoration quality on periodontal health. d) Effect of bad restoration quality on periodontal health. �� e) The effect of the position of the crown margin to the e) The effect of the position of the crown margin to the

periodontium.periodontium.�� f) f) PonticPontic design and the edentulous mucosal area.design and the edentulous mucosal area.�� g) g) OverconturingOverconturing of restorations.of restorations.�� h)h) Temporary restorations and their effect on the Temporary restorations and their effect on the

periodontium.periodontium.

a) a) Dental Dental ccariesaries�� Dental caries Dental caries

enhance plaque enhance plaque retentionretention -- promoting promoting periodontal disease. periodontal disease.

�� AinamoAinamo (1970) first (1970) first noted a strong noted a strong relation between the relation between the GI value and GI value and untreateduntreated dental dental caries,.caries,.

AinamoAinamo J.: J.: ConcominantConcominant periodontal disease and dental caries in young periodontal disease and dental caries in young adult males. adult males. SuomenSuomen HammaslaakariseuranHammaslaakariseuran ToimituksaToimituksa 66:303, 197066:303, 1970

a) Da) Dentalental cariescaries

5 years5 years followfollow--upup studystudy: :

�� 15.4% of the 15.4% of the supragingivallysupragingivallylocated amalgamlocated amalgam--restoration restoration

�� 30.4% of the subgingivally 30.4% of the subgingivally located amalgamlocated amalgam--restoration restoration

exhibited secondary cariesexhibited secondary caries

Hammer and Hammer and HotzHotz

SSecondaryecondary caries in caries in restoredrestored teeth and the relationship teeth and the relationship of its incidence to the location of the preparation marginof its incidence to the location of the preparation margin

b) b) DentalDental calculuscalculus

�� In the practice In the practice calculus calculus is is always an important factor in always an important factor in the development of the development of periodontitis. periodontitis.

�� It is a plaque retentive factor. It is a plaque retentive factor.

�� Its surface is always covered Its surface is always covered by fresh bacterial by fresh bacterial plaqplaqueue

�� it can also guide the plaque it can also guide the plaque bacteria subgingivally bacteria subgingivally

The calculus per se is not a primary etiologic factor.The calculus per se is not a primary etiologic factor.

Patient’s and dentist’s negligence

c) Dental materials and plaque c) Dental materials and plaque retention.retention.

�� Dental materials posses a Dental materials posses a greater capacity to greater capacity to accumulate and retain accumulate and retain plaque than do either plaque than do either enamel or dentin. enamel or dentin.

�� PoPolymethyllymethyl--methacrylatemethacrylateaccumulates plaque accumulates plaque faster than gold and faster than gold and porcelain, porcelain,

Dental gold, porcelain and composites irritate tissues hardly if at all.

Porosity contribute to the plaque retentive potentials.

c) Dental materials and plaque c) Dental materials and plaque retention.retention.

�� Especially the transition zone Especially the transition zone at restoration margins at restoration margins represents a predilection site represents a predilection site for plaque accumulation. for plaque accumulation.

�� The "cement line" associated The "cement line" associated with seated crowns may with seated crowns may approach several square approach several square millimeters. millimeters.

�� Histological investigations by Histological investigations by WaerhaugWaerhaug have shown that the have shown that the subgingivalsubgingival cement roughness cement roughness enhances plaque accumulation enhances plaque accumulation in the gingival sulcusin the gingival sulcus

d) Effect of bad restoration quality d) Effect of bad restoration quality on periodontal health.on periodontal health.

�� TThe World Workshop he World Workshop in Periodontics (1966) in Periodontics (1966) reported that the reported that the overhanging at the overhanging at the margins of a margins of a restoration are local restoration are local plaqueplaque retentiveretentivefactors promoting factors promoting periodontitis.periodontitis.


�� Teeth with inadequate Teeth with inadequate restorations had significantly restorations had significantly more plaque, gingivitis and more plaque, gingivitis and periodontal pocket formation periodontal pocket formation than adequately restored than adequately restored teeth. teeth.

�� For both amalgam and crown For both amalgam and crown restorations, the health of the restorations, the health of the periodontium is adversely periodontium is adversely affected by the presence of a affected by the presence of a restoration. restoration.

Grosso E. J. et al.: Effect of restoration quality on periodontal health. J. ProstheticDentristy. 1985; 53: 14-19.


�� BjBjöörnrn et al. reported a et al. reported a generally poor generally poor marginal fit in marginal fit in retainers for fixed retainers for fixed partial dentures. partial dentures.

�� Eighty percent of the Eighty percent of the radiographicallyradiographicallystudied restorations studied restorations exhibited marginal exhibited marginal defects on the defects on the proximal surfaces. proximal surfaces.


�� In a German survey, only 18.2% of crown In a German survey, only 18.2% of crown margins were clinically perfect. margins were clinically perfect.

�� Margins that were open by more than 0.2mm Margins that were open by more than 0.2mm were always associated with alveolar bone were always associated with alveolar bone loss. loss.

