Over 15% of the population studied had additional foramina in the anterior palate, between 1 mm and 1.9 mm wide, with variable locations. In most cases the canals associated with these foramina either presented as a direct extension of the canalis sinuosus, or coursed towards the nasal cavity floor.

The neurovascular bundle may be vulnerable during surgical procedures involving the mandible, especially when anatomical variations are present. Increased demand of implant surgeries, wider availability of three-dimensional exams, and lack of clear definitions in the literature indicate that features of anatomical variations should be revisited. The objective of the study was to evaluate features of anatomical variations related to mandibular canal (MC), such as bifid canals, anterior loop of mental nerve, and corticalization of MC. Additionally, bone trabeculation at the submandibular gland fossa region (SGF) was assessed and related to visibility of MC. Cone beam computed tomography exams from 100 patients (200 hemimandibles) were analyzed and the following parameters were registered: diameter and corticalization of MC; trabeculation in SGF region; presence of bifid MC, position of bifurcations, diameter, and direction of bifid canals; and measurement of anterior loops by two methods. Corticalization of the MC was observed in 59% of hemimandibles. In 23%, MC could be identified despite absence of corticalization. Diameter of MC was between 2.1 and 4 mm for nearly three quarters of the sample. In 80% of the sample trabeculation at the SGF was either decreased or not visible, and such cases showed correlation with absence of MC corticalization. Bifid MC affected 19% of the patients, mostly associated with additional mental foramina. Clinically significant anterior loop (>2 mm of anterior extension) was observed in 22-28%, depending on the method. Our findings, together with previously reported limitations of conventional exams, draw attention to the unpredictability related to anatomical variations in neurovascularization, showing the contribution of individual assessment through different views of three-dimensional imaging prior to surgical procedures in the mandible.

The identification of the mandibular canal (MC) is an important prerequisite for surgical procedures involving the posterior mandible. Cone beam computed tomography (CBCT) represents an advance in imaging technology, but distinguishing the MC from surrounding structures may remain a delicate task.ObjectivesThe aim of this study was to assess the visibility of the MC in different regions on CBCT cross-sectional images.Material and methodsCBCT cross-sectional images of 58 patients (116 hemi-mandibles) were analyzed, and the visibility of the MC in different regions was assessed.ResultsThe MC was clearly visible in 53% of the hemi-mandibles. Difficult and very difficult visualizations were registered in 25% and 22% of the hemi-mandibles, respectively. The visibility of the MC on distal regions was superior when compared to regions closer to the mental foramen. No differences were found between edentulous and tooth-bearing areas.ConclusionsThe MC presents an overall satisfactory visibility on CBCT cross-sectional images in most cases. However, the discrimination of the canal from its surrounds becomes less obvious towards the mental foramen region when cross-sectional images are individually analyzed.

The results of this study suggest that CBCT is an effective tool for presurgical tridimensional assessment of the neurovascular structures, such as MF and its variations; On the other hand, PAN examinations were not able to show the AMF cases assessed on CBCT.

Although noise increased at a lower mAs, clinical image quality often remained acceptable at exposure levels below the manufacturer's recommended setting, for certain patient groups. Currently, it is not possible to determine minimally acceptable values for image quality that are applicable to multiple CBCT models.

Variations in jaw bone neurovascularisation must be identified to decrease the potential risk for haemorrhages and neural disturbances during surgical procedures such as implant placement and orthognatic surgeries. The aim of this study is to characterise additional mental foramina (AMF) through cone beam computed tomography (CBCT) images, by describing their frequency, size, location and direction of their associated bony canals, as well as to assess their corresponding ipsilateral and contralateral mental foramina (MF). CBCT images from 285 patients were analysed. Prevalence of AMF was 9·4%. From 0 to 2 AMF were observed, with two bilateral cases. Two cases of unilateral absence of MF were registered. Patients presenting AMF did not differ significantly from those without AMF regarding gender, age or ethnicity. Diameters of AMF and their corresponding ipsilateral and contralateral MF were 1·9 mm (±0·7 mm), 3·8 mm (±0·6 mm) and 4·1 mm (±0·6 mm), respectively. Ratios between diameters of AMF and corresponding ipsilateral MF ranged between 0·24 and 0·99. Location of AMF was variable, with most cases located posteriorly, posterior-inferiorly, posterior-superiorly or anterior-superiorly to their respective MF. Significant anatomical variability regarding neurovascularisation was observed among patients and CBCT examinations presented as a valuable tool for individually assessing these anatomical features.

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Objectives: To evaluate and compare the detection of gubernacular canals (GC) and their characteristics in normal and abnormal tooth eruption. Materials and Methods: Patients with unerupted teeth were classified according to sex and age. Each tooth was classified according to dental group, eruption status, formation status, angulation, and GC detection. The opening of the GC in the alveolar crest and the attachment sites in relation to the dental follicle were assessed. Data were analyzed by the chi-square and Kruskal-Wallis tests, with a significance level of 5%. Results: Cone-beam computed tomography scans of 159 patients were evaluated. The final sample (N = 598) consisted of 423 teeth with normal eruption, 140 impacted teeth, and 35 teeth with delayed eruption. The overall detection rate of GC was 90.6%. These rates were 94.1%, 87.1%, and 62.9% for normal eruption, impacted teeth, and delayed eruption, respectively. GC detection rates were higher in the early stages of tooth formation in normal tooth eruption and in impacted teeth. The rate of GC detection was even lower in delayed teeth when they were angulated. Unusual attachment sites of the GC to the dental follicle were associated with abnormal eruption status. Conclusions: The results of the present study suggest that GC characteristics may indicate an abnormal eruption status.