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Efficacy of a calcium hydroxide and chlorhexidine digluconate mixture as disinfectant during retreatment of failed endodontic cases

Authors:

Abstract

The purpose of this in vivo investigation is to compare the effect of a slurry of Ca(OH)2 mixed in aqueous 2% chlorhexidine (CHX) versus aqueous Ca(OH)2 slurry alone on the disinfection of the pulp space of failed root-filled teeth during endodontic retreatment. Forty single-rooted previously root-filled teeth with associated periradicular lesions were included. The teeth were nonsurgically retreated and medicated over 3 treatment visits with 7-10-day intervals with either Ca(OH)2 in water or Ca(OH)2 in 2% aqueous CHX. Root canal cultures were collected in fluid thioglycollate, and bacterial growth was assessed by turbidity daily for 1 week, then weekly for an additional 3 weeks. The presence of enterococci in the root canals at the initial treatment session was determined. Of the total sample population, 12 of 40 (30%) were positive for bacteria before root filling. The control medication disinfected 12 of 20 (60%) teeth including 2 of 4 teeth originally diagnosed with enterococci. The experimental medication resulted in disinfected 16 of 20 (80%) teeth at the beginning of the third appointment. None of the teeth originally containing enterococci showed remaining growth. This difference between the overall positive cultures was not statistically significant (P > .05). Canal dressing with a mixture of 2% CHX and Ca(OH)2 slurry is as efficacious as aqueous Ca(OH)2 on the disinfection of failed root-filled teeth.
ENDODONTOLOGY Editor: Larz S. W. Sp!
angberg
Effectiveness of a calcium hydroxide and chlorhexidine digluconate mixture
as disinfectant during retreatment of failed endodontic cases
Joseph A. Zerella, DMD, MDS,
a
Ashraf F. Fouad, BDS, DDS, MS,
b
and
Larz S. W. Sp
!
angberg, DDS, PhD,
c
Farmington, Conn, and Baltimore, Md
UNIVERSITY OF CONNECTICUT AND UNIVERSITY OF MARYLAND
Objective. The purpose of this in vivo investigation is to compare the effect of a slurry of Ca(OH)
2
mixed in aqueous 2%
chlorhexidine (CHX) versus aqueous Ca(OH)
2
slurry alone on the disinfection of the pulp space of failed root-filled teeth during
endodontic retreatment.
Study design. Forty single-rooted previously root-filled teeth with associated periradicular lesions were included. The teeth
were nonsurgically retreated and medicated over 3 treatment visits with 7-10-day intervals with either Ca(OH)
2
in water
or Ca(OH)
2
in 2% aqueous CHX. Root canal cultures were collected in fluid thioglycollate, and bacterial growth was assessed
by turbidity daily for 1 week, then weekly for an additional 3 weeks. The presence of enterococci in the root canals at the initial
treatment session was determined.
Results. Of the total sample population, 12 of 40 (30%) were positive for bacteria before root filling. The control
medication disinfected 12 of 20 (60%) teeth including 2 of 4 teeth originally diagnosed with enterococci. The experimental
medication resulted in disinfected 16 of 20 (80%) teeth at the beginning of the third appointment. None of the teeth originally
containing enterococci showed remaining growth. This difference between the overall positive cultures was not statistically
significant (P[.05).
Conclusions. Canal dressing with a mixture of 2% CHX and Ca(OH)
2
slurry is as efficacious as aqueous Ca(OH)
2
on the
disinfection of failed root-filled teeth.
(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:756-61)
The success of endodontic treatment is negatively influ-
enced by the presence of microorganisms within the root
canal system.
1-2
Studies have shown the relationship
between the development of apical periodontitis and
the colonization of the pulp space by bacteria.
3-6
The
necrotic pulp harbors a delicate ecology of resident
microbes and microbial by-products.
7
The necrotic tis-
sue remnants and dentin serve as a sufficient environment
for the establishment of bacterial growth. Apical peri-
odontitis is an inflammatory process of the periradicular
region and is initiated and sustained by endodontic
infection.
3,7
Endodontic treatment of teeth with apical periodon-
titis consists of the elimination of microorganisms from
the root canal. Thus, the success of endodontic treatment
is directly contingent on the eradication of the infection
before root filling.
1,8,9
The flora of untreated necrotic
teeth consist of polymicrobial infection, often 8-11
different species, dominated by obligate anaerobes.
Studies have found that the microbial flora of failed cases
is significantly different from those of necrotic pulps.
Previously root-filled teeth with chronic periradicular
lesions often contain an isolated microflora, dominated
by gram-positive facultative anaerobes. Enterococcus
faecalis, which is not normally recovered in high
quantities of initially infected teeth, has been isolated
more often from failed root-filled teeth.
10-12
Therefore,
a
Former Resident and Postgraduate Student in Endodontology,
Department of Endodontology, School of Dental Medicine, Univer-
sity of Connecticut.
b
Associate Professor and Chairman, Department of Endodontics,
Prosthodontics and Operative Dentistry, Baltimore College of Dental
Surgery, University of Maryland.
c
Professor of Endodontology, Department of Endodontology, School
of Dental Medicine, University of Connecticut.
Received for publication Oct 10, 2003; returned for revision Jan 15,
2004; accepted for publication May 17, 2005.
1079-2104/$ - see front matter
!2005 Mosby, Inc. All rights reserved.
doi:10.1016/j.tripleo.2005.05.072
756
Vol. 100 No. 6 December 2005
a very selective environment may exist within the root
canal system of previously root-filled teeth that favors
the survival of microorganisms like E faecalis and
Candida albicans.
13
These microorganisms appear to
have an ability to utilize opportunities created by the
removal of other microorganisms and to survive and
multiply in the low-nutrient environment of the treated
root canal. E faecalis and C albicans are also less
susceptible to common deposit medicaments such as
calcium hydroxide.
14-17
Efforts have been made to enhance the antimicrobial
effectiveness of Ca(OH)
2
using the addition of suitable
antimicrobial mixing vehicles. Chlorhexidine (CHX)
is an antimicrobial agent currently under investigation
as an endodontic irrigant.
18,19
CHX possesses broad-
spectrum antibacterial activity, biocompatibility with
periodontal tissues, and substantivity.
20-22
However, the
effectiveness of aqueous CHX as a mixing vehicle on
enhancing the antimicrobial efficacy of Ca(OH)
2
slurry
has not been fully examined in vivo.
