Detection of the gubernacular canal and its attachment to the dental follicle may indicate an abnormal eruption status

Extracellular vesicles derived from dental follicle stem cells regulate tooth eruption by inhibiting osteoclast differentiation

Tooth eruption as a crucial part in tooth development and regeneration is accompanied by ongoing osteogenesis and osteoclast activity. The dental follicle (DF) surrounding the developing tooth harbors dental follicle stem cells (DFSCs) which play a crucial role in maintaining bone remodeling. However, the mechanisms through which they regulate the balance between osteogenesis and osteoclast activity during tooth eruption remain poorly understood. Notably, extracellular vesicles (EVs) in bone homeostasis are considered essential. Our study revealed that the DFSCs could modulate tooth eruption by inhibiting osteoclast differentiation via EVs. Further investigation showed that EVs from DFSCs could inhibit osteoclast differentiation through the ANXA1-PPARγ-CEBPα pathway. Animal experiments indicated that EVs from DFSCs and the cargo ANXA1 affected tooth eruption. In summary, this study suggests the critical role of the dental follicle in tooth eruption through EVs, which may provide therapeutic targets for abnormal tooth eruption and effective approaches for the eruption of regenerated teeth.

Imaging characteristics of gubernaculum tracts in patients with cleidocranial dysplasia: a computed tomography study

OBJECTIVES

To elucidate the imaging characteristics of the gubernaculum tract (GT) in patients with cleidocranial dysplasia (CCD) as visualized with computed tomography (CT).

STUDY DESIGN

This was a retrospective analysis of the presence and shape of GTs of unerupted permanent teeth and supernumerary teeth on CT in 9 patients with CCD.

RESULTS

The overall GT detection rate for unerupted permanent teeth was 83.5% (81/97), with no significant difference between permanent teeth without and with adjacent supernumerary teeth (P = .414). The overall GT detection rate for unerupted supernumerary teeth was 83.1% (49/59). Of the 156 total unerupted teeth analyzed, 83.3% (130/156) were judged to have GTs. No significant difference in detection rate of GTs was found between permanent and supernumerary teeth (P > 0.999). A composite morphology consisted of a single GT for a permanent unerupted tooth with 1 or 2 supernumerary teeth in which the dental follicles of the permanent and supernumerary teeth were confluent. In total, 44 groups consisted of 1 permanent and 1 or 2 supernumerary teeth; 79.5% (35/44) had GTs.

CONCLUSIONS

A specific composite structure of GTs and dental follicles may signify that 2 or 3 teeth are derived from a single dental lamina in patients with CCD. In such cases, tooth eruption may fail due to the presence of only 1 GT for multiple teeth.

Association between gubernacular canals characteristics and teeth eruption status: a cone-beam computed tomography study

Background

There have been few studies that have evaluated the imaging characteristics of the gubernacular canal. Additionally, it is important to understand the role of this structure and its relationship with tooth erupt. Therefore, the objective of this study was to investigate the association between gubernacular canal features and teeth eruption status on cone-beam computed tomography (CBCT) images.

Material and Methods

In this cross-sectional study, 150 CBCT images were obtained from patients referred to a maxillofacial radiology clinic in Babol, northern Iran, in 2021. Eruption status (normal, delayed, and impacted) and the presence of the gubernacular canal were recorded. If the gubernacular canal was detected, its opening site in the alveolar crest (buccal, lingual, and central) and its attachment site to the dental follicle (usual, unusual) were further assessed.

Results

Gubernacular canal was observed in 133 (88.7%) of the total 150 CBCT images. Also, 41 cases (27.3%) had impacted teeth. The detection rate of the gubernacular canal in the normal, delayed, and impacted eruption of teeth was 92.1% (n=93), 75.0% (n=6), and 82.9% (n=34), respectively (p=0.135). Opening the gubernacular canal in the alveolar crest was not associated with teeth eruption status. Also, unusual attachment sites of the gubernacular canal to dental follicles were mostly seen in abnormal eruptions.

Conclusions

According to the findings, observing the presence of the gubernacular canal on CBCT may not help anticipate teeth eruption problems. Key words:Gubernacular canal, Cone-beam computed tomography, Tooth eruption.

Morphological variation of gubernacular tracts for permanent mandibular canines in eruption: a three-dimensional analysis

OBJECTIVES

This study aims to evaluate the morphological features of gubernacular tract (GT) for erupting permanent mandibular canines at different ages from 5 to 9 years old with a three-dimensional (3D) measurement method.

