Jan Lindhe. Clinical Periodontology

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ENDODONTICS AND PERIODONTICS • 323

Fig. 14-6. (a) Destruction of alveolar bone is observed in the furcal region of the second lower left molar. (b)

Upon endodontic treatment a lateral became filled suggesting that the furcal lesion had an endodontic origin.

Courtesy of Dr Pierre Machtou.

Fig. 14-7. Frequency of accessory canals at different

lev- els of the root. The data are average values

obtained from De Deus (1975). Observations were

made after the teeth had been rendered transparent and

the root- canal system filled with China ink. The

figures for the coronal portion of the root include those

of the bi- and trifurcations.

Fig. 14-8. Photograph of the furcation area of an ex-

tracted maxillary molar with cut roots demonstrating

the opening of an accessory canal (arrow). Scanning

electron microscopic observations indicate that the fre-

quency of such furcation foramina is great (Burch &

Hulen 1974, Koenigs et al. 1974), whereas the number

of openings at the pulpal floor is small (Perlich et al.

1981). This suggests that furcation foramina at the ex-

ternal surface of the root do not necessarily represent

patent communications with the pulpal chamber. Cour-

tesy of Dr Robert C. Bowers.

volve the marginal periodontium, unless they are de-

veloping close to the bone margin. A potential path-

way for infectious elements in root canal in such in-

stances may be lateral canals.

Manifestations of endodontic lesions in the

marginal periodontium from lateral canals

Endodontic lesions, where bacterial elements reach the

periodontium by way of lateral canals, may, except for

lateral aspects of roots (Fig. 14-5), appear in furcation

areas of two and three-rooted teeth (Fig. 14-3). If there

is an existing periodontal lesion, the two soft tissue

lesions may merge and in the radiograph appear as

one lesion (Fig. 14-5a). Although, clinically, one may

be able to bring a probe through both lesions, it

is important from a therapeutic point of view to un-

derstand that the coronal part is directed towards an

infection in the marginal periodontium, and the apical

part to an infection emanating from the root canal

system. This means that in order to obtain healing,

elimination of both the sources of infection is required (

see further below).

Lateral canals normally harbor connective tissue

and vessels, which connect the circulatory system of

the pulp with that of the periodontal ligament. Such

anastomoses are formed during the early phases of

tooth development. During the completion of root

formation, several anastomoses become blocked and

reduced in width by continuous deposition of dentin

and root cementum. This may explain why endodontic

lesions are rarely seen in furcal areas of the adult

dentition, while in primary and young permanent

324 • CHAPTER 14

molars such lesions often are the first sign of an in-

fected pulp necrosis. Patent communications of vary-

ing sizes (10-250 1m), numbers and locations in the

root, however, may remain and bring about endodon-

tic lesions in the adult dentition (Figs. 14-3, 14-6).

Lateral canals can be observed in all groups of teeth.

The majority are found in the apical portion of the root.

In the middle and cervical root portions, the preva-

lence is small. In a study of 1140 extracted human teeth

from adult subjects, De Deus (1975) reported lateral

canals in 27%. These canals were distributed at vari-

ous levels of the root as depicted in Fig. 14-7.

The frequency of lateral canals in the furcation area

of two and three-rooted teeth has been determined in

numerous studies of extracted human teeth (Fig. 14-8).

A variety of techniques have been employed, which

may explain the divergent results obtained. While

some studies found furcation canals in between 20%

and 60% of examined teeth (Lowman et al. 1973, Ver-

tucci & Williams 1974, Gutmann 1978), others have

failed to demonstrate the presence of such canals at

furcation sites (Pineda & Kuttler 1972, Hession 1977).

Radiographically, it is seldom possible to identify lat-

eral canals unless they have been filled with a con-

trasting root-filling material following endodontic

therapy (Figs. 14-5, 14-6). A lateral position of a radi-

olucency associated with a tooth with a necrotic and

infected pulp may also indicate the presence of a

lateral canal (Fig. 14-5a).

