E. Zdanavičienė et al.

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SCIENTIFIC ARTICLES
Stomatologija. Baltic Dental and Maxillofacial Journal, 22: 86-91, 2020

Study and evaluation of the gubernacular canal by means

of cone beam computed tomography
Thaís Silva Cerqueira1, Kariza Vargens Diniz Correia2

SUMMARY

The aims of this review of the literature were to conceptualize the gubernacular canal, by an
approach to its function, importance and characteristics of its image in Cone Beam Computed
Tomography. The bibliographic survey of scientific articles was conducted in the following
databases: PubMed, Bireme, Scielo and Google Scholar. The gubernacular canal, which carries
the gubernacular cord within it, is an anatomic structure that starts in the dental follicle and
goes through to the alveolar bone crest behind the deciduous tooth. This set appears to play
an important role in the tooth eruption process, serving as guide to the permanent tooth in the
eruptive trajectory, in addition to being a possible factor in the etiology of odontogenic tumors.
Therefore, knowledge about and visualization of this canal in terminological exams such as
Cone Beam Computed Tomography are relevant in dental clinical practice to help with the
diagnosis of tumors and abnormalities in the eruptive process, thus enabling early intervention
when necessary.

Key words: tooth eruption, cone beam computed tomography, diagnoses by image.

INTRODUCTION

The gubernacular cord (GuCo) is a structure of alveolar crypts and the GuCa (3). The GuCo and
composed of connective tissue, formed from epi- GuCa appear to play an important role in tooth
thelial cells of the dental lamina, which unites the eruption, guiding the tooth in formation in direc-
reduced epithelium of the enamel organ to the tion towards the alveolar process (1, 4). However,
oral mucosa, participating in the direction of the little attention has been paid to these structures
course of tooth eruption (1, 2). This structure is by professionals in the field of dentistry, and rare
localized in the alveolar crest behind the decidu- are the scientific studies that have pointed out its
ous tooth, above the occlusal portion of the dental presence and importance (5, 6).
follicle. The epithelial cells present in this cord The GuCa, a narrow structure approximately
release chemical mediators, such as the Epidermal 1 to 3 mm in diameter, is difficult to visualize in
Growth Factor (EGF) that causes stimulus in the two-dimensional images, such as panoramic ra-
clastic cells, resulting in bone resorption in the diography, for example. In addition to its narrow
region (1, 3). The space formed around the GuCo, diameter, there are inherent limitations to these
between this and the alveolar bone, gives rise to a images, such as superimpositions and magnifica-
delicate canal denominated the gubernacular canal tions (4, 6). It can, however, be precisely analyzed
(GuCa) (1, 3). in Computed Tomography (CT) images (4, 6).
Both tooth germs and GuCos release EGFs that Cone Beam Computed Tomography (CBCT),
constantly stimulate neighboring bone resorption, the type most used in the field of dentistry, pro-
thereby simultaneously establishing the formation duces high quality images with less exposure to
radiation when compared with conventional CT (7,
1
Faculdade Independente do Nordeste – FAINOR, Vitória da 8). Thus, it has become an essential tool for exami-
Conquista, BA, Brasil
2
Departamento de Odontologia, Faculdade Independente do Nor- nation of the maxillae and teeth, as it allows better
deste – FAINOR, Vitória da Conquista, BA, Brasil visualization without superimpositions (6, 8).
Address correspondence to Kariza Vargens Diniz Correia, Depar- Few studies that cite the importance of the
tamento de Odontologia, Faculdade Independente do Nordeste – GuCa have been found in the literature, and in
FAINOR., Av. Luís Eduardo Magalhães, 1035 – Candeias, Vitória day to day Dentistry. Frequently it is not identified
da Conquista, BA, Brasil, CEP: 45055-420.
E-mail: karizacorreia@hotmail.com in either two- or three- dimensional radiographic

