Variation in Location of
the Distobuccal Root Canal in a permanent Maxillary Second Molar: A Case
Report and Literature Review
ABSTRACT
This case report describes the unusual location of the distobuccal root
canal in a maxillary second molar with root fusion. On access opening,
three distinct root canal orifices, the mesiobuccal canal, palatal
canal, and a third orifice closer to the palatal canal, were seen,
giving an illusion of an additional palatal canal. An attempt was made
to search for the distobuccal canal in its usual position, leading to
the gouging of the pulp chamber floor. An intra-operative limited field
of view cone-beam computed tomography (CBCT) revealed the root orifice
adjacent to the palatal canal was the distobuccal canal. CBCT also
revealed fusion of both the buccal and palatal roots in the root’s
coronal and middle third region, but they were not fused apically.
Keywords: cone-beam computed tomography, distobuccal, fused
roots, maxillary second molar, variation.
INTRODUCTION
The root canal system is highly complex and variable.1Numerous case reports and earlier studies have reported variations in
maxillary molars.2-4 Variations have been mostly
reported in the form of extra canals being present. However, Zhanget al., in an in-vitro study, found maxillary second molars to
have more variations than the first molars.5 Most of
the earlier studies have focused on the Mesiobuccal (MB) root of the
maxillary first molar, as it frequently has two root canals with
variations in the root canal pattern.6,7
The case reports published in the literature pertaining to the
variations in maxillary second molar are most frequently in relation to
the alterations in the number of roots or root canals. Kottor et
al. reported a case of a maxillary second molar with five roots and
five separate canals in each of these roots.8 In
contrast, Ahuja et al. reported a case of a maxillary second
molar with a single root and single canal.9Regarding the distobuccal (DB)
root canal, variations have been reported in the form of one additional
canal (DB2) being present or fused with the MB canal. Fusion can also
occur between one or both the buccal roots with the palatal (P)
root.10-14 Fusion of the roots is more common in
maxillary second molars, which
could result in complete or partial fusion of the root
canals.15,16
For successful endodontic treatment, clinicians should be aware of
the variations in the number of roots and root canals and the peculiar
or eccentric location of root canals as described in this case report.
This case report highlights the anatomic variation of the distobuccal
root canal in a maxillary second molar and its management with the aid
of an intra-operative limited field of view (FOV) Cone-beam computed
tomography (CBCT), along with a literature review of variations reported
in distobuccal roots and root canals in human maxillary second molar.
The case presentation is based on the Preferred Reporting Items for Case
reports in Endodontics (PRICE) 2020 guidelines.17
CASE PRESENTATION
A 34-year-old male patient reported to the department with a chief
complaint of pain in his upper left back tooth for the past ten days.
History revealed an intermittent, localized throbbing type of pain,
occurring during the night and aggravated during mastication. The
patient’s medical history was non-contributory. Clinical intra-oral
examination revealed deep occlusal caries in the maxillary left second
molar (27) with tenderness to percussion. The tooth had an old amalgam
restoration on the occlusal surface. The tooth mobility was within
physiological limits, and the gingival attachment apparatus was normal.
Thermal and electric pulp testing (Parkel Electronics Division,
Farmingdale, New York, USA) elicited a negative response. The
preoperative intraoral periapical radiograph (IOPA) revealed occlusal
radiolucency involving pulp space with no periapical radiolucency
(Figure 1A, 1B). Extra orally, no swelling was noticed. From the
clinical and radiographic findings, a diagnosis of pulpal necrosis with
symptomatic apical periodontitis was made, and endodontic treatment was
initiated after obtaining consent from the patient.
