Dental - Pathways of the Pulp - S. Cohen, R. Burns

747 Pages·2006·16.7 MB·English

Contents

PART ONE:
THE ART OF ENDODONTICS

1
Diagnostic Procedures, 2
Stephen Cohen

2
Orofacial Dental Pain Emergencies: Endodontic Diagnosis and Management, 25
Alan H. Gluskin and William W. Y. Goon

3
Nonodontogenic Facial Pain and Endodontics: Pain Syndromes of the Jaws that Simulate
Odontalgia, 51
Lewis R. Eversole

4
Case Selection and Treatment Planning, 60
Samuel (). Dorn and Arnold H. Gartner

5
Preparation for Treatment, 77
Gerald Neal Clickman

6
Armamentarium and Sterilization, 110
Robert E. Averbaeh and Donald J, Kleier

7
Tooth Morphology and Access Openings, 128
Richard C. Burns and I.. Stephen Buchanan

8
Cleaning and Shaping the Root Canal System, 179
John D. West, James B. Roane, and Albert C. Goerig

9
Obturation of the Root Canal System, 219
Nguyen Thanh Nguyen, with section by Clifford J. Ruddle

10
Records and Legal Responsibilities, 272
Edwin J. Zinman

PART T W O :
T H E SCIENCE OF ENDODONTICS

11
Pulp Development, Structure, and Function, 296
Henry O. Trowbridge and Syngcuk Kim

12
Periapical Pathology, 337
James H. S. Simon

13
Microbiology and Immunology, 363
James D. Kettering and Mahmoud Torabinejad

14
Instruments, Materials, and Devices, 377
Leo J. Misercndino, with section by Herbert Schilder

15
Pulpal Reaction to Caries and Dental Procedures, 414
Syngcuk Kim and Henry O. Trowbridge

XI

Xll
Contents

PART THREE:
RELATED CLINICAL TOPICS

16
Traumatic Injuries, 436
Stuart B. Fountain and Joe H. Camp

17
Root Resorption, 486
Martin Trope and Noah Chivian

18
Endodontic-Periodontal Relations, 513
James H. S. Simon and Leslie A. Werksman

19
Surgical Endodontics, 531
Gary B. Carr

20
The Management of Pain and Anxiety, 568
Stanley F. Malamed

21
Bleaching of Vital and Pulpless Teeth, 584
Ronald E. Goldstein, Van B. Haywood, Harald O. Heymann, David R. Steiner, and John D. West

22
Restoration of the Endodontically Treated Tooth, 604
Galen W. Wagnild and Kathy I. Mueller

23
Pediatric Endodontic Treatment, 633
Joe H. Camp

24
Geriatric Endodontics, 672
Carl W. Newton

25
Endodontic Eailures and Re-treatment, 690
Adam Stabholz, Shimon Friedman, and Aviad Tamse

PART FOUR:
ISSUES IN ENDODONTICS

26
Ethics in Endodontics, 730
James T. Rule and Robert M. Veatch

Answers to Self-Assessment Questions, 737
Daniel B. Green, H. Robert Steiman, and Richard E. Walton

PART ONE

THE ART OF ENDODONTICS

Chapter 1

Diagnostic Procedures

Stephen Cohen

THE ART AND SCIENCE OF DIAGNOSIS

The dictionary* defines diagnosis as "the art of identifying
a disease from its signs and symptoms." Although scientific
devices can be used to gather some information, diagnosis is
still primarily an art because it is the thoughtful interpretation
of the data that leads to a diagnosis. An accurate diagnosis is
a result of the synthesis of scientific knowledge, clinical expe-
rience, intuition, and common sense.

To be a good diagnostician a clinician must learn the fun-
damentals of gathering and interpreting clinical information.
An inflamed or diseased pulp is a common, straightforward,
and nonurgent condition. Systematic recording of a patient's
presenting signs and symptoms and careful analysis of the find-
ings from clinical tests inevitably lead to a correct diagnosis.
There arc instances, however, when a patient presents with an
acute situation, conflicting signs and symptoms, or inconsis-
tent responses to clinical testing. Chapter 2 explores the meth-
ods for diagnosing and testing these endodontic riddles. Chap-
ter 3 discusses the ostensible toothache of nonodontogenic or-
igin.

