Morphometric Analysis of the Mental Foramen Using Cone-Beam Computed Tomography

Cone Beam CT Assessment of Mandibular Foramen and Mental Foramen Positions as Essential Anatomical Landmarks: A Retrospective Study in Vietnam

INTRODUCTION

The mandibular foramen (MnF) and the mental foramen (MF) are essential anatomical landmarks that should be considered before any surgical procedures in the mandible. This study aimed to investigate the characteristics of the MnF and MF in relation to adjacent anatomical structures, as well as age and gender differences, using cone beam computed tomography (CBCT) projections.

METHODS

The study was conducted from August 2023 to January 2024 at the Can Tho University of Medicine and Pharmacy Hospital, Vietnam. In this retrospective study, 50 CBCT images of Vietnamese patients were randomly taken for various clinical purposes. Furthermore, relevant data, such as gender and age groups, were selected to evaluate the correlations, along with specific inclusion criteria. Patients within the age range of 18-69 with a symmetrical mandible were included.

RESULTS

The distance of the MnF-MN was 29.6±5.0 mm (right) and 30.1±4.6 mm (left) in males and 25.0±4.2 mm (right) and 26.3±5.0 mm (left) in females. The distance of the MnF-posterior border of the ramus (P) was 16.2±3.6 mm (right) and 15.0±2.3 mm (left) in males. For females, it was 17.1±2.9 mm (right) and 13.8±1.7 mm (left). The distance of the MF-body mandible (MB) was 15.4±2.4 mm (right) and 15.6±2.0 mm (left) in males and 14.0±2.1 mm (right) and 14.3±1.6 mm (left) in females. The distance of the MF-mandibular midline (MM) was 27.0±2.6 mm (right) and 27.0±2.9 mm (left) in males and 25.3±2.0 mm (right) and 25.1±2.2 mm (left) in females. These distances showed statistically significant differences depending on gender (P<0.05).

CONCLUSION

It can be said that CBCT provides comprehensive information about the MnF and the MF for dentists in research and clinical practice.

Associations between the 3D position of the mental foramen with sagittal skeletal relationships (classes I, II, and III) and vertical facial growth patterns (normal, long, and short faces) in different ages and sexes: a retrospective cohort study of 360 CBCTs

BACKGROUND

The 3D position of the mental foramen (MF) is of significant clinical value in dental implantology and mandibular surgeries or in local anesthesia. Despite its importance, it is not clearly known how the position of MF can alter in different individuals, since the literature on the associations between the MF position with vertical growth patterns is non-existent and those on links between the MF position and skeletal malocclusions are scarce. Therefore, we aimed to investigate these, for the first time, on cone-beam computed tomographies (CBCTs).

METHODS

Archival CBCTs of 9 sub-groups (i.e., 3 skeletal Classes I, II, and III × 3 vertical growth patterns 'long face, short face, normal face') were collected by evaluating patients' SNA, SNB, ANB, facial angle, lower facial height, and FMA (n = 9 × 40 = 360). Included cases were older than 17 years and without any history of orthodontic/orthognathic treatments (243 women, 117 men, mean age: 22.28 ± 2.80 years). Perpendicular distances between the MF and 3 fixed bony structures (the mandibular symphysis [S/width], the mandibular ramus [R/length], and the mandibular lower cortex [C/height]) were measured on different sectional planes on both hemimandibles. Left- and right-side measurements were combined. Data were analyzed using the 3-way ANCOVA, Bonferroni, one-way ANOVA, Tamhane, Pearson, and t-test (α = 0.05).

RESULTS

Width was the smallest in Class II and greatest in Class III cases (all P values < 0.000001, Bonferroni). It was the shortest in long faces and longest in short faces (all P values ≤ 0.00008). The inferior-superior height was larger in Class III than both Classes I and II (both P values ≤ 0.003); there was no significant difference between Classes I and II in terms of height (P = 0.684). Height was the largest in long faces and smallest in short faces (all P values < 0.000001). The anterior-posterior length was the largest in Class III and smallest in Class II (all P values < 0.000001). Length was larger in short-face people versus normal- or long-face individuals (P ≤ 0.00003); nevertheless, long and normal faces did not differ in terms of length (P = 0.448). Subjects' age was not correlated with their MF positions (P ≥ 0.579, Pearson coefficient). Sex dimorphism existed only for height (P = 0.009, t-test) but not for length or width.

