UMEÅ UNIVERSITY ODONTOLOGICAL DISSERTATIONS
Abstract No 27, ISSN 0345—7532
From the Departments of Endodontics and Oral Microbiology
University of Umeå, Umeå, Sweden
EVALUATION OF ENDODONTIC TREATMENT
OF TEETH
WITH APICAL PERIODONTITIS
ANDERS BYSTRÖM
Umeå 1986
EVALUATION OF ENDODONTIC TREATMENT
OF TEETH
WITH APICAL PERIODONTITIS
AKADEMISK AVHANDLING
som med vederbörligt tillstånd av
Odontologiska Fakulteten vid Umeå Universitet
för avläggande av odontologie doktorsexamen
kommer att offentligen försvaras i föreläsningssal B,
Odontologiska kliniken, 9 tr, Umeå,
lördagen den 6 december 1986, kl 09.00
ANDERS BYSTRÖM
Avhandlingen baseras på följande delarbeten:
I
BYSTRÖM A, SUNDQVIST G. Bactériologie evaluation of the
efficacy of mechanical root canal instrumentation in
endodontic therapy. Scand J Dent Res 1981; 89: 321-328.
II
BYSTRÖM A, SUNDQVIST G. Bactériologie evaluation of the
effect of 0.5 percent sodium hypochlorite in endodontic
therapy. Oral Surg Oral M e d Oral Path 1983; 55: 307312.
III
BYSTRÖM A, SUNDQVIST G. The antibacterial action of
sodium hypochlorite and EDTA in 60 cases of
endodontic therapy. Int Endod J 1985; 18: 35-40.
IV
BYSTRÖM A, CLAESSON R, SUNDQVIST G. The antibacterial
effect of camphorated paramonochlorophenol, camphorated
phenol and calcium hydroxide in the treatment of
infected root canals. Endod Dent Traumatol 1985; 1:
170-175.
V
BYSTRÖM A, HAPPONEN R-P, SJÖGREN U, SUNDQVIST G.
Healing of periapical lesions of pulpless teeth after
endodontic treatment with controlled asepsis. Endod
Dent Traumatol 1987; In press.
Umeå 1986
ABSTRACT
Byström, Anders, 1986. Evaluation of endodontic treatment of teeth with
apical periodontitis. Umeå University Odontological Dissertations.
Abstract No. 27 ISSN-0345-7532.
Apical periodontitis, an acute or chronic inflamination around
the apex of the tooth, is caused by bacteria in the root canal. In
Sweden the dentists devote around 10X of their total time to treating
this disease. The treatment usually requires 3 to 5 sessions. The
treatment may fail in up to 25X of the cases. In the present study
various treatment regimens were evaluated. One hundred and forty single­
rooted teeth with apical periodontitis were treated. The importance of
mechanical instrumentation, irrigating solutions and antibacterial
dressings in eliminating bacteria from the infected root canals was
studied using bacteriological techniques. The healing of the apical
periodontitis after treatment was followed for 2 to 5 years on recall
radiographs.
Bacteria were found in all 140 root canals at the beginning of
the treatment. Most of these bacteria were anaerobes and they
represented a restricted group of bacteria compared to the bacteria
present at other sites in the oral cavity. Mechanical instrumentation
with files and reamers in combination with saline irrigation reduced the
number of bacterial cells in the root canal 100- to 1000-fold during one
treatment session. Bacteria could be eliminated from about half the
number of root canals if this treatment was performed at 4 sessions.
Mechanical instrumentation and irrigation with 0.5X or 5X
sodium hypochlorite solutions or with the 5X solution in combination
with 15X EDTA solution wa3 more efficient and the bacteria were
eliminated from about half the treated canals after one treatment
session. The bacteria which persisted in the root canal after this
treatment usually increased in number during the interval up to the next
session and reached levels which were often as high as in the initial
sample at the previous session.
All bacteria persistent in the root canals after the previous
treatment regimens were with 2 exceptions eliminated by dressing the
root canals for 1 to 2 months with calcium hydroxide paste. Thirty-four
out of 35 root canals treated at the first session with mechanical
instrumentation, irrigation with sodium hypochlorite solution and
dressed with calcium hydroxide paste were free of bacteria at the second
session. Calcium hydroxide paste was superior to camphorated phenol and
camphorated paramonochlorophenol as dressing.
Healing of 79 out of the 140 treated teeth was followed for 2
to 5 years. The majority of the lesions healed completely or decreased
in size in such a way that they could be expected to heal. There was no
or only an insignificant decrease in the size of the lesions in 5 cases.
In 2 of these cases bacteria were demonstrated in the periapical tissues
and in a third case dentin chips. Periapical lesions may thus fail to
heal in a few cases due to an establishment of bacteria outside the root
canal, and in that site the bacteria are inaccessible to conventional
endodontic treatment.
The present study showed that treatment of the majority of
infected non-vital teeth can be completed in only 2 sessions, if
mechanical instrumentation, sodium hypochlorite irrigation and calcium
hydroxide dressing are combined.
Key words: Endodontic treatment, bacteriological evaluation.
UMEÅ UNIVERSITY ODONTOLOGICAL DISSERTATIONS
Abstract No 27, ISSN 0345—7532
From the Departments of Endodontics and Oral Microbiology
University of Umeå, Umeå, Sweden
EVALUATION OF ENDODONTIC TREATMENT
OF TEETH
WITH APICAL PERIODONTITIS
ANDERS BYSTRÖM
Umeå 1986
ABSTRACT
Byström, Anders, 1986. Evaluation of endodontic treatment of teeth with
apical periodontitis. Umeå University Odontological Dissertations.
Abstract No. 27 ISSN-0345-7532.
Apical periodontitis, an acute or chronic inflammation around
the apex of the tooth, is caused by bacteria in the root canal. In
Sweden the dentists devote around 10X of their total time to treating
this disease. The treatment usually requires 3 to 5 sessions. The
treatment may fail in up to 25X of the cases. In the present study
various treatment regimens were evaluated. One hundred and forty single­
rooted teeth with apical periodontitis were treated. The importance of
mechanical instrumentation, irrigating solutions and antibacterial
dressings in eliminating bacteria from the infected root canals was
studied using bacteriological techniques. The healing of the apical
periodontitis after treatment was followed for 2 to 5 years on recall
radiographs.
Bacteria were found in all 140 root canals at the beginning of
the treatment. Most of these bacteria were anaerobes and they
represented a restricted group of bacteria compared to the bacteria
present at other sites in the oral cavity. Mechanical instrumentation
with files and reamers in combination with saline irrigation reduced the
number of bacterial cells in the root canal 100- to 1000-fold during one
treatment session. Bacteria could be eliminated from about half the
number of root canals if this treatment was performed at 4 sessions.
Mechanical instrumentation and irrigation with 0.5X or 5X
sodium hypochlorite solutions or with the 5X solution in combination
with 15X EDTA solution was more efficient and the bacteria were
eliminated from about half the treated canals after one treatment
session. The bacteria which persisted in the root canal after this
treatment usually increased in number during the interval up to the next
session and reached levels which were often as high as in the initial
sample at the previous session.
All bacteria persistent in the root canals after the previous
treatment regimens were with 2 exceptions eliminated by dressing the
root canals for 1 to 2 months with calcium hydroxide paste. Thirty-four
out of 35 root canals treated at the first session with mechanical
instrumentation, irrigation with sodium hypochlorite solution and
dressed with calcium hydroxide paste were free of bacteria at the second
session. Calcium hydroxide paste was superior to camphorated phenol and
camphorated paramonochlorophenol as dressing.
Healing of 79 out of the 140 treated teeth was followed for 2
to 5 years. The majority of the lesions healed completely or decreased
in size in such a way that they could be expected to heal. There was no
or only an insignificant decrease in the size of the lesions in 5 cases.
In 2 of these cases bacteria were demonstrated in the periapical tissues
and in a third case dentin chips. Periapical lesions may thus fail to
heal in a few cases due to an establishment of bacteria outside the root
canal, and in that site the bacteria are inaccessible to conventional
endodontic treatment.