Medical History

Even though there are virtually no systemic contraindica-
tions to endodontic therapy (except uncontrolled diabetes or a
very recent myocardial infarction), a recent and succinct, com-
prehensive preprinted medical history is mandatory (see box
on p. 3). It is only with such a history that the clinician can
determine whether medical consultation or premedication is re-

Unless otherwise indicated, the illustrations in this chapter were prepared by
Dr. Albert Goerig.
*Wehster's ilurd Imem.ahona! Dicuonaiy. Springfield. Mass. 1976. Merriam-
Webster Inc.

quired before diagnostic examination or clinical treatment is
undertaken. Some patients require antibiotic prophylaxis be-
fore clinical examination because of systemic conditions like
heart valve replacement, a history of rheumatic fever, or ad-
vanced AIDS. Patients who daily take anticoagulant medica-
tions may need to have the dose reduced or dosing suspended
if the clinician is to conduct the thorough periodontal exami-
nation, which is integral to a complete endodontic workup.
When patients report being infected with communicable dis-
eases such as AIDS, hepatitis B, or tuberculosis, dentist and
staff need to be especially attentive to the use of protective
barriers. In case endodontic therapy is required, the clinician
must know what drugs the patient is taking so that adverse drug
interactions can be avoided. In such cases, consultation with
(he patient's physician is recommended. Patients who present
with mental or emotional disorders are not uncommon. Some
patients are aware of their disorder and inform the dentist. Oth-
ers may have undiagnosed psychological or emotional prob-
lems; abnormal or highly inappropriate behavior may suggest
the presence of illness. In these cases, too, medical consulta-
tion before the diagnostic examination would be in the best
interests of patient, doctor, and staff. A brief summary of these
consultations with treating physicians and an outline of their
suggestions should be recorded and dated in the patient record.

Dental History

After completing the medical history the clinician should de-
velop the dental history. The purpose of a dental history is to
create a record of the chief complaint, the signs and symp-
toms the patient reports, when the problem began, and what
the patient can discern that improves or worsens the condition.
The most efficacious way for the clinician to gather this im-
portant information is to ask the patient pertinent questions re-

garding the chief complaint, and to listen carefully and sensi-
tively to the patient's responses. For example, the doctor might
begin by simply asking the patient. "Could you tell me about
your problem?" To determine the chief complaint, this ques-
tion should be followed by a series of other questions, such as
"When did you first notice this?" (inception). Affecting fac-
tors that improve or worsen the condition should also be de-
termined. "Docs heat, cold, biting, or chewing cause pain?"
(provoking factors). "Does anything hot or cold relieve the
pain?" (attenuatingfactors). "How often does this pain occur?"
(frequency). "When you have pain, is it mild, moderate, or
severe?" (intensity). The answers to these questions provide
the information the dentist needs to develop a brief narrative
description of the problem.

The majority of patients present with evident problems of
pain or swelling, so most questions should focus on these ar-
eas. For example, "Could you point to the tooth that hurts or
the area that you think is swelling?" (location). "When cold
{or heat) causes pain, docs it last for a moment or for several
seconds or longer?" (duration). "Do you have any pain when
you lie down or bend over?" (postural). "Does the pain ever
occur without provocation?" (stimulated or spontaneous).
"What kind of pain do you get? Sharp? Dull? Stabbing?
Throbbing?" (quality). Questions like these help the clinician

establish the location, nature, quality, and urgency of the prob-
lem and encourage the patient to volunteer additional infor-
mation that completes the verbal picture of the problem. The
clinician may be able to formulate a tentative diagnosis while
taking a dental history. The examination and testing that fol-
low often corroborate the tentative diagnosis. It is then merely
a matter of identifying the problem tooth/1'7

In the gathering of a dental history, common sense must pre-
vail. The questions outlined here, along with other questions
described in Chapter 2, should be asked if the diagnosis is elu-
sive. If the clinician can see a grossly decayed tooth while sit-
ting and talking with the patient and if the patient points to
that tooth, the dental history should be brief because of the
obvious nature of the problem. Furthermore, if the patient is
suffering from severe distress, with acute symptoms (Chapter
2), the dental history should be brief so the clinician can re-
lieve the pain as soon as possible.