METHODS

The cone-beam CT images of 50 patients were divided into five age groups. The 3D models of the GT for mandibular canines were reconstructed and analysed. The characteristics of the GT, including length, diameter, ellipticity, tortuosity, superficial area, volume, and the angle between the canine and GT, were evaluated using a centreline fitting algorithm.

RESULTS

Among the 100 GTs that were examined, the length of the GT for mandibular canines decreased between the ages of 5 and 9 years, while the diameter increased until the age of 7 years. Additionally, the ellipticity and tortuosity of the GT decreased as age advanced. The superficial area and volume exhibited a trend of initially increasing and then decreasing. The morphological variations of the GT displayed heterogeneous changes during different periods.

CONCLUSIONS

The 3D measurement method effectively portrayed the morphological attributes of the GT for mandibular canines. The morphological characteristics of the GT during the eruption process exhibited significant variations. The variations in morphological changes may indicate different stages of mandibular canine eruption.

Assessment of gubernacular canal frequency with CBCT in a group of Turkish population

OBJECTIVE

The aim of this study is to investigate the frequency of the gubernacular canal observed on cone-beam computed tomography (CBCT) images in a group of Turkish populations according to age and gender.

MATERIALS AND METHODS

CBCT images of 500 cases were evaluated retrospectively, and a total of 117 impacted or erupting teeth were included in the study, and the presence of gubernacular canal was recorded according to age, gender and eruption status of the tooth. SPSS program was used for statistical analysis.

RESULTS

The mean age of 117 buried/continuing patients was 17 ± 15.32, 55 (47%) were female and were 62 (53%) male patients. Presence of gubernacular canal was observed in 91 (77.8%) cases and this duct was not detected in 26 (22.2%) cases. While 40.2% of female were found to have canals, 37.6% of male had canals. When the presence of canals was examined, the presence of canals was found to be significantly higher in the erupting teeth. A significant difference was found when analyzed according to the mean age.

CONCLUSIONS

CBCT is a useful method of detecting the gubernacular canal. The presence of gubernacular canal was significantly higher in erupting teeth.

CBCT Assessment of Gubernacular Canals on Permanent Tooth Eruption in Down's Syndrome

BACKGROUND

The gubernacular canal (GC) is an important dental structure that enables the alveolar bone ridge cohesion of permanent teeth, although GC absence may indicate a dental eruption that might be associated with certain syndromes such as Down's syndrome. This study aims to correlate the eruptive delay of permanent teeth in individuals with Down's syndrome (Ds) and the gubernacular canal (GC) through cone-beam computed tomography (CBCT).

METHODS AND RESULTS

This cross-sectional study was conducted between January and July 2022 with a total of 31 individuals (G1 = 16 nonsyndromic and G2 = 15 Down's syndrome) who went through imaging evaluation using CBCT with the following acquisition parameters: tube voltage of 95 kVp, tube current of 7 mA, exposure time of 5.9 s and voxel sizes and field of view 0.15 mm and 0.30 mm, respectively. The imaging evaluation was to assess whether all teeth analyzed had the presence of GC and/or teeth eruption disturbance, with a descriptive statistical analysis of relative frequencies and quantitative variables as well as the p-value (p < 0.005) by G Test.

RESULTS

A total of 618 teeth among 31 individuals were analyzed, 475 (76.8%) GC were detected by CBCT in 23/31 patients and of these, 6 belonged to G2. G2 had a decreased GC detection rate (n = 180-37.9%) and the most common tooth with GC detected was the mandibular 1st molar (21 GC/25 teeth-84%) and the absence of GC was most frequently observed in impacted and delayed/unerupted teeth of Ds individuals.

CONCLUSION

We concluded that GC absence was higher among Ds individuals, explaining the increased rates of unerupted or impacted teeth in Ds individuals.

Detection and characteristics of the gubernacular tract in supernumerary teeth on cone beam computed tomography

OBJECTIVES

The aim of this study was to evaluate the prevalence and visualization of supernumerary teeth (ST) and imaging characteristics of their gubernacular tract (GT) using cone beam computed tomography (CBCT).

METHODS

Presence and visualization of ST were retrospectively evaluated using 960 CBCT images. The imaging characteristics of GT were analyzed to determine various presentations of GT according to type, shape, and orientation of ST.

RESULTS

ST were radiographically detected in 93 patients, for a prevalence of 9.7%. Premolar shaped ST were more common (p = 0.003). GT was detected in 104 (77.2%) of impacted ST and mostly found straight in shape (49.0%). It was most frequently observed in peridens (n = 51, 49.0%) followed by mesiodens (n = 41, 39.4%) and more frequently seen in premolar-like ST (n = 44, 42.3%). The mean length of the GT in mandible was 2.8 mm, the mean length of the GT in maxilla was 1.0 mm (p < 0.001). The mean angle of the GT in mandible was 17.0, and the mean angle of the GT in maxilla was 43.0 (p = 0.004).