The present study showed that treatment of the majority of
infected non-vital teeth can be completed in only 2 sessions, if
mechanical instrumentation, sodium hypochlorite irrigation and calcium
hydroxide dressing are combined.
Key words: Endodontic treatment, bacteriological evaluation.
CONTENTS
P R E F A C E ..................................
4
INTRODUCTION.. ..........................
5
A I M S .....................................
8
MATERIALS AND M E T H O D S ..................
9
Clinical m ater i a l ......................
9
Bacteriological m e t h o d s................
9
Endodontic treatment...................
12
H e a l i n g ..................................
17
R E S U L T S ..................................
20
Microorganisms in infected root canals
20
Endodontic treatment...................
20
H e a l i n g ..................................
24
D I S C USSION
.........................
29
Microbial changes during treatment....
29
Comparison of treatment regimens.....
30
H e a l i n g ..................................
31
SUM M A R Y..................................
34
ACKNOWLEDGEMENTS........................
35
REFERE N C E S ..............................
36
PAPER I ..................................
PAPER I I .................................
PAPER I I I ...............................
PAPER I V .................................
PAPER V ..................................
PREFACE
This thesis is based on the following Papers, which will be
referred to in the text by their Roman numerals.
I
BYSTRÖM A, SUNDQVIST G. Bactériologie evaluation of the
efficacy of mechanical root canal instrumentation in
endodontic therapy.
II
Scand J Dent Res 1981; 89: 321-328.
BYSTRÖM A, SUNDQVIST G. Bactériologie evaluation of
the
effect of 0.5 percent sodium hypochlorite in endodontic
therapy.
Oral Surg Oral M e d Oral Path 1983;
55: 307-
312.
III
BYSTRÖM A, SUNDQVIST G. The antibacterial action of
sodium hypochlorite and EDTA in 60 cases of endodontic
therapy.
IV
Int Endod J 1985;
18: 35-40.
BYSTRÖM A, CLAESSON R, SUNDQVIST G. The antibacterial
effect of camphorated paramonochlorophenol, camphorated
phenol and calcium hydroxide in the treatment of
infected root canals. Endod Dent Traumatol 1985;
1:
170-175.
V
BYSTRÖM A, HAPPONEN R-P, SJÖGREN U, SUNDQVIST G.
Healing of periapical lesions of pulpless teeth after
endodontic treatment with controlled asepsis. Endod
Dent Traumatol 1987;
4
In press.
1
INTRODUCTION
Apical periodontitis is an acute or chronic inflammatory lesion around
the apex of a tooth.
Generally there are no clinical symptoms in the
chronic state of this disease and it is therefore not identified until a
radiograph is taken. The chronic state may, however,
pain and swelling,
become acute with
sufficient to send the patient to a dentist.
Epidemiological studies (Bergenholtz et al.
1974, Erselius et al.
Bergman et al.
et al.
I, II 1973, Molven
1975, Kerekes and Bervell 1976, Lavstedt 1978,
1979, Hugosson and Koch 1979, Holm et al.
1982, Petersson
1986) have shown that apical periodontitis is very common.
Erselius et al.
(1975) found from radiographs that in Sweden about 60%
of evaluated adult patients had some form of apical periodontitis.
Epidemiological studies have also shown that 25 to 30% of root-filled
teeth have apical periodontitis (Bergenholtz et al.
1974, Kerekes 1978, Hugosson and Koch 1979).
treatment are, however,
I, II 1973, Molven
Such failures in endodontic
only recorded in 10 to 20% of teeth treated by
students under supervision or by dentists who specialize in endodontics
(Strindberg 1956, Grahnén and Hansson 1961, Engström et al.
Seltzer et al.
1964,
I, II 1967, Oliet and Sorin 1969, Kerekes 1978, Kerekes
and Tronstad 1979).
It has been established beyond all doubt that bacteria cause
apical periodontitis (Kakehashi et al.
Bergenholtz 1980, Möller et al.
1965, Sundqvist 1976, Dahlén and
1981). This implies that the goal of
endodontic treatment should be to eliminate all bacteria from the root
canal (White 1976, Grossman 1981, Schilder 1984). This is achieved by
mechanical instrumentation supported by various irrigating solutions and
the placement of antibacterial dressings in the canals between
appointments.
A higher failure rate for endodontic treatment has been found
when the presence of bacteria has been demonstrated in the root canal
just before root-filling (Zeldow and Ingle 1963, Engström et al.
Oliet and Sorin 1969, Heling and Shapira 1978).
1964,
In a follow-up study of
teeth w ith such persistent infection (Engström et al.
1964) 24% of the
root-fillings were judged as failures whereas the corresponding figure
for teeth without persistent infection at the time of root-filling was
11%. The reasons for failure in endodontic treatment may be related to
faults in the root-fillings themselves such as overfilling,
5
or gaps
apical to the root-filling or between the root-filling and the canal
walls (Strindberg 1956, Bergenholtz et al.
1978, Bergman et al.
1979).
II 1973, Molven 1974, Kerekes
It has also been found that a persistent
infection in combination with root-filling excesses significantly
increased the failure rate (Engström et al.
Mechanical
1964).
instrumentation of the root canal has been
considered the most important step in eliminating these bacteria
(Grossman 1981,
Schilder 1984,
Ingle et al.
1985). There are, however,
divergent results concerning the efficacy of mechanical instrumentation
and irrigation in rendering the root canals free of bacteria (Ingle and
Zeldow 1958, Grahnén and Krasse 1963, Stewart et al.
1969).
The instrumentation techniques have shortcomings in that some
sites in the root canal may not be reached by the files, and that a
smear layer is formed on the canal walls by the files (Baker et al.
1975, McComb and Smith 1975, McComb et al.
1980, Goldman et al.
1981,
1976, Bolanos and Jensen
1982). This smear layer consists of organic
and inorganic tissue components.
It covers the dentinal tubules in which
bacteria may be ensconced (Baker et al.
and Boyde 1977, Rubin et al.
1975, McComb et al.
1976, Lester
1979).
Irrigating solutions are an important adjunct in the
preparation of the root canal. The main objective of the irrigating
solution is to wash out debris from the root canal during
instrumentation.
Other properties considered desirable are that the
solution be antibacterial, will assist in the removal of the smear layer
and be capable of digesting organic matter and debris.
Sodium
hypochlorite and ethylenediaminetetra-acetic acid (EDTA) are commonly
recommended as irrigating solutions.
Sodium hypochlorite has a strong
antibacterial effect in vitro (Shih et al.
Blomfield and Miles 1979, Flink et al.
1970, Spångberg et al.
1981, Foley et al.
1973,
1983), but its
efficacy under clinical conditions has not yet been fully established.
Sodium hypochlorite also has the capacity to degrade organic matter
(Handt et al.
1982),
1978, Thé 1979, Koskinen et al.
1980, Moorer and Vesselink
although some scanning electron microscopic studies have produced
conflicting results. Baker et al.
(1975) and Bolanos and Jensen (1980)
have reported that sodium hypochlorite was not effective, while McComb
and Smith (1975), McComb et al.
(1976), Goldman et al.
found it highly effective.
6
(1981,
1982)
EDTÂ has been used to degrade the inorganic matter/debris
remaining in the root canal (for review see Dow,
1984).
It has been
claimed that the combination of sodium hypochlorite and EDTA removes the
smear layer from the root canal walls (Goldman et al,
1982).
It is not
known whether this regimen improves the efficacy of the endodontic
treatment in eliminating bacteria from the root canal.
In addition to adequate mechanical instrumentation and
irrigation of the root canal,
endodontic treatment also involves an
antibacterial dressing placed in the canal between the appointments for
treatment.
The chosen dressing should have a long-lasting antibacterial
effect and should be able to reach all parts of the root canal system
(Chirnside 1958,
al,
Shovelton 1964, Åkpata and fclechman 1982, Armitage et
1983). Calcium hydroxide,
camphorated phenol and camphorated
paramonochlorophenol are frequently used as dressings.
The antibacterial
effect of these agents has been reported to be strong in vitro (Hermann
1936, Proell 1949, Vander Wall et al.
