Characteristics of Accessory Mental Foramina Observed on Limited Cone-beam Computed Tomography Images

Evaluation of mental foramen and accessory mental foramen using cone beam computed tomography in a Turkish population

BACKGROUND

The aim is to assess mental foramen (MF) and anatomical variations using cone beam computed tomography (CBCT) images in a Turkish population.

METHODS

In this retrospective study, CBCT images of 301 patients (162 females, 139 males) obtained between November 2021 and February 2022 were evaluated. Patients were analyzed in 4 groups according to age (Group 1: 18-30 years, Group 2: 31-45 years, Group 3: 46-55 years, Group 4: 56 years and older). The position of the MF relative to the teeth, vertical (MFV) and horizontal (MFH) dimensions; the distances of the MF to the mandibular midline (MF-MM), ramus posterior border (MF-MP), lower border (MF-ML) and upper border (MF-MU); the presence of an accessory mental foramen (AMF); and if any, the position of the AMF relative to the MF and the distance of the AMF to the MF (MF-AMF) were recorded separately for the right and left sides. Associations with gender and age were evaluated. The independent samples t test was used to determine the relationship between the measurements and gender and the evaluation of the measurement values according to age groups. The evaluation of the location of MF according to gender and age groups was performed using the Chi-Square Test.

RESULTS

On the right and left sides, MF was most commonly seen at the apical level of the second premolars (45.4% and 52.1%, respectively). MFV, MFH, MF-MM, MF-MP and MF-ML were significantly higher in males than in females, p < 0.001 on both sides and for each parameter. There was a significant difference between the age groups for MF-MU and MF-ML on the right side, MF-MU on the left side (p < 0.001, p < 0.05, p < 0.001, respectively). A total of 42 AMFs were seen in 39 (13%) of the 301 patients. AMFs were frequently located posteroinferior to the MFs (35.5%). The mean MF-AMF was 7.83 mm.

CONCLUSIONS

The findings of this study contribute to the existing literature on the anatomy and variations of MF. The results of this study show that the prevalence of AMF in the Turkish population studied is high at 13%.

Prevalence of accessory mental foramen and lateral lingual foramen using cone beam computed tomography: A single-center cross-sectional study

PURPOSE

This study aimed to assess the prevalence, dimensions, and positions of accessory mental foramen (AMF) and lateral lingual foramen (LLF) in an Iranian population using cone beam computed tomography (CBCT).

METHODS AND MATERIALS

In this cross-sectional study, CBCT images of 2082 patients were retrospectively reviewed based on inclusion criteria, including images from the mandibular region taken in the past five years with accurate demographic data. Exclusion criteria included images with significant pathologies, fractures, or poor quality. CBCT images were captured, and AMF and LLF presence (primary outcome variable), dimensions, and positions (secondary outcome variables) were recorded relative to the mental foramen and adjacent teeth. Data analysis was performed using the Chi-square test with a 5% significance level.

RESULTS

A total of 2082 CBCT samples (46.54% females and 53.46% males) with a mean age of 48.30 ± 12.70 years were examined. Among these, 246 AMFs were observed in 222 individuals with a prevalence at the foramen level of 11.815%, with 24 having two AMFs. AMF was mostly observed unilaterally, with bilateral occurrence noted in 10.81% of patients with AMF. Additionally, 86 patients were found to have LLF with a prevalence at the foramen level of 5.907%. There were no significant differences between genders in AMF and LLF prevalence.

CONCLUSION

AMF and LLF were detectable using CBCT in the selected Iranian population. AMF was commonly situated posterior and superior to the mental foramen, while LLF was often found near the first premolar. This knowledge is crucial for preventing nerve injury during surgery and ensuring effective nerve block procedures.

Morphological Characteristics of the Double Mental Foramen and Its Relevance in Clinical Practice: An Observational Study

The mental foramen (MF) is an opening found bilaterally on the anterolateral aspect of the mandible; it can be round or oval and have different diameters. One of the anatomical variants of the jaw is the presence of an accessory mental foramen (AMF). These are usually smaller than the MF and can be located above, below, or to the sides of the main MF. The objective of this study was to recognize the presence of AMF in dry jaws of the Chilean population and collect information about its clinical relevance reported in the literature. In this descriptive observational study, we have collected dried jaws obtained from three higher education institutions in Santiago de Chile, from the Department of Morphology of the Andrés Bello University, the Normal Human Anatomy Unit of the University of Santiago, and the Human Anatomy pavilion from the Faculty of Medicine of the Finis Terrae University. The samples for this research were obtained by convenience, and the observation of the jaws was carried out in the human anatomy laboratories of each institution by three evaluators independently, and a fourth evaluator was included to validate that each evaluation was correct. The sample for this research came from 260 dry jaws, showing the following findings from the total jaws studied, and to classify as an accessory MF, it will be examined and measured so that it complies with what is declared in the literature as the presence of AMF, which is between 0.74 mm. and 0.89 mm. There were 17 studies included with a sample that fluctuated between 1 and 4000, with a cumulative total of 7946 and an average number of jaws analyzed from the studies of 467.4, showing statistically significant differences between the means with the sample analyzed in this study; p = 0.095. For the cumulative prevalence of the presence of AMF, this was 3.07 in this study, and in the compared studies, the average of AMF was 8.01%, which did not present a statistically significant difference; p = 0.158. Regarding the presence of variants of unilateral AMF, this occurred in five jaws, which is equivalent to 1.84% in the sample of this study, while in previous studies, it was 7.5%, being higher on the left side than on the right. The presence of AMF is a variant with high prevalence if we compare it with other variants of the jaw. Knowledge of the anatomy and position of the AMF is crucial to analyze different scenarios in the face of surgical procedures or conservative treatments of the lower anterior dental region.