Pain

Because dental pain frequently is the result of a diseased
pulp, it is one of the most common symptoms a dentist is re-
quired to diagnose.14" The source of the pain is usually made
evident by dental history, inspection, examination, and test-
ing. However, because pain has psychobiologic components—

4
The art of endodontics

physical, emotional, and tolerance—identifying the source is
at times quite difficult. Furthermore, because of psychological
conditioning, including fear, the intensity of pain perception
may not be proportional to the stimulus. When patients present
with a complaint of pain that is subsequently determined to be
of odontogenic origin, the vast majority of these cases reflect
conditions of irreversible pulpitis, with or without partial ne-
crosis.19'23

Patients may report the pain as sharp, dull, continuous, in-
termittent, mild, severe, etc. Because the neural portion of the
pulp contains only pain fibers, if the inflammatory state is lim-
ited to the pulp tissue it may be difficult for the patient to lo-
calize the pain. However, once the inflammatory process ex-
tends beyond the apical foramen and begins to involve the peri-
odontal ligament, which contains proprioceptive fibers, the pa-
tient should be able to localize the source of the pain. A
percussion test at this time to corroborate the patient's percep-
tion of the source will be quite helpful.

At times pain is referred to other areas within, and even be-
yond, the mouth. Most commonly it is manifested in other
teeth in the same or the opposing quadrant. It almost never
crosses the midline of the head. However, referred pain is not
necessarily limited to other teeth. It may, for example, be ipsi-
laterally referred to the preauricular area, or down the neck,
or up to the temporal area. In these instances the source of
cxtraorally referred pain almost invariably is a posterior tooth.
Ostensible toothache of nonodontogenic origin (i.e., resulting
from neurologic, cardiac, vascular, malignant, or sinus dis-
eases) is described in Chapter 3.

Patients may report that their dental pain is exacerbated by
lying down or bending over. This occurs because of the in-
crease in blood pressure to the head, which increases the pres-
sure on the confined pulp.

The dentist should be alert for patients who manifest emo-
tional disorders as dental pain. If no organic cause can be dis-
covered for what appears as dental pain, the patient should be
referred for medical consultation. Patients with atypical facial
pain of functional rather than organic cause may begin their
long journey through the many specialties of the health sci-
ences in the dentist's office.

If the dentist can determine the onset, duration, frequency,
and quality of the pain and the factors that alter its perception,
and if the dentist can reproduce or relieve the pain by clinical
testing, then surely the pain is of odontogenic origin. The pa-
tient will usually gain immeasurable psychological benefit if
the clinician provides caring and sincere reassurance that, once
the source is discovered, appropriate treatment will be pro-
vided immediately to stop the pain.

EXAMINATION AND TESTING

The inspection phase of the extraoral and intraoral clinical
examination should be performed in a systematic manner. A
consistent step-by-step approach, always following the same
procedure, helps the clinician develop good working habits and
minimizes the possibility of inadvertently overlooking any part
of the examination or testing. The extraoral visual examina-
tion should begin while the clinician is taking the patient's den-
tal history.

Talking with the patient provides an opportunity to observe
the patient's facial features. The clinician should look for fa-
cial asymmetry (Fig. 1-1, A) or distensions that might indi-
cate swelling of odontogenic origin or a systemic ailment. The

patient's eyes should be observed for the pupillary dilation or
constriction that may indicate systemic disease, premedication,
or fear. Additionally, the patient's skin should be observed for
any lesion(s) and, if there is more than one, whether the le-
sions appear at random or follow a neural pathway.