CHX is a synthetic cationic bis-biguanide (pKa 2.3
and 10.3) that remains stable at pH 5-7. As the pH is
increased, ionization will decrease.
23
Thus, at higher
pH values, there are a greater proportion of unionized
CHX molecules present. At high pH the CHX precipi-
tates and may be unavailable as an antimicrobial agent.
In preparation for this investigation, pilot studies were
performed to explore the chemical interaction between
Ca(OH)
2
and CHX and the CHX concentration needed
for clinical effectiveness. Therefore, the pH of mixtures
of various concentrations of CHX with Ca(OH)
2
were
recorded. The average pH of an aqueous solute of CHX
as a mixing vehicle for Ca(OH)
2
was 12.7, which is
similar to the pH value when using sterile water as the
mixing vehicle. This suggests that high concentrations
of hydroxide ion are generated when aqueous CHX is
used as a mixing vehicle.
CHX precipitates when mixed with Ca(OH)
2
.Theresult
of this precipitation on CHX was investigated. When a
slurry of Ca(OH)
2
in 0.5%, 0.4%, 0.3%, 0.2%, and 0.1%
CHX was centrifuged to separate the insoluble Ca(OH)
2
particulate from the fluid, a supernatant containing a
saturated solution of Ca(OH)
2
ions in aqueous CHX
resulted. The absorbance of ultraviolet light at 254 nm,
which is the peak absorbance for CHX, showed that
there was a significant loss of CHX ([99%) when mixed
with Ca(OH)
2
at this span of concentrations. Some
residual CHX is still available in this aqueous mixture
but in very low concentrations and dependent on the
original CHX concentration. When the Ca(OH)
2
pre-
cipitate was suspended again in water, the supernatant
was devoid of free CHX. Thus, after being mixed with
Ca(OH)
2
the CHX remains as a base, with little or no
solubility in water. Because of this observed loss of
CHX when mixed with Ca(OH)
2
, the bactericidal efficacy
of mixtures of various concentrations of Ca(OH)
2
in
aqueous CHX on cell suspensions of E faecalis
(ATCC19433) was studied. Despite the potential loss of
CHX ([99%) when mixed with Ca(OH)
2
, the anti-
microbial efficiency of this mixture was as effective as
CHX alone on E faecalis (ATCC19433) in agar inhibi-
tion tests in vitro. Thus, despite the remarkable high loss
of CHX when mixed with Ca(OH)
2
the combined
resulting effect may have clinical value. Other recent
studies in vitro have demonstrated a reduced effective-
ness of CHX after mixing with Ca(OH)
2
powder.
24,25
Because there is significant loss of CHX when
mixed with Ca(OH)
2
powder a 2% aqueous solution
was chosen as the mixing vehicle for the clinical trial.
The purpose of this in vivo investigation was to
compare the effect of a mixture of aqueous 2% CHX and
Ca(OH)
2
powder with an aqueous mixture of Ca(OH)
2
alone on the disinfection of the pulp space of failed
root-filled teeth during endodontic retreatment.
MATERIALS AND METHODS
Preparation of test medicament
A 2% solution of CHX was prepared by diluting a
20% stock solution (Sigma Chemical, St Louis, Mo) in
sterile deionized water. The CHX solutions were mixed
with sterile Ca(OH)
2
powder (Sigma Chemical; 0.5 g
Ca(OH)
2
to 1 mL CHX in water) until smooth slurry
was formed. Aqueous calcium hydroxide slurry was
prepared with sterile water in the same proportions.
Patient/sample selection
The subjects for this study were selected from
patients referred to the Department of Endodontology,
University of Connecticut School of Dental Medicine.
Forty single-rooted previously root-filled teeth with asso-
ciated apical periodontitis were included. The patients
were 20 years of age or older. Exclusion criteria included
teeth that could not be easily isolated with a rubber dam,
crowns with leaky cervical margins, and teeth with large
intraradicular posts. Informed consent was obtained
from all patients who participated in this investigation
in accordance with protocol obtained from the institu-
tional review board (IRB #03-041). A nonparticipating
dental assistant prepared the intracanal dressing on a
case-by-case basis. The operator was blinded to all inter-
visit medications. After complete instrumentation of the
root canal, and just before the time of initial placement
of intracanal medication, a lot was drawn from an initial
sample of 40, marked with either A or B, representing
control and experimental. The medication was coded as
A or B. This determined which medication was to be
used on that tooth for all treatment visits.
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Tooth preparation
The surface of the tooth was isolated with a rubber
dam and old restorations were removed and caries ex-
cavated. Before accessing the root filling, the operating
field was disinfected and then neutralized according
to the protocol by Mo
¨ller (1966)
26
Briefly, the rubber
dam, retainer, tooth, and surroundings were disinfected
for 2 minutes each with 30% hydrogen peroxide and
5% tincture of iodine. The disinfectants were neutralized
with 5% sodium thiosulfate, and then a bacteriologic
sample (CR
1
) of the tooth surface was obtained with
sterile paper points.
Endodontic treatment
The root filling was mechanically removed with
Gates-Glidden burs and hand files. An operating
microscope (Leica Microsystems, Bannockburn, Ill)
was used to aid in the removal of residual root filling
and sealer. A sterile endodontic file was placed into the
canal and the length was adjusted to within 1 mm of the
apex with the aid of a Root ZX electronic apex locator
(J Morita Corp, Irvine, Calif). A digital radiograph (Schick
CDR, Schick Technologies, Long Island City, NY) was
exposed to confirm the working length. Sterile saline
was then added to the root canal. A sterile #20 file,
advanced to the working length, was used to agitate the
canal contents for 1 minute. The entire canal contents
were absorbed onto sterile paper points and transfered
to prereduced thioglycolate broth (Becton-Dickinson
Microbiology, Cockeysville, Md), and the culture was
labeled (C1). The root canal was then cleaned and
shaped with endodontic files using conventional end-
odontic technique. A copious amount of 1.0% NaOCl
solution was used for irrigation. The canal was dried
with sterile paper points, and 5% sodium thiosulfate was
used to neutralize the sodium hypochlorite. The canal
was again dried and saline was added to the root canal,
and the entire contents were cultured as described
above (C2).
Next, the root canal was irrigated with 5 mL of 1%
NaOCl and agitated with the master apical file. The
canal was dried with sterile paper points and packed
with either aqueous Ca(OH)
2
slurry or 2%CHX 1
Ca(OH)
2
slurry and temporized with a thick layer of
Cavit (3M ESPE, St Paul, Minn). The next appointment
was scheduled for 7-10 days thereafter.