CONCLUSIONS

CBCT can be used for evaluations in dental practice to provide comprehensive information about ST and their GT characteristics. Clinicians should be able to identify the characteristics of GTs on CBCT for dental treatments, especially traction and extraction of ST.

CBCT Assessment of the Anatomical Characteristics of Gubernacular Canal in Impacted Teeth

STATEMENT OF THE PROBLEM

Gubernacular canal (GC) is a canal that extends from the follicle of unerupted permanent teeth to the alveolar bone crest filled with remnants of the dental lamina. This canal is thought to guide tooth eruption and be related to some pathologic conditions.

PURPOSES

This study aimed to determine the presence of GC and its anatomical characteristics in teeth, which failed to erupt normally on cone beam computed tomography (CBCT) images.

MATERIALS AND METHOD

This cross-sectional study evaluated CBCT images of 77 impacted permanent and supernumerary teeth obtained from 29 females and 21 males. The frequency of GC detection, its location in relation to the crown and root, the anatomical surface of the tooth from which the canal has originated, and the adjacent cortical table to which the canal opens, along with the length of the GC were studied.

RESULTS

GC was observed in 53.2% of teeth. The anatomical tooth aspect of origin was occlusal/ incisal in 41.5% and crown in 82.9% of teeth. Moreover, 51.2% of GCs opened in palatal/lingual cortex and 63.4% of canals were not located along the tooth long axis. Finally, GC was detected in 85.7% of teeth undergoing the crown formation stage.

CONCLUSION

Although GC was introduced as an eruption pathway, this canal is also present in impacted teeth. This means that presence of this canal does not promise the normal eruption of tooth and the anatomical characteristics of GC may influence the eruption process.

Imaging characteristics of the gubernaculum tracts in successional teeth related to deciduous fused teeth on computed tomography

The purpose of this study was to elucidate the imaging characteristics of the gubernaculum tracts in successional teeth related to fused deciduous teeth on computed tomography. The imaging findings of 15 gubernaculum tracts in successional teeth related to fused deciduous teeth were retrospectively analyzed using cone-beam computed tomography or multidetector computed tomography. In cases without a congenitally defected successor, the two gubernaculum tracts of two successional teeth related to fused deciduous teeth were fused into one. Gubernaculum tracts (GTs) in mesial successors were vertical, but in distal successors they were inclined to mesial. The major abnormalities of the successional teeth related to fused deciduous teeth were delayed eruption and delayed formation. No inclined mesial successors were found, whereas most of the distal successors were inclined to mesial along with the inclined GT. The gubernaculum tracts of successors with a congenital defect of the other successors were vertical, and such successors had no abnormalities. The present study showed the imaging characteristics of gubernaculum tracts in successional teeth related to fused deciduous teeth. The abnormal eruption of successional teeth related to fused deciduous teeth may be associated with the characteristics of their gubernaculum tracts.

Overview of Radiological Studies on Visualization of Gubernaculum Tracts of Permanent Teeth

The eruption pathway from the dental follicle to the gingiva for permanent teeth is known as the gubernaculum tract (GT), a physiologic structure thought to play a role in tooth eruption. Cone beam computed tomography and multi-detector computed tomography have recently been used to visualize the GT, with the results indicating that this structure might be related to the normal eruption of teeth. By contrast, curved and/or constricted GTs may lead to abnormal tooth eruption. In addition, complex odontomas have been reported from within the GT or dental sac of unerupted permanent teeth. If an odontoma occurs within the GT, the tooth will not erupt normally. Moreover, the imaging characteristics of the GT from the top of the odontogenic mass to the alveolar crest are extremely useful for making a differential pathological diagnosis and for differentiating between odontogenic and non-odontogenic masses. Therefore, radiological studies on the GT have been attracting increasing attention. Given this background, the present review aims to clarify the imaging characteristics and review recent studies on the GT considering the importance of the research.

Imaging peculiarities of gubernaculum tracts in molars as accessional teeth on CT

Objectives

The shapes of gubernaculum tracts (GTs) in molars as accessional teeth remain unidentified. To elucidate imaging peculiarities of GTs in molars with aging on multidetector‐row computed tomography (MDCT).

Material and methods

This retrospective study was conducted using CT images, including maxillary and mandibular molars, with no abnormal findings from 239 patients. Shapes of alveolar bone, GTs, and dental sacs of the maxillary and mandibular molars were analyzed multi‐sectionally. Correlations between 2‐ and 3‐dimensional imaging figures of GTs in molars and chronological age or stage of molar formation were analyzed.

