49
Članek prispel / Received
8. 1. 2021
Članek sprejet / Accepted
10. 10. 2022
Abstract
Purpose: This study aimed to re-
port the diagnosis and management 
of a permanent maxillary first molar 
(PMFM) with unusually complex root 
canal morphology. 
Case report: A 30-year-old male pa-
tient was referred to the endodontic 
department to continue endodontic 
treatment of the left PMFM. The 
referring dentist could not establish 
the patency of the canals in the me-
siobuccal and distobuccal roots. Ra-
diographically, the tooth had three 
almost straight roots associated with 
periapical radiolucencies, indicating 
periapical periodontitis. The exami-
nation of the pulp chamber floor, 
using a dental operating microscope, 
revealed the presence of six root canal 
Izvleček
Namen: Namen prispevka je pred-
staviti diagnostiko in zdravljenje 
prvega zgornjega stalnega kočnika 
(PZSK) z nenavadno zapleteno mor-
fologijo kanalskega sistema. 
Poro~ilo o primeru: V primeru 
predstavljamo 30-letnega pacienta, 
ki je bil v specialistično ambulanto 
napoten zaradi nadaljevanja endo-
dontskega zdravljenja levega PZSK. 
Zobozdravniku ni uspelo vzpostaviti 
prehodnosti kanalov v meziobukalni 
in distobukalni korenini. Na rentgen-
skem posnetku so bile vidne tri sko-
raj ravne korenine s periapikalnimi 
radiolucencami, značilnimi za peria-
pikalni parodontitis. Med pregledom 
dna pulpine komore z zobozdravni-
škim mikroskopom smo ugotovili šest 
Ključne besede: 
anatomija zob, morfologija 
koreninskih kanalov, zobozdravniški 
mikroskop, strojni endodontski 
instrumenti
Key words: 
dental anatomy, root canal 
morphology, dental operating 
microscope, rotary endodontic 
instruments
Opis primera: Endodontsko zdravljenje prvega 
zgornjega stalnega kočnika s tremi koreninami in 
šestimi koreninskimi kanali 
Case report: Endodontic treatment of a permanent 
maxillary first molar with three roots and six root 
canals
Avtor / Author Marko Novak1, Iztok Štamfelj2, 3 
Ustanova / Institute 1Lotus dentalni center, Ljubljana, Slovenija; 2Univerza v Ljubljani, Medicinska fakulteta, 
Katedra za zobne bolezni in normalno morfologijo zobnega organa, Ljubljana, Slovenija; 
3Univerzitetni klinični center Ljubljana, Center za zobne bolezni in endodontijo, Ljubljana, 
Slovenija;
1Lotus Dental Centre, Ljubljana, Slovenia; 2University of Ljubljana, Faculty of Medicine, 
Department of Dental Diseases and Dental Morphology, Ljubljana, Slovenia; 3University 
Medical Centre Ljubljana, Department of Operative Dentistry and Endodontics, Ljubljana, 
Slovenia;
ACTA MEDICO-BIOTECHNICA
2022; 15 (2): 49–53
Poročilo o primeru / Case report
https://doi.org/10.18690/actabiomed.242, CC BY 4.0
© 2022 Avtor(ji) / The Author(s)
50
INTRODUCTION
The detection and management of variations in root 
canal morphology, especially in permanent maxillary 
first molars (PMFMs), present a constant challenge for 
a clinician (1, 2). Although PMFMs have three roots, 
four root canals have been found in more than half of 
the cases, in which the mesiobuccal (MB) root has two 
canals (3). Variants with more than four root canals 
are uncommon; however, a maximum of eight root 
canals have been detected clinically: three in the MB 
root, three in the distobuccal (DB) root, and two in 
the palatal (P) root (4). The present study provided 
insight into the internal anatomy of the PMFM with 
six root canals and suggestions for detecting and man-
aging multiple root canals.
CASE PRESENTATION
A 30-year-old male patient presented for the continu-
ation of the endodontic treatment of the left PMFM. 
The referring dentist was not able to establish paten-
cy of the canals in the MB and DB roots. After sev-
eral sessions, the tooth was left open for more than 
a year. The patient did not report any other health 
problems. The tooth was asymptomatic, physiologi-
cally mobile, and not sensitive to percussion. Radio-
graphically, the tooth had three apparently straight 
roots associated with periapical radiolucencies, indi-
cating periapical periodontitis (Fig. 1).
The tooth was anesthetized using 2% mepivacaine 
with epinephrine and isolated using a rubber dam. 
Under a dental operating microscope (OPMI Pico, 
vhodov v koreninske kanale – tri v 
meziobukalni, dva v distobukalni in 
enega v palatinalni korenini. Z ele-
ktronskim določevalnikom apikalne 
odprtine in K-iglami nismo ugotovili 
medsebojnega združevanja multiplih 
kanalov. Med endodontskim zdravlje-
njem smo koreninske kanale razširili 
in očistili z reciprocirajočimi nikelj-ti-
tanovimi instrumenti ter zapolnili z 
gutaperčnimi poeni in biokeramično 
polnilno pasto. Po dveh letih je pa-
cient na ponovnem pregledu bil brez 
simptomov ter brez kliničnih in rent-
genskih znakov prisotnosti vnetja ob 
zdravljenem zobu.
Zaklju~ek: Povečava in ustrezna 
osvetlitev omogočata natančen pre-
gled dna pulpine komore, kar je 
ključnega pomena pri obravnavi zob 
z zapleteno morfologijo kanalskega 
sistema. Med endodontskim zdravlje-
njem je treba upoštevati, da ima v 
nekaterih primerih PZSK več kot štiri 
koreninske kanale.
orifices, three in the mesiobuccal root, 
two in the distobuccal root, and one 
in the palatal root. No confluence of 
multiple canals was detected using 
the electronic apex locator and K-fi-
les. The canals were shaped and cle-
aned with reciprocating nickel-titani-
um instruments and obturated using 
gutta-percha cones and a bioceramic 
sealer. After 2 years, the patient was 
asymptomatic and the tooth was cli-
nically and radiographically without 
pathological findings.
