Similarities in the Micro Floras of Root Canals and Deep Periodontal Pockets

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Review article Similarities in the microfloras of root canals and deep periodontal pockets Kerekes K, Olsen I. Similarities in the microfloras of root canals and deep periodontal pockets. Endod Dent Traumatol 1990; 6: 1-5. Abstract Although not universally accepted, retrospective his- tological, roentgcnological and microbiological studies have in- dicated that cross-infection can occur between infected pulps and deep periodontal pockets. This review provides examples of simi- larities in the microfloras of these adjacent oral sites, supporting the idea that infection spreads from one site to the other. The organisms most often involved are probably bacteroides, fusobac- teria, eubacteria, spirochetes, wolinellas, selenomonas, campy- lobacter, and peptostreptococci. Important qualities of cross- infecting organisms may be the ability to survive in highly reduced environments and motility. Precautions should be taken to pre- vent in vivo seeding of such micro-organisms, particularly in compromised teeth and hosts. , Kasmer Kerekes', Ingar Olsen^ Departments of 'Endodontics and ^Microbiology, Dental Faculty, University ot Osio, Oslo, Norway Key words: endodontics; periodontoiogy; cross- infection. Dr. Kasmer Kerekes, Dental Faculty, University of Oslo, Box 1109, Blindern, 0317 Oslo 3, Norway. Accepted for publication July 7, 1989. Knowledge about the etiology and pathogenesis of periodontal diseases has increased in recent years. The most important factor may be the increasing recognition that certain micro-organisms or com- plexes of organisms may be more important as pathogens than others in vexed periodontal flora (1-3). Endodontal microbiology has also received increasing attention during recent years (4). Con- tinuous anaerobic culture techniques have provided a more detailed knowledge of the microflora within and apically to the root canal. Such techniques have increased the recovery of anaerobic bacteria, and periapical lesions, frequently considered sterile, have now been found to harbour anaerobes (5). Demonstration of bacteria in periapical lesions is not consistent. Using light and electron microscopy, Nair (6) found that only a small fraction of the periapical lesions revealed bacteria within the body of the lesions, but such lesions were invariably acute and symptomatic. Recent research has demonstrated large similarit- ies in the microfloras of advanced periodontitis and pulpal lesions, suggesting that cross-infection be- tween these sites can occur (7). This review gives examples of this similarity, focusing on the bacteria most likely to participate in such cross-infection. The floras of the root canal and periodontal pocket will not be fully reviewed. Gram-negative bacteria dominate in root canais of intact teeth with necrotic pulps and in periodontai pockets The predominance of gram-negative anaerobic bac- teria in root canal infections and in marginal perio- dontitis has been demonstrated repeatedly. Sundqvist (8) showed by culture that as much as 90% of the microflora of necrotic pulps of intact, previously traumatized teeth contained gram-nega- tive rods. Slots (9) found that gram-negative anaer- obic rods constituted 74.9% of the predominant cultivable flora from the apical portion of deep periodontal pockets. In patients with localized juv- enile periodontitis, Newman & Socransky (10) found that 50% or more of the most apical pocket flora contained gram-negative rods. Furthermore, Listgarten (11), using transmission electron micro- scopy, demonstrated that periodontal pockets ex- hibited diflerent microbial zones and that the most apical portion consisted of gram-negative bacteria. Regional variation in the composition of the flora has also been demonstrated in the root canal (12). The more apically the sample is taken, the larger 1

Transcript of Similarities in the Micro Floras of Root Canals and Deep Periodontal Pockets

Page 1: Similarities in the Micro Floras of Root Canals and Deep Periodontal Pockets

Review article

Similarities in the microfloras of root canals anddeep periodontal pocketsKerekes K, Olsen I. Similarities in the microfloras of root canalsand deep periodontal pockets. Endod Dent Traumatol 1990; 6:1-5.

Abstract — Although not universally accepted, retrospective his-tological, roentgcnological and microbiological studies have in-dicated that cross-infection can occur between infected pulps anddeep periodontal pockets. This review provides examples of simi-larities in the microfloras of these adjacent oral sites, supportingthe idea that infection spreads from one site to the other. Theorganisms most often involved are probably bacteroides, fusobac-teria, eubacteria, spirochetes, wolinellas, selenomonas, campy-lobacter, and peptostreptococci. Important qualities of cross-infecting organisms may be the ability to survive in highly reducedenvironments and motility. Precautions should be taken to pre-vent in vivo seeding of such micro-organisms, particularly incompromised teeth and hosts. ,

Kasmer Kerekes', Ingar Olsen^Departments of 'Endodontics and ^Microbiology,Dental Faculty, University ot Osio, Oslo, Norway

Key words: endodontics; periodontoiogy; cross-infection.