After a careful external visual examination the clinician
should, with the aid of a mouth mirror and the blunt-ended
handle of another instrument, begin an oral examination to
look for abnormalities of both hard and soft tissues. With a
head lamp and good magnification the lips, cheek pouch,
tongue, palate, and throat should be briefly examined (Fig.
1-1, B). Because it is easier to observe abnormalities when tis-
sues are dry, the liberal use of 2x2 inch gauze, cotton rolls,
and a saliva ejector is strongly recommended (Fig. 1-1, C).
During the visual phase of the examination the clinician should
also be checking both the patient's oral hygiene and the integ-
rity of the dentition. Poor oral hygiene and/or numerous miss-
ing teeth may indicate that the patient has minimal interest in
maintaining a healthy dentition.

Visual inspection of the teeth begins with drying the quad-
rant under examination and looking for caries, toothbrush abra-
sion (Fig. 1-1, D) (cervical lesions occasionally are over-
looked), darkened teeth (Fig. 1-1, £), observable swelling
(Fig. 1-1, F), fractured or cracked crowns (Fig. 1-1, G), and
defective restorations.

The clinician should observe the color and translucency of
the teeth. Are the teeth intact or is there evidence of abrasion,
attrition, cervical erosion, or developmental defects in the
crowns?

A high index of suspicion must prevail during examination
for numerous types of soft-tissue lesions.8,20 This also means
looking for unusual changes in the color or contour of the soft
tissues. For example, the clinician should look carefully for
lesions of odontogenic origin such as sinus tracts (fistulas)
(Fig. 1-2, A) or localized redness or swelling involving the at-
tachment apparatus. The presence of a sinus tract may indi-
cate that periapical suppuration has resulted from a pulp that
has undergone complete necrosis in at least one root. The sup-
purative lesion has burrowed its way from the cancellous bone
through the cortical plate and finally to the mucosal surface.
All sinus tracts should be traced with a gutta-percha cone (Fig.
1-2, JS to E) to locate their source, because occasionally the
source can be remote.13

All observable data indicating an abnormality should be re-
corded on the treatment chart while the information is still fresh
in the clinician's mind. If a tooth is suspected of requiring en-
dodontic treatment, it should be assessed in terms of its re-
storability after endodontic treatment, its strategic importance,
and its periodontal prognosis.

Palpation

When periapical inflammation has developed as an exten-
sion of pulpal necrosis, the inflammatory process may burrow
its way through the facial cortical bone and begin to affect the
overlying mucopcriosteum. Before incipient swelling becomes
clinically evident, it may be discerned by both the clinician
and the patient using gentle palpation with the index finger
(Fig. 1-3, A). The index finger is rolled while it presses the
mucosa against the underlying bone. If the mucoperiostcum is
inflamed, this rolling motion wiil reveal the existence and de-
gree of sensitivity caused by the periapical inflammation.

To improve tactile skill and learn the full extent of normal

Diagnostic procedures
5

FIG. 1-1 A, Swelling around the right mandible can be readily observed by the clinician
while preparing the dental history. B, The Designs for Vision fiberoptic headlamp along with
2'/2 to 3'/2 x magnification allows the clinician to examine the soft tissues and teeth without
any shadows. C, A thorough tissue examination is facilitated by drying with cotton rolls, 2
X 2 inch gauze, and a saliva ejector. The initial examination of the teeth and surrounding
tissues is conducted with the patient's mouth partly open. With good illumination and mag-
nification, as shown in Fig. 1-1 B, changes in color, contour, or texture can be determined
by a careful visual examination. D, Class V caries lesion, or abrasion, not always detectable
radiographically, can be observed. E, Tooth discolored following a traumatic incident. Al-
though the tooth appears necrotic, vitality tests should still be conducted because the pulp
could remain vital, F, Intraoral swelling from periapical disease usually appears around the
mucobuccal fold; however, the entire mouth must be thoroughly examined because swelling
from periapical disease may occur in unusual locations (e.g., the palate). G, With careful
visual examination the clinician may observe crown fractures that may not appear in radio-
graphs.

