Bifid variations of the mandibular canal: cone beam computed tomography evaluation of 1000 Northern Chinese patients

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.

Mandibular Canal Branching Assessed With Cone-Beam Computed Tomography

This study aimed to evaluate the prevalence and type of mandibular canal branching in a sample of the Iranian population through cone-beam computed tomography (CBCT) images. This cross-sectional study was performed on CBCT records of 300 patients (112 males and 188 females; mean age 30.14 ± 10.96 y). The presence of mandibular canal branch (MCB) was evaluated by reconstructing multiple panoramic views and buccolingual cross-sections, according to Naitoh's classification. The prevalence of MCB, the type of MCB, and the demographic information of all patients were recorded. The maximum number of branching and the maximum type of branching were also registered for each patient. Mandibular canal branching was observed in 131(43.7%) of 300 CBCT images without side or sex differences ( P > 0.05). The most frequent type was dental, followed by the retromolar, forward, and buccolingual types, respectively. There was a statistically higher frequency of retromolar canal in females than in males (odds ratio: 1.14 ± 4.25; P = 0.013). About 46% of patients with MCB had more than one accessory canal and 29% displayed more than one type of MCB. The coincidence of dental and retromolar canals in a patient was the most prevalent combination. Considering the relatively high prevalence of MCB (43.7%), it is recommended to keep in mind the possibility of anatomical variations of the inferior alveolar nerve during dental procedures to avoid postsurgical complications. The high possibility of observing multiple numbers and types of branching in the patients should also be considered during preoperative assessments.

Prevalence and characteristics of accessory mandibular canals in an eastern Chinese population by cone beam computed tomography

PURPOSE

This retrospective study aimed to determine the prevalence and morphological characteristics of accessory mandibular canals (AMCs) in an eastern Chinese population to provide clinical guidance for reducing intraoperative and postoperative complications.

METHODS

Cone beam computed tomography (CBCT) scans of 300 Chinese patients were used to identify AMCs according to a modification of Naitoh's classification. The length of the branch (L0) and the upper and lower angles between the branch and mandibular canal were measured on sagittal images. Additionally, the branches were divided into narrow or wide types by calculating the ratio of the branch diameter to the main canal diameter. The location of the bifurcation point was characterized by measuring its distance to the buccal wall of the mandible (L1), lingual wall of the mandible (L2) and alveolar ridge (L3).

RESULTS

The prevalence rate of AMCs was 40.7% (95% CI: 35.1-46.3), and the most common type was the retromolar canal, followed by the forward canal, dental canal, trifid mandibular canals (TMCs) or others, inferior canal and buccolingual canal. Twenty-one cases of multiple branches with unusual patterns were observed in the study. The average values of L0, L1, L2 and L3 were 15.05 ± 0.63 mm, 5.79 ± 0.14 mm, 4.40 ± 0.18 mm and 14.61 ± 0.31 mm, respectively. The mean upper angle and lower angle were 141.59° ± 2.44° and 50.64° ± 2.57°, respectively. Approximately 20.8% of the branches were defined as wide type, and no statistical significance was found between different types.

CONCLUSION

AMCs are not rare anatomic variations of the mandibular canal in the eastern Chinese population; thus, CBCT examination is highly recommended for precise evaluation before surgeries involving the mandibles.

Prevalence of bifid variations of the mandibular canal in an Iranian population using cone-beam computed tomography

OBJECTIVES

Bifid mandibular canal (MC) is an anatomical variation of the MC. This study aimed to assess the prevalence and shape of bifid MC in an Iranian population.

MATERIALS AND METHODS

A total of 681 patients who had undergone cone-beam computed tomography (CBCT) for different purposes between 2018 and 2020 were evaluated. After detection, bifid MCs were classified into four types forward, buccolingual, dental, and retromolar. CBCT images were assessed by two oral and maxillofacial radiologists. Data were analyzed by SPSS using an independent t-test and Chi-square test.

