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Chandra SS and Nagar S IJRD ISSUE 3, 2014
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RADIX ENTOMOLARIS IN PERMANENT
MANDIBULAR FIRST MOLARS – CASE SERIES
AND LITERATURE REVIEW
Saurabh S Chandra*, Shashank Nagar
**
* Specialist Endodontist, Al-Salam International Hospital, Kuwait. ** Private Practice, Kashipur, INDIA.
Address for correspondence: Dr. Saurabh Chandra, Specialist Endodontist, Al-Salam International Hospital, Kuwait.
Mob: +965-60798333
Email: [email protected]
Abstract : The foremost goal of endodontic therapy is to prevent or heal apical periodontitis. However, root canal anatomy might
present a clinical challenge, which may have a bearing on the treatment outcome. Anatomical racial variations are an acknowledged
characteristic in permanent molars. Generally mandibular first molars have two roots; however the presence of a third root - Radix
Entomolaris (RE) is a major anatomic variant amongst many population groups. The RE is considered to be unusual and is primarily an
Asiatic trait. This paper reports a series of mandibular first molars featuring this dysmorphic root morphology.
Keywords: mandibular molars, radix entomolaris, root canal morphology.
INTRODUCTION
The treatment of the entire root canal system is
essential to maximize the possibility of obtaining
success in the endodontic therapy. It is indispensable
for the clinician to possess thorough knowledge of
the root anatomy, canal morphology, as well as their
variations.
The mandibular first molar is the first permanent
tooth to erupt in the oral cavity and the one that most
often requires root canal treatment.1 Majority of
permanent first molars are two-rooted with two
mesial and one distal canal.1-3
The major variant in
this tooth type is the presence of an additional third
root; a supernumerary root which can be found
lingually. This macrostructure, which was first
mentioned in the literature by Carabelli, is called
radix entomolaris (RE).4,5
The RE can be found on
the first, second and third mandibular molar,
occurring least frequently on the second molar.6
Studies have shown that this supernumerary root can
either be separate or partially fused to other roots. It
is typically smaller than the mesial and distobuccal
roots and is usually curved, requiring special
attention when endodontic intervention is
considered.7-9
The coronal part of RE is completely
or partially fixed to the distal root and its dimension
CASE REPORT
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Chandra SS and Nagar S IJRD ISSUE 3, 2014
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can vary from short conical to a root of normal
length and root canal. Carlsen and Alexandresen
described four different types of RE while DeMoor
et al. suggested a classification with three different
types of RE; Type I refers to a straight root, Type II
to an initially curved entrance that continues as a
straight root and Type III to an initial curve in the
coronal third of the root canal and a second curve
beginning in the middle and continuing to the apical
third.8,9
A review of the relevant endodontic literature
(Table. 1) revealed that the prevalence of RE has a
high genetic and ethnic predilection.10-30
It is seldom
found in European, Caucasian10-14
and African15
populations but appears to be more frequent in races
of Mongoloid and Asian origin.16-34
Virtually, all of
the reported results either focus on the actual
occurrence of three-rooted mandibular first molars
based on the extracted teeth or radiological studies
that were examined for different ethnicities.14,22,23
The aim of this study was to report a series of cases
featuring RE in permanent mandibular first molars.
Author Yea
r
Populati
on
/Ethnic
Group
No. of
Teeth
Evaluat
ed
Three Rooted
Molars
Numb
er
(No.)