The clinical significance of lateral canals for the

dissemination of infectious elements from an infected

pulp to the periodontium is not well established. In

fact, there is no documention as to how often such

lesions occur. It is conceivable that the wider the

lateral canal, the greater is the likelihood for a lateral

lesion to develop. Although clinical observations

demonstrate their occurrence (Figs. 14-3, 14-5 and

14-6), the

rate at which endodontic lesions appear in the mar-

ginal periodontium seems to be low.

In this context, it should be recognized that there is

little evidence suggesting that infectious products

from a necrotic pulp can affect the periodontal tissue

through intact walls of dentin and cementum. Even if

the width of the dentinal tubules is large enough to

allow passage of both bacteria and their components,

an intact outer layer of cementum evidently acts as an

effective barrier against such penetration. Once ce-

mentum has been damaged, for example by root re-

sorption, inflammatory periodontal lesions may be

sustained by an active root canal infection (see below,

Fig. 14-26).

Conclusion

Inflammatory lesions may develop from a root canal

infection at the lateral aspects of the root and in furca-

tion regions of two and multirooted teeth. In these

instances, the lesions may be induced and maintained

by bacterial products, which reach the periodontium

through lateral canals. These types of lesions appear

to be rare and do not seem to emerge at a rate that

corresponds to the frequency with which lateral ca-

nals occur in teeth.

MANIFESTATIONS OF ACUTE

ENDODONTIC LESIONS IN THE

MARGINAL PERIODONTIUM

Inflammatory lesions in the periodontal tissue, in-

duced and maintained by root canal infection, often

have a limited extension around the apex of the tooth (

Fig. 14-2) or at the orifice of a lateral canal (Fig. 14-3).

Fig. 14-9. Angular bone defect is observed along the distal root surface of a mandibular canine (a). Apical-

marginal communication was confirmed by periodontal probing (b). Endodontic treatment resulted in complete

reestablishment of the periodontal structures, demonstrating that the periodontal defect in this case was the result

of endodontic infection only. Courtesy of Dr Ralph Milthon.

ENDODONTICS AND PERIODONTICS • 325

Fig. 14-10. Schematic illustration demonstrating possible pathways for drainage of a periapical abscess into the gin-

gival sulcus/pocket. (a) periodontal ligament fistulation. (b) extraosseous fistulation.

Fig. 14-11. Drainage of pus from probing a periodontal

ligament fistulation of an endodontic lesion associated

with an upper molar.

In conjunction with the initial expansion of an endo-

dontic lesion, the periodontal tissue support can be

lost to the extent that an apical-marginal communica-

tion emerges, in particular when there is already a

substantial loss of periodontal tissue support due to

periodontal disease (Fig. 14-5). Following the exacer-

bation of an established lesion, the subsequent abscess

formation may cause the destruction of the support-

ing tissue structures along the entire root length (Fig.

14-9). This may occur even in a tooth with a normal

height of the attachment apparatus.

The emergence of these processes may or may not

be associated with clinical signs of acute inflammation

including throbbing pain, tenderness to percussion

and apical palpation, increased tooth mobility and

swelling of the marginal gingiva. Note that the same

symptoms are typical of a periodontal abscess due to

either periodontal disease, root fracture, root resorp-

tion or iatrogenic root perforation (see also Fig. 14-27).

In general, drainage of endodontic abscesses into

the sulcus/pocket follows one of two routes (Fig. 14-

10):

1. The suppurative process may cause a sinus tract

along the periodontal ligament space (periodontal

ligament fistulation; Fig. 14-10a). This usually re-

sults in only a narrow opening of the fistula into

the gingival sulcus/pocket and may not be de-

tected unless careful probing of the sulcus is carried

out at multiple sites. Such a fistula may readily be

probed down to the apex of the tooth (Fig. 14-9b), where

no increased probing depth otherwise exists around the

tooth. In multirooted teeth a periodontal ligament

fistulation can drain off into the furcation area (Fig.

