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Research, Society and Development, v. 12, n. 8, e10812842868, 2023
(CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v12i8.42868
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High-resolution CBCT assessing a maxillary central incisor with root bifurcation: A
case report
TCFC de alta resolução utilizada na avaliação de um incisivo central superior com bifurcação
radicular: Relato de caso
CBCT de alta resolución evaluando un incisivo central superior con bifurcación radicular: Reporte
de un caso
Received: 07/31/2023 | Revised: 08/15/2023 | Accepted: 08/17/2023 | Published: 08/21/2023
Ana Luiza Esteves Carneiro
ORCID: https://orcid.org/0000-0002-3799-5043
University of São Paulo, Brazil
E-mail: ana.esteves.carneiro@usp.br
Rubens Spin-Neto
ORCID: https://orcid.org/0000-0002-9562-0610
Aarhus University, Denmark
E-mail: rsn@dent.au.dk
Daniela Miranda Richarte de Andrade Salgado
ORCID: https://orcid.org/0000-0003-4646-7389
University of São Paulo, Brazil
E-mail: daniricharte@usp.br
Núbia Rafaelle Oliveira de Meneses
ORCID: https://orcid.org/0000-0002-0933-650X
University of São Paulo, Brazil
E-mail: nu_meneses@usp.br
Edna Alejandra Gallardo López
ORCID: https://orcid.org/0000-0002-3312-1939
University of São Paulo, Brazil
E-mail: e.gallardo@usp.br
Alice Souza Villar Cassimiro Fonseca
ORCID: https://orcid.org/0000-0001-5119-3760
University of São Paulo, Brazil
E-mail: alicesvcf@usp.br
Claudio Costa
ORCID: https://orcid.org/0000-0003-2831-8670
University of São Paulo, Brazil
E-mail: clacosta@usp.br
Abstract
Cone beam computed tomography (CBCT) is an imaging modality widely used in endodontics, since it provides
three-dimensional images without superposition of structures. The maxillary central incisor usually presents a single
root and one root canal, but anatomical variations can happen. The aim of the present paper is to report a high-
resolution CBCT evaluation of an upper central incisor with root bifurcation. This paper shows a descriptive and
qualitative assessment of high-resolution CBCT images for endodontic purposes. A 39-year-old male patient was
referred to a radiologic clinic to acquire CBCT images of the right upper central incisor, as the referring clinician
noticed an anatomical difference between the two upper central incisors on a panoramic radiograph and suspected of
dens invaginatus. CBCT images were acquired in high resolution (voxel size of 0.08 mm) and a restricted field-of-
view (4x4 cm). CBCT volume displayed an anatomical variation of the central incisor, which presented root
bifurcation and two root canals, with a normal clinical crown. The present case report shows a rare diagnosis of a
maxillary central incisor presenting bifurcated root with two root canals, and to the best of the authors’ knowledge,
this is the first case report to present high-resolution CBCT images with disclosed acquisition protocols to diagnose a
bifurcated central incisor. The documentation of unusual cases has great didact value and contributes to information
propagation. In the present case, high-resolution CBCT allowed a detailed evaluation of both roots and root canals,
facilitating the clinician’s diagnostic task.
Keywords: Cone-Beam Computed Tomography; Anatomic Variation; Endodontics.
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Resumo
A tomografia computadorizada de feixe cônico (TCFC) é uma modalidade de imagem amplamente utilizada em
endodontia, pois fornece imagens tridimensionais sem sobreposição de estruturas. O incisivo central superior
geralmente apresenta uma única raiz e um canal radicular, mas variações anatômicas podem ocorrer. O objetivo deste
trabalho é relatar a avaliação de um incisivo central superior com bifurcação radicular por meio de TCFC de alta
resolução. Este artigo apresenta uma avaliação descritiva e qualitativa de imagens de TCFC de alta resolução para fins
endodônticos. Um paciente do sexo masculino de 39 anos foi encaminhado a uma clínica radiológica para adquirir
imagens de TCFC do incisivo central superior direito, pois o dentista solicitante notou uma diferença anatômica entre
os dois incisivos centrais superiores em uma radiografia panorâmica e suspeitou de dens invaginatus. As imagens
TCFC foram adquiridas em alta resolução (voxel de 0,08 mm) e um campo de visão restrito (4x4 cm). O volume da
TCFC apresentou uma variação anatômica do incisivo central, que apresentava bifurcação radicular e dois canais
radiculares, com coroa clínica normal. O presente relato de caso mostra um diagnóstico raro de um incisivo central
superior apresentando uma raiz bifurcada com dois canais radiculares e, até onde sabemos, este é o primeiro relato de
caso a apresentar imagens de TCFC de alta resolução, com protocolos de aquisição divulgados, para diagnosticar um
incisivo central bifurcado. A documentação de casos inusitados tem grande valor didático e contribui para a
propagação da informação. No presente caso, a TCFC de alta resolução permitiu uma avaliação detalhada das raízes e
dos canais radiculares, facilitando o diagnóstico.