Percenta
ge (%)
Taylor 189
9
United
Kingdom
119 4 3.4
Bolk 191
5
Dutch 1713 18 1.1
Fabian 192
8
Germany - - 1.6
Hjelmma
n
192
9
Finnish - - 0.9
Tratman 193 Chinese 1615 95 5.8
8
Tratman 193
8
Eurasian 282 11 4.2
Tratman 193
8
Malaysia
n
475 41 8.6
Tratman 193
8
Japanese 168 2 1.2
Laband 194
1
Malayans 134 8.2
Harada
et al
196
9
Japanese 2331 440 18.8
Skidmor
e et al
197
1
Caucasian 45 1 2.2
Turner 197
1
Aleutian
Eskimo
263 84 32
Curzon
et al
197
1
Keewatin
Eskimo
98 28 27
Turner 197
1
American
Indian
1983 116 5.8
Somogyl
-
Csizmazi
a
197
1
Canadian
Indian
250 39 15.6
De
Souza –
Freitas et
al
197
1
Japanese 233 83 17.8
De
Souza –
Freitas et
al
197
1
European 844 3.2
Curzon 197
4
Baffin
Eskimo
69 15 21.7
Hochstett
er
197
5
Guam 400 14.3
Jones 198
0
Chinese 52 7 13.4
Jones 198
0
Malaysia
n
149 25 16
Reichart
et al
198
1
Thai 364 70 19.2
Walker 198 Hong 213 31 14.6
Chandra SS and Nagar S IJRD ISSUE 3, 2014
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et al 5 Kong
Chinese
Steelman 198
6
Hispanic 156 6.4
Walker 198
8
Hong
Kong
Chinese
100 15 15
Onda et
al
198
9
Hindu in
Japan
198 2 1
Loh 199
0
Singapore
an
Chinese
304 24 7.9
Younes
et al
199
0
African
(Egypt)
457 3 0.7
Younes
et al
199
0
Asian
(Saudi
Arabia)
385 9 2.3
Ferraz et
al
199
2
Japanese 105 12 11.4
Ferraz et
al
199
2
Brazilian 117 5 4.2
Yew et al 199
3
Chinese 832 179 21.5
Suarez-
Feito
199
5
Spanish 198 0 0
Rocha et
al
199
6
Brazil 232 12 5.2
Zaatar et
al
199
8
Kuwait 49 0 0
Sperber
&
Moreau
199
8
African
(Senegal)
480 15 3.1
Al-
Nazhan
199
9
Saudi
Arabia
251 15 6
Gulabiw
ala et al
200
1
Burmese 139 10.1
Gulabiw
ala et al
200
2
Thai 118 15 12.7
Tu et al 200
7
Taiwanes
e
332 59 17.8
Ahmed
et al
200
7
Sudanese 100 3 3
Peiris et
al
200
7
Sri
Lankan
100 3 3
Furri et
al
200
7
Unspecifi
c
231 124 53.7
Huang et
al
200
7
Taiwanes
e
332 72 21.7
Reuben
et al
200
8
India
(Hindu)
125 0 0
Pattanshe
tti et al
200
8
Kuwaiti
& Non
Kuwaiti
110 4 3.6
Schafer
et al
200
9
German 1024 7 0.68
Al-
Qudah &
Awawde
h
200
9
Jordanian 330 13 3.9
Chen et
al
200
9
Taiwanes
e
183 36 19.7
Rwenyon
yi et al
200
9
African
(Uganda)
224 0 0
Chen et
al
200
9
Taiwanes
e
293 29 9.9
Chen et
al
200
9
Taiwanes
e
183 36 19.7
Tu et al 200
9
Taiwanes
e
246 63 25.6
Garg et
al
201
0
Indian 1054 35 5.97
Gu et al 201
0
Chinese
(Jiangsu)
122 39 32
Huang et
al
201
0
Taiwanes
e
237 60 25.3
Song et
al
201
0
Korean 3088 756 24.5
Wang et
al
201
0
Western
Chinese
558 70 31.4
Chandra
et al
201
1
South
Indian
1000 133 13.3
CASE REPORTS
Case1:
A 20-year-old female patient was referred to the
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Department of Conservative Dentistry and
Endodontics, SDS, Sharda University, Greater
Noida, India with severe spontaneous pain in her
mandibular left first molar (tooth #19) for the
preceding few days. Pretreatment examinations
(thermal and electric pulp tests) revealed irreversible
pulpitis warranting endodontic treatment. Initial pre-
operative radiographic examination suggested that
the tooth had an additional distal root (Fig.1). The
tooth was anesthetized using 2% lignocaine with
1:100,000 adrenalin (Lignox; Indoco Remedies,
Mumbai, India) and isolated under rubber dam
(Hygenic Dental Dam, Colténe Whaledent,
Germany). The access cavity was prepared using an
Endo Access bur (Dentsply Maillefer, Ballaigues,
Switzerland). The dentinal map on the floor of the
chamber was traced and explored using a DG 16
endodontic explorer (Hu-Friedy, Chicago, IL, USA)
following which the pulp tissue was extirpated using
barbed broaches (Dentsply Maillefer, Tulsa, OK,
USA). On inspection with 2.5X magnification
prismatic loupes (Seiler, St. Louis, MO), 4 distinct
orifices were identified (Fig. 2); two in the mesial
root (mesiobuccal and mesiolingual) and 1 in the
distal root (distobuccal). A fourth canal was located
in the distolingual (DL) extension. The access cavity
was modified with a DL extension to provide proper
access to the canal. Canal patency was established
using a #10 K file (Mani, Tochigi, Japan). Working
length was determined using an electronic apex
locator (Root ZX-II; J. Morita, Tokyo, Japan) and
subsequently verified with a radiograph that
confirmed the presence of the additional root
(Fig.3).