Multiple Mental Foramina: A Rare Anatomical Variation Detected by Cone-Beam Computed Tomography (CBCT)

The mental foramen is a single anatomical structure that can be seen bilaterally in the body of the mandible and generally in the lower area of the premolars. Sometimes, the mental foramen can have accessory foramina that should be considered. Clinical evaluation of the accessory mental foramina is critical because of its neurovascular fibers. Identifying the secondary mental foramen reduces the possibility of paraesthesia and pain after surgery.

The mental foramen, anatomical parameters through a radiographic approach to aid in dental implantology: A retrospective analysis in a sample of a Palestinian population

Purpose

This study aims at analyzing the mental foramen (MF) structure, dimension, position, and emergence profiles among a sample of a Palestinian population.

Methods

212 mental foramina (106 patients) were analyzed on two panoramic views (CBCT reformatted (CRP) & conventional (CP)) and CBCT coronal views. The visibility score, position, size, presence of loop & supplementary foramina, distances coronal and apical to the foramen, and the emergence profiles of the mental canals with associated course angles were all noted.

Results

No statistically significant relationship was found between the type of panoramic radiographic view used (i.e., CP & CRP) and the resultant visibility level and position of MF. The majority of the MF showed an intermediate visibility score on both CP & CRP. The highest percentage of MF's position was under the 2nd mandibular premolar. The emergence profile was shown to be, in most, superior (S) in 47.6% of the sample and posterosuperior (PS) in 28.3%. The MF mean height and width were 4.08 mm & 4.11 mm, respectively. The coronal and axial angles averages were 46.25° and 91.49°, respectively. The distance superior and inferior to the MF showed averages of 12.39 mm and 13.52 mm, respectively. 28.3% of the sample presented with a mental loop, with a mesial extension average of 2 mm.

Conclusion

On both panoramic views (CBCT & conventional), the majority of the mental foramina displayed an intermediate visibility level, with no significant difference between the two techniques. The MF was found mostly under the second premolar. The majority of the examined mental canals had a superior emergence profile.

Trifurcated Mental Foramina: A Cone-Beam Computed Tomography Incidental Finding During the Implant Treatment Planning

The mental foramen is a known skull anatomical structure located bilaterally on the mandible along the buccal cortical plate. It is located approximately between the roots of premolars in the anteroposterior dimension, and its supero-inferior level on the alveolar height varies in every individual. The position of the mental foramen is very crucial when surgical interventions are planned in the area. An accessory mental foramina can be very well detected in the three-dimensional (3D) imaging modality, especially in 3D volume rendering images. It can still be appreciated in two-dimensional (2D) imaging modalities such as a panoramic; however, at times it can be confused with periapical pathology, especially in cases where caries are present in the teeth. Three-dimensional imaging modality plays a critical role in identifying such anatomical variation, and hence, it is important to evaluate any surgical site in three dimensions prior to surgical intervention.

Evaluation of accessory mental foramen and accessory infraorbital foramen with cone-beam computed tomography in Turkish population

It was aimed to evaluate the frequency of accessory mental foramen (AMF) and accessory infraorbital foramen (AIOF) and analyse the correlation between these two foramina using cone-beam computed tomography (CBCT). The retrospective study reviewed the CBCT images of 1020 patients. The rates of AMF and AIOF were evaluated according to sex and age distributions. Correlations between the localizations of AMF and AIOF in the right and left jaws and the correlations between the occurrences of these foramina were evaluated. In the CBCT images of the 1020 patients, AMFs were detected in 48 patients, among which 14 were in the right half jaw, and 34 were in the left half jaw. AIOFs were detected in 143 patients, among which 65 were in the right half jaw, and 78 were in the left half jaw. Recognising and detecting AMF and AIOF with CBCT is important in terms of preventing complications that may occur in surgical procedures.

Interventive dental therapy in Ancient Egypt (ca. 2686 BCE - AD 323): A critical review

OBJECTIVE

This paper critically reviews the history of research concerning ancient Egyptian interventive dental therapy between the Old Kingdom - Graeco-Roman Period (c. 2686 BCE-AD 323), concentrating on the published osteological evidence.

MATERIALS

Eight osteological examples reportedly exhibiting markers of interventive dental therapy, including a mandible presenting purported evidence for a drilling procedure for the relief of an abscess; four dental bridges; a maxilla with multiple teeth extracted; and two carious lesion fillings.

METHODS

Previous claims are critically reviewed using a qualitative research method involving collecting and critiquing published data, both primary evidence and relevant secondary literature.