The tooth was anesthetized by using 1.8 ml (30 mg) of 2% lidocaine
containing 1:200,000 epinephrine (AstraZeneca Pharma India Ltd.,
Bengaluru, India). Isolation was done using a rubber dam (Coltene
Whaledent, Inc., Ohio, USA), and access opening was initiated using an
endo access bur (#1) in high speed (Dentsply Sirona, Tulsa, USA) under
a dental operating microscope (Prisma DNT Microscope, Labo America,
Inc., California, USA). The pulp chamber floor examination with a DG-16
endodontic explorer (Hu-Friedy, Chicago, USA) revealed three distinct
root canal orifices, the MB canal, and P canal, and another orifice in
close approximation to the P canal, giving an illusion of an additional
P canal (Figure 1C). An attempt was made to search for the DB canal in
its usual position, but without success, this led to the gouging of the
floor in that area (Figure 1C). As the DB canal was not identified in
its usual location and a canal orifice was seen unusually placed between
the buccal and P canal, an intra-operative limited FOV-CBCT was taken
after obtaining consent from the patient. CBCT images of the maxillary
second molar revealed fusion of both the buccal and palatal roots in the
coronal and middle third region of the root, but apically they were
separate. CBCT images confirmed the canal adjacent to the P orifice to
be the DB canal. Even though the roots were fused partially, the canals
remained separate (Figure 2A to 2F). The coronal section of the tooth in
the CBCT scan also revealed early periapical radiolucency in the palatal
root, which was not evident in the two-dimensional IOPA (Figure 2D).
Working length was determined using IOPA and an electronic apex locator
(Root ZX; Morita, Tokyo, Japan). Shaping and cleaning were performed
using ProTaper Gold (Dentsply Maillefer, Ballaigues, Switzerland) and
the crown-down technique. The MB and DB canals were enlarged to ProTaper
F2 (25/08), and the P canal was enlarged until ProTaper F3 (30/09). The
instrumentation was performed using 2.5% sodium hypochlorite solution
and normal saline. Final irrigation was performed with 2.5 % sodium
hypochlorite solution (Sisco Research Laboratories Pvt. Ltd., Mumbai,
India), 17% EDTA (Prime Dental Product Pvt Ltd, Mumbai, India), and
normal saline. The canals were medicated with Calcium hydroxide paste
(Calcicur, VOCO, Cuxhaven, Germany) using a lentulo spiral (Dentsply
Maillefer, Ballaigues, Switzerland), and the access cavity was sealed
with Cavit (3M ESPE Dental Products, St Paul, MN, USA). The patient was
asymptomatic during recall after 2 weeks. Calcium hydroxide was removed,
and obturation was done by single cone obturation technique using F2 and
F3 Gutta-percha (Dentsply Maillefer, Ballaigues, Switzerland) and AH
plus resin sealer (Dentsply Maillefer Company, Tulsa, OK, USA) (Figure
3A). The access cavity was sealed using resin composite (Z-100; 3M ESPE
Dental Products, St Paul, MN). The patient was asymptomatic during a
follow-up period of 1 year (Figure 3B).
DISCUSSION
Root fusion occurs due to disturbance in Hertwig’s epithelial root
sheath during developmental stages. It can also occur due to fusion in
the furcation area or deposition of cementum over
time.18 Root fusion is a common entity in maxillary
second molars compared to the first molars.4 Fusion of
roots can result in partial or complete fusion of the root canals and
can lead to intra-canal communications or canal divisions that are
challenging to shape and clean.19
In this case report, the root canals remained separate without any
communication. Based on Zhang et al. classification for fused
roots in maxillary second molars, this tooth can be classified as a Type
5 pattern where the P root fused with MB and DB
root.15 According to the recent classification of
anomalies by Ahmed et al. , it can be classified as
(RF5)327MB/DB/P.20
In maxillary second molars, the three roots are grouped closer together,
making the orifices form a flat triangle to almost a straight line. DB
orifice is closer to the MB orifice and is usually located in the
midpoint when a line is drawn from the MB to P orifices (Figure
4A).21 However, there are few cases reports on the
variation of DB roots or root canals (Table 1). These variations are in
the form of an extra root or root canal present close to the main DB
canal. Variations in the DB root canals in literature are also present
in the form of partial or complete fusion to either MB or P canals
forming C-shaped canals or fusions leading to double or single-rooted
maxillary second molars.8-14 These case reports also
point to the fact that when a root canal orifice deviates from its
actual position, there always is a need for careful inspection and
exploration for possible additional canals.