6
The art of endodontics

FIG. 1-2 A, Sinus tract (fistula). B, When a sinus tract is detected, it should always be traced
with a gutta-percha cone to its source. In this case, the sinus tract appeared between the first
and second premolars. C, The source of the sinus tract was the lateral incisor, as the gutta-
percha probe indicates. D, Gutta-percha cone used to trace a sinus tract discovered on the
palate. E, An occlusal jaw radiograph revealed that the sinus tract crossed the midline. The
source was a cuspid. F, After numerous unsuccessful dermatologic treatments, this patient
consulted a dentist. G, The dentist discovered the source.

range to be expected, the clinician is urged to perform palpa-
tion testing routinely.

Other techniques involving extraoral bidigital or bimanual
palpation (e.g., palpating lymph nodes or the floor of the
mouth) arc described in complete detail by Rose and Kaye.18

Occasionally a patient is able to point to a particular facial
area that felt tender when shaving or applying makeup. The
clinician can follow up by palpating in the mucofacial fold,
which may help pinpoint the source of the tenderness. If a site
that feels tender to palpation is discovered, its location and ex-
tent should be recorded as well as whether or not the area is
soft or firm. This provides important information on the pos-
sible need for an incision and drainage.

If a mandibular tooth is abscessed, it is prudent also to pal-
pate the submandibular area bimanually to determine whether
any submandibular lymph nodes have been affected by exten-
sion of the disease process (Fig. 1-3, B).

Finally, the cervical lymph nodes should be palpated bidig-
itally to discern any swollen or firm lymph nodes.

The use Of extraoral and intraoral palpation helps the clini-
cian determine the furthest extent of the disease processes.

Percussion

The percussion test may reveal whether there is any inflam-
mation around the periodontal ligament. The clinician should
remember that the percussion test does not. give any indication

Diagnostic procedures
7

FIG. 1-3 Palpation. A, Bilateral intraoral digital palpation aids
the clinician in detecting comparative changes in contour or
consistency of the soft tissue and underlying bone. A "mushy"
feeling detected during palpation around the mucolabial fold
may be the first clinical evidence of incipient swelling. B, Bi-
manual extraoral palpation to tactilely search for the extent of
lymph node involvement when there is a mandibular dental in-
fection. The clinician should palpate the submandibular nodes
(as shown here), the angle of the mandible, and the cervical
chain of nodes.

of the health or integrity of the pulp tissues; it indicates only
whether there is inflammation around the periodontal ligament.
Before the test, the patient should be instructed that making a
small audible sound or raising a hand is the best way to let the
clinician know when a tooth feels tender, different, or painful
with percussion.

Before tapping on the teeth with the handle of a mouth mir-
ror, the clinician is advised to use the index finger to percuss
teeth in the quadrant being examined (Fig. 1-4, A). Digital per-
cussion is much less painful than percussion with a mouth mir-
ror handle. The teeth should be tapped in a random fashion
(i.e., out of sequence) so the patient cannot anticipate when
"the tooth" will be percussed. If the patient cannot discern a
difference in sensation with digital percussion, the handle of a
mouth mirror should be used to tap on the occlusal, facial,
and lingual surfaces of the teeth (Fig. 1-4, B). Using the most
appropriate force for percussing is one of the skills that the
clinician will develop as part of the art of endodontic diagno-
sis. Percussing the teeth too strongly may cause unnecessary
pain and anxiety for the patient. The clinician should use the
chief complaint and dental history as a guide in deciding how
strongly to percuss the teeth. The force of percussion need be
only great enough for the patient to discern a difference be-
tween a sound tooth and a tooth with an inflamed periodontal
ligament. The proprioceptive fibers in an inflamed periodontal
ligament, when percussed, help the patient and the clinician
locate the source of the pain. Tapping on each cusp can, on
occasion, reveal the presence of a crown fracture.

A positive response to percussion, indicating an inflamed
periodontal ligament, can be caused by a variety of factors
(e.g., teeth undergoing rapid orthodontic movement, a recent
high restoration, a lateral periodontal abscess, and, of course,
partial or total necrosis of the pulp). However, the absence of
a response to percussion is quite possible when there is chronic
periapical inflammation.