CONCLUSIONS

Without further scientific analysis, only four specimens can currently be plausibly attributed to ancient Egyptian interventive dental therapy including the Tura el-Asmant Bridge, the enucleation described for a Graeco-Roman child, and two carious lesion fillings identified in the mummified individuals known as the 'Redpath Mummy' (RM2718) and 'Sekhem' (AIG3343).

SIGNIFICANCE

Several enduring historiographical and museological problems within the discourse are identified, revising our understanding of the nature and scope of ancient Egyptian interventive dental therapy based on currently known osteological evidence.

LIMITATIONS

This review relies on the published documentation for each osteological example, namely images, which in several cases are poor quality.

SUGGESTIONS FOR FURTHER RESEARCH

There is significant opportunity for further scientific analysis of the osteological evidence discussed. In each case, specific potential methods to improve our understanding and interpretation have been identified.

Observation of mandibular second molar roots and root canal morphology using dental cone-beam computed tomography

The mandibular second molars show various morphological features in the roots and root canal, and a gutter-shaped root (GSR) caused by fusion of the mesial and distal roots is frequently encountered. In this study the number of the roots associated with mandibular second molars were observed using dental cone-beam computed tomography (CBCT). For those with a GSR, determination of root morphology and root canal classification were performed. CBCT image data from 173 Japanese mandibular second molars were obtained. Using sliced images, the number of the roots and root morphology were determined. In cases with a GSR, the ratio for the fused roots was determined and root canal morphology features were classified. A GSR was found in 61 (35.3%), with greater prevalence in females. In addition, the overall ratio of the fused part to root thickness in those with a GSR was 48.7%, with no significant difference related to sex. Furthermore, a C-shaped root canal morphology was commonly observed in both males and females with a GSR. In the present cohort examined in Japanese, most of the mandibular second molar were found to have two roots, with a GSR noted in 35.5%. While a GSR was more often observed in females, a C-shaped root canal was the most common root canal morphology in both sexs. It is considered that assessment using CBCT findings is helpful for precise determination of root canal morphology and presence of a GSR in mandibular second molars.

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.

Cone-beam computed tomography observation of maxillary first premolar canal shapes

A variety of shapes has been reported for the roots and root canals of maxillary first premolars. The purposes of the present study were to determine branching and shapes of the roots of maxillary first premolars, as well as age-related changes using slice images obtained with cone-beam computed tomography (CBCT) for dental use. CBCT-reconstructed images of 125 cases that included maxillary first premolars were used as subjects. Slice images at the cervical one-third, center, and apical one-third positions of the root were prepared. Root branching and number of root canals was determined at each measurement position in the images. The subjects were divided into three groups: younger than 30 years, 30 to 50 years, and over 50 years. The root canal morphology was compared among these age groups. Single-rooted premolars were the most frequent. As for number of root canals, a single-canal premolar was observed at the position of the cervical one-third in 33.6%, at the center in 35.2%, and at the apical one-third in 56.0%. Thereafter the subjects were divided into groups by age, namely, younger than 30 years, 30 to 50 years, and over 50 years old, and it was revealed that the ratio of the two-canal type increased with age. In regard to tooth morphology, it was confirmed that the two-canal type shows more frequent occurrence with aging in maxillary first premolar. Based on our findings, we consider that CBCT can be useful for determining the root canal morphology with complicated shapes.

Morphometric Analysis of the Mandibular Canal, Anterior Loop, and Mental Foramen: A Cone-Beam Computed Tomography Evaluation

This study investigated the cone-beam computed tomography (CBCT)-based features of the mandibular canal, mental foramen, anterior loop, and accessory mental foramina with respect to age and sex. A total of 306 CBCT mandibular images were included in this retrospective study to measure the mandibular canal location and extension, the mental foramen position, the presence of the anterior loop, and the accessory mental foramina. The measurements were obtained in sagittal, coronal, and axial views. Descriptive statistics are presented. Sex-related differences, correlations, and comparisons were calculated using SPSS at 5% significance level. The mandibular canal was located more coronal and medial in male patients. The majority of cases had the mental foramen located just apical to the mandibular second premolar with a mean height of 2.94 mm and a mean length of 3.28 mm. Age affected the size of the mental foramen. The mental canal in all cases tended to show a coronal direction. Mesial extension of the anterior loop was found in 66.01% of the images while accessory mental foramina were detected in 2.6%. The complexity of the mandibular canal, mental foramen, anterior loop, and accessory mental foramina among Sudanese patients with respect to age and sex was confirmed.

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.