Conclusion: Careful examinati-
on of the pulp chamber floor using 
magnification and illumination is 
important for successfully managing 
complex canal morphologies. During 
endodontic treatment, dentists must 
consider that the PMFM may have 
more than four root canals.
Poročilo o primeru / Case report
ACTA MEDICO-BIOTECHNICA
2022; 15 (2):49–53
Naslov za dopisovanje /  
Correspondence
Doc. dr. Iztok Štamfelj, dr. dent. med., 
spec. za zobne bolezni in endodontijo, 
Univerza v Ljubljani, Medicinska 
fakulteta, Katedra za zobne bolezni in 
normalno morfologijo zobnega organa, 
Hrvatski trg 6, 1000 Ljubljana, 
Slovenija 
Telefon: +386 15224372 
E-pošta: iztok.stamfelj@mf.uni-lj.si 
51ACTA MEDICO-BIOTECHNICA
2022; 15 (2): 49–53
Poročilo o primeru / Case report
Figure 1. Preoperative periapical radiograph of the 
left maxillary first molar showing severe calcification 
of the root canals and periapical radiolucencies (ar-
rows). M, mesial side; D, distal side.
Zeiss, Zaventem, Belgium), the access cavity was re-
shaped.
The inspection and probing of the pulp chamber 
floor with an endodontic explorer revealed the pres-
ence of one palatal (P), two DB, and three MB root 
canal orifices (Fig. 2). The patency of the canals was 
established manually using K-files of sizes 8 and 10. 
No confluence of multiple canals was detected us-
ing an electronic apex locator and K-files. The ca-
nals were shaped and cleaned using Reciproc nickel-
titanium rotary instruments (VDW Dental, Munich, 
Germany). The R50 was suitable in size for the P 
canal and the R25 for all other root canals. Through-
out the treatment, 2.5% NaOCl was used as an irrig-
ant. After shaping, the canals were rinsed with 17% 
ethylenediaminetetraacetic acid and 2.5% NaOCl 
according to the protocol of manual dynamic activa-
tion described by Machtou (5). Finally, the canals 
were dried with sterile paper points and obturated 
using Reciproc gutta-percha cones and TotalFill BC 
Figure 2. Access cavity during treatment. Ar-
rows show one palatal (P), two distobuccal (DB1 
and DB2), and three mesiobuccal root canal ori-
fices (MB1, MB2, and MB3).
Figure 3. Ac-
cess cavity af-
ter completed 
o b t u r a t i o n . 
Arrows show 
endodontic fil-
ings in all six 
root canals.
Sealer (FKG Dentaire, La Chaux-de-Fonds, Switzer-
land) (Figs. 3 and 4). 
A composite restoration was placed (Fig. 5). After 2 
years, the patient was asymptomatic and the tooth 
was clinically and radiographically without patholog-
ical finding (Fig. 6).
52
Poročilo o primeru / Case report
Figure 5. Restored crown after the endodontic treat-
ment. M, mesial; D, distal; B, buccal; P, palatal.
Figure 6. A 24-month recall radiograph.
DISCUSSION
The prevalence of PMFMs with six root canals is rela-
tively small. A retrospective assessment of 338 end-
odontically treated PMFMs in Spanish patients identi-
fied three teeth (0.89%) with a root canal anatomy 
that matched the case in this study (6). In a similar 
Brazilian study of 291 PMFMs, one tooth (0.35%) had 
six root canals; however, contrary to the case discussed 
in this study, two canals were present in each of the 
three roots (7). A microcomputed tomography study 
of MB roots of 153 extracted PMFMs revealed three 
separate canals in one tooth (0.65%) (8).
The external crown morphology presents no clues 
to the presence of unusually complex canal anatomy 
when the number of roots is normal. In the patient 
discussed in this study, the size and external morphol-
ogy of the crown and images of the roots on the preop-
erative radiograph were unremarkable. It is reasonable 
to take a cone-beam computed tomography (CBCT) 
scan when suspecting a complex morphology because 
2D imaging is relatively inaccurate for the detection 
of additional canals (9). However, even in these cases, 
CBCT should not be used routinely, but only after 
Figure 4. 
Postoperative 
r a d i o g r a p h . 
Canals MB2 
and MB3 in 
the mesiobuc-
cal root and 
canals DB1 
and DB2 in 
the distobuccal 
root appear su-
perimposed.
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53
Poročilo o primeru / Case report
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careful consideration of the benefits and risks for the 
patient (9, 10). In our patient, CBCT was not indi-
cated because periapical radiography and clinical aids 
provided all the key data necessary for the completion 
of the treatment.
Magnification and careful examination of the pulp 
chamber floor and wall anatomy can greatly increase 
the chances of uncovering additional root canals. 
Moreover, staining the pulp chamber floor with 1% 
methylene blue dye, performing the NaOCl “cham-
pagne bubble” test, and searching for bleeding points 
can aid in locating additional root canal orifices (11). 
In addition to these technical advancements, knowl-
edge of anatomical variations that might exist in the 
root canal system is crucial. 
As Trope and Debelian (12) emphasized, a clinician 
will never find more root canals than he or she is look-
ing for.
CONCLUSION
During endodontic treatment, dentists must consider 
that PMFM may have more than four root canals.
ACTA MEDICO-BIOTECHNICA
2022; 15 (2): 49–53