Mobility

Using the index fingers, or preferably the blunt handles of
two metal instruments, the clinician applies alternating lateral
forces in a facial-lingual direction to observe the degree of mo-

FIG. 1-4 Percussion test to determine whether there is any apical periodontitis. If the patient
has reported pain during mastication, the percussion test should be conducted very gently. A,
First only the index finger should be used. The teeth should be percussed from a facial as
well as an incisal direction. B, If the patient reports no tenderness when the teeth are per-
cussed with the finger, a more definitive, sharper percussion can be conducted with the han-
dle of the mouth mirror.

8
The art of endodontics

bility of the tooth within the alveolus (Fig. 1-5). In addition,
tests for the degree of depressibility arc performed by press-
ing the tooth into its socket and observing if there is vertical
movement. First-degree mobility is barely discernible move-
ment; second-degree is horizontal movement of 1 mm or less;
third-degree is horizontal movement of greater than 1 mm, of-
ten accompanied by vertical mobility. Tooth movement usu-
ally reflects the extent of inflammation of the periodontal lig-
ament.

The pressure exerted by the purulent exudate of an acute
apical abscess may cause some mobility of a tooth. In this sit-
uation the tooth may quickly stabilize after drainage is estab-
lished and the occlusion adjusted. There are additional causes
for tooth mobility—including advanced periodontal disease,
horizontal root fracture in the middle or coronal third, and
chronic bruxism or clenching.

Radiographs

Radiographs are essential aids in endodontic diagnosis. Un-
fortunately, some clinicians rely exclusively on radiographs in
their attempt to arrive at a diagnosis. This obviously can lead
to major errors in diagnosis and treatment.2 Because the ra-
diograph is a two-dimensional image of a three-dimensional
object, misinterpretation is a constant risk, but with proper an-

FIG. 1-5 The degree of mobility can be most effectively de-
termined by applying lateral forces with a blunt-handled in-
strument in a facial-lingual direction.

gulation of the cone, accurate him placement, correct process-
ing of the exposed film (Fig. 1-6), and good illumination with
a magnifying glass, the hazards of misinterpretation can be
substantially minimized. The full benefit of periapical radio-
graphs for diagnostic purposes can be achieved if the technique
described here is employed.

After correct film placement, either bisected-angle or long-
cone methods are effective for film exposure. It is important
to expose two diagnostic films. By maintaining the same ver-
tical cone angulation and changing the horizontal cone angu-
lation 10 to 15 degrees for the second diagnostic film, the cli-
nician can obtain a three-dimensional impression of the teeth
that will aid in discerning superimposed roots and anatomic
landmarks. (Refer to Chapter 5 for further discussion of this
phase of dental radiology.)

The state of pulpal health or pulpal necrosis cannot be de-
termined radiographically; but any of the following findings
should arouse suspicion of degenerative pulp changes: deep
carious lesions, deep and extensive restorations, pulp caps,
pulpotomies, pulp stones, extensive canal calcification, root re-
sorption, radiolucencies at or near the apex, root fractures,
thickened periodontal ligament, and periodontal disease that is
radiographically evident.

Radiographic interpretation

Interpretation of good-quality diagnostic radiographs must
be done in an orderly and consistent manner. With good illu-
mination and magnification the clinician can detect nuances of
change that may reveal early pathologic changes in or around
the tooth. First, the crown of each tooth and then the root(s)
are carefully observed, then the root canal system, followed
by the lamina dura, bony architecture, and finally the anatomic
landmarks that may appear on the film. When posterior teeth
are being investigated, a bite-wing film provides an excellent
supplement for finding the extent of carious destruction, the
depths of restorations, the presence of pulp caps or pulpoto-
mies, and dens invaginatus or evaginatus. Generally it is true
that the deeper the caries and the more extensive the restora-
tion the greater is the probability of pulpal involvement. Fol-
lowing the lamina dura usually reveals the number and curva-
ture of the roots. A root canal should be readily discernible; if
the canal appears to change quickly from dark to light, this
indicates that it has bifurcated or trifurcated (Fig. 3-7, A). The
presence of "extra" roots or canals in all teeth (Fig. 1-7, B) is

FIG. 1-6 A, An improperly exposed or poorly processed radiograph like this one is difficult
or impossible to interpret. B, The condition of the crown, roots, and surrounding tissue can
be seen only with a properly prepared radiograph.