RESULTS

Bifid MC was found in 23 (3.4%) out of 681 patients, with a mean age of 32.21 years. Ten patients (1.5%) had a bifid MC on the right side, 6 (0.9%) on the left side, and 7 (1%) bilaterally. However, no significant correlation was found between laterality and the prevalence of bifid MC (P > 0.05). Bifid MC was found in 8 males (34.8%) and 15 females (65.2%). Gender had no significant correlation with the prevalence of bifid MC (P > 0.05). Forward type was the most common (n = 8, 1.2%) followed by buccolingual (n = 5, 0.73%), dental (n = 2, 0.3%), and retromolar (n = 1, 0.14%) types.

CONCLUSION

According to the present results, bifid MC was not uncommon in the Iranian population of the present study, and forward type was the most common, followed by buccal and then dental bifid MCs. There was no significant correlation between sex and age with bifid MC but bifid MC was detected more frequently in females than males, and it was seen unilaterally in a higher percentage of the cases.

An evaluation of mandibular canal variations: a systematic review and meta-analysis

The inferior alveolar nerve and vessels are carried via the mandibular canal, which extends bilaterally from the inferior alveolar foramen to the mental foramen. Bifid and trifid mandibular canals result from abnormal fusions of nerve canals. The purpose of this study was to provide an up-to-date and comprehensive analysis of the prevalence of mandibular canal variations among healthy adults, and to identify any potential ethnic, sex, or laterality predilections. The prevalence of the bifid mandibular canal was 18.87% and that of the trifid canal 1.3%. Unilateral variants were three times commoner than bilateral. Each mandibular half had four canals emanating from separate openings on the lingual surface of the mandibular ramus. Retromolar and forward canals were the predominant subtypes, followed by dental; buccolingual were the least frequent. The mean length and diameter of the bifid mandibular canal were 13.62 mm and 1.63 mm, respectively. The possibility of a bifid mandibular canal is a crucial consideration in dental medicine. Because anatomical variations of the mandibular canal are fairly common, awareness of them is essential for anatomy teachers and for surgeons who operate in the oromaxillofacial region.

Bifid Mandibular Canal: A Proportional Meta-Analysis of Computed Tomography Studies

Introduction

Growing body of evidences showed different grades in prevalence of bifid mandibular canals. Because the previous reviews focused solely on patient-level occurrence, hemi-mandible-level prevalence, bilateral symmetry, length, and diameter of bifid mandibular canals were required to be estimated collectively. The research question of this meta-analysis was "What is the prevalence of bifid mandibular canal among patients seeking computed tomography examinations"?

Materials and Methods

In vivo, computed tomography, and cross-sectional studies were eligible. Studies, with less than 100 subjects or anatomic site restriction or controlled class of bifid mandibular canal, were excluded. Joanna Briggs Institute (JBI) critical appraisal tool for prevalence studies was used to assess methodological quality of all included studies. Random effect meta-analyses for proportion of bifid mandibular canal were done.

Results

40 studies met the inclusion criteria. All studies were selected for both systematic review and meta-analyses. Totally, 17714 patients and 31973 hemi-mandibles were included. All eligible studies showed moderate risk of bias on average. Resulting from the random effect model, more than 20% of patients seeking computed tomographic examinations had bifid mandibular canals (BMCs) which penetrated into slightly more than 14% of hemi-mandibles. Of the patients having bifid mandibular canals (BMCs), nearly 23% exhibited such anatomy on both sides of their mandibles. Estimated mean length and diameter of the accessory canals of bifid mandibular canals were 12.17 mm and 1.54 mm, respectively.

Conclusion

The geographical locations, classifications, reliability test, and voxel size of computed tomography were all implicated in the prevalence of bifid mandibular canals along with gender and laterality, although considerable heterogeneity and bias were detected.

Prevalence and Characterization of bifid mandibular Canal Using Cone Beam Computed Tomography: A Retrospective Cross-Sectional Study in Saudi Arabia

Aim

The purpose of this study is to determine the prevalence and morphological characteristics of the bifid mandibular canal in a Saudi Arabian subpopulation, to aid in preventing surgical complications near the mandibular canal.

Patients and Methods

Using CBCT images obtained from the Radiology unit database in a University Hospital Clinics. A total of 488 CBCT images were investigated (244 Female – 178 Male). In the present study, the Naitoh classification was used to categorize the bifid mandibular canal into the following types: 1) Retromolar canal; 2) Dental canal; 3) Forward canal (with or without confluence); and 4) Buccolingual canal. Additional variation (Trifid canal) was included. All CBCTs were assessed in coronal, sagittal, axial, as well as panoramic views using specialized software.