86 Stomatologija, Baltic Dental and Maxillofacial Journal, 2020, Vol. 22, No. 3
REVIEWS T. S. Cerqueira et al.

Fig. 1. Bibliographic survey design Fig. 2. Indication of gubernacular canals localized on the
alveolar crests of mandibular incisors

images. Moreover, this structure is unknown to a among them. Out of a total of 19 articles found, 8
large portion of dental surgeons. The aims of this were selected. No chronological inclusion criterion
literature review were to conceptualize the GuCa, was established, because the authors observed that
point out its importance, characteristics and func- there were a very limited number of scientific pub-
tions, and characterize its image in CBCT. lications that offered an approach to this structure.
The search for scientific articles about Cone
MATERIAL AND METHODS Beam Computed Tomography was conducted with
the following words: “Cone Beam Computed To-
For this review of the literature, a search for mography” and “Tomografia Computadorizada
scientific articles was conducted in the following de Feixe Cônico”, using filters for reviews of the
databases: PubMed – https://www.ncbi.nlm.nih. literature published between 2012 and 2018. Thus,
gov/pubmed; Bireme – http://bvsalud.org; Scielo eight articles were selected. A third research was
- http://www.scielo.org/php/index.php; and Google conducted using the descriptors: “gubernacular
Acadêmico – https://scholar.google.com.br/; in the cord” or “gubernacular tract” or “gubernaculum
period from February to May 2018. tracts” in addition to the descriptor “Cone Beam
The bibliographic survey was performed in Computed Tomography” and only 3 articles that
three stages: in the first a research about the gu- coincided with the previous findings were found.
bernacular canal was conducted; in the second, A total of 16 scientific articles were selected and
the topic researched was Cone Beam Computed used in this review (Figure 1). The inclusion and
Tomography; and in the third stage a search was exclusion criteria adopted are described in (Table).
made for articles that were an intersection of the
two topics. REVIEW
In the search the following terms were used:
“cordão gubernacular”, “gubernacular cord”, “gu- Concept and clinical characteristics of the
bernacular canal”, “gubernacular tract”, “guber- gubernacular canal
naculum dentis”, “gubernaculum tracts”, “guber- The GuCa is a small bony canal that starts
naculum cord”, individually, without combinations from the occlusal portion of the dental follicle,

Table. The criteria for study selection

Inclusion Criteria: Exclusion Criteria:

• Literature in the English and Portuguese languages; • Access to resumo/abstract only
• Clinical Studies; • Monographs, dissertations and theses;
• Scientific Researches; • Studies based on researches with animals;
• Literature Reviews; • Studies that cite only the gubernacular cord or canal.
• Literature review of the last 6 years for articles about
CBCT.

Stomatologija, Baltic Dental and Maxillofacial Journal, 2020, Vol. 22, No. 3 87
T. S. Cerqueira et al. REVIEWS

