ISSN:
Electronic version: 1984-5685
RSBO. 2013 Apr-Jun;10(2):167-71
Literature Review Article
Gubernacular cord and canal – does these
anatomical structures play a role in dental
eruption?
Danielly Cunha Araújo Ferreira1
Ana Caroline Fumes1
Alberto Consolaro2
Paulo Nelson-Filho1
Alexandra Mussolino de Queiroz1
Andiara De Rossi1
Corresponding author:
Danielly Cunha Araújo Ferreira
Departamento de Clínica Infantil, Odontologia Preventiva e Social
Faculdade de Odontologia de Ribeirão Preto – USP
Av. do Café, s/n.
CEP 14040-903 – Ribeirão Preto – SP – Brasil
E-mail: daniellycaf@hotmail.com
1
Department of Child Clinics, Preventive and Social Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo
– Ribeirão Preto – SP – Brazil.
2
Department of Pathology, School of Dentistry of Bauru, University of São Paulo – Bauru – SP – Brazil.
Received for publication: May 22, 2012. Accepted for publication: November 5, 2012.
Abstract
Keywords:
tooth eruption;
primary dentition;
permanent dentition.
Introduction: The gubernacular cord is an original structure of the
dental lamina, which undergoes apoptosis and their remnants were
organized in the form of epithelial islets and strands that lined up,
leaving the reduced epithelium of the enamel organ towards the oral
mucosa. This structure is located within the gubernacular canal,
which can be identified as a small opening in the alveolar region
of the lingual or palatal surface of the deciduous teeth. Objective:
To conceptualize, identify and assess the possible contribution of
the gubernacular cord and canal in the process of tooth eruption.
Literature review: A review of literature on Pubmed, Medline and
Bireme databases, without datum restriction. Little amount of scientific
articles were found, and only 14 studies were identified. The authors
addressed the matter succinctly, with little information about these
structures, which can play an important role in the process of tooth
eruption. Conclusion: The gubernacular cord and canal are anatomical
structures located in the alveolar bone crest of the maxilla or mandible,
168 –
Ferreira et al.
Gubernacular cord and canal – does these anatomical structures play a role in dental eruption?
behind the deciduous teeth. These structures appear to exhibit the
ability to aid the eruption path of the permanent teeth successors.
Despite being a relevant subject, few professionals know this structure
and its possible role in the process of tooth eruption.
Introduction
Tooth eruption is a physiologic process in
which a tooth undergoing formation migrates from
its development site within the alveolar processes
to its functional positions inside the oral cavity
[18]. During this process, the participation of
different anatomic structures, cells, chemical and
molecular mediators occurs and although there
have been a great advancement in the scientific
knowledge regarding this issue, still today the
cellular, molecular and anatomic mechanisms
involved in tooth eruption process are not fully
understood [17, 28, 29]. Aiming to explain the
tooth eruption process, countless theories have
been proposed over the years, such as the theory
of root growth [18], alveolar bone growth [4, 20],
pulpal growth [25], in addition to the theory of
the combination of genetic factors [26] and the
follicular theory [6, 15], which has been the most
accepted nowadays.
The follicular theory postulates that the
dental follicle is capable of inducing, guiding
and coordinating the bone resorption above the
crown of a teeth undergoing formation and bone
apposition below this same crown, which enables
that during the intraosseous eruptive phase of
the tooth eruption process the formation of a
eruptive path occur and the tooth undergoing
formation be passively conducted through this
path [6, 15].
The gubernacular cord is a structure composed
of conjunctive tissue which link the tooth follicle
to the overlying gingiva, showing the function
of guiding or directing the course of the tooth
eruption. The formation of this structure starts
from the remnants cells of the tooth lamina which
are organized as a fibrous cord leaving the reduced
epithelium of the enamel organ towards the oral
mucosa [9, 10]. This structure is located in the
alveolar ridge behind the deciduous tooth [7, 12].
