Three-dimensional analysis of mandibular and mental canals corroborating with teeth and mental foramen by cone beam computed tomography.

BACKGROUND: This study aimed to analyse the 3D patterns of the mandibular and mental canals (MDC and MC) referring to the surrounding prominent surgical landmarks such as teeth and mental foramen by cone beam computed tomography (CBCT). METHODS: CBCT scans of 354 patients aged 18-67 years with mandibular first premolar to second molar were included and reconstructed 3-dimensionally (3D) by mimics. The parameters of MDC and MC were measured referring to teeth and mental foramen. RESULTS: From the first premolars to the second molars, the mandibular canals showed a trend of gradually closer to the cementoenamel junction (CEJ) of the adjacent teeth and farther away from the buccal cortical plate. The distance of the MDC with the root apexes (RA) was relatively constant from the first premolar to the first molar, but became much closer to the second molar. About 10.8% of the second molars had MDC-RA distances of shorter than 2 mm, and 1.34% even had the MDC superior to the RA. Moreover, the Type III of MC presented in 66.0% of the subjects and had a relatively longer length. Besides, the existence of Type I MC may be related to the MDC featuring with close distances to the RA and CEJ of the adjacent teeth. CONCLUSION: Dentists and surgeons should know the patterns of mandibular and mental canals. A better understanding of the MDC and MC and their relationship to local anatomical landmarks may facilitate the planning of surgeries and alert potential nerve injuries in the operative procedures.

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.

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.

Assessment of the prevalence and length of the anterior and caudal loops of the mental nerve as anatomical variants of exiting the mandible at the mental foramen using cone-beam computed tomography: a systematic review and meta-analysis.

OBJECTIVES: This systematic review aimed to identify the studies that performed cone-beam computed tomography analysis of the prevalence and length of the anterior loop (AL) and caudal loop (CL) of the mental nerve. MATERIALS AND METHODS: An electronic database search was performed across PubMed, EMBASE, Web of Science, Scopus, the Cochrane library, and Google Scholar. Original studies reporting the frequency and length of the AL and CL were selected. Qualitative synthesis and meta-analysis were then conducted to assess the prevalence and length of the AL and CL and their associations with age, gender, sides, and dentition status. RESULTS: A total of 21 studies were included in this review. The pooled prevalence of the AL (95% confidence interval) of the mental nerve at the patient and side level was 51% (31-71%) and 53% (37-69%) while the mean anterior loop length was 2.08 (1.46-2.70) mm. The pooled prevalence of the CL and mean caudal loop length were 100% and 4.73 (3.44-6.01) mm. No significant associations were found between the prevalence and length of the AL and CL and age, gender, sides, and dentition status. CONCLUSIONS: Overall, the pooled prevalence and mean length of AL of the mental nerve varied among different populations while CL seems to be a constant anatomical landmark with a longer CL than AL. CLINICAL RELEVANCE: Surgeons performing inter-foraminal oral surgeries like dental implant placement and genioplasty should be aware of the possible distance of the AL and CL to avoid iatrogenic mental nerve injury.

Inferior Alveolar Nerve Lateralization Surgery for Implant Installation in Atrophic Posterior Mandible With Accessory Mental Foramen: A Challenge for the Usual Technique.

ABSTRACT: Implantology allows edentulous patients to smile and chew with confidence. However, the atrophy at posterior region of the mandible is still a challenge due the presence of the inferior alveolar nerve (iAN). The options of restoration with oral implants in this area with great atrophies are few and hazardous. The possibilities are: bone grafting, short implants, which are not always possible. So, the solution falls on the techniques of inferior alveolar nerve lateralization (IANL) or transposition. The knowledge of the anatomy and path of the IAN is decisive in this type of surgery. But anatomical variations may occur. Like the presence of an accessory mental foramen. This clinical study will present a relatively rare case of the occurrence of an accessory mental foramen that obliged to change the technique of iAN lateralization to contour this anatomical variance and install oral implants, maintaining the integrity of the iAN bundle.

Morphometric Analysis of the Mental Foramen Variation in an Iraqi Population by Using Cone-Beam Computed Tomography.