Preserving the Neurovascular Bundle in Targeted Endodontic Microsurgery: A Case Series

Endodontic microsurgery encompasses the use of microscopy, specialized instruments, and advanced imaging with cone-beam computed tomographic (CBCT) imaging. This treatment modality results in high clinical success rates and facilitates the enucleation of osteolytic lesions, the resection of apical root canal complexities harboring persistent bacterial biofilms, and the evaluation of possible root defects and fractures. However, there is the risk of injury to important anatomic structures, particularly when treating posterior teeth. Neurovascular bundles are among these structures at risk for injury. Fortunately, high-resolution CBCT scans can be used to detect these structures that are known to have a high anatomic variability. In addition, CBCT information can be combined with high-resolution intraoral scans to plan, design, and fabricate surgical guides to be used in a targeted endodontic microsurgery (TEMS) approach. We report 3 cases with previous endodontic treatment having persistent apical periodontitis that were treated with TEMS to avoid damage to the neurovascular bundles at risk of injury. In the first case, the palatal root of tooth #14 was adjacent to the greater palatine artery. In the second case, the mental nerve exited through 2 separate foramina close to the predictive osteotomy site for the mesial root of tooth #19. In the third case, the posterior superior alveolar artery was in close proximity to the mesiobuccal root of tooth #14. Collectively, these cases illustrate the diagnostic value of CBCT imaging for detecting neurovascular bundles and the use of TEMS to mitigate the risk of injury to these important structures. Thus, the combination of CBCT imaging and TEMS can potentially minimize the risk of intraoperative complications and postoperative sequelae while increasing the predictability of endodontic microsurgeries in complex cases.

Cone beam CT-based measurement of the accessory mental foramina in the Chinese Han population

Anatomical data of accessory mental foramina (AMFs) were investigated in a Chinese Han population using cone beam CT (CBCT). A retrospective analysis was performed on 527 selected sets of CBCT images. The average frequency and diameter of AMFs, the diameter of the ipsilateral mental foramen (MF), and the center distance and relative position between the AMFs and MF were measured and calculated by three professional dentists. Among the 527 patients, AMFs were identified in 36 cases (frequency 6.83%), of which 68.75% of AMFs were larger than 1 mm. The mean diameters of the AMFs and the ipsilateral MF were 1.32±0.61 mm and 3.26±0.90 mm, respectively. The average distance from the AMFs to the alveolar ridge crest (ARC) was 15.05±3.50 mm, and the average distance to the mandibular plane was 15.87±3.64 mm. The positions of the AMFs relative to the MF varied widely. The AMFs were mostly positioned distal-inferior to the ipsilateral MF and under the mandibular second premolars. Nutrient foramina around the MFs were distinguished from AMFs. The reference plane for measuring AMFs was suggested to be the mandibular plane to increase the repeatability and accuracy of the experiment. Standard planes were proposed to determine the relative position between AMFs and the MFs. Based on our results, we propose that for implant surgeries, the safety region of 2 mm above the MFs should be reevaluated. CBCT examination is recommended before the operation to identify important anatomical structures around the MF region and their variations and set the safety distance on an individual basis.

The mandibular incisive foramen, a false mental foramen

BACKGROUND

The mandibular incisive foramen (MIF) is an opening on the external surface of the dentate mandibular body, medial to, and facing the mental foramen (MF). There is actually scarce evidence of such MIF.

CLINICAL PRESENTATION

A retrospective Cone Beam CT (CBCT) study of the archived files of a 56 y.o. male patient was documented anatomically for dental medical purposes. In the 2^nd premolar region of the left hemimandible were found two adjacent foramina facing one each other: the distal one was opened medially, while the medial one was oriented distally. On axial CBCT slices the mandibular canal was detected to open at the distal foramen in the outer cortical plate of the mandible. The medial foramen in that cortical plate served as entrance to the mandibular incisive canal, thus being a MIF.

CONCLUSION

CBCT accurately distinguishes the canals opening on the outer cortical plate of the mandible thus is of use to differentiate a MIF from a MF. Such adjacent foramina expose at risk not just the mental nerve, as in cases with true multiple MF, but also the IAN and the mandibular incisive nerve.

Variability in the number of mental foramina in the African green monkey (Grivet) (Chlorocebus aethiops)

This study aimed to determine the number of mental foramina (MFs) in vervet monkeys of the Cercopithecini tribe and perform a µCT analysis of mental foramina and mandibular canal morphology. A total of 19 simian skulls belonging to Chlorocebus aethiops species were used in the analyses. An average of three mental foramina was present in most individuals from the analyzed group. The Mann–Whitney test revealed no statistically significant difference between the number of foramina on the right- and left-hand side. Likewise, no statistically significant differences between the number of MFs across sexes were observed. Correlation coefficient values between mandibular length and the ipsilateral number of MF indicate a weak and statistically non-significant (p > 0.05) linear relationship. Volumetric reconstructions revealed the presence of a single periosteal sheathed mandibular canal terminated with four small mental foramina.

A case with multiple accessory foramina of mandible in a fetus

It is aimed to better recognize the mandibular variations by understanding the diversity and positions of accessory foramina better. Accessory formations on a full-term fetal mandible dissected for a mandibular study were examined under a microscope. To observe these formations more clearly, they were photographed with the help of a camera and microscope. In one of the mandibles dissected for a fetal mandibular study, a lateral accessory foramen (LAF1) was detected in the right half just near the mental foramen, and also a medial accessory foramen (MAF1) was detected over the mandibular foramen. In the left half, on the lateral surface relative to the mental foramen, one in the medial (LAF3) and one just above it (LAF2), and last one is near to the ramus of mandible (LAF4), three lateral accessory foramina, were detected. Again, a medial accessory foramen just above the left mandibular foramen (MAF3), and another foramen is near to mandibular symphysis (MAF2), also two medial accessory foramina on the lateral surface were detected. Detection and recognition of such variations are quite important for clinicians in the diagnostic methods and prevention of possible surgical complications.