runs through the mandibular/maxillary bone and The dental germs present epithelial tissue in
erupts in the alveolar crest behind the decidu- their constitution, represented by the reduced epi-
ous tooth (Figure 2) (1). Because it is a delicate thelium of the enamel organ, therefore, in a man-
intraosseous structure, this canal cannot be vi- ner similar to that of the GuCos, they also release
sualized clinically; moreover, due to its small EFG and maintain the bone tissue at a distance,
diameter, it is unlikely to be found in two-di- due to bone resorption induced by this mediator
mensional radiographic exams such as panoramic (3). Thus, at the time of new bone tissue formation
radiographs, but it can be detected and analyzed by the mesenchyme, circumscription of the dental
with precision in CBCT (6). germ occurs, keeping it away from the bone, and
This anatomic structure may be found in all the the alveolar crypts are established simultaneously
groups of permanent teeth in patients with normal with formation of the GuCa (3).
dental eruption (6). Running through within it is
the GuCo, composed of fibrous tissue associated Function and importance of the gubernacular
with remnant epithelial cells of the dental lamina canal
that link the epithelial portion of the dental follicle The GuCa appears to perform the important
of the permanent tooth to the gingiva, functioning function of guide for the normal eruption of the
as an eruptive pathway (4, 9). permanent teeth (1, 3, 6, 10). As the eruptive pro-
cess advances, this canal becomes smaller, and
Origin and formation of the gubernacular disappears when the tooth reaches the alveolar
canal crest (6). Therefore, the closer the dental follicle
The first known record of the GuCa and were to the alveolar crest, the shorter would be the
GuCo in the literature was made by an English- length of the GuCa (6).
man John Hunter 1778; although without sci- During the eruptive stage, as the successor
entific proof, he described these structures as a tooth moves in the direction of the oral mucosa,
connection between the alveolar bone crypt of the the diameter of the GuCa is enlarged due to the
tooth germ and oral mucosa (1). Over one hun- osteoclastic activity in the region (1, 3). This
dred years later, in 1887, the French histologist widening occurs for the purpose of accommo-
Louis-Charles Malassez conducted microscopic dating the crown of the tooth in the process of
studies and reported the presence of epithelial eruption (1, 3). As the permanent tooth moves
cells, remnants of the dental lamina, and fibrous in the direction of the gingiva, islets and epi-
cords filling a canal connecting the dental follicle thelial cords of the GuCo are incorporated into
to the gingiva (1). the coronal follicle, increasing its epithelial
The GuCo together with the bone canal, the component (1, 3).
gubernacular canal, which surrounds it, constitute The delay in tooth eruption may be directly
an anatomic structure denominated the gubernacu- associated with some defect of the GuCa, because
lum dentis (2). This structure and the alveolar bone a significant angulation of this canal in relation to
crypts are formed simultaneously after the period the long axis of the tooth, and deformation may
of the dental germ formation (3). be found in unerupted teeth (6, 10). In situations
Initially the GuCo is formed; this process oc- in which there is complaint of delay in tooth erup-
curs when the dental germ has been constituted tion, the shape, angulation and localization of the
and the dental lamina undergoes apoptosis, but GuCa must be minutely analyzed, using CBCT,
strategically some of its cells are not destroyed because when the canal cannot be detected, or it
(3). These remnant cells organize themselves in a presents and abnormal angulation, this may result
manner interlaced with connective fibers to form in delay in eruption of the tooth with which it is
cords that start from the reduced epithelium of the associated (6, 10).
enamel organ, go through to the oral mucosa, and In addition to influence tooth eruption, the
connects them (1, 3). GuCa and GuCo may represent one of the origins
Due to the presence of epithelial cells, the of some odontogenic tumors, which develop from
GuCo releases EGF, a mediator that stimulates the dental lamina or from its remnant epithelial
bone resorption in the region, inducing the activity cells present in the GuCo (4, 5). Abnormal cell
of clastic cells (3). Thus, an area surrounding the proliferation of the epithelial component of this
GuCo and maintaining a space between it and the structure has been pointed out as the cause of the
alveolar bone is always respected, giving origin to appearance of lesions such as the odontoma and
the GuCa (1-3). adenomatoid odontogenic tumor (2, 4, 5, 9).

