Momentousness of the Mental Loop: A Comparative Study

Prevalence, length, and patterns of Anterior Loop among the South Indian population: A comparative study between Panoramic Radiography and Cone Beam Computed Tomography

Purpose

To assess the prevalence, length, and patterns of the anterior loop of the inferior alveolar nerve by panoramic radiography and cone beam computed tomography (CBCT).

Materials and Methodology

A prospective study was conducted on 300 mental foramen regions by exposing them to panoramic radiography and CBCT scan. Two individual observers evaluated the images to assess the presence of an anterior loop, the mean length of the loop, and the most frequent pattern of the loop in our population.

Result Analysis

The prevalence of the anterior loop for male patients and female patients by panoramic radiography was 34% and 32% on the right side and 30% and 36% on left side, respectively. By CBCT, the corresponding values were 69% and 72% on the right and left side, respectively, for male patients, and 73% and 81% on the right and left side, for female patients, respectively.

Conclusion

The results from our study strongly emphasize the need for CBCT imaging before planning for procedures in the mental foramen region because the prevalence, length, and pattern of loop significantly varies with respect to age, sex, and population.

Prevalence, Patterns and Variations of Anterior Loop of Inferior Alveolar Nerve-A CBCT Based Retrospective Study

The fragment of inferior alveolar nerve (IAN) existing anterior to the mental foramen (MF), before dividing the canal, is known as the "Anterior Loop of the IAN". The presence of anterior loop (AL) is important when placing the implant in inter foraminal area of the mandible or during any other surgical procedure. It is imperative to precisely determine the position and dimensions of these anatomical variations on a cone-beam CT (CBCT) scan. To estimate the prevalence and pattern of anterior loop of IAN and establish any corelation between dimension of the MF with length and angulation of the AL of the IAN. Total 178 CBCT samples were collected fulfilling the inclusion criteria from a private diagnostic centre in Bhubaneswar, Odisha. The greatest diameter of the mental foramen was measured along with anterior loop length and angulation in the panoramic section of the CBCT scan. The angulation formed and the length was corelated with the greatest diameter of the mental foramen and analysed. Our study reveals that the AL was more frequently seen among males, predominantly on the left side of the mandible. The relationship between length of the anterior loop and diameter of the mental foramen demonstrated a mild negative corelation. There was no possible corelation present between angle formed by anterior loop with inferior alveolar canal and diameter of mental foramen. A small positive corelation was established between length of anterior loop and angle formed by the anterior loop with inferior alveolar canal. CBCT scans should be recommended for pre-surgical evaluation of anatomical variations in the mandibular region. Also, a safe margin of 3-4 mm anterior to mental foramen should be maintained while working in the premolar area.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-021-02691-w.

Prevalence and extension of the anterior loop of the mental nerve in different populations and CBCT imaging settings: A systematic review and meta-analysis

Purpose

Materials and Methods

Results

Conclusion

Mental Foramen and Anterior Loop Anatomic Characteristics: A Systematic Review and Meta-analysis of Cross-sectional Imaging Studies

INTRODUCTION

The present study aimed to review the epidemiologic, topographic, and morphometric aspects of the mental foramen (MF) and anterior loop (AL) on cone-beam computed tomographic imaging studies.

METHODS

An International Prospective Register of Systematic Reviews (PROSPERO)-registered systematic review (CRD42018112991) was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two reviewers independently performed data extraction from observational studies that evaluated MF and AL on 7 electronic databases. MedCalc (MedCalc Software bv, Ostend, Belgium) software was used to perform a meta-analysis with a 95% confidence level.

RESULTS

Of 1545 articles, 66 met the inclusion criteria, totaling 14,233 patients from 5 continents, with a total of 6655 females and 5884 males (some studies did not report sex), with an age range between 8 and 89 years. The most prevalent shapes of MF were oval (48.72%) and circular (44.36%), and the most frequent horizontal positions were between premolars (43.66%) and in line with the long axis of the second premolar (43.12%).

CONCLUSIONS

Based on the articles that assessed AL, the mean prevalence was 43.18%, with most studies reporting bilateral localization as the most prevalent.

Evaluation of Mental Foramen with Cone Beam Computed Tomography: A Systematic Review of Literature

Purpose

The aim of this systematic review is to assess whether the anatomy of mental foramen is precisely evaluable with cone beam computed tomography (CBCT) before implantation in humans.

Methods

A systematic review was carried out to evaluate the anatomy of mental foramen (size, position, symmetry, anterior loop, and accessory mental foramen or multiple mental foramina). According to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, an electronic search of three databases (Medline, Web of Science, and Cochrane Library) was undertaken until June 2020 and was supplemented by manual searching. Two reviewers will independently perform the processes of study inclusion, data extraction, and quality assessment. Systematic reviews, studies about children, and case reports were excluded. Only studies using CBCT to do preoperative evaluation were selected.

Results

From 728 potentially eligible articles, 72 were included in the qualitative analysis and quantitative synthesis. This systematic review provided an assessment of the anatomy of the mental foramen. The mental foramen was located mostly between the two premolars (between 50.4% and 61.95%) or apically to the second premolar (from 50.3% to 57.9%). The mean diameter of the mental foramen was bigger in males than in females; the difference between them could reach 0.62 mm. The anterior loop seemed to be longer in males (between 0.87 ± 1.81 and 7.25 ± 2.02 mm) than in females (between 0.81 ± 1.18 and 6.52 ± 1.63 mm) and with the presence of teeth (from 0.91 ± 1.18 to 2.55 ± 1.28 for dentate people and from 0.25 ± 0.61 to 2.40 ± 0.88 mm for edentate population). The anterior loop and the accessory mental foramina were detected more frequently with CBCT than panoramic X-ray: only between 0.0 and 48.6% AMFs detected with CBCT were also seen with panoramic images. Clinical Significance. The mental foramen (MF) is an important landmark for local anesthesia and surgical and implantology procedures. Its location, morphology, and anatomical variations need to be considered to avoid mental nerve injury. The aim of this review is to evaluate the mental foramen using CBCT through a systematic literature review to improve knowledge of this complex area for the clinician.