Variation in accessory mental foramen frequency and number in extant hominoids

Nerves providing sensation to the lower face and jaw exit the mandibular canal via the mental foramen. In humans, there are many documented occurrences of additional foramina (accessory mental foramina, AMFs) on the lateral mandibular surface that may also contain nervous structures. There are large discrepancies in the literature regarding how often AMFs occur in humans, and investigations of non-human hominoid AMFs are rare. Consequently, the causes of interspecific diversity in this variable have not been explored. This project seeks to compare the frequency and number of AMFs between males and females, and among human regional groups and hominoid subspecies and species, and to investigate possible causal factors for any differences identified. No significant differences were found between males and females in any group. Gorillas and orangutans had the highest percentages of individuals with AMFs and the highest mean number of foramina, while modern humans and siamangs had the lowest figures for these variables. Significant differences (p < .05) were found for the mean number of foramina between most pairs of species. The results also showed that species with mandibles that are larger overall, have a larger area anterior to mental foramen, and a longer mandibular canal typically present more AMFs. The strongest correlation was found between the mean number of mental foramina and mandibular canal length. We suggest that these results provide preliminary support for the hypothesis that increasing mandibular canal length increases the likelihood that that nerves will ramify, leading to greater frequencies of accessory mental foramina.

A rare anatomic variation: Triple mental foramina

Multiple mental foramina (MF) are rarely found in the human mandible. We report on the case, as documented using cone beam computed tomography (CBCT), of the triple MF that were identified on the right hemimandible of a 28-year-old female patient. The distal foramen was located on the mandible between the apices of the second premolar root and the first molar mesiovestibular root, being reached by a thin canal that left the mandibular canal. A pair of mesial foramina were identified between the apices of the premolar teeth. Thus, the three foramina corresponded to a surface area of 23.49mm² of the mandible. On the opposite side, a single mental foramen had a surface area of just 13.25mm². On each side, retromolar canals that opened into the retromolar fossae were also found. The anatomic possibility of multiple MF increases the surface area at risk during surgical procedures, increases the risk of neurovascular damage and obscures the common tooth-related location of the mental foramen. Practitioners should, therefore, consider a personalised and imaging-documented approach so as to avoid treatment failure.

Cone-beam computed tomography and anatomical observations of normal variants in the mandible: variant dentists should recognize

Many types of cone-beam computed tomography (CBCT) have recently been developed and are being used in many dental clinics. CBCT has significantly changed imaging diagnosis in dentistry by showing detailed structures in multiple dimensions with high spatial resolution. This allows dentists to confirm what cannot be recognized with conventional two-dimensional images, such as small neurovascular canals, the buccolingual location of structures/lesions, and the three-dimensional shapes of hard tissue structures. The aim of this study was to review the normal variants of detailed anatomical structures in relation with the mandibular canal by comparing the previous reports and anatomical evaluations. These structures are likely to be observed on CBCT images by dental practitioners prior to dental procedures involving the mandibular teeth and bone. Understanding the relationship of these structures is useful for dental practitioners and oral surgeons to reduce the possibility of causing damage and patient discomfort during dental procedures.

Topographical distribution of neurovascular canals and foramens in the mandible: avoiding complications resulting from their injury during oral surgical procedures

Purpose

Certain oral surgical procedures can injure neurovascular canals and foramens in the mandible. Hence, before performing surgical procedures, it is important to assess the distribution of the bifid mandibular canal (BMC), accessory mental foramen (AMF), medial lingual canal (MLC), lateral lingual canal (LLC), buccal foramen (BF), and lingual alveolar canal (LAC). This study aimed to assess the distribution of different types of canals and foramens. Furthermore, we investigated the limitations associated with finding these structures in panoramic images.

Methods

Fifty-eight patients who had undergone panoramic radiography and computed tomography (CT) scans at our hospital were randomly selected for this study. Imaging data obtained from these patients were retrospectively reviewed.

Results

We found that the occurrence of BMC was 60.3%, AMF was 6.9%, MLC was 98.2%, LLC was 75.9%, BF was 43.1%, and LAC was 98.3%. Edge-contrasted inverted panoramic images revealed BMCs in 21.7% and AMFs in 25%; however, most of these canals could not be detected. In the panoramic images, the average diameter of the BMC was significantly different between the detected group and not detected group. The number of canals and foramens in the anterior region to the molar region decreased on the buccal and lingual sides, and most BMCs were in the retromolar to the ramus region.

Conclusion

Our results indicated different distributions and occurrence rates of each type of neurovascular canal and foramens.

3D CBCT morphometric assessment of mental foramen in Arabic population and global comparison: imperative for invasive and non-invasive procedures in mandible

BACKGROUND

Recent advancements in clinical dentistry have increased the possibilities of surgical procedures in the mental region. A detailed knowledge of mental foramen (MF) morphometry is significant to preserve integrity of the mental nerve trunk in surgical interventions such as orthognathic surgery, implant placement and anaesthetic block.