At the second appointment, the tooth was isolated
with a rubber dam, disinfected, and again neutralized,
as outlined earlier. A microbial sample of the operating
field was obtained (CR
2
). The temporary filling was
removed with a sterile round bur and the dressing was
flushed with copious sterile saline. The canal was dried
with sterile paper points. All root canals were filled with
a mixture of 0.3% lecithin (Sigma Chemical), 3%
Tween 80 (Sigma Chemical), and 5% sodium thiosulfate
(American Regent Laboratories, Shirley, NY) to neu-
tralize any residual CHX and were agitated with the
master apical file at working length. The canal was
dried and then filled with saline, and a culture sample
was obtained and labeled (C3). The root canal was
instrumented with the master apical file to working
length and irrigated with 1% NaOCl. The root canal was
dried with sterile paper points. The sodium hypochlorite
was neutralized with 5% sodium thiosulfate and the root
canal again dried. Saline was added to the root canal and
the entire contents were cultured (C4). The tooth was
remedicated with a fresh mixture of the same medica-
ment that was used during the first visit and temporized
with Cavit. The third visit was scheduled for 7-10 days
thereafter.
At the third appointment, the tooth was treated
similarly to the preceding appointments and cultured
twice again (CR
3
and C5). The root canals were finally
filled with gutta percha and AH26 sealer using cold
lateral compaction. The tooth was temporized with
Cavit and a permanent restoration planned.
All cultures were collected in prereduced fluid
thioglycolate.
27
The thioglycolate broth cultures were
incubated at 378C and inspected daily for turbidity
for the first 7 days, then weekly for another 3 weeks
to assure that slow-growing microorganisms were in-
cluded. The initial cultures (C1) were also analyzed
with molecular technique using PCR amplification and
molecular sequencing for identification of enterococci.
The results of this analysis were previously reported.
28
Statistical analysis
The material from the culture data was distributed
into 2 groups: experimental and control. The cultures
were recorded according to turbidity as positive or
negative and were compared using the chi-square test
(significance level set at P\.05).
RESULTS
Clinical experiment
The control cultures (CR
1
, CR
2
, and CR
3
) were all
negative, indicating successful disinfection of the opera-
ting field before the root canal was accessed. All teeth
contained cultivable microorganisms when first sam-
pled (C1). Four teeth in each group harbored E faecalis
as determined by molecular technique.
28
Bacterial cultures obtained after root canal medica-
tion at the beginning of the second appointment resulted
in 10 positive cultures (50%) for the control group, of
which 3 belonged to the group that initially contained
enterococci. In the experimental group there were 7
positive cultures (35%), of which 2 belonged to the
group that initially contained enterococci (Table I).
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These differences were not statistically significant
(P[.05).
Bacterial cultures obtained after root canal medica-
tion and at the beginning of the third appointment
resulted in 8 positive cultures (40%) for the control
group, of which 2 belonged to the group that initially
contained enterococci. In the experimental group
there were 4 positive cultures (20%), of which none be-
longed to the group that initially contained enterococci
(Table I). These differences between the overall positive
cultures were not statistically significant (P[.05).
Of the total sample population, 12 of 40 (30%) were
positive for bacteria before root filling. The control
medication disinfected 12 of 20 (60%) teeth, including
2 of 4 teeth originally diagnosed with enterococci. The
experimental medication resulted in disinfected 16 of 20
(80%) teeth at the beginning of the third appointment.
None of the teeth originally containing enterococci
showed remaining growth. This difference between
the overall positive cultures was not statistically signif-
icant (P[.05).
DISCUSSION
Numerous treatment strategies and regimens have
been suggested for the treatment of teeth with failed
endodontic therapy. Thorough chemomechanical de-
bridement is still the mainstay of therapy and the
placement of an intracanal antimicrobial dressing is
usually recommended. However, owing to the special
microflora present in retreatment cases, the traditional
intracanal antimicrobial dressing with Ca(OH)
2
may
under certain circumstances be ineffective.
16,29
Ca(OH)
2
is poorly soluble in water but dissociates
into OH
!
ions, which creates a highly alkaline solution
(pH [12.0 at 378C). The hydroxide ion concentration
remains constant in solution as long as the presence of
undissolved Ca(OH)
2
is in contact with the saturated
solution.
30,31
Sukawat and Srisuwan
32
tested the antimicrobial
efficacy of 3 Ca(OH)
2
-slurry formulations on human
dentin infected with E faecalis. After exposure to the 3
Ca(OH)
2
mixtures (distilled water, 0.2% chlorhexidine,
or camphorated paramonochlorophenol (CMCP)) for
7 days, the CMCP mixture was completely effective
against dentinal tubule infection, and distilled water
and CHX mixed with Ca(OH)
2
were ineffective. The
low effectiveness of the CHX and Ca(OH)
2
mixture was
attributed to a possible decrease in the resulting pH. Our
results, however, indicate that the high pH is maintained
in a mixture. Therefore, the substantial reduction of
CHX concentration, due to the precipitation at high pH
of an already low concentration of CHX is most likely
responsible for the lack of effect in the study by Sukawat
and Srisuwan. Podbielski et al
33
used a combination
of Ca(OH)
2
and CHX and tested the effectiveness of
this mixture in disinfecting dentin. They concluded that
an antibacterial synergism exists between the Ca(OH)
2
suspension and CHX when used against E faecalis.
They also found that Ca(OH)
2
did not adversely affect
the solubility and activity of CHX but rather exhibited
an additive effect on common endodontic pathogens.
In contrast, our preliminary studies showed that most
CHX precipitates out of solution when mixed with
Ca(OH)
2
. However, at higher concentrations of CHX it
appears that a small residue of active CHX may still be
present. The reduced efficacy of the CHX and Ca(OH)
2
mixtures, in addition to precipitation, may be due to
the deprotonation of the biguanide at pH [8.0 and
therefore to a reduced solubility, which may hinder
the interaction with the negatively charged bacterial cell
membrane. Therefore, a mixture of CHX and Ca(OH)
2
may not provide a sufficient reservoir of free CHX
molecules.
The present study shows that sodium hypochlorite
in conjunction with mechanical instrumentation is only
partially effective as a method to reduce microbial con-
tent of previously treated root canals that have failed.
