Re-treatment of a mandibular first molar with five canals case report

Re-treatment of a mandibular first molar with five canals
── case report
SHU-FANG CHANG
Department of Dentistry, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan, ROC.
This case demonstrates a 5-canal mandibular first molar involving a middle mesial canal treated by
non-surgical root canal therapy. Acute exacerbation was noted on a previously root-filled left mandibular
first molar with periapical lesions, and endodontic re-treatment was arranged. Initially, 4 canals (the
mesiobuccal, mesiolingual, distobuccal, and distolingual) were identified. The mesiobuccal and
mesiolingual canals were found in their normal locations, and a fifth canal was noted between these two.
Clinicians need to be aware of the unusual root canal anatomy of the mandibular first molar. After
thorough root canal cleaning and shaping, root canal obturation with gutta-percha and Roth 801 sealer
by a lateral compaction technique was performed. A 12-month recall radiograph showed complete
healing. （J Dent Sci, 1(2)：74-78, 2006）
Key words: mandibular first molar, endodontic re-treatment, root canal anatomy.
To achieve success with an endodontic
procedure, the entire root canal system must be
thoroughly debrided, disinfected, and hermetically
obturated. Many studies have been published which
explore the reasons for endodontic failure1-3. The
mnemonic device, POOR PAST4, representing
perforation, obturation, overfilling, a missed root
canal, periodontal disease, another tooth, splitting,
and trauma, can be used in the differential diagnosis
of endodontic failures. If a case fails, endodontic
re-treatment, endodontic surgery, and extraction are
the alternative treatment plans.
Since the mandibular first molar is the most
frequently endodontically treated tooth, it is
important to recognize the root canal anatomy in
order to improve treatment outcomes. In 1971,
Skidmore and Bjorndal5 made plastic casts to
duplicate the root canals of extracted human
mandibular first molars. They found that the
incidence of 3 root canals was 64.4%, while 28.9%
Received: February 18, 2006
Accepted: April, 12, 2006
Reprint requests to: Dr. Shu-Fang Chang, Department of Dentistry, Shin
Kong Wu Ho-Su Memorial Hospital, No. 95, WenChang Road, Shihlin, Taipei, Taiwan 11120, ROC.
74
had 4 root canals in their case study. Barker et al.6
utilized a radiopaque elastomer injection technique
and translucent replicas to observe the anatomy of
permanent mandibular molars. They concluded that
the root canal anatomy in posterior teeth must not be
oversimplified. In the study, an uncommon specimen
of a mesial root with 3 discrete canals was noted. In a
series of studies on extracted teeth in which Vertucci7
observed 100 mandibular molars in vitro, he found
that 1% of the cases had a middle mesial canal in the
mandibular first molar. In 1981, Pomeranz et al.8
treated 100 mandibular first and second molars in
vivo. Of these cases, 12 separate middle mesial
canals were identified and treated. In the group of
mandibular first molars, the incidence of a middle
mesial canal was as high as 11.4% (7 of 61). Since
then, many clinical surveys and case reports have
pointed out the complicated root canal anatomy of
mandibular first molars9-14. As we have discussed,
several previous studies reported having found 5
canals in a mandibular first molar during a patient’s
initial endodontic treatment, but very few have
mentioned re-treated cases. The purpose of this
article is to report the successful root canal
re-treatment of mandibular first molar with 3 mesial
and 2 distal canals.
J Dent Sci 2006‧Vol 1‧No 2
Re-treatment of 5-canal lower molar
CASE PRESENTATION
A 36-year-old female with a noncontributory
medical history was referred to the Endodontic
Department for endodontic treatment on the left
mandibular first molar by her periodontal dentist.
The chief complaint of the patient was “biting
pain in the lower left back tooth.” A clinical
examination revealed amalgam restoration in the left
mandibular first molar (tooth 36). Tooth 38 had
drifted mesially. Tooth 36 had a sensitive response
when tested by percussion. The probing depths of
tooth 36 were less than 3 mm. Radiographic
examination revealed a previous root canal filling of
tooth 36 and periradicular radiolucencies in relation
to the mesial and distal roots (Figure 1). A pulpal
diagnosis was previous root canal therapy, and acute
exacerbation of chronic periradicular periodontitis
was also diagnosed. The definitive treatment plan of
tooth 36 was non-surgical root canal therapy.
Tooth 36 was opened under rubber dam isolation.