OBJECTIVE

The aim of this study was to determine the most accurate position of the mental foramen by using new assessment approach in a sample of dental patients presenting to the specialist dental clinic, College of Dentistry, Al Jouf University, Saudi Arabia.

STUDY DESIGN

A retrospective study was performed using cone beam computed tomography (CBCT) of 600 patients (40.1 ± 11.78 years old). Following inclusion and exclusion criteria, 395 CBCT were finally obtained and analyzed for the most accurate position of the mental foramen (MF) by OnDemand 3D software (Seoul, Korea). Prevalence of shape of MF and accessory MF were also assessed. Pearson chi-square test was employed to test significant differences between genders and races.

RESULTS

The most common horizontal and vertical position of the mental foramen was in line with the long axis of 2nd premolar (41.3%) and below the root apex level (93.2%), respectively. The most common shape of MF was round type (72.66%). The prevalence of accessory 2MF and 3MF was 2.28% and 0.25%, respectively.

CONCLUSION

New information about MF presented in this article can help anatomists, prosthodontists, orthodontists, surgeons, forensic odontologists and paleoanthropologists to predict the position of the MF and perform safer surgeries.

Detection and characterization of the accessory mental foramen using cone-beam computed tomography

OBJECTIVE

This study aimed to investigate the frequency and characteristics of accessory mental foramina (AMFs) and their bony canals in a selected Chinese population using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Reconstructed CBCT images of the mandible in 784 Chinese patients (305 males and 479 females) were retrospectively analysed to identify the AMF. The presence, dimension and location of the AMF as well as the origin and course of the associated bony canal were evaluated and classified. Variations in these characteristics were analysed according to gender, side and age.

RESULTS

A total of 66 AMFs were found in 57 (7.3%) of the 784 patients. The frequency of AMFs was significantly influenced by gender and side of the mandible (p < .05). Most AMFs were located apically between apices of the first and second premolars. The high-position AMFs (above the mental foramen) accounted for 54.5% of the total. The mean horizontal and vertical diameters of the AMF were 1.38 ± 0.47 and 1.23 ± 0.37 mm, respectively. Two typical types of the bony canal leading to the AMF were identified according to their bifurcation site from the mandibular canal. Most bony canals originated from the anterior loop of the mental canal (56.1%) and coursed posterosuperiorly (36.3%). The mean length of the bony canals was 5.78 ± 2.31 mm.

CONCLUSIONS

This study presents a considerable frequency of AMFs in a Chinese population. The high-position AMF and the associated bony canal coursing in the oblique upward direction appear frequently. Thus, clinicians should be alert to the presence of the AMF to avoid neurovascular complications especially when dental procedures require periosteum detachment and implant insertion in the mental region.

Assessment of the anterior loop of the inferior alveolar nerve via cone-beam computed tomography

Objectives

The aim of this study was to evaluate different anatomical variants of the anterior loop of the inferior alveolar nerve (IAN) via cone-beam computed tomography (CBCT).

Materials and Methods

CBCT images of 71 patients (36 males and 35 females) were evaluated. We used the classification described by Solar for IAN evaluation. In this classification, three different types of IAN loops were introduced prior to emerging from the mental foramen. We classified patients according to this system and introduced a new, fourth type.

Results

Type I was seen in 15 sites (10.6%), type II in 39 sites (27.5%), and type III in 50 sites (35.2%). We found a new type in 38 sites (26.8%) that constituted a fourth type.

Conclusion

We found that type III was the most common variant. In the fourth type, the IAN was not detectable because the main nerve was adjacent to the cortical plate and the incisive branch was thinner than the main branch and alongside it. In this type, more care is needed for surgeries including inferior alveolar and mental nerve transposition.

Accessory Mental Foramen and Maxillofacial Surgery

Accessory mental foramens should be considered in surgical procedures performed in mandibular body and symphysis. Location and content of these foramina has significant impact on the result of surgery.Lip numbness is the catastrophic result if these foramina are violated while their content is nerves that carry sensory inputs from lower lip. Examples of interferences with dental implant, orthognathic, and periapical surgeries are presented and it is discussed in which conditions they complicate oral surgical procedures.

Relationship between the Mental Foramen, Mandibular Canal, and the Surgical Access Line of the Mandibular Posterior Teeth: A Cone-beam Computed Tomographic Analysis

INTRODUCTION

The purpose of this study was to investigate the relationships between the location of the mental foramen (MF) and the mandibular canal (MC) and the surgical access line (SAL) of the mandibular posterior teeth using cone-beam computed tomographic (CBCT) scans.

METHODS

CBCT scans of 204 subjects ranging in age from 18-76 years old were evaluated. The vertical and horizontal distances from the MF to the SAL of the mandibular premolars and first molars and the vertical distance from the MC to the SAL of the second premolars and first molars were measured via CBCT scans.