Lange D.: Attitudes and behaviour with respect to oral hygiene and periodontal treatment need in selected group in West Germany. Ín: Frandsen A. Public health aspects of periodontal disease. Berlin: Quintessence, 1984: 83-97

IncidenceIncidence of bad restorationof bad restorationss

18 18 % (% (nn == 162)162)BitewingBitewing radiographsradiographsJanssonJansson etet alal., 1994 ., 1994

27% (27% (nn == 826)826)BitewingBitewing radiographsradiographsClamanClaman etet alal., 1986 ., 1986

76% (76% (nn == 50)50)BitewingBitewing radiographsradiographs, , mirrormirror, , probeprobe

CoxheadCoxhead, 1985 , 1985

86% (86% (nn == 176)176)BitewingBitewing radiographsradiographs, , microscopemicroscope

Keszthelyi & Keszthelyi & SzaboSzabo, 1984 , 1984

25% (25% (nn == 175)175)BitewingBitewing radiographsradiographs, , microscopemicroscope

LervikLervik & & RiordanRiordan, 1984 , 1984

60% (60% (nn == 240)240)CalculusCalculus probeprobeThanThan etet alal., 1982 ., 1982

50% (50% (nn == 85)85)OrthopantogramsOrthopantogramsHakkrainenHakkrainen & & AinamoAinamo, , 1980 1980

30% (30% (nn == 825)825)BitewingBitewing radiographsradiographsBurchBurch etet alal., 1976 ., 1976

25% (25% (nn == 1976)1976)BitewingBitewing radiographsradiographsGilmoreGilmore & & SheihamSheiham, 1971, 1971

% % restoredrestored surfacessurfaces withwithoverhangsoverhangs

((nn == numbernumber ofof subjectssubjects))

DiagnosticDiagnostic methodmethod forfor detectiondetectionReferenceReference


�� overhanging restorations overhanging restorations disturb the ecological disturb the ecological balance in the balance in the gingivalgingivalsulcussulcus

�� allow the growth of a allow the growth of a group of disease group of disease associated associated microorganisms.microorganisms.

Lang PN, Kiel AR, Anderhalden : Clinical and microbiological effects of subgingivalrestorations with overhangings or clinically perfect margins. J. Clin Periodontol 1983; 10: 563-578


�� Even an adequately restored Even an adequately restored tooth tooth cancan lead lead to gingivitis to gingivitis and periodontal pocket and periodontal pocket formation. formation.

�� the larger the number of the larger the number of restorations, the more restorations, the more important important thethe plaque control plaque control isis

Grosso E. J. et al.: Effect of restoration quality on periodontal health. J. ProstheticDentristy. 1985; 53: 14-19.

OVERCONTOURED CROWN MARGIN WITH SEVERE OVERGANG

THE WHOLE DENTAL PROBE CAN BE PUT UNDER THE CROWN MARGINE!!!!!!

CLASS TWO FURCATION LAESION TOTALLY COVERED BY OVERHANGING CROWN MARGIN

OVERCONTOURED CROWN MARGIN WITH SEVERE OVERGANG


�� The early detection of The early detection of overhanging overhanging dentaldentalrestorations is an restorations is an important part of important part of preventive dental carepreventive dental care

�� The removal of The removal of overhanging margins overhanging margins should be part of should be part of initial periodontal initial periodontal therapytherapy

BRAND NEW FULL ARCH BRIDGE WITH SEVERE OVERHANGS AND OVERCOUNTURED CROWNS AND PONTICS

The effect of the position of the The effect of the position of the crown margin to the periodontium.crown margin to the periodontium.

�� In the past, Black's theory In the past, Black's theory dominated dentistry for dominated dentistry for decadesdecades

�� The concept of "extension The concept of "extension for prevention" by Black for prevention" by Black (1908). (1908).

�� IIt postulates that the t postulates that the cervical margins of all cervical margins of all reconstructions should be reconstructions should be placed placed subgingivalysubgingivaly. .


�� BodeckerBodecker and and ApplebaumApplebaum (1934) where the first (1934) where the first to question Black's theory about extension of the to question Black's theory about extension of the cavity boarders in the gingival sulcus.cavity boarders in the gingival sulcus.

�� WaerhaugWaerhaug (1967, 1968), stated that there is (1967, 1968), stated that there is scientific proof that scientific proof that subgingivalsubgingival crown margins crown margins create periodontal destruction due to plaque create periodontal destruction due to plaque retention. retention.

�� LoeLoe (1968), (1968), ZanderZander and Kennedyand Kennedy (1970) (1970) supported the position of the crown margins supported the position of the crown margins above the free gingivaabove the free gingiva


�� FollowFollow--up up examinations of fixed examinations of fixed reconstructions have reconstructions have demonstrated demonstrated ::

�� ccrownrown margins margins positioned positioned subgingivally were subgingivally were associated with the associated with the highesthighest

�� and and supragingivalsupragingivalcrown margins with the crown margins with the lowest GI values.lowest GI values.