14-11). The resulting lesion may then resemble a "

through and through" furcation defect from peri-

odontal disease (Fig. 14-12).

2. A periapical abscess can also perforate the cortical

bone close to the apex and elevate the soft tissue

including the periosteum from the bone surface,

and drain into the gingival sulcus/pocket (Fig. 14-

10b). This type of drainage will result in a wide

opening of the fistula into the sulcus/pocket (ex-

traosseous fistulation), and is most often seen at the

buccal aspect of the tooth. Since this type of fistula

is not associated with loss of bone tissue at the inner

walls of the alveolus, a periodontal probe cannot

penetrate into the periodontal ligament space.

326 • CHAPTER 14

Fig. 14-12. A large radiolucent area is seen in the furcation region of the lower left first molar (tooth #36)

mimicking what potentially could be a through and through furcation involvement (a). There is, however, a

distinct caries lesion and the pulp is necrotic. Upon endodontic therapy (b,c) the 18-month follow-up

radiograph demonstrates complete bone fill in the region (d). Courtesy of Dr Kevin Martin.

It is important to realize that the lesions described are

strictly of endodontic origin. Therefore, following

conventional endodontic therapy, directed to elimi-

nate the root canal infection, both types of marginal

communications should, following proper treatment,

heal rapidly without a persistent periodontal defect (

Figs. 14-5, 14-12 and 14-13). Thus, there is generally

no need for adjunctive periodontal therapy. The endo-

dontic treatment of the involved tooth should be per-

formed without delay to prevent repeated exacerba-

tions and the establishment of a permanent apical-

marginal communication.

Conclusion

Acute manifestations of root canal infections can re-

sult in rapid and extensive destruction of the attach-

ment apparatus. Abscesses may drain off in different

directions of which (1) a sinus tract along the peri-

odontal ligament space and (2) an extraosseous fistu-

lation into the gingival sulcus/pocket warrant par-

ticular attention from a differential diagnostic point of

view. Following proper endodontic therapy, these le-

sions should be expected to heal without a persistent

periodontal defect.

IMPACT OF ENDODONTIC

TREATMENT MEASURES ON THE

PERIODONTIUM

When breakdown of periodontal tissue is associated

with a root-filled tooth, endodontic etiology should be

taken into account, particularly if the root filling is of

poor quality. From unfilled spaces in the root canal,

sustaining bacterial growth, infectious products may

emerge into the periodontium along the very same

pathways as in an untreated tooth with infected pulp.

Clinical observations suggest that such infections may

contribute to increased probing depth (Jansson et al.

1993) and results of clinical follow-ups have shown

retarded or impaired periodontal tissue healing sub-

sequent to periodontal therapy of endodontically

treated teeth with periapical pathology (Ehnevid et al.

1993a,b). From these observations, it follows that en-

dodontic retreatment may be considered as an adjunct

to periodontal therapy whenever a root canal filling is

defective and/or displays signs of periapical inflam-

mation. Root-filled teeth in general, however, do not

seem to be associated with an impaired periodontal

status (Miyashita et al. 1998).

ENDODONTICS AND PERIODONTICS • 327

Fig. 14-13. Facial swelling associated with tooth #46 as a result of a periapical abscess (a). Patient had experienced

pain and tenderness in the area for 1 week. Periodontal probing disclosed a deep facial pocket along the mesial

root (b). Radiographically, the lesion circumscribed the mesial root with marginal extension in the furcation (c).

It was not possible to determine the condition of the pulp by conventional pulp-vitality tests. Test cavity

preparation revealed a necrotic pulp that was endodontically treated including intracanal dressing with calcium

hydroxide. Obvious reduction in lesion size was observed 3 months after treatment (d). Gingival lesion resolved

leaving no abnormal probing depth (e), although radiographically a small bone defect remained in the furcation

area (d, f) Endodontic treatment was completed by filling the root canals with gutta-percha. Twelve months after

root filling complete resolution of the bone defect had occurred (f). Diagnosis and treatment of this case was

carried out by one of the authors (G.B.) in collaboration with Dr David Simpson.