1972, Spångberg et al.
1973), but
clinically camphorated phenol and camphorated paramonochlorophenol have
been shown to be inefficient (Ingle and Zeldow 1958, Sommer et al.
Goldman and Pearsson 1969). Calcium hydroxide,
however,
1962,
has also been
shown to be efficient under clinical conditions (Cvek et al.
1976).
The ultimate aim of endodontic treatment is to eliminate
bacteria from the root canal before filling takes place.
Surprisingly
little, however,
is known about the antibacterial efficacy of mechanical
instrumentation,
irrigation,
in the root canal.
and placement of an antibacterial dressing
In recent years improved bacteriological techniques
have been successfully used to reveal the presence of bacteria in the
root canals (Kantz and Henry 1974, Wittgow and Sabiston 1975, Sundqvist
1976, Dahlén and Bergenholtz 1980). This means that it is now possible
to evaluate by bacteriological methods the efficacy of various steps in
endodontic treatment.
7
2
AIM OF THE INVESTIGATION
The aim of this investigation was, using bacteriological methods,
to
evaluate the antibacterial effect of the various regimens in the
treatment of infected root canals with apical periodontitis.
The
following stages of root canal preparation were studied:
1. mechanical instrumentation
2. irrigation
3. dressing
The ultimate goal of successful treatment is the healing of the
periapical lesion.
Therefore the state of healing after the various
treatment regimens was studied.
8
3
MATERIALS AN D METHODS
3.1
CLINICAL MATERIAL
One hundred and forty single-rooted non-vital teeth with intact pulp
chamber walls were treated. All teeth showed radiographic evidence of
apical periodontitis when examined with a modified long cone technique
(Oralix 65 Philips) with Kodak ultra-speed film (24x36 mm) and a film
holder (Eggen 1974).
3.2
BACTERIOLOGICAL METHODS
3.2.1
Sampling from the tooth surface (I, II, III, IV)
The procedure outlined by Möller (1966) was followed. An aseptic
technique was used throughout the treatment.
In all phases of the
treatment
sterile instruments, medicaments and filling materials
used. The
operator wore surgical gloves.
were
The tooth was cleaned with
pumice and isolated with rubber dam. The tooth, the clamp and the rubber
dam were cleansed with 30Z hydrogen peroxide and then swabbed with 5Z
tincture of iodine. After the tincture had dried the tooth surface was
swabbed with sterile 5% sodium thiosulphate solution to inactivate the
tincture of iodine before the sterility of the tooth surface was tested.
A sterile paper point was then scrubbed against the lingual tooth
surface and transferred to a fluid thioglycollate medium USE (11260,
BBL; Carlsson and Sundqvist 1980). Entrance to the pulp chamber was
effected from the lingual surface.
Before the pulp chamber was opened a
second sample for testing sterility was taken. At each appointment a
similar sterility control sample of the lingual tooth surface was taken
before the pulp chamber was entered.
3.2.2
Sampling from the root canal (I, II, III,
IV)
When access to the pulp chamber had been gained a small amount of
sterile saline was introduced into the canal by syringe. A measurement
file was placed in the root canal and a radiograph was taken to
determine the working length. The canal was instrumented and enlarged
with Hedström files (Sjödings,
Sweden) until a No. 40 file could be
introduced approximately 1 m m short of the tooth apex. The fluid in the
canal was soaked up into charcoaled paper points and transferred to a
tube containing 5 ml peptone yeast glucose (PYG) broth (Holdeman et al.
9
1977). Three subsequent points were used and each was le£t in the canal
until it could absorb no more fluid. To avoid oxidation of the PYG-broth
during sampling, the tube was flushed with oxygen-free gas (97Z
3X
H^)* A ”mobile anaerobe laboratory” as described by Fulghum (1971) was
used to facilitate this procedure. The canal was instrumented and
irrigated (see below). When the instrumentation was completed a second
bacterial sample was taken (I, II, III) in the manner described above.
At subsequent appointments bacterial samples were taken at the beginning
and at the end of each appointment in the manner described (I, II, III).
The interval between the appointments was 2-4 days.
When sodium hypochlorite was used in the irrigating solution
(II,
III) the canal was irrigated with saline after the instrumentation
was completed. Then the canal was dried with sterile paper points and
refilled with 5Z sodium thiosulphate solution for 2 min to inactivate
any remaining sodium hypochlorite (Möller 1966). The canal was then
filled with saline and a bacterial sample was taken in the manner
described.
When calcium hydroxide,
paramonochlorophenol
camphorated phenol and camphorated
(see below) were used as intracanal dressings,
the
dressing was removed by irrigation with saline at the following
appointment.
Thereafter a bacterial sample was taken in the manner
described above. Then the canal was sealed without dressing,
to provide
an opportunity for persistent bacteria in the root canal to multiply
before the final sample was taken at the next appointment,
2 to 4 days
later.
3.2.3
Cultivation of the specimen
The bacterial samples were transported to
with within 30 min of sampling.
the laboratory and were dealt
The PYG-broth
specimen was introduced into an anaerobic
which contained the
box (Sundqvist 1976). The
atmosphere in the box was 10Z hydrogen and 5Z carbon dioxide in
nitrogen.
The tube, which contained glass beads, was agitated in a
mechanical mixer until the paper points disintegrated and three 10-fold
serial dilutions were made in dilution blanks (Holdeman et al.
Aliquots of 0.5,
1977).
0.2, and 0.1 ml from the PYG-broth were inoculated onto
duplicate blood agar plates (Holdeman et al.
1977), and aliquots of
0.1 ml onto one mitis salivarius agar (Difco 0298-01) and one Rogosa SL
medium (Difco 0480-01). From each serial dilution tube aliquots of
10
0.1 ml were inoculated onto duplicate blood agar plates. One set of
blood agar plates was incubated aerobically for 48 h at 3 7 !C and the
other set of blood agar plates,
SL medium,
the mitis salivarius agar and the Rogosa
anaerobically in the box for 10 days at 37*C. The plates vere
prepared outside the box. They vere placed in the box as soon as they
had solidified and kept for at least 48 h before use. The plates
incubated in the box vere observed daily for grovth. When no grovth
occurred on the second day another blood agar plate vas inoculated from
the PYG-broth.
If no grovth occurred the process vas repeated three
times at intervals of 1 veek before the sample vas judged free of living
bacteria.
3.2.4
Isolation and identification of bacterial strains
In Papers I and II bacterial samples taken from 15 root canals irrigated
vith saline and 15 root canals irrigated vith 0.5% sodium hypochlorite
solution vere analysed for the total number of bacterial strains and all
strains vere identified.
In Paper III bacterial samples taken at the first and second
appointment from 5 root canals irrigated vith 0.5% sodium hypochlorite
solution,
20 root canals irrigated vith 5% sodium hypochlorite solution,
20 root canals irrigated vith 5% sodium hypochlorite solution and EDTA
solution (see belov) vere analysed for the number of bacterial cells and
strains.
The bacterial strains vere preliminarily characterized,
and stored.
frozen
Bacterial strains isolated at the third appointment vere
identified.
In Paper IV bacterial samples taken at the first appointment
from root canals subsequently dressed vith calcium hydroxide paste,
camphorated phenol or camphorated paramonochlorophenol vere analysed for
the number of bacterial cells. The isolated strains vere frozen and
stored.
Bacterial strains,
isolated at the second and third
appointments, vere identified. When bacteria persisted at the final
appointment of the treatment regimen (III,
IV) the bacterial strains,
isolated at the first appointment, vere identified.
Each type of colony vas registered after 2 days on the aerobic
and after 7-10 days on the anaerobic plates.
The frequency of various
colony types and the total number of colonies on the plates vere
recorded.
A representative number of strains of each colony type vas
isolated.
The isolated anaerobic bacteria vere characterized by the
11
methods described in the manual of the Virginia Polytechnic Institute
and State University Anaerobe Laboratory, USA
(Holdeman
et al.
1977).