Table I. Positive culture results from the root canals during retreatment of failed endodontic cases in forty single-
rooted teeth
Dressing: CHX1Ca(OH)
2
Dressing: Ca(OH)
2
Sample # All samples C contained Enterococcus All samples C contained Enterococcus Total positive
C1 20 4 20 4 40
C2 2 7 9
C3 7 2 10 3 17
C4 2 3 5
C5 4 0 8 2 12
Ca(OH)
2
,calcium hydroxide slurry.
All teeth were treated in similar fashion except for the intervisit dressing.
Cultures C1, C3, and C5 were obtained at the beginning of visits 1, 2, and 3, respectively. C2 was obtained at the end of visits 1 and 3. C4was taken at the end of visit 2.
Chi-square analysis. The distribution is not significant at the 0.05 level.
No difference between 1- and 4-week observations.
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Our findings correspond to results reported by others
when treating teeth with necrotic pulp.
34,35
Although
there were fewer samples with growth in the CHX1
Ca(OH)
2
group compared to the Ca(OH)
2
group, these
findings did not reach statistical significance. The sam-
ple size, however, does not allow the conclusion that
there is no significant difference. Further research is
needed to explore whether the difference between the
experimental and control groups in residual cultivable
bacteria of 20% and 40%, respectively, remains consis-
tent in larger samples of cases.
An analysis of the original samples from the infected
root canals showed an even distribution of Enterococcus
species between the 2 groups. Four out of 20 teeth in
both the experimental as well as the control group
initially contained Enterococcus species. The Ca(OH)
2
and CHX slurry was effective in completely eliminating
bacteria in these specimens but a Ca(OH)
2
slurry was
only partially effective. If the presence of Enterococcus
species in therapy resistance is important these trends
may be of value. Therefore, to further explore the
observed enhancement in disinfection when using a
slurry of Ca(OH)
2
in 2% CHX, larger size clinical
experiments must be undertaken to verify or reject the
trend.
There were noticeable differences in the rate of
growth in cultures taken at the end of each appointment
compared with the culture obtained at the beginning of
the subsequent visit. There is always the risk of leakage
and contamination of the pulp space between visits but
great care was taken to maintain reliable temporary
fillings and asepsis. The difference observed is more
likely associated with a significant decrease in number
of bacterial cells after thorough instrumentation and
irrigation during each treatment session. If the cell
numbers are too low the cultures obtained at the end of
the treatment session may fail to grow in this specific
culture medium.
Myers et al
36
determined the incidence of microor-
ganisms present in the root canals of teeth scheduled to
be filled following 1 or 2 consecutive negative cultures.
They found that root canals to be filled following
1 negative culture yielded 25.9% positive cultures at the
time of root filling and root canals filled following
2 successive negative cultures produced a reversal rate
of 13.2%. Engstro
¨m and Lundberg
37
found a reversal
rate of 16.2% after 2 successive negative cultures.
The length of time elapsed between the last treatment
and the final filling appointment was regarded as the most
important factor differentiating the culture results between
canals filled after 1 negative culture and those filled
after 2 negative cultures.
Another reason for the difficulty to more successfully
eliminate microorganisms from these root canals may
be the effect of remaining root filling materials inhibi-
ting effective disinfection of the root canal walls. Despite
the intracanal dressing used, all microorganisms
may not have been reached by the antiseptics, which
allowed bacterial repopulation during the intervisit
period. This observation is not unique, but difficult to
explain, because the root canals were filled with some
form of calcium hydroxide slurry between visits.
38
Our results suggest that 2 sessions of intracanal
dressing may be of value when retreating teeth with
failed endodontic treatment. No cultures were obtained
after irrigation and instrumentation during the third
visit. Judging from the remarkable decrease in numbers
of root canals with microorganisms between the begin-
ning and end of the first and second visit, an equivalent
decrease might be expected immediately before the
placement of the root filling. All teeth where enterococci
were found at the initial sampling were successfully
disinfected when Ca(OH)
2
was mixed with CHX. Only
2 of the 4 teeth with initial content of enterococci were
successfully disinfected when a Ca(OH)
2
slurry was
used as intracanal dressing. These observations are
similar to the observations by Evans et al,
39
who found
dentin cylinders infected with E faecalis (ATCC 29212)
were more effectively disinfected with 2% CHX 1
Ca(OH)
2
compared with Ca(OH)
2
alone.
CONCLUSION
Root canal dressing with a mixture of 2% CHX
and Ca(OH)
2
slurry is at least as efficacious as aqueous
Ca(OH)
2
on the disinfection of root canal dentin of
failed root-filled teeth. The difference, however did
not reach statistical significance in this study. When
using an alkaline canal dressing for the retreatment of
failed endodontic cases, a 3-visit retreatment procedure
resulted in fewer cases of root canals with residual in-
fection than a 2-visit treatment routine. Complete dis-
infection of all cases was not achieved but all cases that
initially harbored Enterococcus species were success-
fully disinfected with the Ca(OH)
2
and CHX combina-
tion. To elucidate if the slurry of Ca(OH)
2
in CHX has an
enhanced clinical disinfection efficacy over a Ca(OH)
2
slurry a larger clinical trial must be undertaken.
This study was funded by Endodontic Alumni Association at
the University of Connecticut Health Center School of Dental
Medicine, University of Connecticut.
REFERENCES
1. Zeldow BJ, Ingle JI. Correlation of the positive culture to the
prognosis of endodontically treated teeth: a clinical study. JADA
1963;66:9-13.
2. Engstro
¨m B, H
!
ard AF, Segerstad LH, Ramstro
¨m G, Frostell G.
Correlation of positive cultures with the prognosis for root canal
treatment. Odontol Revy 1964;15:257-70.
OOOOE
760 Zerella, Fouad, and Sp
!
angberg December 2005
3. Kakehashi S, Stanley HR, Fitzgerald RJ. The effects of surgical
exposures of dental pulps in germ-free and conventional
laboratory rats. Oral Surg Oral Med Oral Pathol Oral Radiol
Endod 1965;20:340-9.
4. Fabricius L. Oral bacteria and apical periodontitis. An experi-
mental study in monkeys [thesis]. Go
¨teborg, Sweden: University
of Go
¨teborg; 1982.
5. Fabricius L, Dahle
´n G, O
¨hman AE, Mo
¨ller A
˚JR. Predominant
indigenous oral bacteria isolated from infected root canals after
varied time of closure. Scand J Dent Res 1982;90:134-44.
6. Fabricius L, Dahle
´n G, Holm SC, Mo
¨ller A
˚JR. Influence of
combinations of oral bacteria on periapical tissues of monkeys.