Periodontal inflammatory lesions may also result hand, strong antiseptic drugs used for root canal dis-

from mechanical as well as chemical irritation initi- infection and pulp devitalization cause severe dam-

ated by root canal treatment. However, medicaments age if they leak into the periodontal tissue (Fig. 14-

for canal irrigation and disinfection as well as materi- 14a,b).

als for filling used in modern endodontics are comparatively

well tolerated by the connective tissue of the periodontium, even

if, during treatment, they are forced into the periodontal

ligament. On the other

328 • CHAPTER 14

Fig. 14-14. (a) Clinical photograph showing a periodontal defect at the mesial aspect of tooth #46. The pulp of the

tooth had been subjected to a treatment with paraformaldehyde applied in order to cause its devitalization.

Leak-age of the agent along a defect temporary restoration had obviously occurred as indicated by the loss of

proximal bone and presence of a bone sequestrum (b).

Root perforations

During endodontic treatment, and in conjunction with

preparation of root canals for the insertion of posts,

instrumentation can accidentally cause perforation of

the root and wounding of the periodontal ligament (

Alhadainy 1994). Perforations can be made through

the lateral walls of the root or through the pulpal

floor in multirooted teeth. At the site of perforation,

the subsequent inflammatory reaction can result in

the formation of a periodontal pocket, if the

perforation is located close to the gingival margin (

Lantz & Persson 1967, Stromberg et al. 1972, Peters-

son et al. 1985). Other complications include exacer-

bation of a preexisting periodontal lesion and devel-

opment of clinical symptoms, similar to those of a

periodontal abscess, e.g. acute pain, swelling, drain-

age of pus from the pocket, increased tooth mobility

and further loss of fibrous attachment (Fig. 14-15).

Early detection of the complication is crucial to

provide reasonable conditions for successful treat-

ment. Diagnosis may be based on the occurrence of

sudden pain and bleeding during preparation of root

canals coronal to the working length. Such signs are

likely to be less distinct if the perforation occurs dur-

ing a procedure conducted under local anesthesia. In

such cases bleeding may not invariably be provoked.

For example, when post preparations are carried out

by means of a machine-driven instrument, a smear

layer is formed that may clog up the blood vessels.

Thus, in many instances no bleeding will be noticed

until the following visit, when granulation tissue is

formed and has proliferated into the root canal space

from the site of perforation. These granulations some-

times bleed profusely on attempts to remove them,

which in turn may jeopardize adequate placement of

an internal perforation seal. For this reason treatment

of a root perforation should be initiated once discov-

ered.

The series of radiographs in Fig. 14-16 demon-

strates the successful outcome of a treatment of a

Fig. 14-15. Angular bone defect at the distal root sur-

face of a mandibular premolar (arrows). The root is per

forated. Conceivably, this occurred in conjunction with

preparation of the root canal for a post and core. Clini-

cal symptoms included drainage of pus from the

pocket and increased tooth mobility. The tooth was ex

tracted.

perforation made in the furcation of a mandibular

molar. Healing of the lesion in the periodontium de-

pends largely on whether bacterial infection can be

excluded from the wound site by a tight seal of the

perforation (Beavers et al. 1986). If the perforation is

close to the sulcus area, or conducted through the floor

of a multirooted tooth, the inflammatory response

may induce the proliferation of sulcular epithelium to

form a deepened periodontal pocket (Petersson et al.

1985).

ENDODONTICS AND PERIODONTICS • 329

Fig. 14-16. Perforation of the pulpal floor of the mandibular first molar occurred in conjunction with a search

for root canal openings (a). The perforation was immediately sealed with gutta-percha (b). One month after

treatment a slight radiolucency appeared at the perforation site (arrow) in the periodontium (c). After an

observation period of 2 years, normal periodontal conditions were re-established both clinically and

radiographically (d). Courtesy of Dr Gunnar Heden.