Silness J.: Periodontal conditions in patients treated with dental bridges. J. Periodont Res. 1970; 5:225-229.


�� 102 patients with 108 bridges were studied over 102 patients with 108 bridges were studied over 15 years. 15 years.

�� Loss of the periodontal supporting apparatus was Loss of the periodontal supporting apparatus was significantly higher around teeth with significantly higher around teeth with subgingivally located crown margins subgingivally located crown margins

�� than around teeth with crown margins located than around teeth with crown margins located supragingivallysupragingivally. .

Valderhaug J., Birkland JM: Perodontal conditions in patients 5 years following insertion of fixed prosthesis. Pocket depth and loss of attachment. J. Oral Rehab. 1976; 3(3)Valderhaug J.: Periodontal conditions and carious lesions following the insertion of fixed prosthesis: a 10-year follow up study. Int. Dent. J. 1980;30


�� A A followfollow--upup survey of 423 crown margins survey of 423 crown margins

�� Gingival tissues tended to bleed 2.42 times more Gingival tissues tended to bleed 2.42 times more frequently with frequently with subgingivalsubgingival margins margins

�� hhadad a 2.65 times higher chance of gingival a 2.65 times higher chance of gingival recessionrecession

�� Crowns with Crowns with supragingivalsupragingival margins did not differ margins did not differ significantly compared with the contrasignificantly compared with the contra--lateral lateral tooth, tooth,

Orkin DA, Reddy J. & Bradshaw D.: The relationship of the position of the crown margin to gingival health. J. Prosthetic Dentristy. 1987; 4: 421-424.

The effect of the position of the crown The effect of the position of the crown margin to the periodontium.margin to the periodontium.

�� From a caries From a caries preventive point of preventive point of view, view, the location the location of crown margins of crown margins does not seem to does not seem to be of great be of great importance if importance if patientpatientss maintainmaintaina satisfactory oral a satisfactory oral hygiene. hygiene. Valderhaug J, Loe H: Oral hygiene in a group of supervised patients with fixed prosthesis. J. Periodontol. 1977; 48:221- 224

NO CARIUOUS LEASIONG AFTER 12 YEARS


�� SubgingivalSubgingival margins margins can also lead to can also lead to gingival recession as gingival recession as a possible a possible consequence of consequence of chronic irritation and chronic irritation and the violation of the violation of biologic widthbiologic width

Valderhaug J, Loe H: Oral hygiene in a group of supervised patients with fixed prosthesis. J. Periodontol. 1977; 48:221- 224

f) f) PonticPontic design and the edentulous design and the edentulous mucosal areamucosal area

�� Badly designed Badly designed ponticspontics are very are very frequently the cause frequently the cause of tissue damage, of tissue damage, gingival gingival infammationinfammation, , hyperplasia of the hyperplasia of the underlying mucosa underlying mucosa and bone resorption.and bone resorption.

�� . .

f) f) PonticPontic design and the edentulous design and the edentulous mucosal areamucosal area

�� The distribution of The distribution of P.gingivalisP.gingivalis, , P.intermediaP.intermedia

TT. . forsythforsythiaia

underunder thethe ponticsponticsadjacent to healthy adjacent to healthy and and inflammedinflammedmucosa is differentmucosa is different

. . Wang JC, Lai CH, Listgarten M A: Porphyromonas gingivalis, Prevotellaintermedia and Bacteroides forsythus in plaque subjacent bridge pontics. J. Clin Periodontol 1998 ; 25: 330-333

g) g) OverconturingOverconturing of restorations.of restorations.

�� Oral hygiene Oral hygiene practices may be practices may be severely hampered severely hampered by by overconturingoverconturingrestorations. restorations.

�� it is more difficult for it is more difficult for the patient to the patient to effectivelyeffectively clean the clean the areaarea

g) g) OvercontouringOvercontouring of restorations.of restorations.

�� Interdental Interdental space should space should be kept wide, be kept wide,

�� for the normal for the normal development of the development of the gingival papilla,gingival papilla,

�� to make to make accessaccess to to hygienic oral devices. hygienic oral devices.

�� access to interdental access to interdental spaces is spaces is oneone ofof thethe most most important factorimportant factorss for a for a longlong--time expectancytime expectancy

h)h) Temporary restorations and their Temporary restorations and their effect on the periodontiumeffect on the periodontium

THE QUALITY AND THE MARGINAL ADAPTATION OF A PROVISIONAL RESTORATION SHOULD ALSO BE CORRECT

QualityQuality ofof restorationsrestorations

Morman W. et al.: Gingival reaction to well fitted subgingival proximal gold inlays. J. ClinPeriodontol. 1:120, 1974.

From a periodontal point of view, a supragingival position of the crown margin is the most favorable.

�� The most expensive The most expensive techniques and techniques and materalmateral can cause can cause severe periodontal severe periodontal disease if the quality disease if the quality is is questionablequestionable

dental plaque the oral micro-ecological...

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