Scand J Dent Res 1982;90:200-6.
7. Sundqvist G. Bacteriologic studies of necrotic dental pulps [PhD
thesis]. Ume
!
a, Sweden: University of Ume
!
a; 1976.
8. Bystro
¨m A, Happonen RP, Sjo
¨gren U, Sundqvist G. Healing of
periapical lesions of pulpless teeth after endodontic treatment
with controlled asepsis. Endod Dent Traumatol 1987;3:58-63.
9. Sjo
¨gren U, Figdor D, Persson S, Sundqvist G. Influence of
infection at the time of root filling on the outcome of endodontic
treatment of teeth with apical periodontitis. Int Endod J 1997;30:
397-406.
10. Sundqvist G, Figdor D, Persson S, Sjo
¨gren U. Microbiologic
analysis of teeth with failed endodontic treatment and the
outcome of conservative re-treatment. Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 1998;85:86-93.
11. Molander A, Reit C, Dahlen G, Kvist T. Microbiological status of
root-filled teeth with apical periodontitis. Int Endod J 1998;31:1-7.
12. Hancock HH III, Sigurdsson A, Trope M, Moiseiwitsch J.
Bacteria isolated after unsuccessful endodontic treatment in a
North American population. Oral Surg Oral Med Oral Pathol
Oral Radiol Endod 2001;91:579-86.
13. Nair PNR, Sjo
¨gren U, Krey G, Kahnberg K-E, Sundqvist G.
Intraradicular bacteria and fungi in root filled, asymptomatic
human teeth with therapy-resistant periapical lesions: a long-
term light and electron microscopy follow-up study. J Endod
1990;16:580-8.
14. Waltimo TMT, Siren EK, Ørstavik D, Haapasalo MPP. Suscep-
tibilities of oral Candida species to CH in vitro. Int Endod J
1999;32:94-8.
15. Bystro
¨m A, Claesson R, Sundqvist G. The antibacterial effect
of camphorated paramonochlorophenol, camphorated phenol
and CH in the treatment of infected root canals. Endod Dent
Traumatol 1985;1:170-5.
16. Haapasalo M, Ørstavik D. In vitro infection and disinfection
of dentinal tubules. J Dent Res 1987;66:1375-9.
17. Evans M, Davies JK, Sundqvist G, Figdor D. Mechanisms
involved in the resistance of Enterococcus faecalis to CH. Int
Endod J 2002;35:221-8.
18. Gomes BP, Ferraz CC, Vianna ME, Berber VB, Teixeira FB,
Souza-Filho FJ. In vitro antimicrobial activity of several concen-
trations of sodium hypochlorite and chlorhexidine gluconate in the
elimination of Enterococcus faecalis. Int Endod J 2001;34:424-8.
19. Ferguson DB, Marley JT, Hartwell GR. The effect of
chlorhexidine gluconate as an endodontic irrigant on the apical
seal: long-term results. J Endod 2003;29:91-4.
20. Davis GE, Francis J, Martin AR, Rose FL, Swain G. 1:6-di-49-
chlorophenyldiguanidohexane (‘‘hibitane’’). Laboratory investi-
gation of a new antibacterial agent of high potency. Br J
Pharmacol 1954;9:192-6.
21. Newman MG, Sanz M, Nachnani S, Saltini C, Anderson L.
Effect of 0.12% chlorhexidine on bacterial recolonization
following periodontal surgery. J Periodontol 1989;60:577-81.
22. White RR, Hays GL, Janer LR. Residual antimicrobial activity
after canal irrigation with chlorhexidine. J Endod 1997;23:229-31.
23. Jones DS, Loftus AM, Gorman SP. Physical factors affecting the
sporicidal activity of CHX gluconate. Int J Pharm 1995;119:
247-50.
24. Gomes BPFA, Souza SFC, Ferraz CCR, Teixeira FB, Zaia AA,
Valdrighi L, et al. Effectiveness of 2% chlorhexidine gel and
calcium hydroxide against Enterococcus faecalis in bovine root
dentine in vitro. Int Endod J 2003;36:267-75.
25. Sch
afer E, Bo
¨ssmann K. Antimicrobial efficacy of chlorhexidine
and two calcium hydroxide formulations against Enterococcus
faecalis. J Endod 2005;31:53-6.
26. Mo
¨ller AJR. Microbiological examination of root canal and
periapical tissues of human teeth. Odontol Tidskr 1966;
74(Suppl):1-380.
27. Fouad AF, Zerella J, Barry J, Sp
!
angberg LS. Molecular detection
of Enterococcus species in root canals of therapy-resistant
endodontic infections. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2005;99:112-8.
28. Carlsson J, Sundqvist G. Evaluation of methods of transport and
cultivation of bacterial specimens from infected dental root
canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1980;
49:451-4.
29. Haapasalo HK, Siren EK, Waltimo MT, Ørstavik D, Haapasalo
MPP. Inactivation of local root canal medicaments by dentin:
an in vitro study. Int Endod J 2000;33:126-31.
30. Bystro
¨m A, Claesson R, Sundqvist G. The antibacterial effect
of camphorated paramonochlorophenol, camphorated phenol
and CH in the treatment of infected root canals. Endod Dent
Traumatol 1985;1:170-5.
31. Sienko MJ, Plane RA, editors. Chemistry: principals and
properties. New York: McGraw-Hill; 1966.
32. Sukawat C, Srisuwan T. A comparison of the antimicrobial
efficacy of three CH formulations on human dentin infected with
Enterococcus faecalis. J Endod 2002;28:102-4.
33. Podbielski A, Spahr A, Haller B. Additive antimicrobial activity
of CH and CHX on common endodontic bacterial pathogens.
J Endod 2003;29:340-5.
34. Bystro
¨m A, Sundqvist G. Bacteriologic evaluation of the effect
of 0.5 percent sodium hypochlorite in endodontic therapy.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1983;55:
307-12.
35. Cvek M, Nord CE, Hollender L. Antimicrobial effect of root
canal debridement in teeth with immature root. A clinical and
microbiologic study. Odontol Revy 1976;27:1-10.
36. Myers JW, Marshall FJ, Rosen S. The incidence and identity of
microorganisms present in root canals at filling following culture
reversals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
1969;28:889-96.
37. Engstro
¨m B, Lundberg M. The frequency and causes of reversal
from negative to positive bacteriological tests in root canal
therapy. Odontol Tidskr 1966;74:189-95.