88 Stomatologija, Baltic Dental and Maxillofacial Journal, 2020, Vol. 22, No. 3
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Cone Beam Computed Tomography GuCo, which have not received adequate atten-
Cone Beam Computed Tomography, developed tion (6).
specifically for dentistry, allows precise evaluation For some authors the relationship of GuCa
of the mineralized tissues in the maxillofacial re- and GuCo with the eruptive process is evident
gion (8). The first reports of its use date back to the and significant, since the guide teeth in the direc-
end of the 1990s, in Italy, when a new CT appliance tion of the alveolar crest (5, 6, 10). According to
created for the area of dentistry was presented (8, Consolaro (3) these structures appear to influence
11). The appliance used the technique of circular the eruption of permanent teeth, however this cor-
scanning around the vertical axis of the patient’s relation still needs to be elucidated. The authors
head, using the beam in the shape of a cone (8, appear to agree that although the gubernacular
11, 12). canal and cord have been known about for a long
Different structures of the maxillofacial time, there is a need for further studies to make
region cannot be well interpreted by means of their participation in the eruptive process clearer
radiographs, therefore CBCT is an extremely (1, 3, 6, 10).
important imaging exam for the diagnosis and Historically, the existence of the GuCa was
planning of dental cases in which the details are pointed out only in the permanent teeth with de-
determinant (16). The quality of its 3D images ciduous predecessors, and in deciduous dentition,
and the possibility of good visualization of the their absence was reported (1). However, at present
three spatial planes (axial, coronal and sagittal) this canal can be identified in the incisors, canines,
allow dentists to make a precise analysis of the premolars and also in the permanent molars that do
bone tissue and teeth, helping to make diagnosis not have deciduous predecessors (1, 6).
and take decisions with regard to the treatment to Recent studies have been conducted with the
be adopted (13-16). purpose of localizing and characterizing the GuCa
in teeth found to be in different stages of eruption
To m o g r a p h i c C h a r a c t e r i s t i c s o f t h e (6, 10). With the use of CBCT, Multidetector Com-
gubernacular Canal puted Tomography (MCT) and even in panoramic
By means of CBCT the GuCa can be identified radiographs, it was possible to observe a significant
in the majority of patients with normal tooth erup- difference in the angulation of the GuCa of maxil-
tion, during different periods of their growth and lary central incisors in a normal process of eruption
development (6, 10). Characterized in the sagittal in comparison with incisors with delayed eruption
and coronal cuts as a low density bone canal con- (4). Furthermore, it was also demonstrated that the
nected to the dental follicle of unerupted permanent group of teeth with delayed eruption presented a
teeth, the GuCa may also be observed by means smaller canal than those teeth with normal erup-
of the axial cut as a narrow, low density circular tion (4).
structure, with a diameter of approximately 1 to 3 In another study, by means of tridimensional
mm, localized in the lingual region of the decidu- images a low rate of visualization of the GuCa in
ous predecessors (6, 10). supernumerary teeth was presented (6). Changes
In some cases of impacted and supernumer- in shape, position and in some cases obliteration of
ary teeth, evaluation by means of CBCT images the canal were noted in teeth with delayed eruption,
is indispensable (13). In these teeth abnormal corroborating the idea that the characteristics of
tomographic characteristics of the GuCa may be the GuCa may indicate abnormality of the eruptive
observed, with changes capable of occurring in process (6, 10).
their angulation, as well as deformation and oblit- A relationship between the GuCa and the
eration (10). etiology of odontogenic tumors was described
in the literature (4). Due to the fact that the gu-
DISCUSSION bernaculum dentis presented remnant epithelial
cells of the dental lamina in its histological com-
The GuCa and GuCo are anatomic structures position, this structure was pointed out as one
that help tooth eruption, however, few studies of the origins of the adenomatoid odontogenic
elucidating their participation in this process tumor (AOT) and of the odontoma (5, 9, 10). In
could be found in the scientific literature (1, 6). the literature researched, no clear association
Professionals from different areas of Dentistry, of the ameloblastoma odontogenic tumor and of
including pediatric dentists and radiologists the Dentigerous Odontogenic Cysts with GuCa
often neglect the importance of the GuCa and was found.

Stomatologija, Baltic Dental and Maxillofacial Journal, 2020, Vol. 22, No. 3 89
T. S. Cerqueira et al. REVIEWS

The association of the AOT with GuCo was observing the characteristics of the GuCa and its
proposed by different authors (2, 5, 9). This hy- stages of development, due to the possibility of
pothesis perhaps explains the fact that this tumor is visualizing it without superimpositions (6, 10). In
rarely associated with deciduous teeth (5). In CBCT all the groups of teeth these canals could be seen
images it was possible to visualize the abnormal in detail in the axial, sagittal and coronal cuts of
widening of the GuCa associated with the lesion. the CBCT, described as a low density rounded
Histologically the continuity of the fibrous capsule area, contiguous to the dental follicle in the region
of the AOT with the GuCo and dental follicle could of the unerupted permanent tooth crown (6, 10).
be observed (5). Particularly in panoramic Computed Tomography
Although it is more common in incisors and images the GuCas of maxillary and mandibular
canines, the AOT could also be found in association molars were visualized with a rectangular shape
with the GuCa of permanent molars (9). Although (6). However, in the majority of cases it is not
the GuCo was pointed out in one study (5) as being possible to detect this structure in radiographs
the origin in 96% of the AOTs in incisors, canines and panoramic tomographs, in spite of it being
and premolars, the tissues present in the pericoronal present (6, 10).
region of unerupted teeth, including the GuCo must
be studied and explored in greater depth, to make it CONCLUSION
possible to affirm that the proliferation of the AOT
occurs from its epithelial cells (5, 9). Evaluation of characteristics such as shape,
The majority of odontomas are found in as- diameter, angulation and localization of this canal,
sociation with unerupted teeth (4). By using tridi- precisely observed by means of CBCT, may help
mensional CBCT and MCT images it was possible to indicate abnormalities in the eruptive process,
to find that 70% of the odontomas of unerupted and to predict the development of odontogenic tu-
teeth showed no connection with the GuCo (4). This mors, thereby making early intervention possible,
ratified the need to be aware of this structure that is whenever necessary. However, little attention has
frequently forgotten or unknown to dentists (4, 5, 9). been paid to this structure by professionals in the
In this scenario, CBCT is considered the field of dentistry, and rare are the scientific studies
best terminological method for identifying and that have emphasized its presence and importance.