Results

The prevalence of BMC was 28.7% (95% CI, 24.5 to 33.2), Gender (p = 0.404) and age (p = 0.654) had no statistical significances, laterality of BMC, patients with unilateral BMC were significantly older than those with bilateral BMC (mean ± SD ages of 40.5 ± 13.5 and 32.9 ± 13.8, respectively, p = 0.009). About two-thirds (67.5%) of the investigated BMC cases were found unilateral. The most common reported type of BMC was retromolar canal.

Conclusion

The incidence of bifid mandibular canal using CBCT is considered relatively high in Saudi Arabian subpopulation, with the most common type was the retro-molar canal.

Prevalence and Characteristics of Accessory Mandibular Canals: A Cone-Beam Computed Tomography Study in a European Adult Population

The purpose of this observational study is to evaluate the prevalence and main characteristics of bifid canals within a European adult population, analyzing cone-beam-computed tomography (CBCT). The population study examined 300 subjects. The CBCTs were performed between 2012 and 2019, using PaX-Zenith3D with a standard protocol of acquisition. The parameters analyzed were the presence and lengths of the bifid mandibular canals. The sample included 49% male and 51% female participants. The mean age of the patients was 47.07 ± 17.7 years. Anatomical variants of the mandibular canal were identified in 28.8% of the sides and 50.3% of the patients. In 7.3% of the subjects, the anatomical variants were present bilaterally. The most frequently encountered bifid canal was Type 3 (40.5%), followed by the Type 1 canal (39.3%), the Type 2 canal (14.5%), and the Type 4 canal (5.9%), 40% on the right side and 60% on the left side. The average length of the bifid canals located on the right side of the mandible was 11.96 ± 5.57 mm, compared to 11.38 ± 4.89 mm for those measured on the left side. The bifid mandibular canal is a common anatomical variation of the mandibular canal. It is fundamental to performing an accurate preoperative evaluation using CBCT analysis to avoid and/or reduce intraoperative and postoperative complications.

Prevalence of bifid and trifid mandibular canals with unusual patterns of nerve branching using cone beam computed tomography

Lack of knowledge concerning the inferior alveolar canal anatomical variations had proven to increase the incidence of surgical complications, so the study aimed to assess the configuration and prevalence of bifid and trifid mandibular canals using cone beam CT in Egyptian subpopulation. Cone beam CT scans of 278 patients (530 hemi-mandibles) were included in the study, in which bifid and trifid mandibular canals or any other branching patterns were recorded and evaluated. Bifid canals were categorized following Naitoh classification, and the diameter of the main mandibular and accessory canals was measured. Bifid canals were detected in 181 canals (34%) while trifid canals in 46 canals (8.7%). Upon classifying the bifid canals, 78 canals showed forward type, 40 retromolar type, 33 dental type, and 7 canals showed buccolingual type. Two special bifid canals subtypes were reported in 23 canals and nine distinct patterns of trifid canals were reported in our study. In addition, unusual patterns of canal branching were reported in 5 cases. The mean diameter of the accessory canals was 1.18 ± .54 mm and the main canal was 3.98 ± 1.31 mm. This study reported a high prevalence (54%) of canal branching, which reinforces the importance of cone beam CT in pre-surgical planning.

Anatomical variations of the mandibular canal and their clinical implications in dental practice: a literature review

INTRODUCTION

The anatomical variations of the mandibular canal have been described according to the number of additional branches it presents, bifid and trifid. Within the bifids we can also find subtypes of variations such as the retromolar mandibular canal. These anatomical variations can have important clinical implications for the work of dental professionals.

METHODS

A systematic search of the literature was carried out in different databases that met the following criteria: articles published between 2000 and 2020, and articles that established a clinical correlation with variations in the mandibular canal.