38. Peters LB, van Winkelhoff A-J, Buijs JF, Wesselink PR. Effects
of instrumentation, irrigation and dressing with calcium hydrox-
ide on infection in pulpless teeth with periapical bone lesions.
Int Endod J 2002;35:13-21.
39. Evans MD, Baumgartner JC, Khemaleelakul S, Xia T. Efficacy
of CH CHX: paste as an intracanal medication in bovine dentin.
J Endod 2003;29:338-40.
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... Ayrıca Ca(OH) 2 'nin CHX'in çözünürlüğünü ve aktivitesini olumsuz etkilemediğini, bunun yerine yaygın endodontik patojenler üzerinde ilave bir etki sergilediğini bulmuşlardır. Buna karşılık (Zerella et al., 2005) çalışmalarında CHX'in Ca(OH) 2 ile karıştırıldığında çökeldiğini bununla birlikte, daha yüksek CHX konsantrasyonlarında ise aktif CHX kalıntısının mevcut olabileceğini, Ca(OH) 2 'nin alkalinitesi değişmezken etkinliğinin azalacağını göstermişlerdir. Molander et al., (1999) dentin tübüllerine penetre olabilen IKI'nin kök kanallarını Ca(OH) 2 'nin tek başına kullanılmasından daha etkili şekilde dezenfekte ettiğini bildirmiştir. ...
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Inlays and onlays can be preferred for the restoration of teeth with excessive material loss that are not suitable for direct restorations or where direct restorations have failed. It is also a conservative alternative to full veneer crown preparations. Unlike full ceramic veneers and ceramic crowns with metal substructure, they offer the opportunity to change the appearance of the tooth with less material loss. Restorations that do not include the tubercles in the occlusal regions of the teeth are considered inlays, while restorations that include the tubercles are called onlays.
... The use of CHX resulted in a significant reduction in fungal growth, indicating that it was the most effective agent among the experimental and Ca(OH) 2 paste groups The antibiofilm effect with the use of CHX alone or in combination of Ca(OH) 2 was previously reported against C. albicans [20,21,63]. Waltimo et al. demonstrated that a combination of Ca(OH) 2 and CHX acetate was more effective against C. albicans than pure Ca(OH) 2 ; however, this combination was less effective than CHX alone [25]. ...
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Introduction: The purpose of this study was to assess the antifungal activity of silver nanoparticles (AgNPs) in combination with calcium hydroxide (Ca(OH)2) against Candida albicans (C. albicans). Methods: AgNPs was mixed with pure Ca(OH)2 powder in an aqueous base. A standard suspension (1 × 108 bacterial cells/mL) of C. albicans was prepared in a 96-well plate and incubated on shaker at 37 °C in 100% humidity to allow fungal biofilm formation in infected dentin slices (n = 98). The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of AgNPs alone or with Ca(OH)2 were determined. The samples were separately placed in 24-well tissue culture plates and divided into three experimental groups (0.03, 0.04, and 0.06) and three control groups; negative (saline) and positive chlorhexidine gel and Ca(OH)2. Quantitative measurements of fungal activity by XTT colorimetric assay and qualitative measurements using confocal laser microscopy and scanning electron microscopy were performed. Results: The cell viability of C. albicans in the experimental groups was significantly reduced compared to the negative control group. The combination of (AgNPs (0.04%) and Ca(OH)2) was the most potent against C. albicans. Conclusions: The findings demonstrated that combining silver nanoparticles with Ca(OH)2 was more effective against C. albicans biofilm compared to Ca(OH)2 alone, suggesting a combing effect.
... The treatment options for EPD are debatable, with endodontic therapy initiated before periodontal treatments regardless of disease origin [38,39]. The benefits of commencing RCT are that it eliminates infection from the pulp canal space and inhibits microbial irritants from accessing the periodontal region by blocking communication channels between the pulp space and the periodontal tissues [40,41]. There are conflicting data on the optimal time interval between endodontic therapy and periodontal surgery. ...
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The purpose of this review is to determine the effectiveness of intracanal medicament (ICM) on periodontal and periapical healing (PH) of concurrent endodontic-periodontal lesions with/without communication in permanent teeth. The pre-defined protocol was registered in PROSPERO, and a literature search using keywords was conducted on PubMed, Scopus, Cochrane, Embase electronic databases, and Gray literature and was hand-searched until August 2023. Two reviewers independently screened the title and abstracts using the inclusion criteria. Randomized or non-randomized clinical trials, cohort studies, and case-control studies were included in the review. The same reviewers extracted the study-level data and assessed the risk of bias using the Cochrane Risk of Bias 2.0 and the Newcastle-Ottawa Scale (NOS) independently. Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach was used to assess the certainty of evidence. Random effects meta-analysis was performed on eligible studies using Revman software. A total of 598 records were identified from the database search; seven studies met the inclusion criteria and were included in the review. Four randomized clinical trials, two prospective cohorts, and one retrospective case-control study with 362 patients were included. Calcium hydroxide (CH) was the most commonly used ICM, followed by using chlorhexidine gel in four studies. Periodontal therapy was performed as initial scaling and root planning (SRP) in all studies, along with open flap debridement (OFD) in three randomized clinical trials. The time lapse between two treatment protocols was variable (ranging from 1 week to 3 months). All studies exhibited a decrease in probing depth (PD) and an increase in clinical attachment level (CAL) after the treatment. Meta-analysis showed insignificant differences between different ICM materials, and the certainty of evidence was low. In patients with/without concurrent endodontic-periodontal lesions, intracanal medication improved clinical periodontal parameters following endodontic therapy. In terms of influence on periapical healing, the results were inconclusive. Two-visit RCT may be considered since it allows for the placement of an ICM in endodontic-periodontal lesions with/without communication. Sufficient time should be allowed after endodontic therapy for any potential periodontal regeneration to occur.
... In cases where teeth cannot be treated with NERT, or when retreatment seems ineffective, not feasible or contraindicated, O surgical endodontic retreatment is recommended [6]. Several factors during NERT have been investigated in the literature; type of irrigants [8], number of visits [9], intracanal dressings [10], instrumentation techniques [11], endodontic sealers [12], intracanal solvents [13] and other supporting therapies [14,15]. ...