Strains of uncertain taxonomic status were identified only as regards
genus. Unless otherwise stated,
according to Holdeman et al.
anaerobic bacteria were characterized
(1977),
facultatively anaerobic
streptococci according to Hardie and Bowden (1976) and.other facultative
strains according to Cowan (1974). All isolated strains were preserved
by freezing (-80*C).
3.3
ENDODONTIC TREATMENT
3.3.1
Mechanical
instrumentation
Entrance to the pulp chamber was effected from the lingual surface using
a diamond bur in the low-speed handpiece with the water spray shut off.
When access to the pulp chamber had been gained a small amount of saline
was introduced into the canal by syringe.
Then the canal was
instrumented and enlarged with Hedström files (Sjödings,
No.
40 file could be inserted.
described above.
Sweden) until a
The initial bacterial sample was taken as
The canal was thoroughly instrumented using the step
back technique and Hedström files. Reamers (Maillefer Co,
were used to enlarge the coronal part of the canal.
Switzerland)
The same set of
files and reamers was used throughout the instrumentation at the
appointment.
The instrumentation was performed during 15 min (25 min
when EDTA was used as the irrigating solution). After the
instrumentation was completed,
taken (I, II,
and another bacterial sample had been
III), the access cavity was sealed.
At subsequent
appointments the canal was instrumented and irrigated for 10 min.
3.3.2
Irrigation
During the mechanical
instrumentation the root canal was frequently
irrigated with 6 ml of irrigating solution.
The solution was introduced
into the canal by means of a syringe with a 23-gauge needle and soaked
up by means of a vacuum ejector (Aga, Sweden).
To ensure adequate
exchange of the irrigating solution the needle of the syringe was
introduced into the root canal approximately 3 mm short of the tooth
apex.
The root canal was repeatedly dried with sterile paper points.
12
APPOINTMENT
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3.3.2.1
Saline (I)
Fifteen teeth were instrumented and irrigated with saline at 4
appointments (Fig 1.1 refers to Paper I in Fig 1). No antibacterial
dressing was used in the root canal in the period between the
appointments.
The interval between the appointments was 2 to 4 days. At
the fifth appointment 7 root canals,
from which no bacteria were
recovered were filled (see below). One root canal without and 7 root
canals with persistent bacteria were instrumented,
irrigated with 0.5%
sodium hypochlorite solution and dressed (see below) with calcium
hydroxide paste (Calasept
fifth appointment.
Scania Dental AB, Knivsta,
Sweden) at the
The treatment regimen for the root canals irrigated
with saline is presented in Fig 1:1.
3.3.2.2
Sodium hypochlorite solution (II,
III)
Fifteen teeth were instrumented and irrigated with 0.5% sodium
hypochlorite solution at 4 appointments.
In all other respects the
treatment was in accordance with the treatment described for the 15
teeth irrigated with saline. At the fifth appointment 7 bacteria-free
root canals were filled.
Five root canals without and 3 root canals with
persistent bacteria were instrumented,
irrigated with 0.5% sodium
hypochlorite solution and dressed with calcium hydroxide paste
(Fig 1:11).
Five teeth were instrumented and irrigated with 0.5% sodium
hypochlorite solution at 2 appointments (Fig 1:111).
In other respects
the treatment was in accordance with the treatment described for the 15
teeth instrumented and irrigated with 0.5% sodium hypochlorite solution
at 4 appointments.
At the third appointment 3 root canals which were
free of bacteria were filled. Two root canals with persistent bacteria
were instrumented and irrigated with 0.5% sodium hypochlorite solution
and dressed with calcium hydroxide paste (Fig 1:111).
Twenty teeth were instrumented and irrigated with 5% sodium
hypochlorite solution at 2 appointments (Fig 1:111).
In other respects
the treatment was in accordance with the 5 teeth instrumented and
irrigated with 0.5% sodium hypochlorite solution at 2 appointments.
the third appointment the root canals were dressed with calcium
hydroxide paste. When it was established that no bacteria could be
recovered from 14 root canals at the third appointment,
were filled.
these canals
Six root canals with persistent bacteria at the third
14
At
appointment were instrumented and irrigated with 0.5% sodium
hypochlorite solution and dressed with calcium hydroxide paste
(Fig I ï III).
3.3.2.3
Etylenediaminetetra-acetic acid (III)
Twenty teeth were instrumented and irrigated with 5% sodium hypochlorite
solution and 15% EDTA solution for 25 min at 2 appointments (Fig 1:111).
The treatment was initiated by instrumentation and irrigation with
sodium hypochlorite solution for 10 min. Thereafter an EDTA solution was
applied to the canal and repeatedly changed for 10 min. Finally the
canal was instrumented and irrigated with the sodium hypochlorite
solution for 5 min.
In other respects the treatment was in accordance
with the treatment described for the teeth irrigated with sodium
hypochlorite solutions alone at 2 appointments. When it was established
that no bacteria could be recovered from 17 root canals at the third
appointment these canals were filled. Three root canals with persistent
bacteria at thq third appointment were instrumented,
irrigated with 0.5%
sodium hypochlorite solution and dressed with calcium hydroxide paste
(Fig 1:111).
3.3.3
Dressing
3.3.3.1
Bactericidal effect of calcium hydroxide,
in vitro (IV)
The sensitivity of 27 bacterial strains to a calcium hydroxide
suspension was tested. The bacteria were grown on the surface of blood
agar (Holdeman et al.
1977) and harvested after 1 to 4 days depending on
the growth rate of the actual strain. They were suspended in dilution
6
8
solution (IV) to a density of 10 -10
bacterial cells per ml. The
bacterial suspension (0.1 ml) was added to 4 ml of dilution solution
(pH 7.2) and to 4 ml of dilution solution in which 150 mg calcium
hydroxide-paste (Calasept ) had been suspended. The pH of the latter
suspension was 12.5. From the suspension of bacteria and calcium
hydroxide in dilution solution,
aliquots of 0.1 ml were taken after
various time intervals and the survival rate was determined by viable
count on blood agar plates. The time required to decrease the number of
living bacteria to less than 0.1% of the initial number was determined
for each strain. The killing of Enterococcus faecalis (Schleifer and
Kilpper-Bälz 1984) was also tested in the dilution solution adjusted to
15
various pH-levels by 1 N sodium hydroxide and in horse serum in which
calcium hydroxide paste had been suspended.
3.3.3.2
Clinical effect of calcium hydroxide paste (IV)
Fifteen teeth were instrumented and irrigated with 0.5% sodium
hypochlorite solution at the first appointment (Fig 1:IV). After
completion of the instrumentation and irrigation the root canals were
dressed with calcium hydroxide paste (Calasept ) by means of a lentulo
spiral,
packed with the blunted end of a sterile paper point and sealed.
At the second appointment 1 month later the dressing was removed by
irrigation with saline. The canal was dried with sterile paper points
and sealed without dressing.
At the third appointment 2 to 4 days later
another bacterial sample was taken. Thereafter the canal was dressed
with calcium hydroxide paste in the manner described above.
Five teeth were treated in the above manner except that these
root canals were irrigated with an EDTA solution for 10 min at the
second appointment before sealing (Fig 1:IV).
Fifteen teeth were instrumented and irrigated with 5% sodium
hypochlorite solution (Fig 1:IV).
In other respects the treatment was in
accordance with the treatment described for the 15 teeth irrigated with
0.5% sodium hypochlorite solution and dressed with calcium hydroxide
paste for 1 month.
When it was established that no bacteria could be recovered
from the samples taken at the third appointment the root canals were
filled.
One root canal with persistent bacteria at the third appointment
was dressed with calcium hydroxide paste (Fig 1:1V).
3.3.3.3
Camphorated phenol
(IV)
Fifteen teeth were instrumented and irrigated with 0.5% sodium
hypochlorite solution at the first appointment.
After completion of the
instrumentation and irrigation the root canals were dressed with
camphorated phenol by means of a syringe and sealed. At the second
appointment 2 weeks later the dressing was removed by irrigation with
saline. The root canal was then dried with sterile paper points and
sealed without dressing. At the third appointment 1 week later another
bacterial sample was taken and the canal was dressed with camphorated
phenol in the manner described above. When it was established that no
bacteria could be recovered from the samples taken at the third
16
appointment 7 root canals were filled. Three root canals without and
5 root canals wi t h persistent bacteria were instrumented and irrigated
with 0.5X sodium hypochlorite solution and dressed with calcium
hydroxide paste (Fig 1:IV).