ABSTRACT: The effects of gender, side, and ridge condition on the position of the mental foramen (MF) were investigated in this research. A total of 122 cone-beam computed tomography scans were chosen from healthy patients with age ranging from 18 to 72 years. The following parameters were used to evaluate images: MS-MF (horizontal distance to the mandibular symphysis from the anterior MF limit) and MB-MF (vertical measurement of distance from the inferior boundary of the mandible to the lower border of the MF). The mean distance between the MF and mandibular symphysis was 20.98 ±â€Š1.95. The average measurement between the MF and the mandible's lower boundary was 10.36 ±â€Š1.63. The horizontal distance was slightly different between males and females (21.5 ±â€Š1.59 and 20.6 ±â€Š1.6, respectively). In terms of gender and ridge condition, a significant difference in vertical distance (10.97 ±â€Š1.14 versus 9.9 ±â€Š1.24 and 10.13 ±â€Š1.5 versus 10.55 ±â€Š1.07, respectively) was observed. By contrast, in vertical and horizontal distances, significant differences were noted between edentulous men and women. Meanwhile, a significant difference between dentate male and female patients was found at vertical distances only. In conclusion, in both vertical and horizontal measurements, the location of the MF was higher in males than in females and edentulous more than dentate.

Cone Beam Computed Tomography based evaluation of position of mental foramen and its relation to apices of mandibular posterior teeth in a sample of Pakistani population.

OBJECTIVE: To radiographically determine the mental foramen position, its distance to the nearest apex and the prevalence of anterior loop of mandibular nerve using cone-beam computed tomography scans. METHODS: The cross-sectional study was conducted at the Aga Khan University Hospital, Karachi, from January to June 2020, and comprised cone-beam computed tomography scans of males or females of Pakistani origin aged 15-65 years with intact mandibular dentition and fully formed roots with matured apex. The scans were analysed to determine the horizontal position of mental foramen and to classify it according to the Tebo and Telford classification. The vertical distance from mental foramen to the nearest tooth apex was measured and the mandibular nerve configuration was determined. Data was analysed using SPSS 23. RESULTS: Among the 96 scans, the most frequent location of mental foramen MF was along the long axis of 2nd premolars for both right 50(52.1%) and left 49(51%) sides, followed by between 1st and 2nd premolars for both right 28(29.2%) and left 38(39.6%) sides. The mean minimum distance from mental foramen to the nearest root apex was 3.75±2.59mm and 3.99±2.26mm on right and left sides, respectively. There was bilateral symmetry on both sides. The most frequent mandibular nerve configuration on the right 69(72.6%) and left 75(78.1%) sides, with anterior loop being the least common; right side 3(3.2%) and 5(5.2%) left side. Conclusion: The most common position of mental foramen was along the long axis of 2nd premolars while the anterior loop was the least common.

The relative locations of the supraorbital, infraorbital, and mental foramina: A cadaveric study.

The purpose of this study is to investigate the applicability of the current surgical guideline stating that the main facial foramina that transmit cutaneous nerves to the face (supraorbital notch/foramen, infraorbital foramen, and mental foramen) are equidistant from the midline in European and Hispanic populations. Previous studies suggest this surgical guideline is not applicable for all ethnicities; however, to our knowledge, no data have been published regarding the accuracy of this guideline pertaining to the Hispanic population. An experimental study was performed on 67 cadavers donated to the Human Anatomy Program at UT Health San Antonio. The supraorbital, infraorbital, and mental foramina were dissected and midline structures including the crista galli, internasal suture, anterior nasal spine, and mandibular symphysis were identified. The distance from each foramen to midline was recorded using a digital caliper. For all cadavers/ethnicities studied, the supraorbital, infraorbital, and mental foramina were 25.32 mm, 29.57 mm, and 25.55 mm to the midline, respectively. Thus, the infraorbital foramen is located significantly more lateral compared to the supraorbital (p < 0.0001) and mental foramina (p < 0.0001). After dividing the sample based on ethnicity, this relationship was also true for the European sample and tended to be true for the Hispanic sample. Significant anatomical variations exist in the current surgical guideline stating that the supraorbital foramen, infraorbital foramen, and mental foramen are equidistant from the midline. Clinicians may need to adjust their methodology during surgical procedures of the face in order to optimize patient care.

Evaluation of mental foramen and inferior alveolar nerve canal and its relationship to adjacent anatomical landmarks using cone-beam computer tomography.