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Introduction: The nonsurgical endodontic retreatment (NERT) is the first choice of dental ministration when primary/initial endodontic treatment fails. The present study aimed to investigate the presence of postoperative pain (POP) after NERT in permanent asymptomatic teeth as well as possible factors associated with POP. Materials and methods: A comprehensive search of literature was performed in Pubmed/MEDLINE, Embase, Scopus and Web of Science databases, up to January 2023; including randomized clinical trials and prospective studies. The risk of bias was assessed with RoB 2.0 and ROBINS-I tools. Subgroups analyses were conducted to evaluate the differences in the incidence or level of POP between the number of visits, the use/not use of solvent, the removal technique of gutta-percha, and the period of POP analysis. Mean differences and confidence intervals (CI) of 95% were used as measures of effect, and meta-regression was used along with subgroup analysis. The certainty of evidence was assessed using GRADE, and the probability value of <0.05 was considered significant. Results: Twenty-four studies were selected, with thirteen included in the meta-analysis. There was a statistical difference between the incidence of POP after 24 h (95% CI, 0.28 to 0.52) and one week (95% CI, 0.02 to 0.13) from the endodontic retreatment (P<0.01). However, there was no statistical difference between different techniques, number of visits and use of solvent (P>0.05) in the same period. In addition, the certainty of evidence was very low. Conclusions: Post-operative pain is a common response to NERT, independent of the retreatment technique(s) applied, number of visits and use of solvent(s); with very low certainty of evidence as well as low risk of bias. Moreover, the current analysis showed a (very) serious risk of inconsistency and imprecision. However, POP was significantly reduced within 1 week of the NERT.
... In culture studies evaluating the ability of chemomechanical preparation with NaOCl irrigation to reduce intracanal bacteria in endodontic retreatment, negative cultures were found in 70% and 77% of cases. 35,62 Rôças and Siqueira, 41 who used a sophisticated molecular approach based on reverse transcriptase-polymerase chain reaction (RT-PCR) to detect bacterial ribosomal RNA as an indicator of viability, found negative PCR results for bacterial presence in 71% of the samples taken after chemomechanical preparation with 2.5% NaOCl of canals undergoing retreatment. These figures are very similar to the rates observed after initial treatment. ...
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Evaluation and comparison of natural products like triphala, eucalyptus and carvacol with conventional root canal irrigant such as sodium hypochlorite (NaOCL) and Chlorhexidine against persistent root canal pathogens like E. faecalis is of interest. Samples were taken both before irrigation as well as after irrigation. CFU was counted after the plates had been incubated overnight at temperature of 37°C overnight. The herbal products showed antibacterial effectiveness against persistent root canal pathogens like E. faecalis. The antibacterial effectiveness was high in NaOCL, chlorhexidine and eucalyptus extract.
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Introduction This clinical study evaluated the antibacterial effects of calcium hydroxide associated with different vehicles during the treatment of infected teeth with apical periodontitis. Methods Bacteriologic samples were taken from 90 necrotic root canals of teeth with apical periodontitis before (S1) and after preparation with a rotary nickel-titanium instrument system and 2.5% sodium hypochlorite irrigation (S2). The teeth were distributed in 3 groups according to the intracanal medication used, which consisted of a calcium hydroxide paste in glycerin (CHG), camphorated paramonochlorophenol/glycerin (CHPG), or 2% chlorhexidine (CHCHX) for 1 week, and then another sample was taken (S3). The frequency of bacteria-positive cases and the reduction of bacterial counts were evaluated by quantitative real-time polymerase chain reaction (qPCR). Results Substantial intracanal bacterial reduction was observed after preparation in the 3 groups (p<0.001). After CHG medication, the number of bacteria-positive cases decreased from 20/29 (69%) to 17/29 (59%); however, the mean bacterial counts increased 8.4% from S2 to S3. Medication with CHPG reduced the number of bacteria-positive cases from 17/29 (59%) to 15/29 (52%), with a significant mean S2-to-S3 reduction of 71% (p<0.05). In the CHCHX group, the number of bacteria-positive cases decreased from 21/30 (70%) to 17/30 (57%) after medication, with a mean S2-to-S3 reduction of 55%, which however was not statistically significant (p>0.05). Intergroup comparisons showed no significant differences (p>0.05). Conclusion Comparison between the 3 calcium hydroxide pastes showed no significant differences in antibacterial effectiveness in the main root canal. However, only the CHPG paste showed a significant reduction in bacterial counts when postpreparation and postmedication samples were compared.
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Full-text available
Objective: The present study was conducted to evaluate the presence of aerobic bacteria, anaerobic bacteria, E. faecalis, F. nucleatum, Propionibacteria sp., Actinomyces sp., and their reduction at various stages of endodontic retreatment with the use of conventional protocol (5.25 % Sodium Hypochlorite (NaOCl) as the irrigant along with Calcium Hydroxide (Ca (OH)2) as intracanal medicament and advocated protocol (SmearOFF as the irrigant along with 2% Chlorhexidine (CHX) gel as intracanal medicament). Methods: Twenty eight patients fulfilling the eligibility criteria were selected for root canal retreatment and randomly allocated into two groups. Group 1: Final irrigant as SmearOFF+Chlorhexidine 2% gelas intracanal medicament (n=14). Group 2: Final irrigant as 5.25% NaOCl+Ca(OH)2 as intracanal medicament (n=14). With aseptic environment, access opening was performed followed by Gutta Percha (GP) removal and sample S1 was collected for bacterial analysis. The biomechanical preparation was done by using Reciproc system with additional finishing with XP-Endo Finisher R. Sample S2 was then collected for bacterial analysis after the final irrigation protocol in the respective groups. Intracanal medicaments were placed for one week and sample S3 was collected. All the samples were subjected to qualitative analysis using PCR and quantification was done by Colony Forming Unit (CFU) analysis. Results: Aerobic [28/28], Anaerobic [28/28], Propionibacterium sp. [20/28] and F. nucleatum [24/28] were the most frequently isolated in S1 sample followed by Actinomyces sp. [16/28] and E. faecalis sp. [19/28]. Chemico-mechanical preparation followed by irrigation (S2 sample) resulted in significant reduction of all types of bacteria in both groups. Group-1 (SmearOFF as the final irrigant) had significantly superior efficacy against aerobic bacteria, E. faecalis and F. nucleatum (P<0.05) as compared to Group-2 (NaOCl). After medicament placement, significant differences between the groups were noted only for the E. Faecalis group. For the S3 samples, the mean bacterial reduction was significant in Aerobic and F. nucleatum in S3 samples for Group 1 and Group 2. Conclusion: Chemico-mechanical preparation followed by irrigation resulted in significant reduction in bacterial load irrespective of the final irrigant. SmearOFF was significantly better than NaOCl in minimizing bacterial load of E. faecalis and F. nucleatum. 2% Chlorhexidine gel has superior antimicrobial efficacy against E. faecalis and may be recommended in secondary endodontic treatment.