3.3.3.4
Camphorated paramonochlorophenol (IV)
Fifteen teeth were instrumented and irrigated with 0.5% sodium
hypochlorite solution and dressed with camphorated paramonochlorophenol
at the first, appointment (Fig 1:IV).
In other respects the treatment was
in accordance w ith the treatment described for the 15 teeth dressed with
camphorated phenol for 2 weeks. When it was established that no bacteria
could be recovered from the samples taken at the third appointment 7
root canals were filled. Three root canals without and 5 root canals
with persistent bacteria were instrumented and irrigated with 0.5%
sodium hypochlorite solution and dressed with calcium hydroxide paste
(Fig 1 sI V ) .
3.3.4
Sealing
of
the
access cavity
In the period between the appointments the access cavity was sealed with
a more than 3 m m thick layer of zinc oxide-eugenol cement in all cases.
Minifoams (Minnesota Mining and Manufacturing C o . , St. Paul, Minnesota)
in the pulp chamber prevented contact between the temporary filling and
the bacteria in the root canal.
3.3.5
Filling
of
theroot canal
All root canals were filled with gutta percha using the lateral
condensation technique. The master cone was adapted to the canal by
dipping it in rosin chloroform and then multiple accessory cones were
laterally condensed using rosin chloroform as a sealing agent.
3.4
HEALING
The healing of the apical periodontal lesion was recorded 2 to 5 years
after the treatment for 79 of the 140 teeth treated initially. Thirtynine teeth were excluded because the observation period was shorter than
2 years.
Twenty-two teeth were lost to follow-up for other reasons.
17
3.4.1
Clinical and radiographic examination (V)
At the clinical examination,
gingival palpation,
pain, swelling,
tenderness to apical and
as well as tenderness to percussion were recorded.
Radiographs were taken before and during treatment,
6 and 12 months
after the root canals were filled, and thereafter once a year. The
radiographs were studied separately by 2 oral radiologists and 3
endodontists using a viewer with a magnifying glass (Mattson 1953). The
radiographs were coded prior to evaluation by the examiners.
In the
radiographic evaluation the examiners determined the size of the lesion
on each radiograph by measuring the greatest extent of the lesion in mm
using a ruler. The interpretation of the treatment results was then
based on the change in size of the lesions as determined for the entire
series of recall radiographs.
If there was disagreement between the
evaluations of the 5 examiners the median value for each radiograph was
used.
The criterion for complete healing was that the radiographic width
of the periodontal space was normal or slightly widened (<0.5 mm).
3.4.2
Histological examination (V)
Seven of the cases were operated on. The surgical specimens from 6 of
these were studied histologically.
Tissue specimens were fixed in 4%
buffered formalin and embedded in paraffin. Multiple sections were
stained with hematoxylin-eosin,
Gram, Grocott's stain and PAS.
Immunocytochemical demonstration of Actinomyces israelii, Actinomyces
naeslundii and Arachnia propionica was made according to Happonen et al.
(1985).
The avidin-biotin immunoperoxidase technique (Hsu and Raine
TM
ABC Kit (Vector Laboratories Inc.,
1981) was employed using Vectastain
Burlingame,
Ca). The specific rabbit antisera were obtained from the
Center for Disease Control
(CDC), Atlanta, Ga. The substitution controls
were made with the normal sera of two rabbits.
3.4.3
Statistical analysis (V)
Student's t-test and the chi-square test were used for testing
correlations between the outcome of treatment and the apical level of
the root-filling.
18
Table 1.
Bacteria initially recovered from non-vital teeth with
apical periodontitis and bacteria persistent in the root
canals at the fifth appointment when various irrigants
were used.
Bacteria
recovered
Irrigant
No of teeth
Appointment
Salineì
15
5
1
Streptococcus milleri
S. mitior
S. mutans
S. sanguis
S. constellatus
S. intermedius
S. morbillorum
0 . 5% NaOCl
15
5
1
1
1
1
1
2
1
3
1
2
1
1
2
1
2
1
1
1
Peptostreptococcus sp
P. anaerobius
P. micros
Peptococcus magnus
P. prevotii
P. niger
3
5
6
1
3
3
1
4
3
1
1
1
Eubacterium alactolyticum
E. brachy
E. lentum
E . nodatum
E. timidurn
5
1
2
1
1
2
5
1
5
1
1
Arachnia propionica
Actinomyces sp
A. israelii
1
1
1
2
Lactobacillus sp
7
3
3
1
Fusobacterium sp
F. nucleatum
5
6
1
2
5
10
1
1
Bacteroides sp
B. corrodens
B. gingivalis
B. endodontalis
B. oralis
B. intermedius
9
3
1
1
5
5
9
1
1
1
2
4
Capnocytophaga ochracea
Selenomonas sputigena
Wolinella recta
Enterobacter agglomerans
Eikenella corrodens
Veillonella parvula
2
3
2
1
1
1
19
2
1
2
1
1
3
5
1
1
1
1
1
1
1
4
RESULTS
4.1
MICROORGANISMS IN INFECTED ROOT CANALS
Bacteria were found in all Initial samples taken from the 140 treated
root canals. The median number of bacterial cells present in the initial
5
2
samples from these canals before treatment was 3 x 10
(range < 1 0
- 2
X
107 ). In total 165 different bacterial strains were isolated from 30
bacterial samples taken at the beginning of the first appointment (I,
II). The isolated strains are presented in Table 1. The number of
bacterial species in these 30 root canals ranged between 1 and 11. The
most commonly isolated species were Fusobacterium nucleatum
(16 strains), Eubacterium alactolyticum (10 strains),
anaerobius (9 strains),
Peptostreptococcus
Peptostreptococcus m icros (9 strains),
Bacteroides intermedius (9 strains),
Eubacterium lentum (7 strains),
Bacteroides oralis (7 strains),
and Wolinella recta (7 strains). Thirty-
eight isolates could not be identified to the species level. They
represented Fusobacterium (10 strains),
Bacteroides (18 strains) and
Lactobacillus (10 strains).
4.2
ENDODONTIC TREATMENT
No bacteria could be
isolated in any samples taken from
the operation
fields or in samples collected during the preparation of the entrance
into the pulp chambers.
4.2.1
Mechanical
instrumentation (I)
Fifteen teeth were treated.
In these
teeth mechanical instrumentation
reduced the number of bacterial cells recovered from the root canals 100
- 1000-fold during the first appointment. Bacteria persisted,
however,
in all canals at the end of the first appointment (Fig 1:1). No bacteria
could be recovered from 3 root canals at the second appointment,
5 canals at the third and fourth appointment,
fifth appointment.
from
and from 8 canals at the
The bacteria persistent in the root canals at the end
of an appointment usually increased in number by the next appointment.
One such case is illustrated in Table 2. Most of the bacterial species
found at the first appointment could also be recovered at the fifth
appointment (Table 1).
Mechanical instrumentation and irrigation with saline did not
reduce the number of bacteria in the root canal so effectively that the
20
bacteria could be eliminated in a predictable manner within five
appointments.
Table 2. Bac t e r i a recovered fr o m the root canal duri n g the tre a t m e n t of one case.
R e l a t i v e p r o p o r t i o n of the m i c r o b i o t a
B a c t eria
r e c overed
Appoi n t m e n t
Sample
A n a e r o b i c st r e p t o c o c c u s
S. m u t a n s
P e p t o s t r e p t o c o c c u s sp
P. anae r o b i u s
P. m i c r o s
L a c t o b a c i l l u s sp
E u b a c t e r i u m lent urn
B a c t e r o i d e s sp
B. oralis
F u s o b a c t e r i u m sp
Total no. o£
bacterial cells
1
2
a*
b+
a
1
1
7
27
13
4
32
7
4
4
17
100
100
25
a
b
30
17
8
33
a
96
2
4
54
4
2
5
b
100
100
1.,8xl06
2.6xl04
2
2
b
23
94
6
2
1 . 2x l 0 5
1x10
a
3
3
40
10
18
1
2
2
7. 5x10
*
+
4
3
b
(%)
2.1x10
5x10
4
4
9x10
1.75x10
3. 4x10
a, Sample taken at the begin n i n g of the appointment.
b, Sample taken at the end of the appointment.