In the present case report, the search for the DB canal in its usual
position led to the gouging of the pulpal floor. The intraoperative CBCT
revealed that the roots were fused in the coronal and middle third, with
the DB root placed palatally. Hence, the peculiar canal located just
buccal to the P root canal orifice was the DB canal, which seemed to
give an illusion of an additional P canal (Figure 4B). All three root
canals also showed Vertucci Type I root canal pattern with no
intra-canal communications with each other. To the best of our
knowledge, no case report on such peculiarity in the position of the DB
canal orifice has yet been published in the literature.
In an earlier study by Han et al . done in the Chinese population,
the average distance between the DB and P canals was 3-5mm, and between
MB and DB canals was 1.5-3mm.22 The distance between
the DB and P orifice was only 0.6mm, and between DB and MB orifice was
3.9mm in the present case when calculated using the measuring tool in
the CBCT software (Planmeca Romexis version 5.2.0R). The smaller
mesiodistal diameter of 8mm of the involved teeth, partial root fusion,
and/or palatal positioning of the DB root could have been the possible
reason(s) for the unusual position of the DB canal in the current case
report.
The spatial relationship between the roots and adjacent anatomical
structures and the position and shape of anatomical structures inside
the root to be treated is often difficult to assess using a conventional
2-D radiograph.23 Using CBCT in such complex cases
enables us to understand the internal root canal anatomy
better.24
CONCLUSION
Unusual root canal morphology of the maxillary molars is invariably a
norm, and it should be visualized during the planning phase of
endodontic treatment. This will help the treating clinician deliver a
customized treatment plan to the patient precisely. This case report
highlights the variability of the root morphology. It further describes
the exact variation in the root canal system of a maxillary second
molar, i.e., DB root canal close to the P root canal orifice with
partially fused roots. An intraoperative CBCT aided in the better
understanding and management of this particular root canal anatomy,
followed by the precise execution of the treatment plan.
ACKNOWLEDGMENT: None.
FUNDING INFORMATION: None.
CONFLICT OF INTEREST STATEMENT: The authors declare no conflict
of interest related to this publication. This work did not receive any
funding.
DATA AVAILABILITY STATEMENT: Data related to this paper are
available for consultation if requested.
PATIENT CONSENT STATEMENT: A written informed consent was
obtained from the patient to publish this report in accordance with the
journal’s patient consent policy and is in the author’s possession.
REFERENCES
Vertucci FJ. Root canal anatomy of the permanent human teeth. Oral
Surg Oral Med Oral Pathol . 1984;58(5):589-599.
doi:10.1016/0030-4220(84)90085-9.
Martins JNR, Alkhawas MAM, Altaki
Z, Bellardini G, Berti L, Boveda C, et al . Worldwide analyses
of maxillary first molar second mesiobuccal prevalence: A multicenter
cone-beam computed tomographic study. J
Endod . 2018;44(11):1641-9.e1.
doi:10.1016/j.joen.2018.07.027.
Martins JN, Mata A, Marques D, Anderson C, Caramês J. Prevalence and
characteristics of the maxillary C-shaped molar. J
Endod . 2016;42(3):383-389.
doi:10.1016/j.joen.2015.12.013.
Martins JN, Mata A, Marques D, Caramês J. Prevalence of root fusions and
main root canal merging in human upper and lower molars:
A cone-beam computed tomography in vivo study. J
Endod . 2016;42:900-908.
doi:10.1016/j.joen.2016.03.005.
Zhang R, Yang H, Yu X, Wang H, Hu T, Dummer PM. Use of CBCT to identify
the morphology of maxillary permanent molar teeth in a Chinese
subpopulation. Int Endod J . 2011;44:162-169.
doi:10.1111/j.1365-2591.2010.01826.x.
Studebaker B, Hollender L, Mancl L, Johnson JD, Paranjpe A. The
incidence of second mesiobuccal canals located in maxillary molars with
the aid of cone-beam computed tomography. J
Endod . 2018;44(4):565-570.
doi:10.1016/j.joen.2017.08.026.
Martins J. Second mesiobuccal root canal in maxillary molars-A
systematic review and meta-analysis of prevalence studies using cone
beam computed tomography. Arch Oral Biol. 2019;24:104589.
doi:10.1016/j.archoralbio.2019.104589.
