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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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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



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



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



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



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



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



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.

radix entomolaris in permanent …jrdindia.org/ver2/app/upload/case report55.pdfradix entomolaris in...

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