Diagnostic procedures
9

much more common than was previously believed. If the out-
line of the root seems unclear or deviates from where it ought
to be, an extra root should be suspected.24 Accordingly, at
least one canal (or root) more than the radiograph shows must
always be suspected until clinically proved otherwise. Three-
rooted mandibular molars (Fig. 1-7, B) and maxillary premo-
lars as well as two-rooted canines will be found with greater
frequency as the examiner's dental anatomic acumen, index
of suspicion, and diagnostic sophistication improve.

A necrotic tooth does not cause radiographic changes at the
apex until the periapical pathosis has destroyed bony trabecu-
le at their junction with the cortical plate.21 Thus a great deal
of bone destruction may occur before any radiographic signs
are evident. A radioluccnt lesion need not be at the apex of
the root to indicate pulpal inflammation or degeneration. Tox-
ins of pulp tissue degeneration exiting from a lateral canal can
cause bone destruction anywhere along the root. Conversely,

a lateral canal can be a portal of entry for potentially harmful
toxins in teeth with advanced periodontal disease (Fig. 1-8).
If periodontal bone loss extends far enough apically to expose
the foramen of a lateral canal, the toxins from the periodontal
disease can gain entry into a vital healthy pulp via the lateral
canal and cause irritation, inflammation, and even pulpal ne-
crosis in a sound tooth. Periodontal disease extending to the
apical foramen definitely causes pathologic pulpal changes (see
Chapter 18).

Pulp stones (Fig. 1 -9, A) and canal calcifications are not nec-
essarily pathologic; they can be mere manifestations of degen-
erative aging in the pulpal tissue. However, their presence may
cause other insults to the pulp and may increase the difficulty
of negotiating the root canals. The incidence of calcifications
in the chamber or in the canal may increase with periodontal
disease, extensive restorations, or aging. As the percentage of
the population categorized as elderly increases, clinicians

FIG. 1-7 A, A sudden change from dark to light indicates bifurcation or bifurcation of the
root canal system (arrow), as shown by B, premolar with a bifurcated root canal system and
a mandibular first molar with three roots.

FIG. 1-8 A and B, Radiolucent lesions indicates pulp degeneration. These radiographs illus-
trate how toxins of pulp tissue degeneration may exit from a lateral canal, causing bone de-
struction along the side. Conversely, this lateral canal could be a portal of entry for toxins
that might destroy the pulp and create a periapical lesion.

10
The art of endodontics

FIG. 1-9 A, Pulp stones and the extent and depth of restorations can be detected more clearly
with a bite-wing film. B, Periapical osteosclerosis, possibly caused by a mild pulp irritant.
C, Dens in dente. D, Internal resorption, once detected, must be treated promptly before it
perforates the root. E, Horizontal root fractures can usually be detected with a good-quality
radiograph. F, Vitality tests on a tooth with an immature apex may yield erroneous results.

should be more attuned to detecting pulp stones and calcifica-
tion of the canal space30 (see Chapter 24).

Internal resorption (Fig. 1-9, D) (occasionally seen after a
traumatic injury) is an indication for endodontic therapy. The
inflamed pulp, expanding at the expense of the dentin, must
be removed as soon as possible lest a lateral perforation oc-
cur. Untreated internal resorption leading to root perforation
increases the probability of eventual tooth loss (see Chapter
16).

Radiographs are important for identifying teeth with imma-
ture apices (Fig. 1-9, F) and teeth with lingual development
grooves (Fig. 1-10). The clinician must have this information
before conducting thermal and electric pulp tests because teeth
with immature apices often cause erroneous readings with vi-
tality testing (Chapter 23).