At the subsequent visit, root canal instrumentation
was performed with K3 Ni-Ti rotary files (Sybron
Endo, Orange, CA) using a crown-down technique.
Copious irrigation was done using 3% sodium
hypochlorite (Dentpro, Chandigarh, India) and
EDTA (Glyde File Prep, Dentsply Maillefer, Tulsa,
OK). The canals were finally rinsed with normal
saline (Marck Biosciences, Gujrat, India), dried with
sterile absorbent paper points (Dentsply Maillefer),
and obturated with cold laterally condensed gutta-
percha (Dentsply Maillefer) using AH Plus resin
sealer (Dentsply Maillefer). A postoperative
radiograph (Fig. 4) was taken, and the patient was
scheduled for post-endodontic restoration.
Figure 1: Pre-operative radiograph of Tooth # 19
Figure 2: Clinical view of the 4 separate canal orifices in
the chamber Figure 3: Working length radiograph
Figure 4: Post-operative radiograph.
Case 2:
A 24-year-old South East Asian male was referred
for endodontic treatment of the mandibular left first
molar (Tooth #19). The pre-operative radiograph
clearly showed the presence of a three-rooted molar
(Fig.5). The tooth was anesthetized and the pulp
chamber was accessed. One distal and two mesial
canal orifices were located using an endodontic
explorer (DG-16 Hu Friedy, Chicago, IL, USA). On
inspection with 2.5X magnification prismatic loupes
(Seiler, St. Louis, MO), a dark line was observed
between the distal canal orifice and the distolingual
corner of the pulp chamber floor. At this corner
overlying dentin was removed with a diamond bur
with a non-cutting tip (Diamendo, Dentsply
1
3 4
2
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Maillefer) and the second distal canal orifice was
located. The root canals were explored with a K-file
ISO 15 (Dentsply Maillefer, Ballaigues,
Switzerland) and the canal lengths were determined
electronically using an apex locator (Root ZX-II; J.
Morita, Tokyo, Japan). Instrumentation was carried
out with ProTaper rotary instruments (Dentsply
Maillefer). During preparation, File Eze (Ultradent
Products Inc., South Jordan, UT) was used as a
lubricant and the root canals were disinfected with
2.5% sodium hypochlorite solution (Dentpro,
Chandigarh, India). The root canals were filled with
gutta-percha and AH-Plus (De Trey Dentsply,
Konstanz, Germany). The opening cavity was sealed
with silver amalgam and the patient was referred to
his general dental practitioner (Fig.6).
Figure 5: Pre-operative radiograph of Tooth # 19
Figure 6: Post-operative radiograph.
Case 3:
A 29 year old female with a non-contributory
medical history was referred to our office
complaining of severe discomfort associated with
her mandibular right first molar (Tooth #30). A
clinical examination revealed pulpal exposure due to
extensive caries. She reported of a lingering
hypersensitivity to hot and cold stimuli for the past
few weeks. The patient’s general practitioner had
advised an OPG which suggested the presence of a
third root. A pre-operative mesial shift radiograph
was taken confirming the presence of an additional
root. The tooth was isolated and coronal access was
established. The pulp was extirpated and the length
of the root canals was established using a Root ZX
(J. Morita Mfg. Corp., Kyoto, Japan).
Radiographically the outlines of the distal root(s)
were unclear; however, the unusual location of the
orifice far to the disto-lingual indicated a
supernumerary root, and the presence of an RE was
confirmed on the postoperative radiograph. The
canals were instrumented with a crown-down
technique-using rotary Pro-taper and irrigated with
sodium hypochlorite. The canals were filled with
gutta-percha points and AH–Plus resin root canal
sealer (Fig. 7). The treatment was performed in a
single session.