Repair of root perforations is unpredictable and a

questionable prognosis of treatment should be antici-

pated (Petersson et al. 1985). Major reasons are that

perforations frequently are difficult to access for a

proper seal. Furthermore, the perforation is often

made at an oblique angle in the lateral wall of the root

and the artificial canal may then have an oval-shaped

orifice into the periodontium. Obturation of such de-

fects with gutta-percha, for example, can result in a

poor seal and a risk of subsequent bacterial irritation

of the periodontal tissue.

Over the years a large number of therapeutic agents

and methods have been proposed for the manage-

ment of root perforations (Alhadainy 1994). Materials

suggested for sealing include amalgam, zinc oxide

and eugenol cements, calciumhydroxide-containing

pastes both chemically cured and light cured and

plaster of Paris. More recently, mineral trioxide aggre-

gate (MTA) has come into vogue by virtue of promis-

ing clinical results (Arens 8z Torabinejad 1996,

Schwartz et al. 1999) and by observation in animal

experiments of cementum depositions against the ma-

terial (Torabinejad et al. 1997, Holland et al. 2001).

For mid-root and cervical perforations, non-surgi-

cal approaches including placement of an internal seal

are preferable to surgical procedures as the latter often

results in pocket formation and furcation involve-

ment. Furthermore, surgical approaches are not al-

ways feasible because of the inherent difficulty in

accessing many perforation sites. In such cases, as a

last resort, extraction followed by repair and re-im-

plantation of the tooth has been attempted. In multi-

rooted teeth, hemisection and extraction of one or two

roots may be the treatment of choice.

Conclusion

Inflammatory lesions in the marginal periodontium as

manifested by increased probing depth, suppuration,

increased tooth mobility and loss of fibrous at-

tachment may result from an undetected or unsuc-

cessfully treated root perforation. If an iatrogenic root

perforation occurs during instrumentation of root ca-

nals, filling of the artificial canal to the periodontium

should be carried out immediately. Outcome of treat-

ment depends on how well the wound site can be

sealed and protected from infection. The closer the

perforation is to the marginal gingiva, the greater the

330 • CHAPTER 14

Fig. 14-17. Vertical root fracture of a maxillary root-

filled upper canine included as abutment in a pros-

thetic reconstruction. Due to the inflammatory break-

down, alveolar bone facial to the root surface is

absent.

Fig. 14-18. Periapical radiolucency associated with an upper second premolar (a) which turned out to be caused by

a longitudinal root fracture. There was a buccal deep pocket probing depth. (b) A gutta-percha point has been in-

serted in a fistulous tract. The widely prepared root canal and the cantilever most likely contributed to the risk for

fracture in this case. Courtesy of Dr Tomas Kvist.

likelihood of proliferation of sulcular epithelium to

the perforation site.

Vertical root fracture

Clinical symptoms that are typical for endodontic and

periodontal lesions may also appear at teeth with

vertical root fractures. A vertical root fracture is de-

fined as a fracture of the root that is longitudinally

oriented at a more or less oblique angle towards the

long axis of the tooth (Fig. 14-17). It can traverse the

root in different directions mesially/distally or

facially/lingually and may or may not involve the

pulpal chamber. A vertical root fracture can extend the

entire length of a tooth and involve the gingival sul-

cus/pocket area but may also be incomplete and con-

fined to either the coronal or apical ends. Furthermore,

it should be noted that even though vertical root frac-

tures usually involve opposite sides of the root, occa-

sionally only one aspect of the root is involved.

As a result of bacterial growth in the fracture space,

the adjacent periodontal ligament will become the seat

of an inflammatory lesion, which causes breakdown of

connective tissue fibers and alveolar bone (Fig. 14-17)

. Breakdown can manifest itself radiographically in a

number of different ways (Figs. 14-18, 14-19c, 14-20).