4.2.2
Irrigation (II, III)
4.2.2.1
0.5Z sodium hypochlorite solution (II, III)
Twenty teeth were treated. Of these teeth 15 were treated at 4
appointments (Fig 1:11) and 5 teeth at 2 appointments (Fig 1:111). No
bacteria could be recovered from 12 out of 20 root canals after
treatment at 2 consecutive appointments. After treatment at 4
consecutive appointments no bacteria could be recovered from 12 out of
15 root canals.
Bacteria present in the root canals at the third
appointment are presented in Table 3 and at the fifth appointment in
Table 1.
4.2.2.2
5Z sodium hypochlorite solution (III)
Twenty root canals were treated. No bacteria could be recovered from 14
out of 20 root canals after treatment at 2 consecutive appointments
21
(Fig 1:111).
Bacteria persistent at the third appointment are presented
in Table 3.
Table 3.
Bacteria persistent in the root canals at the third
appointment when various irrigants were used.
Bacteria
Irrigant
0.5% NaOCl
recovered
No of teeth
8
Streptococcus milleri
S. mutans
S. sanguis
S. intermedius
S. morbillorum
1
1
1
Peptostreptococcus anaerobius
P. micros
1
Arachnia propionica
Eubacterium alactolyticum
E. brachy
E. lentum
E. timidum
1
5% NaOCl
6
3
1
2
1
1
1
1
1
2
1
1
1
Lactobacillus sp
2
2
Fusobacterium sp
F. nucleatum
5
1
1
2
Bacteroides sp
B. gingivalis
B . endodontalis
B, intermedius
B. oralis
2
1
1
2
1
1
1
1
1
Capnocytophaga ochracea
Wolinella recta
4.2.2.3
5% NaOCl & EDTA
1
1
Sodium hypochlorite - EDTA solution (III)
Twenty teeth were treated. No bacteria could be recovered from 17 out of
20 root canals after 2 consecutive appointments (Fig 1:111).
Bacteria
present at the third appointment are presented in Table 3.
No specific bacteria were found which survived treatment with
all the various irrigating solutions.
hypochlorite solutions (II,
Irrigation with sodium
III) was more efficient than saline (I) in
22
eliminating bacteria from the root canals. There was, however, no
difference between 0.5% and 5% sodium hypochlorite solutions.
The
combined use of EDTA and sodium hypochlorite solutions was somewhat more
effective than the other irrigation
regimens.
4.2.3
Dressing (IV)
4.2.3.1
Calcium hydroxide paste (IV)
Calcium hydroxide has a strong antibacterial effect in vitro. The
killing of various bacterial strains by a calcium hydroxide suspension
is presented in Table 4. Most strains were killed within less than
1 min. The most resistant strain belonged to the species Enterococcus
faecal is. The rate at which E. faecalis was killed was dependent on the
pH and the bacterial cells survived
at pH 11.5
serum caused an insignificant delay
ofthe killing ofE. faecalis.
Table 4.
but not at pH
12.5. Horse
The time required to kill 99.9% or more of bacterial cells
in a calcium hydroxide suspension.
<1 min
1-3 min
Streptococcus sanguis
S. salivarius
S. milleri
S. mitis
S. intermed ius
Campylobacter fetus
Capnocytophaga ochracea
Bifidobacterium dentium
Fusobacterium nucleatum
Lactobacillus acidophilus
Selenomonas sputigena'
Wolinella recta
Bacteroides melaninogenicua
Peptostreptococcus anaerobius
Actinobacillus actinomycetemcomitans
Streptococcus mutans
S. morbillorum
Lactobacillus casei
Actinomyces israelii
A. naeslundii
A. odontolyticus
A. viscosus
Veillonella parvula
3-6 min
>6 min
Arachnia propionica
Eubacterium alactolyticum
Propionibacterium acnes
Enterococcus faecalis
23
Thirty-five teeth vere treated with calcium hydroxide paste.
No bacteria could be recovered from any samples taken from root canals
after they had been dressed with calcium hydroxide paste for 1 month.
samples taken 2 to 4 days after the dressing had been removed,
In
bacteria
were recovered from 1 of the 35 samples. That sample contained Wolinella
recta and Fusobacterium nucleatum. That case (OD) did not heal (Fig 3b).
Bacteria persisted in 21 root canals after the treatment regimens of
studies I, II and III and in 10 root canals after dressing with
camphorated phenol or camphorated paramonochlorophenol
in study IV.
These bacteria were eliminated by dressing the root canals with calcium
hydroxide paste in all but 2 canals.
4.2.3:2
Camphorated phenol/paramonochlorophenol
(IV)
Thirty teeth were treated with camphorated phenol/paramonochlorophenol
for 2 weeks (Fig 1:IV). No bacteria could be recovered from 20 out of 30
root canals after 2 weeks. Bacteria present in the 10 root canals are
presented in Table 5.
4.3
HEALING (V)
In all 140 teeth were treated using the various regimens.
Of these teeth
79 could be followed-up for at least 2 years. Radiographs were regularly
taken during this period and there was complete healing in 67 teeth
within 5 years.
The criterion for complete healing was a normal or
slightly widened apical periodontal space (<0.5 mm).
The size of the
lesions decreased progressively over the review period.
In Fig 2 this
healing pattern is illustrated for lesions of various initial sizes.
Seven lesions also decreased in size,
but after 2 years the
size of the apical periodontal space was more than 0.5 mm (Fig 3a). The
treatment regimen for these teeth before root-filling is presented in
Table 6. In 3 of the 7 cases (A, B, C, Fig 3a) the healing followed the
same pattern as for those which healed completely.
In one case (LL12)
there was a slower decrease in the size of the lesion.
The remaining 3
cases (LL31, LL41, LL42, Fig 3a) were treated surgically.
They were all
involved in a large confluent lesion in the mandibular anterior region
and histological examination of the tissue removed at surgery showed
scar tissue which was almost free of inflammatory cells.
In 5 lesions,
there was no or only an insignificant decrease
in the size of the lesions (Fig 3b). The treatment regimen for these
24
teeth before root filling is presented in Table 6. Four cases (IL, JV,
ABg, LB) were treated surgically and tissue samples from IL, J V and ABg
were subjected to histological examination. The histological examination
of the tissue sample from IL shoved a radicular cyst vith the presence
of Actinomyces israelii and Arachnia propionica. The histological
examination of the tissue sample from J V shoved a periapical abscess
vith A ctinomyces israelii.
In case ABg there vas a radicular cyst vith
chips of dentin in the tissue.
Table 5.
Case
Bacteria persistent in 10 root canals after treatment vhen
camphorated phenol (CP) or camphorated paramonochlorophenol
(CPCP) vere used as dressing betveen appointments.
Dressing
No of bacteria
Appointment
2
3
Persistent bacteria
4
ACS
CP
1.5xl05
5x10
Bacteroides intermedius
Fusobacterium sp
Propionibacterium acnes
Peptostreptococcus micros
EU
CP
-
< io2
Streptococcus milleri
LB
CP
1.8xl03
4 . 2xl02
Eubacterium timidurn
Fusobacterium nucleatum
Lactobacillus catenaforme
Peptostreptococcus anaerobius
Streptococcus constellatus
Wolinella recta
OL
CP
<102
2.5xl03
Actinomyces israelii
TN
CP
2.3xl03
5.6xl03
Eubacterium alactolyticum
Fusobacterium sp
SU
CPCP
2.2xl02
l.lxlO2
Bacteroides sp
Eubacterium alactolyticum
Peptococcus p r e v o t i i
KK
CPCP
<1 0 2
<102
Lactobacillus salivarius
KGS
CPCP
<102
2.lxlO2
Wolinella recta
RA
CPCP
<102
1.2xl02
Bifidobacterium eriksonii
Lactobacillus salivarius
BR
CPCP
2xl02
9xl02
Enterococcus faecal is
25
Table 6.
