Localization of the Mandibular Canal in a Turkish Population: a Retrospective Cone-Beam Computed Tomography Study

Identifying the Anatomical Variations of the Inferior Alveolar Nerve with Magnetic Resonance Imaging

BACKGROUND

The inferior alveolar nerve (IAN) is located in the mandibular canal (MC). It is critical to evaluate the position of the MC during treatment planning to prevent intra or postoperative complications.

AIMS

This retrospective study aimed to identify the anatomy and anatomical variations of the IAN using soft tissue imaging (pulse sequence magnetic resonance imaging [MRI]).

MATERIALS AND METHODS

This study was designed as a retrospective Consolidated Standards of Reporting Trials (CONSORT) study. In total, 220 MR images were obtained. Nutrient canals (NCs) were classified as intraosseous and dental NCs, while bifid MCs (BMCs) were classified as forward, retromolar, and buccolingual canals. IBM SPSS Statistics 22 was used. Kolmogorov-Smirnov and Shapiro-Wilk tests, descriptive statistical methods (means, standard deviations, and frequencies), and the Chi-square test were used. Statistical significance was set at P < 0.05.

RESULTS

In total, 220 patients (172 females and 48 males) were evaluated. NCs were present in 92.3% of all MCs and were significantly higher in patients aged <25 years. BMCs were observed in 106 patients (24.1%). The most common BMC of MC/IAN was in the forward canal (14.4%), followed by the retromolar canal (7.5%).

CONCLUSION

Although previously, the dental canal was considered as an anatomical variation, this study revisited the classification and suggested that dental canals are anatomical structures.

Structural and CBCT analysis of mandibular canal microvessels expressing neurotransmitters in human cadavers

PURPOSE

This study focused on the detailed structure of microvessels of the neurotransmitter-positive vasa nervorum of the inferior alveolar nerve, vein, and artery in the mandibular canal (MC) to obtain information for improved safety in dental treatments. We also observed the detailed structure of the MC from the mental foramen to the mandibular foramen using cone-beam computed tomography (CBCT).

METHODS

In this study, mandibles from 45 sides of 23 human cadavers aged 76-104 years were examined by microscopy, immunohistochemistry, and CBCT analysis. These data were further evaluated by principal component analysis (PCA).

RESULTS

The microvessels of the vasa nervorum with calcitonin gene-related peptide- and neuropeptide Y-positive reactions were classified into 5 types: large (4.19%, 28/667); irregular large (7.35%, 49/667), numerous intermediate (29.23%, 195/667), irregular intermediate (29.23%, 195/667), and scattered fine (30.0%, 200/667) microvessels. The MC showed various structures from the 3rd molar to the premolars and was also classified into three types, including complete (57.0%, 228/400), partial (33.8%, 135/400), and unclear (9.2%, 37/400), from the mandibular foramen to the mental foramen. PCA results revealed that developed capillaries were mainly localized in the molar region.

CONCLUSIONS

Fine microvessels of the vasa nervorum expressing neurotransmitters are present from the molar to premolar region, which is key information for mandibular dental treatments. The different microvessel structures also indicate differences in specific characteristics between dentulous and edentulous cadavers regarding oral surgical and implant treatments.

Bone quality and quantity of the mandibular symphyseal region in autogenous bone grafting using cone-beam computed tomography: a cross-sectional study

BACKGROUND

Bone volume plays a pivotal role in the success of dental implant treatment. Autogenous bone grafts should be harvested from reliable sites in the maxillofacial region. This study sought to assess the quantity and quality of bone in the mandibular symphysis for autogenous bone graft harvesting using cone-beam computed tomography (CBCT).

METHODS

This cross-sectional study evaluated the CBCT scans of 78 adults presenting to three oral and maxillofacial radiology centers. The vertical (VD) and horizontal (HD) alveolar bone dimensions, cortical thickness (CT), and cancellous to cortical bone ratio (C/C) were measured in the interforaminal region of the mandible at the sites of central incisor to first premolar teeth. The interforaminal distance (ID) and the anterior loop length were also measured. Nonparametric statistical tests were used to analyze the data with respect to sex, age, and tooth position.

RESULTS

The median VD, HD, and CT of the symphysis were 20.21 (3.26), 4.13 (0.37), and 2.25 (0.23) mm, respectively. The median C/C was 1.51 (0.11). The median ID was 52.24 (8.24) mm, and the median anterior loop length was 1.82 (1.06) mm. Significant differences were observed in all parameters among different teeth. Most of the measured parameters were greater in males compared with females. There were significant differences in ID, VD, and CT between different age groups.

CONCLUSIONS

The quantity and quality of the available bone in the mandibular symphysis for bone graft harvesting vary by gender, age, and harvesting site, necessitating careful preoperative evaluation.

Effect of CBCT dose reduction on the mandibular canal visibility: ex vivo comparative study

OBJECTIVES

To compare the difference in mandibular canal (MC) visibility using three different cone beam computed tomography (CBCT) acquisition protocols: high resolution (HR), standard resolution (ST) and Quick scan+ (QS+).

METHODS

Twenty-five human dry mandibles were scanned by one CBCT machine; i-CAT FLX (Imaging Sciences International, Hatfield, PA, USA), using three different acquisition protocols: high-resolution (HR), standard (ST) and Quick scan+ (QS+). DICOM data were transferred to a third party software Ondemand 3D (Cybermed Co., Seoul, Korea). The fusion module was used to superimpose images derived from different acquisition protocols to standardize the areas to compare the MC visibility. Comparison was performed at nine selected cross sections extending from an area distal to the third molar posteriorly to the first premolar anteriorly. Two expert radiologists evaluated the degree of MC visibility using five-scale scoring system.

RESULTS

There was a statistically significant difference between the three acquisition protocols (HR, ST, QS+) at all investigated areas regardless of dentition status (p value < 0.001-0.034) except at the MR1M area where there was no statistically significant difference (p value = 0.094). HR protocol showed the highest prevalence of fully and partially corticated MC at almost all investigated areas while QS+ protocol showed the highest prevalence of invisible MC and clear and unclear non-corticated MC at almost all investigated areas.

CONCLUSIONS

QS+ protocol of i-CAT FLX CBCT machine is a recommended low-dose CBCT acquisition protocol for MC visibility at dentulous posterior mandibular regions while ST protocol is recommended at edentulous areas.