Kottoor J, Hemamalathi S, Sudha R, Velmurugan N. Maxillary second molar
with 5 roots and 5 canals evaluated using cone beam computerized
tomography: a case report. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod . 2010;109(2):e162-165.
doi:10.1016/j.tripleo.2009.09.032.
Ahuja P, Ballal S, Velmurugan N. Endodontic management of maxillary
second molar with a single root and a single canal diagnosed with
cone-beam computed tomography scanning. Saudi Endod J.2012;2(2):100-103.doi:10.4103/1658-5984.108162.
Fahid A, Taintor JF. Maxillary second molar with three buccal roots.J Endod. 1988;14(4):181-183.
doi:10.1016/S0099-2399(88)80261-9.
Suresh M, Karthikeyan K, Mahalaxmi S. Maxillary second molar with fused
root and six canals- A case report. J Clin Diagn Res.2017;11:ZD35-ZD37.
doi:10.7860/JCDR/2017/25005.9743.
Zeng C, Shen Y, Guan X, Wang X, Fan M, Li Y. Rare root canal
configuration of bilateral maxillary second molar using cone-beam
computed tomographic scanning. J Endod. 2016;42(4):673-677.
doi:10.1016/j.joen.2015.12.028.
Zmener O, Peirano A. Endodontic therapy in a maxillary second molar with
three buccal roots. J Endod. 1998;24(5):376-377. doi:
10.1016/s0099-2399(98)80138-6 .
Saeed Asgary. Endodontic treatment of a maxillary second molar with
developmental anomaly: A case report. Iran Endod J.2007;2(2):73-76.
Zhang Q, Chen H, Fan B, Fan W, Gutmann JL. Root and root canal
morphology in maxillary second molar with fused root from a native
Chinese population. J Endod . 2014;40(6):871-875.
doi:10.1016/j.joen.2013.10.035.
Ordinola-Zapata R, Martins JNR, Bramante CM, Villas-Boas MH, Duarte
MH, Versiani MA. Morphological evaluation of maxillary second molars
with fused roots: a micro-CT study. Int Endod J. 2017;50(12):1192-1200.
doi:10.1111/iej.12752.
Nagendrababu V, Chong BS, McCabe P, Shah PK, Priya E, Jayaraman J, et
al. PRICE 2020 guidelines for reporting case reports in Endodontics: a
consensus-based development. Int Endod J . 2020;53(5):619-626.doi:
10.1111/iej.13285.
Al-Fouzan KS. C-shaped root canals in mandibular second molars in a
Saudi Arabian population. Int Endod J. 2002;5:499–504.
doi:10.1046/j.1365-2591.2002.00512.x.
Versiani MA, Alves FR, Andrade-Junior CV, Marceliano-Alves
MF, Provenzano JC, Rôças IN, et al . Micro-CT evaluation of the
efficacy of hard-tissue removal from the root canal and isthmus area by
positive and negative pressure irrigation systems. Int Endod
J. 2016;49(11):1079-1087.
doi:10.1111/iej.12559.
Ahmed HMA, Dummer PMH. A new system for classifying tooth, root and
canal anomalies. Int Endod
J. 2018;51(4):389-404.doi:10.1111/iej.12867.
Wu MK, Wesselink PR, Walton RE. Apical terminus location of root canal
treatment procedures. Oral Surg Oral Med Oral Pathol Oral Radiol
Endod. 2000;89(1):99-103.
doi:10.1016/S1079-2104(00)80023-2.
Han X, Yang H, Li G, Yang L, Tian C, Wang Y. A study of the distobuccal
root canal orifice of the maxillary second molars in Chinese individuals
evaluated by cone-beam computed tomography. J Appl Oral Sci.2012;20(5):563-567.doi:10.1590/S1678-77572012000500012.
Cotti E, Campisi G. Advanced radiographic techniques for the detection
of lesions in bone. Endod Topics. 2004;7(1):52-72.
doi:10.1111/j.1601-1546.2004.00064.x.
Patel S, Brown J, Pimentel T, Kelly RD, Abella F, Durack C. Cone beam
computed tomography in Endodontics - a review of the literature.Int Endod J. 2019;52(1):1138-1152.
doi:10.1111/j.1601-1546.2004.00064.x.