Book
Microorganisms play a significant role in the development and progression of pulp and periapical diseases. The primary objective of endodontic therapy is to eradicate root canal infection and create an environment in which any residual microorganisms cannot survive. This can be achieved by employing a combination of aseptic treatment techniques, chemomechanical preparation of the root canal, antimicrobial irrigating solutions and intracanal medicaments. Intracanal medicaments would include any agent with intended pharmacological action introduced in the root canal. While irrigating solutions also demonstrate antibacterial action, intracanal medications more concisely describe medicaments left in the root canal to exert their effects over a longer time period. The popular agents include calcium hydroxide, antibiotics, non-phenolic biocides, phenolic biocides and iodine compounds. Their choice depends upon the pulpal and periapical status of the case being treated.
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Abstract The bactericidal efficacy of calcium hydroxide, camphorated phenol and camphorated paramonochlorophenol as intracanal dressings was evaluated clinically when the root canals of 65 single-rooted teeth with periapical lesions were treated. A bacteriological technique that could detect even small numbers of anaerobic bacteria in the canals was used. After treatment, including intracanal dressing with calcium hydroxide paste (Calasept), bacteria were recovered from one of 35 treated root canals. After use of camphorated phenol or camphorated paramonochlorophenol as the dressing, bacteria were recovered from 10 of 30 treated root canals. The isolated bacteria were predominantly Gram-positive and anaerobic. There was no indication that specific bacteria were resistant to the treatment. The results indicate that the endodontic treatment of infected root canals can be completed in two appointments when calcium hydroxide paste is used as an intracanal dressing.
Article
Abstract – The present study deals with the ability of 11 bacterial strains, in various combinations, to induce periapical reactions. The indigenous oral bacteria were originally isolated from an experimental apical periodontitis in monkey. Eight of the strains were a complete collection isolated from one root canal. These strains were inoculated together, in equal proportions, into 12 root canals. In addition, 63 canals were inoculated with other combinations or separate strains. At the end of the experimental period it was found that in the mixed infections the Bacteroides oralis strain predominated in most root canals. In contrast, this Bacteroides strain was not reisolated in any of nine root canals when inoculated in a pure culmfe. Enterococci, however, survived as pure cultures in all canals. The mixed infections showed the greatest capacity ofindticing apical periodontitis, as revealed by radiography, and most pronounced was the “eight-strain collection”. The facultatively anaerobic streptococci induced only weak periapical reactions.
Article
Abstract Using a careful anaerobic bacteriological technique, bacteria were shown to be eliminated from infected root canals before the endodontic treatment was finished by root filling. Healing of the periapical lesions of the teeth was followed for 2–5 yr. The majority of the 79 lesions healed completely or decreased in size in such a way that they could be expected to heal. In 5 cases there was no or only an insignificant decrease in the size of the lesions. Two of these lesions were shown to contain bacteria of the species Actinomyces or Arachnid. In another case there were dentin chips in the periapical tissue. Periapical lesions which fail to heal in spite of careful bacteriological monitoring of the endodontic treatment may in some cases be due to an establishment of the bacteria outside the root canal in the periapical tissue. In these sites, the bacteria are inaccessible to conventional endodontic treatment.
Article
The effects of pH and indirect ultrasonication on the cidal activity of aqueous and alcoholic solutions of chlorhexidine gluconate against Bacillus subtilis spores were examined. At moderately elevated temperatures, increasing pH enhanced sporicidal activity. pH markedly enhanced the sporicidal activity between indirect ultrasound and chlorhexidine. ‘Alcoholic’ chlorhexidine gluconate was more sporicidal than its aqueous counterpart.
Article
Extra t.p. with thesis statement inserted. Thesis (doctoral)--University of Göteborg, 1982. Includes bibliographical references.
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The aim of present investigation was to compare the antibacterial effect of biochemical root canal cleansing in permanent non-vital upper incisors with immature with those with mature root. The material comprised three groups made up of 34, 46 and 28 teeth in which the mechanical cleansing was accompanied by flushing with sterile saline and sodium hypochlorite solutions giving 0.5 or 5.0% active chloride, respectively. Samples were taken in root canals initially after removal of necrotic tissue and after completed cleansing, transferred to solid and liquid media for aerobically and anaerobically and incubated until growth appeared or up to 10 days. The microorganisms were identified by biochemical tests and gas-chromatographic analysis. The antibacterial effect of mechanical cleansing with sterile saline was very low (9%) and limited to the teeth with mature root. The flushing with sodium hypochlorite increased the antibacterial effect to about 25%. No statistical difference was found in the antibacterial effect between flushing with 0.5 % or 5.0% sodium hypochlorite solutions. The antibacterial effect was, however, irrespective of the sodium hypochlorite concentrations, less good in teeth with immature root at the statistically significant 5% level. It was concluded that mechanical cleansing of root canals in teeth with immature root with the instruments now available is inadequate. This inadequacy cannot be compensated for by use of highly concentrated solution, with dissolving effect on necrotic tissue, for flushing. The use of such substances which also have toxic effect on the tissue should be avoided.
Article
Light and electron microscopy were used to analyze nine therapy-resistant and asymptomatic human periapical lesions, which were removed as block biopsies during surgical treatment of the affected teeth. The cases that required surgery represented about 10% of all of the cases which received endodontic treatment and root fillings during the period 1977 to 1984. These cases revealed periapical lesions when they were examined 4 to 10 yr after treatment. The biopsies were processed for correlated light and electron microscopy. Six of the nine biopsies revealed the presence of microorganisms in the apical root canal. Four contained one or more species of bacteria and two revealed yeasts. Of the four cases in which bacteria were found, only in one biopsy could they be found by light microscope. In the other three specimens, the bacterial presence could be confirmed only after repeated electron microscopic examination of the apical root canal by serial step-cutting technique. Among the three cases in which no microorganisms could be encountered, one showed histopathological features of a foreign body giant cell granuloma. These findings suggest that in the majority of root-filled human teeth with therapy-resistant periapical lesions, microorganisms may persist and may play a significant role in endodontic treatment failures. In certain instances such lesions may also be sustained by foreign body giant cell type of tissue responses at the periapex of root-filled teeth.