RESULTS

The average vertical distance between the MF and the SALs showed significant increases sequentially from the first premolars to the distal roots of the first molars, and the shortest average distance of 2.74 mm was obtained for the first premolars. The SALs of the second premolars were the closest to the MF in the horizontal direction with an average distance of 1.5 mm. In 19.9% of the cases, the vertical and horizontal distances between the MF and the SALs of the second premolars were less than 2 mm. In addition, the MF was located superior to the root apices in 6.62% of the cases. The majority of the SALs were located at a vertical distance from the MC that was more than 2 mm. Men and women exhibited significant differences in both the horizontal distance from the MF to the SALs of the first premolars and the vertical distance from the MC to the SALs of the second premolars.

CONCLUSIONS

To improve the success of endodontic microsurgery, adequate knowledge of the anatomic relationships between the location of the MF and MC and the SAL of the mandibular posterior teeth is indispensable to surgeons.

The assessment of accessory mental foramen in a selected polish population: a CBCT study

Background

Accessory mental foramen (AMF) is a rare anatomical variation. When accessory mental foramen is present, the nerves and vessels that go through the mental foramen (MF) must follow alternative courses and special care must be taken during dental treatment planning. The purpose of this study was to evaluate the occurrence and the location of AMF in a selected Polish population using cone-beam computed tomography (CBCT).

Methods

Two hundred CBCT (105 males and 95 females) examinations were evaluated for the presence of AMFs. The location and side of AMFs were reported. The mean distance between MF and AMF was also calculated. The vertical size of MF on the side with and without AMF was measured. The obtained variables were statistically analyzed.

Results

AMFs were observed in 7% of the patients. There was no statistically significant difference between the appearance of AMF and sex (p > 0.05). We found no significant difference in the vertical size of MF between individuals with and without AMFs (p < 0.05).

Conclusion

Twenty-eight AMFs (7%) were observed from 400 sides of 200 patients. AMFs occurred more often in males (18 AMFs) than in females (10 AMFs). Twenty AMFs (71.4%) were located anteriorly, and eight (28.6%) - posteriorly. Fifteen AMFs (53.6%) were on the right side and thirteen (46.4%) - on the left.

Accessory mandibular foramen during dental implant placement: case report and review of literature

Accurate knowledge of vital anatomical structures, such as the inferior alveolar nerve, mental nerve, and mental foramen, is critical to achieve favorable results during oral surgical procedures and dental implant placement. Although uncommon, variations in mandibular foramina have been reported and if unnoticed and, as a result, injured, may lead to patient morbidity, neurosensory disturbances, and other undesired complications. We present a case report of identification of an accessory mandibular foramen (AMF) encountered during placement of 2 dental implants for a mandibular implant-retained overdenture and demonstrate appropriate management. In addition, we propose a more reasonable terminology for such accessory foramina so as to facilitate communication through common terminology among health care providers. As conventional radiography (periapical and panoramic films) may not allow for proper identification of such anatomical variations, cone-beam computed tomography may be useful in the diagnosis of AMF during treatment planning of dental implants in the mandible.

Unilateral Absence of Mental Foramen with Surgical Exploration in a Living Human Subject

The mental foramen (MF) is an important anatomic landmark of the mandible, in which the somatic afferent sensory nerve of the mandibular nerve emerges as mental nerve and blood vessels. The identification and actual location of MF are important in order to avoid sensory dysfunction or paresthesia due to mental nerve injury. In the literature there are some rare reports on the anatomical variations of the MF such as its location or presence of accessory foramina. The present report describes the absence of mental foramina on the left side of the mandible, as detected by cone-beam computed tomography before impacted tooth removal and observed directly during surgery.

Buccolingual course of the inferior alveolar canal in different mental foramen locations: A cone beam computed tomography study of an Iranian population

Context:

Better understanding of the anatomical location and course of the mandibular canal is necessary to avoid damaging inferior alveolar nerve.

Aims:

The aim of this study was to investigate the buccolingual course of the inferior alveolar canal (IAC) in different mental foramen locations, using cone beam computed tomography.

Materials and Methods:

Three hundred and twelve hemimandibular images were evaluated in this study. The location of mental foramen in relation to the apices of mandibular premolar and molar teeth were recorded. Nine measurements (in millimeters) were taken at the level of the IAC and posterior mandibular premolar and molar root apices. Relative distances of IAC to buccal and lingual mandibular cortex were calculated for different mental foramen types.

Statistical Analysis Used:

Data were analyzed by one-way analysis of variance and P < 0.05 was considered to be statistically significant.

Results:

The distribution of subjects according to the type of mental foramen includes: Type 1 = 50.3% (at the level of second premolar apex), Type 2 = 33% (between the apices of first and second premolars), and Type 3 = 16.7% (between the apices of second premolars and first molars). The buccolingual ratio of the IAC position was statistically significant in different mental foramen types (P = 0.00).

Conclusion:

The position of IAC was affected by the location of the mental foramen. The direction of IAC gradually changed from lingual to buccal and from posterior to anterior.

Anatomical characteristics and visibility of mental foramen and accessory mental foramen: Panoramic radiography vs. cone beam CT

Background

The mental foramen (MF) is a small foramen located in the anterolateral region of the mandible through which the mental nerve and vessels emerge. The knowledge on the anatomic characteristics and variations of MF is very important in surgical procedures involving that area. The aim of this study was two-fold: firstly, to analyze the anatomic characteristics of MF and the presence of accessory mental foramen (AMF) using CBCT and, secondly, to compare the capability of CBCT and PAN in terms of MF and AMF visualization, as well as influencing factors.