REFERENCES

1. Ferreira DCA, Fumes AC, Consolaro A, Nelson Filho Port Estomatol Med Dent Cir Maxilofac 2012;53:47–52.
P, de Queiroz AM, de Rossi A. Gubernacular cord and 8. Rech AS, Toé KPD, Claus J, Junior BP, Freitas MPM,
canal – does these anatomical structures play a role in Thiesen G. Utilização da tomografia computadorizada
dental eruption? RSBO 2013;10:167-71. de feixe cônico no diagnóstico odontológico. Full Dent
2. Philipsen HP, Khongkhunthiang P, Reichart PA. The Sci 2015;6:261-75.
adenomatoid odontogenic tumour: an update of selected 9. Priya SP, Higuchi A, Fanas SA, Ling MP, Neela VK,
issues. J Oral Pathol Med 2016;45:394-8. doi: 10.1111/ Sunil PM, et al. Odontogenic epithelial stem cells: hid-
jop.12418. den sources. Lab Invest 2015;95:1344-52.
3. Consolaro A. Tracionamento ortodôntico: possíveis con- 10. Oda M, Nishida I, Miyamoto I, Habu M, Yoshiga D,
sequências nos caninos superiores e dentes adjacentes. Kodama M, et al. Characteristics of the gubernaculum
Parte 1: reabsorção radicular nos incisivos laterais e pré- tracts in mesiodens and maxillary anterior teeth with
molares. Dental Press J Orthod 2010;15:15-23. delayed eruption on MDCT and CBCT. Oral Surg Oral
4. Oda M, Miyamoto I, Nishida I, Tanaka T, Kito S, Seta Y, Med Oral Pathol Oral Radiol 2016;122:511-16.
et al. A spatial association between odontomas and the 11. Abramovitch K, Rice DD. Basic Principles of Cone
gubernaculum tracts. Oral Surg Oral Med Oral Pathol Beam Computed Tomography. Dent Clin North Am
Oral Radiol 2016;121:91-5. 2014;58:463-84.
5. Ide F, Mishima K, Kikuchi K, Horie N, Yamachika S, 12. Mupparapu M, Nadeau C. Oral and Maxillofacial Imag-
SatomuraK, et al. Development and Growth of Adeno- ing. Dent Clin North Am 2016;60:1-37. doi: 10.1016/j.
matoid Odontogenic Tumor Related to Formation and cden.2015.08.001.
Eruption of Teeth. Head and Neck Pathol 2011;5:123-32. 13. Venkatesh E, Elluru SV. Cone beam computed tomogra-
6. Nishida I, Oda M, Tanaka T, Kito S, Seta Y, Yada N, et phy: basics and applications in dentistry. J Istanbul Univ
al. Detection and imaging characteristics of the guber- Fac Dent 2017;51:102-01.
nacular tract in children on cone beam and multidetector 14. MacDonald D. Cone-beam computed tomography
computed tomography. Oral Surg Oral Med Oral Pathol and the dentist. J Investig Clin Dent. 2017;8:1-6. doi:
Oral Radiol 2015;120:109-17. 10.1111/jicd.12178.
7. Correia F, Salgado A. Tomografia computorizada de feixe 15. Tsapaki V. Radiation protection in dental radiology
cónico e a sua aplicação em Medicina Dentária. Rev – Recent advances and future Directions. Phys Med.

90 Stomatologija, Baltic Dental and Maxillofacial Journal, 2020, Vol. 22, No. 3
REVIEWS T. S. Cerqueira et al.

2017;44:222-6. doi: 10.1016/j.ejmp.2017.07.018. mi M. Dental cone beam CT: A review. Phys Med.
16. Kiljunen T, Kaasalainen T, Suomalainen A, Kortesnie- 2015;31:844-60. doi: 10.1016⁄ j.ejmp.2015.09.004.

Received: 11 07 2019
Accepted for publishing: 25 09 2020

Stomatologija, Baltic Dental and Maxillofacial Journal, 2020, Vol. 22, No. 3 91