Palavras-chave: Tomografia Computadorizada de Feixe Cônico; Variação Anatômica; Endodontia.
Resumen
La tomografía computarizada de haz cónico (CBCT, por sus siglas en inglés) es una modalidad de imagen
ampliamente utilizada en endodoncia, ya que proporciona imágenes tridimensionales sin superposición de estructuras.
El incisivo central superior suele presentar una sola raíz y un conducto radicular, sin embargo, pueden ocurrir
variaciones anatómicas. El objetivo del presente trabajo es reportar la evaluación CBCT de alta resolución de un
incisivo central superior con bifurcación radicular. Este artículo muestra una evaluación descriptiva y cualitativa de
imágenes CBCT de alta resolución con fines endodónticos. Un paciente de 39 años, de sexo masculino, fue referido a
una clínica radiológica para adquirir imágenes CBCT del incisivo central superior derecho, ya que el odontólogo
remitente notó una diferencia anatómica entre los dos incisivos centrales superiores en una radiografía panorámica y
sospechaba de dens invaginatus. Las imágenes CBCT fueron adquiridas en alta resolución (tamaño de vóxel de 0,08
mm) y con un campo de visión reducido (4x4 cm). El volumen CBCT mostró una variación anatómica del incisivo
central, que presentó bifurcación y dos conductos radiculares, con una corona clínica normal. El presente reporte de
caso muestra un diagnóstico poco frecuente de un incisivo central superior que presenta una raíz bifurcada con dos
conductos radiculares y, según el conocimiento de los autores, es el primero que presenta imágenes CBCT de alta
resolución con protocolos de adquisición divulgados para diagnosticar un incisivo central bifurcado. La
documentación de casos inusuales tiene un gran valor didáctico y contribuye a la difusión de la información. En el
presente caso, la CBCT de alta resolución permitió una evaluación detallada tanto de las raíces como de los conductos
radiculares, facilitando la tarea del diagnóstico clínico.
Palabras clave: Tomografía Computarizada de Haz Cónico; Variación Anatómica; Endodoncia.
1. Introduction
Periapical radiographs are widely used for diagnosis and planning of root canal treatment, since they provide detailed
information regarding root anatomy, periapical status, pulp chamber anatomy and probable number of root canals. However,
being a two-dimensional imaging modality, periapical radiographs are often unable to properly illustrate the complex
morphology and peculiarities of the root and root canal system (Caputo et al., 2016).
Cone-Beam Computed Tomography (CBCT) is a relatively novel imaging modality that is being widely used to
determine root canal anatomy in vivo, providing three-dimensional images without superposition of structures, at a reasonable
radiation dose (Durack & Patel, 2012). CBCT images enable the assessment of a tooth in three different planes (axial, sagittal
and coronal), currently being used in various endodontic applications such as analysis of root’s internal and external
morphology, assessment of root canal preparation, obturation, retreatment, coronary infiltration and tooth invagination
(Mabrouk et al., 2021; Setzer & Lee, 2021), overcoming the limitations of conventional radiography.