Dr. Kasmer Kerekes, Dental Faculty, University ofOslo, Box 1109, Blindern, 0317 Oslo 3, Norway.

Accepted for publication July 7, 1989.

Knowledge about the etiology and pathogenesis ofperiodontal diseases has increased in recent years.The most important factor may be the increasingrecognition that certain micro-organisms or com-plexes of organisms may be more important aspathogens than others in vexed periodontal flora(1-3). Endodontal microbiology has also receivedincreasing attention during recent years (4). Con-tinuous anaerobic culture techniques have provideda more detailed knowledge of the microflora withinand apically to the root canal. Such techniques haveincreased the recovery of anaerobic bacteria, andperiapical lesions, frequently considered sterile,have now been found to harbour anaerobes (5).Demonstration of bacteria in periapical lesions isnot consistent. Using light and electron microscopy,Nair (6) found that only a small fraction of theperiapical lesions revealed bacteria within the bodyof the lesions, but such lesions were invariably acuteand symptomatic.

Recent research has demonstrated large similarit-ies in the microfloras of advanced periodontitis andpulpal lesions, suggesting that cross-infection be-tween these sites can occur (7). This review givesexamples of this similarity, focusing on the bacteriamost likely to participate in such cross-infection.

The floras of the root canal and periodontal pocketwill not be fully reviewed.

Gram-negative bacteria dominate in root canais of intactteeth with necrotic pulps and in periodontai pockets

The predominance of gram-negative anaerobic bac-teria in root canal infections and in marginal perio-dontitis has been demonstrated repeatedly.Sundqvist (8) showed by culture that as much as90% of the microflora of necrotic pulps of intact,previously traumatized teeth contained gram-nega-tive rods. Slots (9) found that gram-negative anaer-obic rods constituted 74.9% of the predominantcultivable flora from the apical portion of deepperiodontal pockets. In patients with localized juv-enile periodontitis, Newman & Socransky (10)found that 50% or more of the most apical pocketflora contained gram-negative rods. Furthermore,Listgarten (11), using transmission electron micro-scopy, demonstrated that periodontal pockets ex-hibited diflerent microbial zones and that the mostapical portion consisted of gram-negative bacteria.Regional variation in the composition of the florahas also been demonstrated in the root canal (12).The more apically the sample is taken, the larger

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the chance for recovering anaerobes through culti-vation.

Ciinicai symptoms vs microflora

Sundqvist (8) and, later, Griflee et al. (13) showedthat in cases with acute clinical symptoms relatedto root canal infection, Bacteroides melaninogenicuscould be isolated. Recently, Sundqvist et al. (14)found that 16 of 22 root canals containing black-pigmented Bacteroides were associated with acuteapical abscesses and purulent drainage through theroot canal. Haapasalo et al. (15) recovered B. gingi-valis, B. endodontalis and B. buccae exclusively frompulps with acute symptoms. Further, Yoshida (16)frequently isolated Bacteroides species and Peptococcusmagnus in clinically acute cases, and Heimdal et al.(17) found Fusobacterium nucleatum to be especiallyassociated with the severity of orofacial infections ofodontogenic origin. These results seem to indicatethat certain bacterial species are more importantthan others in inducing pyogenic endodontal infec-tion. However, the accompanying flora may alsocontribute, for example, by providing growth fac-tors for key organisms. Thus, Bacteroides is providedwith naphthoquinone and succinate (1).

It has also been possible to associate certain bac-teria with clinical symptoms in advanced perio-dontitis. A correlation has been demonstrated be-tween the degree of clinical inflammation, includingthe tendency to suppuration, and the quantity o{B.gingivalis cultured (18). When B. intermedius was thepredominant agent, no such correlation could beestablished. . : •

Biack-pigmenting Bacteroiiles

Bacteroides is the dominating anaerobic genus of rootcanal infections, but the rate of recovery by culti-vation varies in different studies. This may be re-lated to variances in the cases examined and in themethodology used. Sundqvist et al. (14) detectedblack-pigmenting Bacteroides in 22 root canals of 72teeth with apical periodontitis; Haapasalo et al. (15)recovered black-pigmenting Bacteroides from 50% ofinfected, necrotic root canals of noncarious teeth.Among these isolates, B. intermedius, B. endodontalisand B. denticola were detected most frequently (14,15). The prevalence of the latter may have beenunderscored in previous reports because the optimalpigmentation of this organism requires specific hostblood in the medium.