The objective of the research was to evaluate the location, size, variability, and morphologic features of mental foramen (MF) and the inferior alveolar nerve canal (IAN) on cone-beam CT. We evaluated the morphologic findings of mental foramen (MF) and inferior alveolar nerve (IAN) canal of 88 mandibular hemiarches of 65 Caucasian subjects (35 males, 30 females; age range 25-75 years) using cone beam CT. The most common horizontal position of MF was type 3 (53.4%), followed by type 4 (39.8%), type 1 (2.3%), type 2 (2.3%), and type 5 (2.3%). Regarding the vertical position, in 71.6% of cases (63/88) we found type 3 position, followed by type 2 (22.7%) and type 1 (5.7%). MF presented as oval in 51.1% and round in 42%, with double oval and triple foramens having been observed in 5.7% and 1.1% respectively. In 36.9% of cases, we found an anterior loop of the IAN. The mean depth of MF was 6.12±1.65mm; width and height were 3.7±0.83mm and 3.14±0.78mm. Width and height of the IAN distal to MF were 2.27±0.53mm and 2.74±0.51mm, while those of the incisive nerve canal mesial to MF were 1.37±0.44mm and 1.54±0.58mm, respectively. An increase in the width of MF was correlated to oval shape (r=0.45; P < 0.01), and there was a low but significant correlation (r=0.23; P < 0.05) between the round shape of MF and the size of the IAN. MF shape appears to be correlated to MF width and size of the IAN. The individual anatomical variability of this structure is a factor that must be considered when dealing with mandibular surgery.

Quantitative and Mathematical Analysis of Mental Foramen along with Its Correlation with Sex and Age Using Cone-beam Computed Tomography.

AIM AND OBJECTIVE: The aim of the present study was to perform quantitative and mathematical analysis of mental foramen (MF) along with its correlation with study subject's sex and age using three-dimensional imaging like cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The CBCT scan images stored in the database were used in this study. Two-hundred sixty-seven scans were selected. They were divided into four different age-groups. These age-groups were 16-23 years, 24-38 years, 39-55 years, and more than 56 years. Each age-group was further divided into two subgroups. One subgroup was of males, while the other subgroup was of females. Following this, there was evaluation of all CBCT-scanned images considering certain parameters like position of MF, size of MF, distance X, distance Y, and distance Z. RESULTS: The MF was located generally apically to the premolar and molar. It was more commonly located between the first premolar and second premolar among females, while in males, it was mostly located along the long axis of the second premolar. In most of the age-groups, the MF was located between the long axis of the first premolar and second premolar. The average distance of MF from the apex of first premolar was 5.01 mm. Further, the average size of MF and its distance from the base of the mandible were greater in males as compared with females. When all these measurements were compared in different age-groups, the difference was not statistically significant. CONCLUSION: The average distance of MF from the apex of the first premolar was 5.01 mm. The average size of MF and its distance from the base of the mandible were greater in males as compared with females. When the measurements were compared in different age-groups, then the difference was not statistically significant. CLINICAL SIGNIFICANCE: MF is an important structure in the mandible because it acts as an important landmark in the anesthetic procedure; therefore, there was a need to carry out detailed quantitative and mathematical analysis for MF.

Detection and characterization of anterior loop, accessory mental foramen, and lateral lingual foramen by using cone beam computed tomography.

STATEMENT OF PROBLEM: The presence of an anterior loop (AL), accessory mental foramen (AMF), or lateral lingual foramen (LLF) adds complexity to the mental foraminal region, and consequently, implant placement in this region can damage the nerves and blood vessels if the structures are not carefully identified. PURPOSE: The purpose of this retrospective study was to evaluate the characteristics of the AL, AMF, and LLF to provide recommendations for surgeons operating in the mandibular mental foraminal region. MATERIAL AND METHODS: Reconstructed cone beam computed tomography (CBCT) images in 306 Southern Chinese patients were retrospectively analyzed. The prevalence of the anterior loop was assessed, and the anterior loop length (ALL) was measured from the most anterior point of the mental foramen to the most mesial part of the anterior loop. The prevalence, location of the AMF as related to the mental foramen, and adjacent teeth were analyzed. Additionally, the distance from the mental foramen to AMF centers were measured. The prevalence, diameter, and location of the LLF were evaluated. The chi-square test was used for prevalence analysis (α=.05). RESULTS: Anterior loops were identified in 67.8% of the 612 hemimandibles, with a mean length of 3.3 ±1.2 mm, ranging from 1.2 to 7.3 mm. A total of 5.56% of the hemimandibles had an ALL ≥5 mm, and male patients had a statistically longer loop length (P=.006). The ALL on the right side was found to be statistically longer than that on the left side (P=.002). No statistically significant differences in the ALL were found among different age groups (P=.124). AMFs were observed in 10.5% of the patients, with most located in the posterosuperior position of the mental foramen. The mean distance between the center of the AMF and the mental foramen was 5.1 ±1.4 mm. LLFs presented in 69.9% of patients, with 74.0% located in the premolar region. The mean vertical diameter of the LLF was 0.9 ±0.3 mm, and the mean distance from LLF to the mandibular inferior border was 7.1 ±1.9 mm. CONCLUSIONS: This study revealed that ALs, AMFs, and LLFs occurred often in the Southern Chinese population. Identifying the presence of the AL, AMF, and LLF is important before surgery in the mental foraminal region.