The maxillary central incisor usually presents a single root and a single root canal, with occasional lateral canals and
apical ramifications (Cabo-Valle, 2001). In other words, it is a tooth with a relatively simple anatomy. Altman (Altman, 1970)
and Vertucci (Vertucci, 1984) state that maxillary central incisors have one root and one canal in 100% of cases. A maxillary
Research, Society and Development, v. 12, n. 8, e10812842868, 2023
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central incisor with more than one root is a rare phenomenon (Heling, 1977). The literature reports a few cases of periapical
radiographs diagnosing double-rooted maxillary central incisors (Cabo-Valle, 2001; Heling, 1977; Henry, 1970; Mader, 1980;
Patterson, 1970; Rao Genovese, 2003) and only once case using CBCT images as the diagnostic tool (Levin, 2015). However,
quite often some development alterations can interfere with the central incisor’s anatomy. Dens invaginatus (DI), also known
as dens in dente, is a development anomaly that happens from the infolding of the outer surface of the tooth towards the pulp,
prior to dental tissues calcification, resulting in an invagination into the tooth (González-Mancilla et al., 2022; Kalogeropoulos
et al., 2023). The invagination may be limited to the pulp chamber, or it might extend to the root, where communication
between the root canal and the invagination could be present (Mabrouk et al., 2021).
In the present case report, a detailed tomographic evaluation revealed a maxillary central incisor presenting a
bifurcated root and two root canals, with a normal clinical crown, while ruling out the presence of developmental anomalies.
2. Methodology
The present paper is a case study of qualitative nature (Pereira et al., 2018) that aims to provide detailed information
regarding high-resolution Cone Beam Computed Tomography (CBCT) assessment of an upper right central incisor with root
bifurcation. This is a retrospective assessment of CBCT images and patient information recorded on University of São Paulo’s
database, approved by the local Research Ethics Committee under the number 3.239.265. The patients provided informed
consent for the use of their anonymized CBCT images.
3. Case Report
This case report has been written according to Preferred Reporting Items for Case reports in Endodontics (PRICE)
2020 guidelines (Nagendrababu et al., 2020) (Figure 1).
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Figure 1 – PRICE 2020 flowchart.
Source: Authors.
The flowchart summarizes the main clinical and radiographic aspects of this case report.
A 39-year-old male patient was referred to a radiology clinic to perform CBCT acquisition of the upper right central
incisor. The referring clinician noticed an anatomic difference between the left and right upper central incisors on a panoramic
radiograph and suspected that the right central incisor might present a developmental anomaly such as dens invaginatus, so
they requested a CBCT scan to further assess it (Figure 2). The patient reported no symptomatology. Due to general data
protection regulation, the initial panoramic radiograph was not available for comparison.
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Figure 2 – Panoramic reconstruction of CBCT images at 45-mm thickness, mimicking a panoramic radiograph.
Source: Authors.
The panoramic reconstruction shows anatomic variations in the root of the upper right central incisor, when compared to the upper
left central incisor.
For image acquisition the high-resolution protocol was performed on Veraview R100 (J. Morita Corporation, Osaka,
Japan), with the following acquisition protocol: 99kV (kilovoltage), 8mA (Milliampere), 9.4 seconds, FOV (Field of View)
4x4mm and voxel size 0.0800 mm. The images were exported in DICOM format and evaluated on OnDemand3D planning
software (CyberMed, Seuol, Korea).
The CBCT images were thoroughly evaluated by an experienced oral and dentomaxillofacial radiologist, that assessed
the region of interest on three main planes: sagittal, coronal and axial. The radiologist also repositioned the tomographic
images in different reformations in order to observe the entire upper right central incisor in longitudinal planes, being able to
perform buccal-lingual and mesial-distal assessments on coronal and sagittal planes, considering the long axis of the tooth.
After detailed evaluation of the tomographic volume, the radiologist diagnosed the presence of an anatomical variation: the
upper right central incisor presented one crown, a bifurcated root and two root canals.
The crown of the upper right central incisor presented no anatomic variations, no filling materials and no cavities. The
coronal third of the root presented a more oval shape compared to the left central incisor, with one single root canal. The root
started to bifurcate on the apical portion of the middle third, where a small accessory root was seen on the mesio-buccal aspect
of the main root, presenting its separate root canal. On the apical third of the tooth the two roots were separated, each one
presenting one root canal that ended on its own apical foramen (Figure 3). The main root had a length of 12.81mm, while the
bifurcated root had a length of 5.37 mm.
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Figure 3 – CBCT axial images showing the crown (A), coronal third (B), middle third (C) and apical third (D) of the upper
right central incisor. The white arrows indicate the accessory root.