The association between B. intermedius and mar-ginal periodontitis is unclear. B. intermedius is fre-quently isolated from advanced periodontitis ofadults but usually together with a higher numberof 5. gingivalis. Sporadically, B. intermedius is recover-

ed as the only black-pigmenting Bacteroides speciesfrom deep periodontal pockets. B. intermedius maybe involved in acute ulcerative gingivitis and preg-nancy gingivitis (1). B. gingivalis is frequently thedominant species in deep periodontal poekets ofadults, where it can constitute more than 40% ofthe cultivable flora (18). Both B. gingivalis and B.intermedius can constitute major parts of the floraassociated with generalized periodontitis. In deeppockets B. gingivalis may proliferate at the expense iof other organisms through the production of hema-;tin and bacteriocin (19). '\

B. gingivalis has also been isolated from necroticpulps (14, 15), which emphasizes that the perio-'dontal pocket is not the only ecological niche of this jorganism. !

B. endodontalis is regarded as a speciflc agent of jendodontal infections. Sundqvist (8) found this or- jganism, which later acquired its name (20), in 11% \of root canal infections of intact teeth. B. endodontalis]is closely related to B. asaccharolyticus, which is gener-ally considered a habitant of the gastrointestinaltract. The reason why B. endodontalis is usually foundin the root canal may be its lack of flmbriae (21),which probably makes adhesion to oral soft tissuesdiflicult. In comparison, B. gingivalis possesses fim-!briae and adheres well to host tissue cells and gram-positive bacteria of preformed dental plaque (22).Like B. gingivalis, B. endodonialis seems to have apronounced ability to induce purulent infections(23).

'•Hi

Nonpigmenting Bacteraides

Nonpigmenting Bacteroides have received little atten-tion in oral microbiology. However, nonpigmentingBacteroides occur in the root canal quite as frequentlyas pigmenting Bacteroides (24). The most frequent;species are B. buccae, B. oris and B. oralis.

Nonpigmenting Bacteroides are also isolated from!marginal periodontitis and were originally de-iscribed as B. ruminicola subsp. brevis. Kornman &Holt (25) described a new Bacteroides species, B.capillus, which constituted the major cultivable partof the flora associated with advanced periodontitis.:B. buccae is a synonym for B. capillus. Infected, necro-tic root canals where B. buccae is present are fre-quently associated with subjective symptoms (24).jThis organism has a surface (S) layer of crystallin'ejprotein highly immunogenic in rabloits (24). Its highjantigenicity may be an explanation for the acute,symptoms. Interestingly, B. heparinolyticus and B.Iforsjthus, of which the latter has been associated withactive marginal periodontitis, also have an S-layen(26,27). . - , , , , • J

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Microfloras

Fusobacterium, Eubaetarium, Peptostreptoeaccus andCampylobactar

Fusobacterium, Eubacterium, Peptostreptococcus and Cam-pylobacter are the most frequent genera in infected,necrotic root canals of intact teeth, in addition toBacteroides (8). Indeed, this is a limited number ofgenera considering the large number that can befound in periodontal pockets. These observationsare supported, however, by lindings in experimen-tally infected monkey teeth, as the number of bac-terial genera that survived in an orally sealed rootcanal decreased considerably with time (12, 28).Others have also found Fusobacterium as a domina-ting genus in the root canal. Haapasalo et al. (15)detected F. nucleatum in 12% of all root canal isolatesand Sundqvist et al. (14) found this organism in 12of 16 teeth with apical abscesses.

F. nucleatum is among the dominant speeies of deepperiodontal pockets. Slots (9) isolated this organismfrom all patients with advanced periodontitis, andit dominated in 2 of the patients. Moore et al. (29)found that F. nucleatum, which was the most commonbacterial speeies, constituted 82% of 2305 isolatesfrom patients with moderately pronounced or juven-ile periodontitis. Fubacterium has been isolated inlarge quantities from advanced periodontitis ofadults and juvenile periodontitis (10, 29). Moore etal. (29) isolated 19 diflerent Eubacterium species,which constituted 12.1%, of the cultivable flora.Peptostreptococcus and Campylobacter seem to be moreabundant in the pocket flora than in the root canal.