Treatment regimens and the outcome o£ the endodontic treatment for
the 79 followed-up teeth.
Teeth
no
Treatment regimens
Irrigant
Dressing
11
NaCl
13
NaOCl(0.51)
14
NaOCl(5Z)
15
NaOCl/EDTA
13
NaOCl(0.5%)
Ca(0H)2
13
N a O C l (0.5Z)
Ca(0H)2
Bacteria
after
treatment
+*
4
Root
filled
dressing*
+
4
7
4
6
2
4
2
11
1
5
9
5
7
5
3
CO)—*3
8
2
12
1
11
1
13
12
7
7
11
9
12
12
13
79
Outcome of treatment+
Heale'd "Healing"
Not
healed
A
ABg
LL12
B,LL41,LL42
18
JW
IL
C
OD
0
61
LB
LL31
11
68
67
7
5
* All teeth in this column subsequently dressed with calcium hydroxide paste.
• Dressing with calcium hydroxide paste after ordinary treatment regimen.
+ Healing and not healed cases are presented in Fig 3a and 3b.
Of the 79 cases followed-up for at least 2 years 12 cases had
acute apical abscesses at the beginning of the treatment and 9 cases
developed acute exacerbations during the treatment. Nineteen of these 21
cases healed completely.
In 38 out of
was within 0.5 to 2 mm
The remaining 2 cases were JW and ABg (Fig 3b).
79 teeth the apical level of the root-fillings
from the radiographic apex of the teeth
(Table 7). Eleven teeth were filled to the radiographic apex and
teeth were overfilled.
30
Three of the 5 cases, with no or only an
insignificant decrease in the size of the lesions, were overfilled.
However,
the root-filling excesses did not significantly influence the
healing of the apical lesions.
26
Table 7.
The apical level of the root filling and the outcome of the
endodontic treatment.
Number
Completely healed
or healing
Not healed
Root filled
to apex
11
11
Root filled
short of apex
38
36
2
Root filled
with excess
30
27
3
4
3
2
1
6
5
4
3
2
1
1
2
1
O B S E R V A T IO N
Fig 2
2
1
2
P E R IO D (Y E A R S )
The change in size of the apical lesions following
treatment. Healed lesions grouped according to initial
sizes. Number of cases in each group are given in the
figure. Sizes given as mean + 2 standard deviations.
27
SIZE OF THE LESIONS (mm)
12
12
11
11
10
10
9
9
8
8
7
JW
7
L L42
6
6
5
5
4
4
3
3
ABg
OD
LB
2
2
LL12
1
1
B,C
1
2
3
1
4
OBSERVATION PERIOD (YEARS)
Fig 3
2
3
OBSERVATION PERIOD (YEARS)
Change in size of the apical lesions following treatment.
a. The decrease in the size of "healing" lesions, b. Not healed
lesions, e.g. lesions with no or insignificant decrease in the
size.
28
5
DISCUSSION
5.1
MICROBIAL CHANGES DURING TREATMENT
The bacteria initially isolated from root canals were predominantly
anaerobic and the variety of bacterial species found was similar to that
reported in previous studies (Kantz and Henry 1974, Wittgow and Sabiston
1975,
Sundqvist 1976, Dahlén and Bergenholtz 1980, Zavistoski et al.
1980). These bacteria represented a restricted group compared with the
total potential pool of bacteria present in the oral cavity. This
indicates that an ecological balance is established in closed root
canals. Möller and associates (1981) have also demonstrated this by
experimental
infection of root canals in monkeys.
They found an increase
in the number and proportions of anaerobic bacteria in samples taken at
the end of experimental periods compared to the initial infecting
microbiota.
The median number of bacterial cells recovered from the root
canals at the beginning of the first appointment was 3 x 105 (range <
2
7
10 - 2 x 10 ). Mechanical instrumentation and irrigation reduced the
number of bacterial cells recovered from the root canals 100 - 1000-fold
irrespective of the treatment regimen. Bacteria which survived the
treatment usually multiplied in the undressed root canals.
Similar
results have been reported by Stewart and collaborators (1969) and Bence
and collaborators (1973). When few bacterial cells were recovered at the
end of one appointment these bacteria in some cases did not survive
until the next appointment.
During a treatment period the composition of the microbiota
recovered from the root canal varied. There was, however, no indication
that specific bacteria were implicated in persistent infections at the
end of the treatment period.
In previous studies (Bender and Seltzer
1952, Grahnén and Krasse 1963, Engström 1964, Goldman and Pearson 1969)
enterococci have been implicated in persistent root canal infections.
We, however,
could identify enterococci in only one out of 140 root
canals. These enterococci were not found in the initial sample but only
after the root canal had been dressed with camphorated
paramonochlorophenol for 2 weeks.
From some root canals no bacteria could be recovered at the
end of one appointment,
but at the next appointment bacteria could again
be found in these canals. The bacteriological technique might not reveal
29
all the bacteria present in the root canal or there might have been a
reinfection of the root canal during the interval between the
appointments.
It is, however, unlikely that reinfection caused the
reappearance of bacteria in the canals.
All bacteria recovered from
these root canals at subsequent appointments were, with one exception,
recovered from the root canals at the beginning of the treatment.
It is
thus obvious that in spite of the very careful bacteriological technique
used in the present study (Möller 1966), the result obtained by means of
this technique cannot always be used as an ultimate proof of the
bacteriological status of the root canal.
One possible improvement in the method for recovering
bacteria from the root canal would be to increase the interval between
appointments to more than 2 to 4 days. Presumably bacteria which remain
in the root canal following treatment could multiply to a detectable
level.
This may, however,
increase the risk of reinfection in the
extended inter-appointment time.
It has recently been shown that in
cases of periodontal disease with loss of attachment,
bacteria could
invade the dentinal tubules and infect the root canal (Adriaens et al.
1986).
It has been proposed that the oxygen tension in the root canal
is changed by the endodontic treatment so that the more oxygen tolerant
bacteria are favoured and thus will outnumber the anaerobes (Naidorf
1985, Matusow 1986). The present results showed, however,
that the
proportion of anaerobes of the microbiota in the root canals did not
change during the treatment.
It is thus likely that anaerobiosis was
reestablished in the root canals when they were sealed (Table 2). This
is consistent with the findings of Möller et al.
et al.
(1981),
and Fabricius
(1982).
5.2
COMPARISON OF TREATMENT REGIMENS
Bacteria could not be eliminated in a predictable manner by combining
mechanical
instrumentation and irrigation with antibacterial solutions.
Furthermore,
there was no difference in efficacy between 0.5% and 5%
sodium hypochlorite solutions.
Similar results have been obtained by
Cvek and collaborators (1976). This implies that other measures than
using irrigants with increased antibacterial potential are required for
the elimination of bacteria from the root canal.
30
An antiseptic only works if it comes into contact with the
target - the bacteria.
In root canals the antiseptic may not reach the
bacteria if they are concealed within or behind a smear layer (Baker et
al.
1975, McComb et al.
1976, Lester and Boyde 1977, Rubin et al.
Bolanos and Jenen 1980, Goldman et al.
al.
1982, Mader et al.
1979,
1984, Berg et
1986) or in dentinal tubules (Chirnside 1958, Shovelton 1964, Akpata
and Blechman 1982, Armitage et al.
1983). By including EDTA in an
irrigating solution this smear layer may be degraded (McComb et al.
1976, Goldberg and Abramowich 1977, Bolanos and Jensen 1980, Goldman et
al.
1981,
1982, Goldberg and Spielberg 1982, Berg et al.
1986), which
might improve the access of the antiseptic to the bacteria.
The
alternate use of 5% sodium hypochlorite and EDTA solutions as irrigants
did not, however,
eliminate all bacteria from the infected root canals.