Source: Authors.
On the apical portion of the incisor root a small accessory root can be observed, presenting a separate root canal.
In order to properly illustrate this anatomic variation to the endodontist, the CBCT volume had to be angled in a way
that captured the long axis of the tooth, both roots and both root canals, enabling the visualization of where the accessory root
began as well as the entire course of the two roots. Figure 4 shows how the CBCT volume was repositioned to better illustrate
each root, and Figure 5 shows the three-dimensional reconstruction the upper right central incisor.
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Figure 4 – CBCT Coronal, Axial and Sagittal images repositioned to show the long axis of the main root (top row) and the
accessory root (bottom row) of the upper right central incisor.
Source: Authors.
When the CBCT slices are positioned according to the long axis of the tooth they are able to properly illustrate the
anatomy of each root in the three dimensions: height, width and depth.
Figure 5 – CBCT three-dimensional reconstruction of the upper right central incisor.
Source: Authors.
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This reconstruction is able to clearly illustrate how the accessory root is positioned on the mesio-buccal aspect of the
main root.
4. Discussion
Although much is known about the usual dental anatomy, anatomical variations may occur in any group of teeth,
depending on the person. The maxillary central incisor in deciduous and permanent dentition most often presents a single root
and one root canal (Cabo-Valle, 2001; Calvert 2014; Castro-Nunez, 2020; Garlapati et al., 2014; Kumar Gupta et al., 2015;
Lambruschini & Camps, 1993; Levin, 2015; Lin et al., 2006; Nunes, 2020; Rao Genovese F, 2003). However, in rare
situations, this group of teeth can contain more than one root or root canal, or even reveal themselves with a series of
anomalous anatomies, such as: fusion, twinning, macrodontia and dens invaginatus. Such changes can occur simultaneously or
separately and may involve a single tooth in the arch or even affect the contralateral tooth (Cabo-Valle, 2001; Calvert, 2014;
Garlapati et al., 2014; Heling, 1977; Henry, 1970; Hosomi et al., 1989; Kumar Gupta et al., 2015; Lambruschini & Camps,
1993; Levin, 2015; Lin et al., 2006; Mader, 1980; Patterson, 1970; Rao Genovese, 2003; Sponchiado et al., 2006; Vinothkumar
et al., 2017). According to Garlapati et al. (Garlapati et al., 2014) the development of accessory root canals emerging through
the root surface may be caused by a failed fusion of the Hertwig’s epithelial root sheath with the cementoenamel junction
during root formation, due to traumatic or idiopathic injuries.
There are some case reports of permanent maxillary central incisors that showed morphological variations exclusively
in their root, most of them documented by periapical radiographs. Heling (Heling, 1977) reported an upper left central incisor
with a supernumerary tiny root turned mesial and smaller than the main root, bifurcating from the cervical root portion.
Patterson (Patterson, 1970) and Mader (Mader, 1980) reported the presence of two roots in both upper central incisors, without
specifying their length and position. Other authors (Lin et al., 2006) in 2006, observed a supernumerary root in the palatal
aspect of an upper left central incisor, presenting the same length of the main root. In 2017, Jajoo (S Jajoo, 2017) reported a
primary upper central incisors presenting two roots of the same length.
Angled periapical radiographs can be used to assess this anatomical variation. Genovese and Marsico (Rao Genovese
F, 2003) reported the presence of two roots (buccal and palatine) and two root canals in an upper right central incisor, while the
literature also shows reports of central incisors presenting two root canals in a single root (Calvert, 2014; Lambruschini &
Camps, 1993). However, assessing these teeth only by periapical radiographs could possibly lead to iatrogenic injuries, since
the information they provide is limited by the superimposition of structures (Garlapati et al., 2014; Heling, 1977; Henry, 1970;
Lambruschini & Camps, 1993; Lin et al., 2006; Mader, 1980; Patterson, 1970; Rao Genovese, 2003).
Failures in endodontic therapy are potentiated by the lack of clinical suspicion of possible changes in root anatomy.