CONCLUSIONS

The MF position may considerably differ in various horizontal or vertical growth patterns and sexes. This should be noted in mandible surgeries.

Shape and anatomical relationship of the mental foramen to the mandibular premolars in an Indian sub-population: a retrospective CBCT analysis

Objectives

This study assessed the shape and anatomical relationship of the mental foramen (MF) to mandibular posterior teeth in an Indian sub-population.

Materials and Methods

In total, 475 existing cone-beam computed tomography records exhibiting 950 MFs and including the bilateral presence of mandibular premolars and first molars were assessed. Images were evaluated 3-dimensionally to ascertain the position, shape, and anatomical proximity of MFs to mandibular teeth. The position and shape of MFs were measured and calculated. The Pythagorean theorem was used to calculate the distance between the root apex of the mandibular teeth and the MF.

Results

MFs exhibited a predominantly round shape (left: 67% and right: 65%) followed by oval (left: 30% and right: 31%) in both males and females and in different age groups. The root apices of mandibular second premolars (left: 71% and right: 62%) were closest to the MF, followed by distal to the first premolars and mesial to the second premolars. The mean vertical distance between the MF and the nearest tooth apex calculated on sagittal sections was 2.20 mm on the right side and 2.32 mm on the left side; no significant difference was found according to sex or age. The distance between the apices of the teeth and the MF was ≥ 4 mm (left; 4.09 ± 1.27 mm and right; 4.01 ± 1.15 mm).

Conclusions

These findings highlight the need for clinicians to be aware of the location of the MF in treatment planning and while performing non-surgical and surgical endodontic procedures.

Anatomy of the accessory mental foramen in a Saudi subpopulation: A multicenter CBCT study

Aim

The aim of this is to evaluate the prevalence and location of the accessory mental foramen (AMF) in a Saudi population using cone-beam computed tomography (CBCT).

Methodology

CBCT data were retrieved from two dental facilities at two universities located in two different cities and filtered over a period of four years. The scans were aligned when the AMF was noticed, and then the size of both the AMF and mental foramen (MF), its location, and the distance from the AMF to the MF were recorded. The AMF measurements were compared between males and females and between the two sides of the mandible.

Results

In total, 603 CBCT scans were investigated. The percentage of scans with an AMF was 9.95% (n = 60), and AMFs were almost equally distributed on both sides. Only four cases (0.66%) of a second AMF were detected among the scans. The MFs on both sides were significantly larger in males than in females (P > 0.05), but they showed no differences in the sizes of the AMFs. The AMFs were most commonly located inferior and posterior to the MF. The distance between the MF and AMF ranged from 2.32 to 5 mm.

Conclusions

The prevalence of the AMF in this Saudi population was 9.95%, and it was significantly more prevalent in males than in females. Its proximity to the MF makes it clinically important to conduct proper detailed planning prior to performing any procedure that might risk the vital structures.

Do the location and dimensions of the mental foramen differ among individuals of different facial types and skeletal classes? A CBCT study

STATEMENT OF PROBLEM

Knowledge about the location and dimensions of the mental foramen is important for surgical planning and implant placement in the posterior mandibular region.

PURPOSE

The purpose of this clinical study was to assess the location and dimensions of the mental foramen in individuals of different facial type, skeletal class, and sex by means of cone beam computed tomography (CBCT) images.

MATERIAL AND METHODS

CBCT images of 142 individuals (72 women and 70 men) were classified according to the facial type (dolichocephalic, mesocephalic, or brachycephalic) and skeletal class (I, II, or III). The vertical and horizontal locations of each mental foramen were evaluated on panoramic reconstructions, and the greatest height and width of the mental foramen were determined on multiplanar reconstructions. Also, the distances from the mental foramen to the alveolar crest and to the inferior cortex of the mandible were obtained. The data were compared by using the Kruskal-Wallis test and multiway analysis of variance (α=.05).

RESULTS

The facial type, skeletal class, and sex did not influence the vertical (P=1.00) or the horizontal (P>.15) location of the mental foramen. The most frequent location of the mental foramen was between the first and second premolars and below their apices. The dimensions of the mental foramen were not influenced by the studied factors in men (P>.07); conversely, the mental foramen dimensions were influenced for women (P<.03).

CONCLUSIONS

The most frequent location of the mental foramen was between the first and second premolars and below their apices. An influence of the facial type and skeletal class was observed on the dimensions of the mental foramen in women.

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.