After removal of the old filling material in the pulp
chamber, the mesiobuccal, mesiolingual, distobuccal,
and distolingual canals were identified. Gates
Glidden drills #4, #3, and #2 were used in a crowndown fashion with a brushing motion to obtain
straight-line access to all 4 canals. Sodium
hypochlorite (2.5%) and RC-Prep (Stone Pharmaceuticals, Philadelphia, PA, USA) were used as
irrigants. Instrumentation and calcium hydroxide
(Pierre Rolland, Amiens, France) placement were
performed. The tooth was sealed with temporary
material and a temporary crown was cemented with
Temp-bond (Kerr, Romulus, USA).
Figure 1. Mandibular first molar with periradicular lesions.
J Dent Sci 2006‧Vol 1‧No 2
Figure 2. Access revealing an additional canal found halfway
between the 2 mesial canals.
One week later, the patient received the second
treatment. After removal of the temporary restoration,
the mesial and distal canals were reexamined. It was
determined that there was a possible extra canal in
the mesial root (Figure 2). An operating microscope
(Carl Zeiss, S5/PRO magis, Oberkochen, Germany)
was used for orifice negotiation. Small, slightly
pre-curved K-flexo files were used to establish a
glide path to the working length. Then, the working
distance was determined by an apex locator (Root ZX,
J. Morita, Kyoto, Japan) and radiographic checking.
All of the canals were cleaned and shaped with hand
K files. Calcium hydroxide was used as an intra-canal
medicament, and the access cavity was sealed with
Caviton (GC Corporation, Tokyo, Japan) and IRM
(Dentsply International INC, Milford, USA) between
appointments.
Two weeks later, the patient returned for
completion of endodontic therapy. The symptoms had
ceased. The canals were irrigated with 2.5% sodium
hypochlorite and RC PrepTM, followed by 17%
ethylenediaminetetraacetic acid (EDTA), which was
left in place for 1 minute to remove the smear layer.
A gutta-percha cone-fit radiograph was made for
further confirmation of the middle mesial canal
(Figure 3). EDTA (17%) was used for the final
flushing. These canals were obturated (Figures 4, 5)
with gutta-percha and Roth 801 sealer (Roth
International LTD, Chicago, USA) by a lateral
compaction technique, and the access was sealed with
Caviton and Glass ionomer cement (GC Corporation).
75
S.F. Chang
Figure 3. Gutta-percha cone-fit radiograph confirming the middle
mesial canal and distal lingual canal.
Figure 6. Twelve-month recall showing complete healing.
Then, the temporary crown was cemented with
Temp-bond. The patient was clinically followed-up to
monitor the periradicular responses.
At the 6-month recall, the patient was asymptomatic. A 12-month recall radiograph showed
complete healing (Figure 6).
DISCUSSION
Figure 4. Obturated tooth with laterally condensed gutta-percha,
Roth 801 sealer, and temporary restoration.
Figure 5. Obturated tooth with laterally condensed gutta-percha,
Roth 801 sealer, and temporary restoration (at a greater distal
angulation).
76
Successful and predictable endodontic treatment
requires knowledge of biology, physiology, and root
canal anatomy. In 2002, Hoen and Pink15 screened
1100 failing endodontically treated teeth. In the study,
the maxillary first molar was the tooth most often
re-treated, followed by the mandibular first molar.
They found the incidence of missed roots or canals of
the retreated teeth to be 42% in their investigation.
Such a high incidence is rather surprising. This
finding reveals that clinicians must have a thorough
knowledge of root canal anatomy and pay more
attention to treatment procedures to minimize the
chance of failure and re-treatment.
Seeing is believing. With the advantages of
illumination and magnification16, the use of microscope enables dentists to locate and treat ‘extra
canals’ more confidently. Coelho de Carvalho and
Zuolo17 examined 204 extracted mandibular molars.
They found that the use of a microscope in access
preparation resulted in a 7.8% increase in the total
number of root canal orifices located. Another study
by Yoshioka et al.18 compared detection rates of root
canal orifices by 3 different methods: with the naked
eye, with surgical loupes, and under a microscope.
They concluded that the microscopic method
J Dent Sci 2006‧Vol 1‧No 2
Re-treatment of 5-canal lower molar
more-accurately detected orifices than could the
others.
The root canal anatomy of the mandibular first
molar can be aberrant. Clinicians must be aware of
the finding that the presence of a third canal in the
mesial root of the mandibular first molars has been
reported to have an incidence rate of 1%~15%14. In
the study of Pomeranz et al.8, the additional canal
may be classified as (1) an independent canal, which
originates in a separate orifice and terminates as
a separate foramen, (2) a confluent canal, that
originates as a separate orifice but is apically joined
to the mesiobuccal or mesiolingual canal, and (3) a
fin, when the instrument can pass freely between the
mesiobuccal or mesiolingual canals and the middle
mesial canal during cleaning and shaping. If one
wants to treat a mandibular molar tooth with 5 canals,
it is necessary to check their clinical and radiographic anatomy. One should perform a thorough
examination of the pulp chamber to ensure a
more-accurate orifice location, and then completely
debride all canals. This increases the chance of
finding an extra canal and the long-term success rate
of endodontic therapy.