Figure 7: Post-operative radiograph
Case 4:
A 65-year-old male with a medical history of type II
diabetes mellitus for the past 28 years was referred
to our office complaining of minor discomfort
associated in the right mandibular posterior region.
The patient was on oral hypoglycemics and insulin
therapy. Clinical examination revealed a temporary
restoration in the right mandibular first molar (Tooth
#30). The tooth was exceptionally sensitive to
percussion and was non-responsive to Endo Ice
(Hygienic Corp., Akron, Ohio, USA). A diagnosis
of necrotic pulp with chronic apical periodontitis
was made. The tooth was isolated and the coronal
access was prepared. Initially, 3 canals were located.
However a “stick” was felt in the distolingual
5 6
7
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corner. On extending the cavity preparation, a fourth
orifice was located and a #10 K file (Mani, Tochigi,
Japan) was introduced to establish the glide path.
The lengths of these canals were measured
electronically (J. Morita Mfg. Corp., Kyoto, Japan).
The canals were cleaned with 5.25% sodium
hypochlorite solution (Dentapro, Chandigarh, India)
and EDTA (Salvizol, Ravens, Konstanz, Germany),
and shaped with ProTaper instruments. The canals
were dried using sterile paper points and intra canal
medicament of calcium hydroxide was placed. The
patient was recalled after 14 days, the canals were
copiously irrigated and obturation was done using
gutta percha and EndoRez resin sealer (Ultradent
Products Inc., South Jordan, UT, USA) (Fig.8).
Three months later the patient was referred to our
office again for tooth #19. The tooth was severely
tender and exhibited grade II mobility. The patient
informed us that endodontic treatment had been
attempted 6 years back. However, the IOPA
revealed an inappropriate access cavity preparation,
incompletely filled canals, a fractured instrument in
the distolingual canal and large periapical
radiolucencies in both roots (Fig.9). It was decided
not to attempt a retreatment due to the guarded
prognosis of the tooth and the patient was referred
back to his practitioner for an extraction. This
patient had the presence of RE bilaterally.
Figure 8: Post-operative radiograph
Figure 9: Periapical radiograph of Tooth #19 confirming
bilateral RE. Case 5:
A 33-year-old healthy lady was referred to our
practice with the chief complaint of spontaneous
pain and an intra-oral swelling in relation to her
mandibular left first molar (tooth #19) since the past
4- 6 weeks. The tooth had a large fractured amalgam
restoration and was severely tender on vertical
percussion. A conventional access was established
under rubber dam and local anesthesia. On careful
evaluation of the distal canal, an orifice was
identified distolingually. The access cavity was
modified and a #10 K - patency file was introduced.
A working length radiograph was taken which
confirmed the presence of an additional root. The
canals were instrumented with rotary K3 Ni-TI
instruments and the tooth was temporized with
calcium hydroxide and IRM. One week later, the
canals were obturated with gutta percha and AH-
Plus resin sealer. The patient was referred back to
her general practitioner for further treatment
(Fig.10).
Figure 10: Post-operative radiograph of Case 5.
DISCUSSION
RE has been associated with certain ethnicities with
a high preponderance in Asians. In these
populations, RE is regarded as a normal racial and
morphological variation rather than as an
abnormality and can be seen primarily as an Asiatic
trait. According to Chandra et al., the occurrence of
the distolingual root in a South Indian population
was reported to be 13.3%; while Garg et al. reported
5.97% prevalence in an Indian population.22,23
This
8 9
10
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macrostructure has a prevalence rate of 1.2% to
21.5%. amongst Asians.35
The presence of an RE has various clinical
implications in endodontic treatment. An accurate
diagnosis of these supernumerary roots can avoid
complications or a ‘missed canal’ during endodontic
treatment. The additional distolingual root is usually
situated in the same buccolingual plane as the
distobuccal root; therefore a superimposition of both
roots appears on the preoperative radiograph. Hence,
a thorough inspection of the preoperative radiograph
and interpretation of particular characteristics, such
as an unclear view or outline of the distal root
contour or the root canal, can indicate the presence
of a ‘hidden’ RE. Variations in the root anatomy can
be identified through very careful observation of
angled radiographs. Buccolingual views, 20° from
mesial or distal reveal the basic information on the
tooth’s anatomy and root canal system required for
endodontic treatment. Apart from a radiographic
diagnosis, clinical inspection of the tooth crown and
analysis of the cervical morphology of the roots by
means of periodontal probing can facilitate
identification of an additional root. According to
Walker and Quackenbush, the accuracy of a correct
diagnosis of three rooted mandibular molars is about
90% even when using only panoramic radiographs.29
One of the cases reported in this paper had an OPG,
which was suggestive of an additional root that was
later confirmed by a mesial shift periapical
radiograph. Recently, the root canal morphology of
permanent three rooted mandibular first molars has
been investigated using micro-computed
tomography scans and Cone-Beam Computed
Tomography.36
The standard triangular access form is no longer
appropriate for three-rooted mandibular first molars
and those two-rooted molars with four canal orifices.