Some authors report the need for endodontic re-approach in central incisors that had previously undiagnosed morphological
variations in their roots. Patients had persistent painful symptoms, caused by the absence of filling of a supernumerary root
canal (Calvert, 2014; 2014; Lambruschini & Camps, 1993; Rao Genovese, 2003). In 2014, Garlapati et al. (Garlapati et al.,
2014) altered the horizontal angle of a periapical radiograph to diagnose the presence of a supernumerary palatal root without
endodontic filling in the upper left central incisor.
The American Association of Endodontists and the American Academy of Oral and Maxillofacial Radiology suggest
the use of CBCT to identify potential accessory canals in teeth when a bidimensional image doesn’t offer enough information
(Endodontists & Radiology, 2011). The risk that radiation poses to the patient has been a constant concern in the scope of
dental radiology, due to the frequent use of intraoral and extraoral radiographs (Bornstein, Scarfe, Vaughn, & Jacobs, 2014).
The ALARA principle (“as low as reasonably achievable”) indicated that the patient should be exposed to the lowest possible
dose of radiation, and has now been replaced by ALADA (“as low as diagnostically acceptable”) which considers that upon the
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indication of the scan, the appropriate FOV, mAs, and kVp settings, such as high definition/high resolution parameters should
be selected to obtain a diagnostically acceptable and interpretable image (Jaju & Jaju, 2015). Considering this case report,
since the clinician’s hypothesis was a developmental anomaly in a tooth that did not present symptomatology, a high-
resolution CBCT protocol shouldn’t have been the first choice, following the ALADA principle. A standard-resolution
protocol would likely be able to diagnose this anatomical variation at a lower radiation burden to the patient. High-resolution
protocols offer a more detailed and clear tomographic image, but it is critical for health care providers to weigh the potential
benefit of diagnostic information against the radiation burden of the imaging procedure (Ludlow, Davies-Ludlow, Brooks, &
Howerton, 2006). Moreover, oral and maxillofacial radiologists have the responsibility to communicate the radiation dose and
the associated risks of CBCT acquisitions to their referring practitioners, spreading awareness about the difference between
“diagnostically acceptable” and “beautiful” images (Jaju & Jaju, 2015).
Few recent studies have employed CBCT as the imaging modality of choice for diagnosis and treatment planning of
upper central incisors. In the case reported by Sponchiado et al. (Sponchiado et al., 2006), an upper right central incisor
presented two roots of similar size, being equidistant from each other (mesial and distal). Levin et al. (Levin, 2015) found the
existence of a supernumerary root in the upper left central incisor, of shorter length and width compared to the main root,
originating from the middle third and mesial aspect of the main root. Gupta et al. (Kumar Gupta et al., 2015) also observed the
presence of a shorter supernumerary root in the upper left central incisor, located in the distal aspect of the tooth, bifurcating
from the cervical third. Vinothkumar et al. (Vinothkumar et al., 2017) reported the fusion of the upper right central incisor with
a supernumerary tooth, presenting a C-shaped root canal.
Only two studies reported information regarding CBCT acquisition. Levin et al. (Levin A, 2015) used CBCT unit
Carestream 9300 (Kodak®) but didn’t report the selected FOV. Vinothkumar et al. (Vinothkumar et al., 2017) used CBCT unit
Promax 3D (Planmeca®) with 0.2 mm voxel, 68x42mm FOV, acquisition time of 10.8s, 54 to 90kV and 1 to 14 mA. The
present case report shows a rare diagnosis of a maxillary central incisor presenting a bifurcated root with two root canals, and
to the best of the authors’ knowledge, this is the first case report to present high-resolution CBCT images with disclosed
acquisition protocols to diagnose a bifurcated central incisor. The limitations of this case report are the absence of clinical
photographs and panoramic radiograph. The documentation of unusual cases has great didact value and contributes to
information propagation, favoring the acknowledgment of similar cases that may require endodontic intervention.
5. Final Considerations
Upper central incisors can present more than one root and more than one root canal, therefore extensive knowledge of
dental anatomy is essential for proper endodontic treatment of this group of teeth. The appropriate use of diagnostic aids like
CBCT with limited FOV and low effective dose has enabled a detailed assessment of root anatomy before endodontic
intervention, facilitating successful endodontic treatment in difficult cases. Future studies with long-term monitoring of
endodontic interventions in teeth with root bifurcation could bring further knowledge regarding this anatomic variation.
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