In this cord, there is the presence of countless
chemical mediators, including EGF (epithelial
g row t h factor), a substa nce secreted by t he
epithelial cells having the capacity of stimulating
the formation of clasts and consequently a bone
resorption, making impossible the filling of
the cord area by alveolar bone, always leaving
a space surrounding this cord, so-called the
gubernacular canal (figures 1 to 3) [8, 9]. Bothe
the gubernacular canal and cord are structures
very little studied on the scientific literature;
however t hey seem to play some role in t he
process of tooth eruption.
The aim of this study was to conceptualize,
identify and assess the possible contribution of
the gubernacular cord and canal in the process
of tooth eruption.
Figure 1 – Dry child skull. Gubernacular canals located
in the alveolar bone crest, behind the mandibular
deciduous incisors
Figure 2 – Dry child skull. Gubernacular canals located
in the alveolar bone crest, behind the mandibular
deciduous incisors
RSBO. 2013 Apr-Jun;10(2):167-71 –
Figure 3 – Dry child skull. Gubernacular canals located in
the alveolar bone crest, behind the maxillary deciduous
incisors
Material and methods
A bibliographic searching was conducted on
the following databases Pubmed, Bireme, Medline,
Google and Central Library of the University of São
Paulo – Campus of Ribeirão Preto, without datum
restriction, through using the terms: gubernacular
cord, gubernacular canal, gubernaculum dentis,
deciduous dentition, permanent dentition and tooth
eruption. Only 14 scientific studies were found
in all literature researched. Of these studies, ten
were written in English, one in Portuguese, one in
Japanese, on in Italian, and one in France.
Literature review
The first reference to the gubernacular cord
and canal occurred in 1778, by an English called
John Hunter, which described these structures after
observing a connection between the bone ridge of the
tooth in development and the gingiva, without little
scientific proof [11]. Almost one century later, this
observation was supported by microscopic studies
conducted by the France histologist Louis-Charles
Malassez, in 1887. He described the existence of
remnants of the tooth lamina (epithelial cells)
and longitudinal fibers that were within a canal
connecting the gingiva with the permanent tooth
bud [14].
The gubernacular canal, which enables the
continuity of the bone ridge of permanent incisors,
canines and premolars with the tissue of the
overlying gingiva itself, it is filled by the gubernacular
cord, which is composed by a fibrous conjunctive
tissue containing peripheral nerves, blood and
169
lymphatic vessels, as well as epithelial cells or cell
aggregates coming from the fragmentation of the
tooth lamina. Thus, the gubernacular cord is the
connection between the conjunctive tissue of the
ridge with the oral mucosa [22].
During the pre-eruptive phase of tooth eruption,
the tooth buds have special relationship with the
growing jaws. At this phase, the gubernacular canal
does not undergo perceptive alterations in shape or
size [5]. During the eruptive phase, according to the
successor tooth moves towards the axial direction
to the oral cavity, the gubernacular canal is widened
by the local osteoclastic activity, with the aim of
accommodating the crown of the permanent tooth
undergoing eruption [7]. The tooth moves towards
the mucosa, the pericoronary follicle incorporates
within its conjunctive tissue the islets and cords
of epithelial cells from the gubernacular cord,
progressively increasing the epithelial component
at this area [9].
The role of the gubernacular cord in the eruption
process was investigated Cahill and Marks [6], who
observed that the surgical section of this structure
in dogs did not alter the eruption rates and the final
position of the tooth. A next study, in which the
section of the gubernacular cord and the surgical
removal of the crown parts of the tooth follicle were
executed, enabled to observe the interruption in the
tooth eruption process, demonstrating that the tooth
follicle has a fundamental role in the physiologic
movement of the tooth towards the oral cavity and
that if the gubernacular cord has some role in the
process of tooth eruption, this is not relevant for
the occurrence of the process [5].
According to Hodson [10], the gubernacular
cord was not described in association with the
deciduous dentition, only with the permanent
dentition with the deciduous predecessor. However,
according to Scott [27], the permanent molar teeth,
which did not have a deciduous predecessor, also
have their follicles connected to the oral mucosa by
gubernacular cords, so-called by the author “molar
gubernacular cords”.