Not even the combination of ultrasonic instrumentation and irrigation
with 0.5% sodium hypochlorite solution has proved to be effective
(Sjögren and Sundqvist 1986). Thus irrespective of instrumentation and
irrigation regimens,
bacteria could persist in the root canals. Although
the need for antibacterial dressings in the period between the
appointments has been questioned (Strindberg 1965, Weine 1982,
1984),
Schilder
our results showed that an antibacterial dressing is an essential
part of the endodontic treatment.
Calcium hydroxide proved to be an excellent antibacterial
dressing.
This is consistent with the results reported by Cvek and
collaborators (1976) and Strömberg and Allard (1976).
The present study
clearly showed that calcium hydroxide paste was superior to camphorated
phenol and camphorated paramonochlorophenol. This confirms previous
observations that calcium hydroxide paste maintains its antibacterial
effect for weeks or months (Tronstad et al.
1981), while camphorated
phenol and paramonochlorophenol quickly lose their antibacterial effect
when they are sealed in the root canal (Messer and Chen 1984, Tronstad
et al.
1985, Fager and Messer 1986). The use of these phenols as
antibacterial dressings in endodontic treatment should therefore be
discontinued.
5.3
HEALING
In the present study no bacteria could be recovered from any root canal
at the appointment when they were filled. The majority of the 79
evaluated lesions healed completely or decreased in size in such a way
31
that they could be expected to heal. Only 5 cases did not heal.
In those
cases there vas no or only an insignificant decrease in the size of the
lesions 2 years after treatment. Persistent bacteria were demonstrated
in the apical tissues in 2 of the 5 cases. Our results suggest that
failure of apical lesions to heal may be due to an establishment of
bacteria outside the root canal.
Survival of bacteria outside the root canal in the periodontal
tissue has, however,
been debated.
It is known that in acute apical
periodontitis bacteria are present in the periapical tissue (van
Vinkelhoff et al.
1985, Lewis et al.
1986), but in the chronic state of
the disease bacteria are rarely found and then only in phagocytizing
cells or in association with necrotic tissue and particles of root
filling materials (Block et al.
1976, Langeland et al.
1977, Pitt Ford
1982). Analysis of biopsy specimens from clinical cases (Block et al.
1976, Langeland et al.
al.
1977) and from animal experiments (Malooley et
1979, Pitt Ford 1982) shows that bacteria may survive on the root
surface especially in exposed dentinal tubules,
cellular cementum,
in lacunae of the
and in apical foramina. A close association between
the survival of bacteria at these sites and failure of the lesion to
resolve was apparent in the animal experiments (Malooley et al.
1979,
Pitt Ford 1982). Healing of a lesion may also be prevented by bacteria
of the genera Actinomyces and Arachnia because they survive in the
tissue without the support of a root surface, necrotic tissue or
particles of root-filling materials (Sundqvist and Reuterwing 1980, Weir
and Buch 1982, Happonen et al.
1985).
In a recent report, Tronstad and
associates (1986) claim that other anaerobic bacteria may also establish
themselves in the apical tissue,
inaccessible to conventional endodontic
treatment.
In clinical work it may sometimes be a problem to judge when
the endodontic treatment should be considered a failure. The present
study provides some clues as to how this problem could be tackled.
The
treatment was evaluated by means of regular radiographic recordings.
It
was thus possible to demonstrate a variety of healing patterns among the
lesions. The analysis of the healing patterns showed that the initial
size of the lesion influenced the healing pattern and that complete
healing of a lesion could take up to 5 years. Our results showed,
however,
that as long as there is a continuous decrease in the size of a
lesion following treatment,
there is no reason to designate a case a
32
failure. Judging success or failure after the endodontic treatment of
teeth with an unknown background on one occasion (Bergenholtz et al.
1973, Erselius et al.
Holm et al.
1975, Bergman et al.
1982, Petersson et al.
I
1979, Hugosson and Kock 1979,
1986) may result in an overestimation
of the failure rate of such treatment.
In routine clinical work this calls for radiographic
examination before the endodontic treatment and at regular follow-ups
until complete healing is achieved.
In order to obtain comparable
radiographs of high quality at different examinations the following
recommendations are made:
1. that the long-cone technique with a
filmholder is employed 2. that the same exposure time is used for the
same tooth on each occasion a radiograph is taken 3. that standardized
processing procedures in accordance with the manufacturers' guidelines
should be followed.
The judgment of the treatment result should be based
on the change in the size of the lesion carefully registered on recall
radiographs.
Every single step in the endodontic treatment has been
evaluated from many angles over the years and this has resulted in an
antibacterial treatment regimen consisting of mechanical
instrumentation,
irrigation and placement of antibacterial dressing.
In
the present study the efficacy of these measures has been evaluated
using bacteriological methods and by recording the healing pattern of
the lesions.
From these results it can be concluded that it is possible
to follow a treatment regimen at the first appointment which eliminates
bacteria so effectively that the treatment can be completed in 2
appointments.
In Sweden dentists devote 12 to 13% of their total time to
endodontic treatment (Andersson et al.
1986). More than 75% of this time
is spent in treating non-vital teeth. The average number of appointments
requested in the treatment is 3 to 5 for each tooth (Andersson et al.
1986).
The treatment regimen finally applied in the present study might
both significantly increase the rate of success and decrease the time
needed for endodontic treatment.
33
SUMMARY
The present study is a clinical and bacteriological
non-vital teeth with apical periodontitis.
in the development of this disease.
investigation of
Bacteria play a decisive role
The aim of the treatment is
therefore to eliminate the bacteria. Earlier studies,
however,
provide
limited information about the relative efficacy of the various measures
used in this treatment.
In the present study it was shown that
mechanical cleansing with files in combination with saline as the
irrigating solution,
reduced the number of bacteria in the root canal
during the treatment sessions but few root canals were completely freed
from bacteria.
The same technique but using sodium hypochlorite as the
irrigating solution,
There was, however,
resulted in more root canals free from bacteria.
no difference in the antibacterial effect between
0.5% and 5.0% sodium hypochlorite solutions, while the combination of
15% EDTA and 5% sodium hypochlorite solutions was somewhat more
efficient than 5% sodium hypochlorite solution alone.
The bacteria which survived the mechanical cleansing and the
irrigation usually increased in number in the period between treatment
sessions.
By dressing the root canal with calcium hydroxide paste the
bacteria that persisted after the mechanical cleansing and the
irrigation were efficiently eliminated.
followed-up.
The healing of 79 lesions was
The majority of these lesions healed within 2 years,
but in
some cases the healing was not completed until 5 years after the
treatment.
Five lesions did not heal. Histological examination of these
lesions showed that in 2 cases bacteria had become established outside
the root canal.
The present study showed,
that the treatment of infected non-
vital teeth can be completed in only 2 sessions.
the root canal is mechanically cleansed,
At the first session
irrigated with sodium
hypochlorite solution and dressed with calcium hydroxide paste. At the
second session,
one month later, the calcium hydroxide paste is removed
and the root canal is filled.
This treatment may however fail in some
cases because of bacteria may establish outside the root canal where
they only can be eliminated by surgery.
34
ACKNOWLEDGEMENTS
I want to express my sincere gratitude to my supervisor and co-author
Professor Göran Sundqvist who introduced me to this field of research
and guided me through it with inspiration,
support.
constructive criticism and
I am also most grateful to Professor Jan Carlsson for his
generous support,
constructive critisism and advices which have been
essential for this work.
I also want to express my sincere thanks to
Docent Kenneth Wing, Drs Jan Ahlqvist, Eva Borssén, Per Nelvig, Ulf
Sjögren and Per Strandberg for analysing the roentgenograms, Mrs Eva
Johansson and Mr Rolf Classon for excellent technical assistance,
Fil.
kand. Tomas L a i t ila for statistical analyses, Mrs Sonja Andersson for
excellent assistance,
assistance.
and Mrs Katarina Wrethén for excellent secretarial
I also want to thank Dr David Figdor and Mrs Patricia
Shrimpton for linguistic revision of the manuscript.
This investigation was supported by grants from the Faculty of
Odontology, University of Umeå and the Swedish Dental Society.
35
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