A Comparative Radiographic Evaluation of Occlusal Plane in Dentulous and Edentulous Subjects: A Clinical Study.

AIM: The aim of this study is to establish a proportion between the inferior border of mandible and lower edge of the mental foramen and inferior border of mandible to occlusal plane for dentulous subjects and to evaluate the validity of this proportion in orienting the occlusal plane for edentulous subjects. MATERIALS AND METHODS: The occlusal plane was evaluated in the selected 50 dentulous and edentulous subjects for its relation to the mental foramen and inferior border of the mandible. The orthopantograms obtained were traced with the markings and the measurements were tabulated under different headings. After measuring the distances, the proportion between the distances was determined. The mean proportions of dentulous, edentulous, male, and female subjects were evaluated. Then the proportion of male subjects was compared with that of female subjects and dentulous subjects with that of edentulous subjects. Comparison of proportion between the different groups was done by using unpaired t test. The mean and standard deviation (SD) were determined for each group separately and were compared within each group. From the calculated "t" value, "p" the probability for error was found out. RESULTS: In dentulous subjects, the proportion ranged from 1:3.53 to 1:4.40. The mean was 1:3.90. In edentulous subjects, the proportion ranged from 1:3.50 to 1:4.15. The mean was 1:3.84. On comparison, the difference between both the groups was 0.06. The difference was statistically insignificant (p = 0.14). In the comparison of dentulous male and female subjects, the difference obtained was 0.02. The difference was statistically insignificant (p = 0.77). The comparison of edentulous male and female subjects and the difference obtained was 0.03. The difference was statistically insignificant (p = 0.51). CONCLUSION: The derived proportion of 1:4 between the inferior border of mandible and mental foramen and inferior border of mandible and occlusal plane in edentulous patients as measured on an orthopantogram may yield a plane of occlusion similar to that existing in the dentulous state. CLINICAL SIGNIFICANCE: The above-drawn proportion between the inferior border of the mandible to the lower edge of the mental foramen and between the inferior border of the mandible and the occlusal plane in edentulous patients may yield a plane of occlusion which is oriented similar to that existing in the dentulous state. The proportions derived radiographically in this study can serve as a basis for future studies to establish the occlusal plane for edentulous subjects.

Neural Network Detection and Segmentation of Mental Foramen in Panoramic Imaging.

Objective: To apply the technique of deep learning on a small dataset of panoramic images for the detection and segmentation of the mental foramen (MF). Study design: In this study we used in-house dataset created within the School of Dental Medicine, Tel Aviv University. The dataset contained randomly chosen and anonymized 112 digital panoramic X-ray images and corresponding segmentations of MF. In order to solve the task of segmentation of the MF we used a single fully convolution neural network, that was based on U-net as well as a cascade architecture. 70% of the data were randomly chosen for training, 15% for validation and accuracy was tested on 15%. The model was trained using NVIDIA GeForce GTX 1080 GPU. The SPSS software, version 17.0 (Chicago, IL, USA) was used for the statistical analysis. The study was approved by the ethical committee of Tel Aviv University. Results: The best results of the dice similarity coefficient ( DSC), precision, recall, MF-wise true positive rate (MFTPR) and MF-wise false positive rate (MFFPR) in single networks were 49.51%, 71.13%, 68.24%, 87.81% and 14.08%, respectively. The cascade of networks has shown better results than simple networks in recall and MFTPR, which were 88.83%, 93.75%, respectively, while DSC and precision achieved the lowest values, 31.77% and 23.92%, respectively. Conclusions: Currently, the U-net, one of the most used neural network architectures for biomedical application, was effectively used in this study. Methods based on deep learning are extremely important for automatic detection and segmentation in radiology and require further development.

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 2nd 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.

Localization of Mental Foramen in Panoramic Radiographs of 18-30 Year Olds: A Hospital Based Study.