Philipsen [23] theorized that the gubernacular
cord could have implication in the development of
the adenomatoid odontogenic tumor (AOT), because
this contains remnants of the tooth lamina. These
epithelial remnants are very closer to the crown of
the permanent tooth and they can move during the
tooth eruption process along with the gubernacular
canal and induce AOT formation, because among
the many hypotheses for the pathogenesis of this
tumor are the remnants of the tooth lamina.
170 –
Ferreira et al.
Gubernacular cord and canal – does these anatomical structures play a role in dental eruption?
Discussion
Despite the first reference to the gubernacular
cord and canal have been shown in 1778 by John
Hunter, 234 years ago, the existence and function of
this structure are still controversial and questioned.
According to Hodson [10], these structures are
present only in association with the permanent
teeth with deciduous predecessor, fact corroborates
by Cahill et al. [5] and Philipsen and Reichart [22].
However, Scott [27] suggested that the permanent
teeth without deciduous predecessor also displayed
gubernacular cord and canal, connecting the bud
to the oral mucosa.
Notably, the description of the gubernacular
cord and canal was only recently incorporated to the
pattern of the American texts [3]. The explanation
could be based on the fact that, by the omission
of this gubernacular canal, the existing theories
on the pressure for the eruption recommended by
some professor and researchers influenced by the
wrong concept that the successor tooth would be
stuck by a complete bone coating, could be more
easily accepted [5]. Some authors [5, 10, 27] believe
that the gubernacular canal and cord have a role
in the direction of the teeth, making the eruption
easier; while others [6] claimed that these structures
do not exert any type of interference. According to
Philipsen et al. [23], the gubernacular cord and
canal can influence on AOT development, because
AOT in about 80% of the cases is located at the
region of the permanent incisors and canines,
where the gubernacular cord and canal is present
[21, 24]. Some authors [13, 19, 30] sympathize with
this hypothesis, because rarely AOT is found in
association with the deciduous teeth, which could be
justified by the absence of the gubernacular cord in
the deciduous dentition, according to Hodson [10].
Ide et al. [12] questioned that sometimes (4% of
the pericoronary lesions) AOT occurs in permanent
molars, which did not have according Hodson [10],
the gubernacular cord and canal. Notwithstanding,
it valid to remember that Scott [27] reported the
presence of the “molar gubernacular cords”, which
could explain the occurrence of this tumor type
in these teeth.
Until now, the ability of the dentist to interfere
or treat an included or impacted tooth due to
eruption failure is limited to surgical or mechanical
procedures, such as: the extraction of a deciduous
tooth, surgical removal of the alveolar bone, the
aid of the mucosal penetration through gingival
incision and orthodontic tooth traction [2]. Perhaps
by knowing deeply the role of the structures such
the gubernacular cord and canal and its possible
role in tooth eruption process, one can develop in
the future mechanisms that allow the interference
in the eruptive process due to these structures.
Conclusion
The gubernacular cord is the structure coming
from the tooth lamina that after undergoing
apoptosis has its remnants organized in islets and
epithelial cords that lined up leaving the reduced
epithelium of the enamel organ towards the oral
mucosa. The gubernacular cord in located within a
alveolar bone scaffold, so-called the gubernacular
canal.
The existence of both the gubernacular canal
and cord is proved in the permanent dentition with
deciduous predecessor; however, their existence
is not still proved in the deciduous dentition.
Concerning to the permanent dentition without
deciduous predecessor, some authors defend their
existence and others do not.
After the careful analysis of the studies, it is
observed that still there are divergences on the
function of the gubernacular cord and canal in
tooth eruption process.
Although the tooth eruption process is a very
researched issue in the literature, the role of the
gubernacular cord and canal in tooth eruption is
still very obscure, and further studies are necessary
to clarify its real function. Therefore, it is necessary
to deepen the knowledge on this issue, which can
interfere on the treatment options for impacted or
included teeth as well as on the guided direction
of tooth eruption.
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