Results

Some forms of GTs in maxillary and mandibular third molars were observed. In the early stage, GTs were visualized as bone defect lines on the dentition and grooves on the mesial alveolar crest continuous with the dental sac to mesial tooth bud. GTs of the third molar formed a J‐shape in maxillary teeth and Y‐shape in mandibular teeth in the middle stage, as alveolar bone around the GT developed. In the mature stage, the course of the GT changed to straight and perpendicular. Some GT forms were also identified in first and second molars. Significant correlations were found between GT alterations and chronological age or stage of molar formation. Moreover, tracts continuing from the distal side of mandibular third molars were detected.

Conclusions

This paper describes the peculiarities and process of progression for GTs in molars, and the existence of tracts continuing from the distal side of mandibular third molars, unlikely dentition with deciduous predecessors. These preliminary data should prove beneficial for studies focusing on GTs in molars.

Case Report: An association of the gubernacular canal, supernumerary tooth and odontoma with an impacted canine on cone-beam computed tomography

This report describes a clinical case of asymptomatic compound odontoma in the anterior left side of the maxilla associated with an impacted canine and supernumerary tooth with a gubernacular canal of a 47- year-old female with no relevant medical history. Cone-beam computed tomography (CBCT) was performed for precise three-dimensional localization of each structure and assessment of their spatial relationship with the associated structures before surgery. The treatment protocol involved surgical enucleation of the odontoma and open extraction of both impacted and supernumerary teeth. The patient had uneventful healing and proceeded with the prosthodontic treatment plan.

The dentist should be aware of the probability of a close relationship between the development of odontoma and presence of the gubernacular tract, which could be used as a future radiographic diagnostic criterion of an odontoma. Also, we recommend that more studies be performed in this field to deeply analyze the imaging characteristics of GT and its spatial association with various pathological lesions in the future.

Imaging characteristics of Gubernacular Tract on CBCT- A pictorial review

The Gubernaculum Dentis (GD) is an anatomical structure connecting the dental follicle of the permanent tooth to the overlying gingiva. It is composed of Gubernacular cord (GCo) and a surrounding bony canal called as Gubernacular canal (GC) or Gubernacular Tract (GT). GD is a physiologic structure that has claimed to play some role in the eruption of teeth. GCo is a histologic structure, however, the surrounding GT can be identified radiographically. But due to its infinitesimal appearance, its differentiation with normal bone marrow spaces on conventional radiographs is extremely difficult and is the reason for its sporadic reference in the oral radiology literature. The advent of advanced imaging modalities such as Cone Beam Computed Tomography (CBCT) has led to its distinct identification in the recent studies not only in the normal erupting teeth but in teeth with altered eruption pattern, impacted teeth, supernumerary teeth, odontogenic cysts and tumors as well. The identification of GT on CBCT is usually an incidental finding and because of its physiologic nature, the imaging characteristics of GT have not been studied extensively. This pictorial review aims to demonstrate the imaging characteristics of GT in diverse relations with the normal teeth, impacted teeth, supernumerary teeth, odontomas and odontogenic cysts and tumors. This will help in understanding the various presentations of GT and will serve as a teaching guide for oral and maxillofacial radiologists for their easy identification and their possible causal association with various eruptive pathologies.

Isorhamnetin 3-O-neohesperidoside promotes the resorption of crown-covered bone during tooth eruption by osteoclastogenesis

Delayed resorption of crown-covered bone is a critical cause of delayed tooth eruption. Traditional herbal medicines may be good auxiliary treatments to promote the resorption of crown-covered bone. This study was carried out to analyse the effect of isorhamnetin 3-O-neohesperidoside on receptor activator of nuclear factor-kB ligand (RANKL)-induced osteoclastogenesis in vitro and resorption of the crown-covered bone of the lower first molars in mice in vivo. Isorhamnetin 3-O-neohesperidoside promoted osteoclastogenesis and the bone resorption of mouse bone marrow macrophages (BMMs) and upregulated mRNA expression of the osteoclast-specific genes cathepsin K (CTSK), vacuolar-type H + -ATPase d2(V-ATPase d2), tartrate resistant acid phosphatase (TRAP) and nuclear factor of activated T-cells cytoplasmic 1 (NFATc1). NFATc1, p38 and AKT signalling was obviously activated by isorhamnetin 3-O-neohesperidoside in osteoclastogenesis. Isorhamnetin 3-O-neohesperidoside aggravated resorption of crown-covered bone in vivo. In brief, isorhamnetin 3-O-neohesperidoside might be a candidate adjuvant therapy for delayed intraosseous eruption.