The orifice of the RE is located disto- to
mesiolingually from the main canal or canals in the
distal root. An extension of the triangular opening
cavity to the (disto) lingual results in a more
rectangular or trapezoidal outline form. In order to
expose the distolingual orifice, the access form
should be modified to a trapezoidal shape. The
distolingual corner of the access cavity should
extend more lingually, theoretically, forming an
angle of 75°.36
If the RE canal entrance is not clearly
visible after removal of the pulp chamber roof, a
more thorough inspection of the pulp chamber floor
and wall, especially in the distolingual region, is
necessary. Visual aids such as a magnifying surgical
loupes or dental microscope can be beneficial.1 A
dark line on the pulp chamber floor can indicate the
precise location of the RE canal orifice. The distal
and lingual pulp chamber wall can be explored with
angled probes or special endodontic explorers like
DG-16 to reveal root canal orifices. Troughing of
the grooves with ultrasonic tips, staining the
chamber floor with 1% methylene blue dye,
performing the sodium hypochlorite “champagne
bubble test,” and visualizing canal bleeding points
are important aids in locating root canal orifices.
Deposition of secondary dentin decreases the space
of the pulp chamber and narrows the root canal and
canal orifice. This can make localization and
management of the DL canal more difficult in older
patients. To gain access to the apical portion, the
dentinal shelf around the DL orifice should be
removed. Sufficient coronal flaring is essential to
decrease the canal curvature.1,9,23,36
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Another challenge related to three-rooted
mandibular first molars is the root canal curvature.
Conventional canal instrumentation of a curved
canal with stiff steel files might produce ledges,
zips, elbows, apical transportation, loss of working
length, or perforations. Nickel-titanium rotary
system can reduce the occurrence of these errors,
because it is superelastic and more flexible in the
canal curvature.21
However, it might undergo
unexpected fracture as a result of cyclic fatigue. DL
canals exhibit severe curvature, and the mean angle
of curvature is the greatest among the 3 roots.37
The aetiology behind the formation of the RE is
unclear. In dysmorphic, supernumerary roots, the
formation can be related to external factors during
odontogenesis or to penetrance of an atavistic gene
or polygenetic system.3 In eumorphic roots, racial
genetic factors influence the more profound
expression of a particular gene that results in the
more pronounced phenotypic manifestation.8,9
The
external contour of the root furcation of the three-
rooted mandibular first molars is more complex than
that of the two-rooted ones. This increases the
difficulty of management of periodontal disease.
Huang et al.38
found a higher magnitude of
periodontal and clinical attachment loss at the
distolingual site of molars that presented with the
RE than in molars without the root in molars with
advanced periodontitis. Although the exact etiology
is unclear, the unique morphological features of the
distolingual root may lead to increased pocket depth
leading to serious periodontal destruction. Evidence
suggests that the presence of the RE contributes to
the formation of distal furcation, which can be
complex. These findings suggest, for long-term
retention, more effort should be made to increase the
success rate of dental treatment of three-rooted
mandibular first molars.36
Conclusion
Treating aberrant root anatomy in posterior teeth can
be a challenging task. Location and identification of
additional roots is imperative, and clinicians must
use all available tools in the diagnostic
armamentarium. Due consideration must be given to
ethnic variations.
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How to cite this article:
Chandra SS, Nagar S. Radix entomolaris in
permanent Mandibular first molars – case
series and literature review. IJRD
2014;3(3):78-87.