Root fractures may cause pulpal degeneration. Fractures of
the root can be difficult to detect on a radiograph. Vertical root
fractures (Fig. 1-11, A and B) are seldom identified with the
radiograph except in advanced stages of root separation. Most
horizontal root fractures can be readily identified with prop-

erly exposed and processed radiographs; however, horizontal
fractures may be confused with linear patterns of bone trabe-
cule. The two phenomena can be differentiated by noting that
the lines of bone trabeculae extend beyond the border of the
root, whereas a root fracture often causes a thickening of the
periodontal ligament.

Finally, the clinician must realize that there are occasions
when periapical, bite-wing, and panoramic films may not suf-
fice. Other types of cxtraoral films, described in greater detail
in Chapter 5, may be necessary (especially when there has been
a traumatic incident) before a diagnosis can be made.

Radiographic misinterpretation

A dental humorist once claimed that if a clinician looked at a
radiograph long enough he would find whatever he was looking
for. This overstatement suggests a sound rule for radiographic
interpretation: be wary—but not necessarily disbelieving—of
what appears to be obvious radiographically. Radiographic in-
terpretation is often quite subjective, as illustrated by a study of
more than 250 cases in which the same endodontists interpreted

Diagnostic procedures
11

FIG. 1-10 A, Lingual development groove. The radiograph shows the canals of both central
incisors to be distinctly different. Arrows point to the groove traced along the root. B, Silver
cone in the sulcular defect tracing the groove toward the apex. C, Although the tooth was
vital, only extraction could resolve this problem. In the near future, lasing these grooves may
allow these types of teeth to be retained.

FIG. 1-11 Vertical fractures arc rarely evident radiographically until there is advanced root
separation. A, Distal root with vertical fracture. B, Following extraction, the fracture can be
seen (arrow).

the same radiographs at intervals of 6 to 8 months. The three
endodontists in this study agreed with themselves only 72% to
88% of the time.10 In an earlier study six endodontists all
agreed with each other less than half the time.9 The radio-
graphic phenomena that caused misinterpretations were these:

1. Radioluccncy at the apex (Fig. 1-12). At first glance this
might appear to be a periapical lesion. However, a pos-
itive response to vitality tests, an intact lamina dura, the
absence of symptoms and probable cause, and the ana-
tomic location clearly show it to be the mental foramen.
Only the confirmed absence of pulp vitality will reveal
which tooth is the source of the periapical lesion (Fig.
1-13).

2. Well-circumscribed radiolucency at or near the apex
(Fig. 1-14, A-C). At first glance (Fig. 1-14, B) it might
appear to be a periapical lesion. However, changing the
horizontal angulation and exposing a second radiograph
show the lesion to have moved (Fig. 1-14, C). Because
the tooth was asymptomatic with lack of probable cause
and because of a positive response to vitality tests and
anatomic location, this was positively identified as the
nasopalatine canal.

3. The periapical radiolucency over the lateral incisor sug-
gests the incisor is the source of the lesion, but vitality
testing showed it was the canine that was nonvital. En-
dodontic treatment remineralized the radiolucency over
the lateral incisor (Fig. 1-15).

14
The art of endodontics

A

FIG. 1-15 A, The periapical radiolucency over the lateral incisor might indicate the lateral
incisors as the source of the lesion. Thermal and electric pulp tests indicated that the lateral
incisor was vital and the canine was necrotic. B, Endodontic treatment completed for the
canine. C, Six months after endodontic treatment the canine has completely remineralized
over the apex of the lateral incisor. (Courtesy Dr. John Saponc.)

FIG. 1-16 Preparing teeth for thermal and electric pulp test-
ing. A, Before testing, the teeth should be isolated with a cot-
ton roll and dried with gauze. B, Air should not be used to
dry the teeth because room temperature air may cause thermal
shock. Air drying could also spray saliva on the clinician.

FIG. 1-17 Thermal test with heat. A, Temporary stopping is
heated over a flame until it becomes soft and begins to bend.
B, Temporary stopping applied to the dried tooth (lightly
coated with cocoa butter to prevent sticking).