In this case, we found that the middle mesial
canal originated as a separate orifice but joined the
apical 1/3 of the mesiolingual canal. According to
Pomeranz et al.’s classification8, the middle mesial
canal is classified as confluent. One of the goals of
endodontic therapy is to reduce or eliminate bacteria
and their by-products from the root canal system.
Proper cleaning, shaping, and irrigation will
significantly reduce and sometimes eliminate bacteria
from canals. The use of intra-canal medications to
disinfect the root canal system has been well
discussed. Calcium hydroxide is the first choice for
intra-canal medication. It has been demonstrated to
improve dissolution of the pulp tissue by sodium
hypochlorite (NaOCl) and provide antimicrobial
activity19,20. Baumgartner and Mader21 stated that the
combination of NaOCI and EDTA, used alternately,
completely removed the smear layer from the
instrumented root canal surfaces as well as the pulpal
remnants and predentin from the un-instrumented
surfaces. We used 17% EDTA to remove the smear
layer, and it helped produce a successful treatment
outcome.
In root canal therapy, it is a challenge to treat
teeth with extra roots and/or canals. Re-treatment
reduces the prognosis. Therefore, clinicians should
J Dent Sci 2006‧Vol 1‧No 2
pay more attention during initial root canal treatment
to obtain maximal treatment benefits.
REFERENCES
1. Seltzers S, Bender IB, Freedman I, Nazimov H. Endodontic
failures: an analysis based on clinical, roentgenographic, and
histologic findings. II. Oral Surg Oral Med Oral Pathol, 23:
517-530, 1967.
2. Swartz DB, Skidmore AE, Griffin JA Jr. Twenty years of
endodontic success and failure. J Endod, 9: 198-202, 1983.
3. Vire DE. Failure of endodontically treated teeth: classification
and evaluation. J Endod, 17: 338-342, 1991.
4. Crump MC. Differential diagnosis in endodontic failure.
Dent Clin North Am, 23: 617-635, 1979.
5. Skidmore AE, Bjorndal AM. Root canal morphology of the
human mandibular first molar. Oral Surg, 32: 778-784, 1971.
6. Barker BCE, Parsons KC, Mills PR, Williams GL. Anatomy
of root canals. III. Permanent mandibular molars. Aust Dent J,
19: 408-413, 1974.
7. Vertucci F. Root canal anatomy of the human permanent teeth.
Oral Surg, 58: 589-599, 1984.
8. Pomeranz H, Eidelman D, Goldberg M. Treatment considerations of the middle mesial canal of mandibular first and
second molars. J Endod, 7: 565-568, 1981.
9. Fabra-Campos H. Unusual root anatomy of mandibular first
molars. J Endod, 11: 568-572, 1985.
10. Ricucci D. Three independent canals in the mesial root of a
mandibular first molar. Endod Dent Traumatol, 13: 47-49,
1997.
11. Bond JL, Hartwell GR, Donnelly JC, Portell FR. Clinical
management of middle mesial root canals in mandibular
molars. J Endod, 14: 312-314, 1988.
12. DeGrood ME, Cunningham CJ. Mandibular molar with 5
canals: report of a case. J Endod, 23: 60-62, 1997.
13. Holtzmann L. Root canal treatment of a mandibular first
molar with three mesial root canals. Int Endod J, 30: 422-423,
1997.
14. Baugh D, Wallace J. Middle mesial canal of the mandibular
first molar: A case report and literature review. J Endod, 30:
185-186, 2004.
15. Hoen MM, Pink FE. Contemporary endodontic retreatments:
an analysis based on clinical treatment findings. J Endod, 28:
834-836, 2002.
16. Carr GB. Microscopes in endodontics. J Calif Dent Assoc, 20:
55-61, 1992.
17. Coelho de Carvalho MC, Zuolo ML. Orifice locating with a
microscope. J Endod, 26: 532-534, 2000.
18. Yoshioka T, Kobayashi C, Suda H. Detection rate of root
canal orifices with a microscope. J Endod, 28: 452-453,
2002.
19. 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 Traumato, 1: 170-175, 1985.
20. Hasselgren G, Olsson B, Cvek M. Effects of calcium
77
S.F. Chang
hydroxide and sodium hypochlorite on the dissolution of
necrotic porcine muscle tissue. J Endod, 14: 125-127, 1988.
21. Baumgartner JC, Mader CL. A scanning electron microscopic
78
evaluation of four root canal irrigation regimens. J Endod, 13:
147-157, 1987.
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