A Central Incisor With 4 Independent Root Canals
A Central Incisor With 4 Independent Root Canals
A Central Incisor With 4 Independent Root Canals
Complete debridement of the root canal system is 1 of the most important factors affecting the
success of root canal treatment(1). It is essential to have a good knowledge of the root canal
anatomy of the specific tooth to be treated and to be aware of possible variations and treatment
options (2). Different studies have investigated the root canal anatomy among different types of
teeth and reached the conclusion that the maxillary central incisor is the tooth with the least
anatomic variations, showing a single root canal in 100% of the cases (3–5). Case reports
describing 2- and 3-canal central maxillary incisors have been previously published (6, 7).
Mangani and Ruddle (8) reported the case of a 4-canal maxillary central incisor. This case
described dens invaginatus type II (Oehlers). Developmental abnormalities, such as invagination,
fusion, or germination, have been relatively frequently described in anterior teeth (9). When this
occurs, the canal anatomy might be altered, and various combinations of canal number and
configuration may consequently be encountered. Cone-beam computed tomographic (CBCT)
imaging was recently suggested as a diagnostic aid in the identification of potential accessory
canals in teeth with suspected complex morphology (10); however, it remains unclear whether
the use of CBCT imaging would improve the outcome of root canal treatment. Furthermore, the
additional radiation and costs are not always justified (11). The present report describes a root
canal treatment conducted in an upper maxillary central incisor presenting 4 canals and no
developmental abnormalities. The identification, preparation, and obturation of the canals are
described in details.
Case Report
(Fig. 2). A glide path up to a size 20 was achieved in all 4 canals with stainless steel hand files
(K-Flexofile; Dentsply, Ballaigues, Switzerland), and the preparation was completed using
Profile rotary files (Dentsply) up to a size 30, 0.04 taper. The canals were irrigated with 1 mL
2% NaOCl at each change of file. Ultrasonic activation was performed by a stainless steel size
25, .00 taper file (IrriSafe; Acteon, Merignac, France) placed 2 mm short of the working length
and driven by an ultrasonic device (P5 Booster; Satelec Acteon, Merignac, France) for 20
seconds at power setting 5. Activation was repeated 3 times with delivery of 1 mL 2% NaOCl
between each activation phase. Thereafter, 17% EDTA was delivered and left in the canals for 1
minute. All irrigants were delivered with a 30-G open-ended needle (Navitip; Ultradent, South
Jordan, UT) placed slightly short of the binding point. The canals were then dried with sterile
paper points and immediately filled with gutta-percha (Autofit; Analytic, Glendora, CA) and AH
Plus sealer (Dentsply) by using the continuous wave of condensation technique with the tip of
the heat carrier reaching 4 mm from the working length and a backfill with a warm gutta-percha
gun (Obtura II; Obtura Spartan, Fenton, MO) for the middle and coronal thirds. The access
cavity was then restored during the same visit with composite (Venus; Heraeus Kulzer GmbH,
Hanau, Germany) placed with an incremental technique, and dental occlusion was checked. The
patient returned for follow-up at 6, 12, and 24 months and was completely symptom free. The
clinical examination revealed that the tooth was neither percussion nor palpation sensitive. The
mobility and probing depths were within normal range. Radiographic control a continuous
periodontal ligament space with no signs of apical periodontitis (Fig. 2).
Discussion
The prevention and treatment of apical periodontitis are the main objectives of
endodontic therapy (12). Adequate instrumentation, disinfection, and obturation of the root canal
system together with the placement of a sealing coronal restoration are the main steps toward
achieving this goal(13)and require a good understanding of root canal anatomy. Mangani and
Ruddle (8) already reported a case of dens invaginatus presenting 4 canals in an upper central
incisor. This invagination can occur at the crown of the tooth and sometimes might extend within
the root, creating complex canal systems(9). To our knowledge, no reports of a 4-canal maxillary
central incisor presenting no developmental abnormalities have been previously published.
The patient was referred to our clinic because of the persistence of symptoms after the
initial therapy. During the first treatment, only a single canal was located and cleaned.
Incomplete debridement of all the canals was the most likely cause for the perpetuation of the
symptoms despite the therapy. Once all the canals were located and could be negotiated and
cleaned, the symptoms disappeared, and a follow-up xray showed the healing of the periapical
alveolar bone. This highlights the importance of a good understanding of the canal anatomic
complexities to be able to effectively disinfect the root canal system. In the preoperative
radiograph, an abrupt narrowing of the canal at the midlevel of the root indicated the possibility
of a split of the main canal (14).
This split was confirmed with the help of the DOM. The DOM is an important tool in the
armamentarium of modern endodontic therapy. It has been shown that its use could help in
locating additional canals during endodontic treatment (15, 16), improving treatment accuracy,
and expediting treatment (17). Potential drawbacks of the use of the DOM are the required
learning curve and high investment costs. The use of the DOM has been shown to improve the
ability of the practitioner to locate canals (18) although it remains unclear whether its use would
improve the outcome of endodontic therapy (19).
CBCT imaging is a modern diagnostic tool that can provide additional 3-dimensional
information to the practitioner for diagnostic purposes(20). For the present treatment, no CBCT
imaging was performed because no developmental abnormality could be detected by clinical and
radiographic inspection. A recent position statement published by the European Society for
Endodontology recommends the use of CBCT imaging for the diagnosis and treatment of teeth in
which development abnormalities are present (21). A recent joint position statement of the
American Association of Endodontists and the American Academy of Oral and Maxillofacial
Radiology on the use of CBCT imaging states that limited field of view CBCT scanning should
be considered the imaging modality of choice for the initial treatment of teeth with the potential
for extra canals and suspected complex morphology (22).
It is unclear whether CBCT imaging is superior to digital periapical radiographs for the
detection of additional canals (15, 23). The ALARA (as low as reasonably achievable) principle
states that every effort should be made to keep the patient’s exposure to ionizing radiation as low
as practically possible (24). In the present case, 4 independent canals could be located and
successfully treated with the help of the DOM but without a CBCT scan. The visualization of the
pulp chamber floor patterns with the DOM allows the clinician to trace the root canals in order to
eventually access them. However, it does not allow visualization of deep dilacerations or apical
bifurcations. Although CBCT imaging could show the root canal system 3-dimensionally (21), it
will not necessarily allow access to deep anatomic aberrations without the risk of damaging the
root. Future studies should further investigate and compare the ability of CBCT imaging and the
DOM in locating root canals against a gold standard, such as histologic sectioning, as well as the
ability of both technologies to improve the clinical outcome.
Conclusion
The present report is the first to describe a maxillary central incisor with 4 canals in a
tooth with no developmental abnormalities. It stresses the importance of using the DOM during
endodontic treatment as well as the necessity of being attentive for morphologic variations that
have not been previously reported in the literature. Successful treatment was performed without
the use of a CBCT scan, questioning the routine use of CBCT imaging for similar cases.