Material and Methods

A sample of 344 CBCT scans was analyzed for presence and characteristics (i.e. diameter, area, shape, exit angle) of MF and AMF. Subsequently, corresponding PANs were analyzed to ascertain whether MF and AMF were visible.

Results

Out of the 344 patients, 344 (100%) MFs and 45 (13%) AMFs were observed on CBCT. Regarding gender, MF diameter and area, MF-MIB and MF-MSB distances, and exit angle were all significantly higher in males. Also, statistically significant differences were found in terms of age and dental status. Statistically significant differences in MF long and short diameters and MF area were found with respect to AMF presence (p=.021, p=.008, p=.021). Only 83.87% of the MFs and 45.83% of the AMFs identified on CBCT were also visible on PANs. MF diameter, shape, exit angle, and age had a significant influence on MF visualization on PAN (B=.43, p=.005; B=-.55, p=.020; B=.20, p=.008; B=.61, p=.005).

Conclusions

PAN is not an adequate technique to properly identify MF and AMF. Diameter, shape, exit angle, and age are all factors influencing MF visualization on PAN images. For surgery involving the MF anatomical region, a preoperative radiological study with CBCT is of crucial importance to avoid complications.

Key words:Mental foramen, accessory mental foramen, mandibular anatomy, cone beam computed tomography, panoramic radiography.

Intraosseous vascularization of anterior mandible: a radiographic analysis

The anterior mandible was initially considered a safe zone from a surgical point of view. Over time, serious complications resulting from dental implantology procedures have been reported. This has led to a greater focus on vascularization of the interforaminal region. The purpose of this article was to evaluate the anterior mandibular region in relation to the presence of canals perforating the buccal and lingual cortical plates. DICOM (Digital Imaging and Communications in Medicine) files of 100 cone beam computed tomography scans were analyzed by imaging software. All radiographic cross-sections between the mental foramina were examined to detect the presence and location of perforating buccal or lingual canals. Lingual perforating canals are present in 98% of the cohort. The most common site is the symphysis region. The presence of 2 lingual canals cranially and caudally to the genial apophysis has been found in 39%. Vestibular perforating canals are absent in 61%. The anterior mandible has several lingual perforating canals, which are variable in number and location. Imaging software is a valuable aid in presurgical planning. Because of the higher prevalence of perforating canals in the symphysis region, this site should be preserved.

Accessory mental foramen: an anatomical study on dry mandibles and review of the literature

PURPOSE

Since numerous surgical procedures in oral and maxillofacial surgery as well as several aspects of dental practice involve the mental region, the knowledge of its anatomical variations is essential for the clinician. Therefore, the aim of the present study was to evaluate the incidence and the anatomical features of the accessory mental foramen, which is occasionally traced additionally to the main mental foramen.

MATERIAL AND METHODS

Ninety-six dry human mandibles of a Greek population and of unknown sex and age were examined in order to notice the presence of possible accessory mental foramina. The frequency of the accessory mental foramen was calculated, and its dimensions and its topographical relationship to the teeth of the mandible and the mental foramen were determined as well.

RESULTS

A single accessory mental foramen was identified in 4.17% of the sample, while its mean transverse diameter was measured to be 1.09 mm and its mean distance from the mental foramen was 5.24 mm.

CONCLUSIONS

The present study revealed an appreciable incidence of the accessory mental foramen in the Greek population, recognizably higher than the discovered incidence of past studies involving the Greek population. Consequently, the clinician should always be prepared to deal with an accessory mental foramen during surgical procedures.

Accessory mental foramen: A rare anatomical variation detected by cone-beam computed tomography

The mental foramen is a bilateral opening in the vestibular portion of the mandible through which nerve endings, such as the mental nerve, emerge. In general, the mental foramen is located between the lower premolars. This region is a common area for the placement of dental implants. It is very important to identify anatomical variations in presurgical imaging exams since damage to neurovascular bundles may have a direct influence on treatment success. In the hemimandible, the mental foramen normally appears as a single structure, but there are some rare reports on the presence and number of anatomical variations; these variations may include accessory foramina. The present report describes the presence of accessory mental foramina in the right mandible, as detected by cone-beam computed tomography before dental implant placement.

Accessory mental foramina, incisive nerve plexus and lingual canals with unusual emergence paths: Report of two rare cases

Being knowledgeable of neurovascularization of anterior mandible is crucial for successful local anesthesia and for safe minor and major oral surgeries of this part. The first case was 62 years old and was found to have two accessory mental foramina with buccal emergence on the left side and two accessory mental foramina with buccal and lingual emergence paths on the right side (overall five mental foramina). Incisive nerve plexus with multiple cephalic branching was obvious on both sides. The second case was 60 years of age and had two lingual foramina on the lingual side with two accessory foramina on the buccal side of the symphysis. Considering our findings, a pre-operation limited cone beam computed tomography is suggested to avoid inadvertent damage, especially when planning a surgery in the mandibular inter-mental region.