Thus, the radiographic defect may be similar to those

found at endodontic and periodontal lesions. In other

situations the appearance may be atypical of

ENDODONTICS AND PERIODONTICS • 331

Fig. 14-19. A typical case of root fracture. The first maxillary premolar had been asymptomatic for 20 years after

completion of endodontic treatment and bridge work. Patient sought treatment because of suddenly occurring pain,

tenderness and facial swelling (a). A deep periodontal pocket can be probed at the buccal aspect of the tooth (b),

while other sites showed no abnormal probing depths. Radiographs (c) revealed a radiolucent area along the

rnesial aspect of the tooth. A set of radiographs taken 6 months earlier at a recall session (d) showed no such lesion.

The elevation of a mucoperiosteal flap (e) revealed substantial loss of marginal bone at the buccal aspect of the root

and a fracture in a mesiodistal direction could be confirmed. Following removal of bone, the root was separated

from the crown (f) and extracted.

these disorders. A widening of the periodontal liga- fracture (Pitts & Natkin 1983, Testori et al. 1993, Tamse

ment space along one or both of the lateral root sur- et al. 1999a).

faces may indicate the presence of a root fracture. A Clinical symptoms associated with vertical root

thin halo-like apical radiolucency is another example fractures show a varying character. Occasionally, there

of a radiographic lesion suggestive of a vertical root may be pronounced pain symptoms and abscess for-

mation – symptoms similar to those occurring with

• CHAPTER 14

Fig. 14-20. Mandibular premolar included in a 4-unit bridge showing a bone lesion at the mesial aspect. In one of

the projections there is no evidence of fracture (a) while in another radiograph, taken with a slight shift of angula

tion, a fracture line is clearly visible (b). Courtesy of Dr K-G. Olsson.

Fig. 14-21. Unrestored, cracked left maxillary first

molar causing symptoms of pulpitis. The patient, a

47-year-old male, had complained of pain in the TMJ

-region. Following the preparation of a test cavity a

clear split line was observed at the bottom of the cavity,

confirming the cause of the pain symptoms. Courtesy

of Dr H. Suda.

periodontal or endodontic abscesses. In other in-

stances, a narrow, local deepening of a periodontal

pocket (Fig. 14-19), associated with the fracture, may

be the only clinical finding. Other clinical symptoms

occurring in conjunction with root fractures are ten-

derness to mastication, fistulous tract, mild pain and

dull discomfort. The diagnosis of a vertical root frac-

ture is often difficult because the fracture is usually not

readily detectable by clinical inspection unless there

is a clear separation of the root fragments. By radio-

graphic examination the central X-ray beam has to be

parallel to the fracture plane to give a radiographic

appearance (Fig. 14-20). The suspicion of a vertical

root fracture is often inferred from a pocket probing

depth in an aberrant position, for example at a buccal

or lingual aspect of a tooth in a dentition which other-

wise is free from symptoms of periodontal disease (Fig

14-18). Another strong indication is the sudden ap-

pearance of clinical symptoms and/or radiographic

lesion on a root-filled tooth that has remained asymp-

tomatic and without lesion for many years (Fig. 14-

19a-d).

A number of diagnostic procedures can be under-

taken to confirm the diagnosis. Application of various

dye solutions, e.g. methylene blue or iodine tincture,

on to the crown and the root surface can sometimes be

indicative. As the dye enters the fracture space, it will

show up as a distinct line against the surrounding

tooth substance. Indirect illumination of the root, us-

ing fiber-optic light, can also be of value. The fiber-op

tic probe should then be placed at various positions

on the crown or the root, whereby the fracture line

may clearly present itself. The surgical microscope or

an endoscope, providing both enlargement and di-

rected light, are other valuable tools to detect a frac-

ture.

In premolars and molars the diagnosis may be

supported from observation of varying pain sensa-

tions elicited by loading facial and lingual cusps. The

procedure includes asking the patient to bite down on a

Burlew disc or a specially designed plastic stick (

FracFinder). Separate loading of either buccal or lin-

gual cusps eliciting pain sensation from one, but not

the other, loaded portion indicates the potential of a

fracture. Often the diagnosis of a vertical root fracture

has to be confirmed by surgical exposure of the root