RESULTS

After applying inclusion and exclusion criteria, 32 articles were obtained, in which the variations of the mandibular canal were identified, their prevalence and incidence, which was very varied between the different articles, it was also found that the CBCT was the main technique to identify the anatomical variations of the mandibular canal. Lastly, the anatomical variations of the mandibular canal have a direct clinical correlation with pre-surgical, intra-surgical and postsurgical complications in pathologies that require surgical intervention.

CONCLUSIONS

The anatomical variations of the mandibular canal have a high incidence, so knowing them is of vital importance both for clinicians and anatomy professors who provide morphological training. We believe that research should focus on describing and diagnosing the causes of these anatomical variations. That said, there is also a continuous challenge for all health professionals to learn about the different anatomical variations that the human body presents and how these can affect clinical practice.

[Importance of cone beam computed tomography in the recognition of the trajectory and anatomical variants of the mandibular canal. A review of the literature]

The objective of this study was to provide an updated review of the literature on the importance of the use of cone beam computed tomography (CBCT) in the recognition of the trajectory and variants of the mandibular canal (MCV).CBCT allows obtaining high quality images and visualization with an accuracy of approximately 94%, compared to 53% with periapical intraoral radiography (RIP) and 17% with panoramic extraoral radiography (REP), making CBCT an important diagnostic tool.The incidences of MCV in CBCT studies were between 1.3% and 69%, with differences between patients of different ethnic origins and within the same ethnic population, and in the types and configurations of MCV within each ethnic group. The studies available in the literature provide a histological description of the content of MCV. The presence of nerve and artery bundles of different calibers suggests that patients present clinical symptoms only if the neurovascular bundle reaches a certain size and number of fascicles. This review provides a description of the different classifications available and updated with CBCT.

Incidence and Anatomical Properties of Retromolar Canal in an Iranian Population: A Cone-Beam Computed Tomography Study

Objectives

Retromolar canal (RC) is an anatomic structure, and due to increasing demand for surgical procedure in the retromolar area of the mandible, the identification of the retromolar canal has become an issue of clinical concern. It can innervate the third molar and some of the muscles around the posterior segment of the mandible, complicating surgical procedures in the retromolar area and root canal treatment of third molars. The aim of this study was to evaluate the incidence and anatomical properties of RC in a western Iranian population using cone-beam computed tomography (CBCT) images. Materials and Methods. Two hundred bilateral CBCT images were collected and screened in the three spatial planes for the presence of an RC. Anatomical properties and location of the RCs were assessed according to their course and distance from the surrounding structures. The relationship between the presence of RC and age, sex, side, and presence of second and third molars was also evaluated. Independent samples t-test, ANOVA, Tukey's post hoc test, paired t-test, ANOVA, Tukey's post hoc test, paired

Results

At least one RC was observed in 22% of the mandibles. Its bilateral incidence was 5.5%. Two major types of canals were detected, namely, type I, following a straight or curved course from the mandibular canal (MC) to the retromolar area (47.3%), and type II, coursing from the retromolar area to the radicular part of the third molar (52.7%). Regarding linear measurements, the mean RC diameter and the mean distance to the MC, second, and third molars were 0.68 ± 0.31, 13.7 ± 2.8, 15.3 ± 3.0, and 7.3 ± 2.3 mm, respectively.

Conclusion

Based on the results of this study, RC was found in 22% of the cases; thus, it should be considered as a normal anatomical variation in the Iranian population rather than a rare finding.

The clinical significance of the retromolar canal and foramen in dentistry

The mandibular canal is nowadays acknowledged as a major trunk with multiple smaller branches running roughly parallel to it. Most of these accessory canals contain branches of the inferior alveolar neurovascular bundle that supplies the dentition, jawbone, and soft tissue around the gingiva and lower lip. This article reviews the prevalence, classification and morphometric measurements of the retromolar canal and its aperture. A retromolar canal is a bifid variation of the mandibular canal that divides from above this main canal, and travels anterosuperiorly within the bone to exit via a single foramen or multiple foramina into the retromolar fossa. This foramen, termed the retromolar foramen, allows accessory branches of the inferior alveolar neurovascular bundles to supply tissues at the retromolar trigone. Clinically, it is of the utmost importance to determine the exact location of the mandibular canal and to identify its retromolar accessory branches when surgery in the posterior mandible is to be performed.