Motiie bacteria

During recent years interest has been devoted notonly to Campylobacter but also to other motile bac-teria. Both Wolinella and Selenomonas can be amongthe dominating genera in periodontal pockets withattachment loss (29, 30). W. recta is frequently iso-lated from periodontal sites with aetive disease, to-gether with nonmotile fusiform Bacteroides, B. inter-medius and Actinobacillus actinomycetemcomitans (30).In one study anaerobic, gram-negative motile rodsincluding speeies of the genera Wollinella and Selen-omonas constituted 9% of the cultivable root canal

, flora (15). Interestingly, Tanner et al. (31) foundlarge DNA/DNA homology between W. recta fromroot canals and periodontal pockets. All the endo-dontal W. recta isolates came from teeth with peri-apical radiolucencies. The periodontal isolates werecultured from pockets with pronounced bone lossand clinically demonstrable inflammation. W. rectahas a crystalline surface layer (32-34).

Spirochetes have been demonstrated with darkfleld microscopy in samples from nonexposed rootcanals (35) and endodontal abscesses (36). In deep

periodontal pockets the number of spirochetes in-creases as the periodontal conditions deteriorate,except for localized juvenile periodontitis, in whichfew spirochetes are usually present (37). Spirochetescan constitute up to 50% of the microflora of deeppockets in postjuvenile and actively progressiveperiodontitis (37). The microscopic profile of spiro-chetes follows numerically the culture profile of B.gingivalis. Plaque taken from stable pockets, i.e.pockets that have not exhibited bone loss during1 year or more, contains only small numbers ofspirochetes (3%) (37). It is generally accepted thatspirochetes can invade tissue. Some of them havean S-layer (38).

Actinobacillus actinamycatamcomitans

Actinobacillus actinomycetemcomitans is considered to bethe main etiologie agent in localized juvenile perio-dontitis (39). Besides, Tanner et al. (18) found A.actinomycetemcomitans as one of the most frequent iso-lates in advanced periodontitis of adults. In infectedneerotic pulps of intact teeth this organism seems tobe rare. Haapasalo (15) isolated A. actinomycetemcomi-tans from only 1 of 62 necrotic pulps. This is sup-ported by experimental studies. Strict anaerobic or-ganisms survive better in root canals that are closedafter exposure than do facultatively anaerobic or-ganisms (12).

Microfiora of root canal and adjacent periodontal pocket

Remarkably few studies have directly compared themicroflora of the root canal and that of the adjacentperiodontal pocket in the same patient. Kipioti etal. (7) found large similarity in such floras. Theexamined teeth were intact and without periapicallesions, which supported the idea that the pocketcan be regarded as a possible source of root canalinfection. In such cases there is a correlation be-tween the existence of bacteria in the root canaland radiographically recorded marginal bone lossrather than with radioluceiicy of the periapical bone(8, 40). Roots of periodontally diseased teeth canalso act as bacterial reservoirs in the recolonizationof mechanically treated root surfaces and can infectthe dental pulp (41). Since these bacterial reservoirsare not eliminated by conventional mechanicalperiodontal treatment, it has been suggested thatmechanical periodontal therapy be combined withthe use of chemotherapeutic agents (42).

Conclusions

Similarities in the endodontal and periodontal mi-croflora of intact teeth without periapical lesionsindicate that cross-infection between the root canal

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and periodontal pocket can occur. This idea is sup-ported by theoretieaOy communicable pathways be-tween the pulp and the periodontal ligament (43).Considering the large variety of organisms coloniz-ing the periodontal pocket vs that recovered fromnecrotic pulps of intact teeth, the number of speciesparticipating in such cross-infection must be limited.First of all, they include anaerobes such as Bacteroi-des, Fusobacteria, Eubacteria, Spirochetes, Wolinella, Se-lenomonas, and Peptostreptococcus. (Most peptococcihave now been transferred to genus Peptostreptococ-cus.) Of these spirochetes, wolineflas and selenomon-as are motile. Facultatively anaerobic and motilecampylobacter may also participate, whereas fa-cultative, nonmotile actinobacilli do not. The pro-portion of anaerobic and motile organisms suggeststhat the ability to sustain highly reduced environ-ments and motility are not prerequisites for cross-infection, but they are bacterial qualities likely to beof advantage. A chronic infection in the periodontalpocket or in the root canal may represent a persist-ent supply of bacteria to the bloodstream, spreadingorganisms to nonaffected parts of the tooth organas well as to other organs of the body. Precautionsshould be taken to prevent such in vivo seeding,particularly in compromised teeth and individuals.

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