Background The position of the mental foramen demonstrates anatomical variations, although typically it is reported to be either between the apices of the first and second premolars or below the apex of the second premolar. Objective To determine the radiographic position of mental foramen in relation to Premolar crown and apex, in panoramic radiographs. Method Following ethical approval a retrospective study was conducted in 510 panoramic radiographs of 18-30 year olds from archives of Department of Oral Medicine and Radiology. The position of mental foramen was scored using crown and apex scores according to scoring criteria given by Jasser and Nwoku, 1998. Descriptive statistics was calculated and Chi-square test was applied to assess variation in position of mental foramen between genders and right and left side of mandible. Kappa statistics was applied to assess intra-observer reliability. Result The most common scoring for position of mental foramen on right side crown and apex was 3 (49.4%) followed by 4 (45.9%). Similarly, on left side the most common score for crown and apex was 3 (50.8%) followed by 4 (44.3%). There was no statistically significant difference in position between the genders. Comparing the right and left sides, the position was symmetrical in 83.3% for crown and apex scores. The Kappa values indicated good agreement for intraobserver reliability. Conclusion The most common position for the mental foramen is between the first and second premolar teeth; though, anatomical variations are seen.

Evaluation of bone texture imaging parameters on panoramic radiographs of patients with Sheehan's syndrome: a STROBE-compliant case-control study.

Sheehan's syndrome (SHS) is a rare condition related to the risk of osteoporosis and evaluation of bone texture imaging features on panoramic radiographs would be suitable for this condition, which was the aim of the present study. Fractal dimension, lacunarity, and trabecular morphologic aspects were significantly altered in these patients. INTRODUCTION: SHS is an important public health problem particularly in developing countries. It is characterized as postpartum hypopituitarism secondary to obstetric complications-related ischemic pituitary necrosis that shows significant systemic metabolic repercussions. Thus, this study aimed to evaluate bone texture parameters in digital panoramic radiographs of patients with SHS. METHODS: A case-control study was conducted with 30 SHS patients from an Endocrinology and Diabetology Service of reference in Brazil, and 30 age- and sex-matched healthy controls. A custom computer program measured fractal dimension, lacunarity, and some morphologic features in the following mandibular regions of interest (50 × 50 pixels): below the mental foramen (F1), between the first and second molars (M1), and at the center of the mandibular ramus (R1). RESULTS: The fractal analysis showed a statistically significant difference between the studied groups in all regions of interest. The fractal dimension in F1 (p = 0.016), M1 (p = 0.043), and R1 (p = 0.028) was significantly lower in SHS group, as well as lacunarity in R1 (p = 0.008). Additionally, several morphologic features were statistically significant in the SHS group (p < 0.05). CONCLUSION: Therefore, individuals with SHS showed altered imaging texture parameters on panoramic radiographs, which reflect a smaller spatial organization of the bone trabeculae and, possibly, a state of reduced mineral bone density.

Anthropometrics Analysis of Mental Foramen and Accessory Mental Foramen in Zambian Adult Human Mandibles.

The mental foramen (MF) and accessory mental foramen (AMF) are the strategically important landmarks during surgical interventions and anaesthetic nerve blocks procedures involving the mental nerve. The study aimed at evaluating anthropometrics of MF and AMF in Zambian adult human mandibles and it was cleared for ethics from TDRC Ethics Review Committee (Reg. No.: 00002911; FWA: 00003729). A total of 33 Zambian adult human mandibles were evaluated for shape, position, and direction of opening of foramen. All measurements were performed using a Digital Vernier Calliper and statistically analysed for per cent frequency and mean and standard deviations, and we performed the one sample t-test for comparative analysis. Data were considered significant at p<0.05. All mandibles that were examined had bilateral MF while unilateral AMF was found in two mandibles (6%). The foramens were mostly oval in shape and their most common position was between the second premolar and first molar and the most common orientation was posterior-superior. The comparative analysis of mandibular anthropometrics showed significant variations (p<0.05) with different ethnic groups. The findings emphasize the ethnic variations and edify that the foramen position is not always as stated in reference textbooks. The clinical creditability of the study is cautioning the surgeons on possible variations of the MF and AMF anthropometrics compared to existing literature in order to avoid any unforeseen injury related to anaesthesia or dental surgeries. Further studies with large sample sizes representing whole country are recommended to establish the standard MF and AMF anthropometrics of Zambian population.

Prevalence of Accessory Mental Foramina: A Study of 4,000 CBCT Scans.

The presence of accessory mental foramina (AMF) is an important consideration prior to any dental implant and surgical treatment to avoid injury to the neurovascular bundle and subsequent postoperative complications. The aim of this retrospective study was to determine the prevalence of AMF from a substantially large sample of the Australian population. The cone beam computed tomography (CBCT) scans of 4,000 patients showing the mandible were examined. All mental foramen (MF) were visualized and no cases were excluded. The number of MF/AMF, sex, and age were recorded. The prevalence of AMF was found to be 6.4% (254 patients) in this study. Twelve patients exhibited bilateral AMF, and 11 had three mental foramina on one side. One case had a total of five mental foramina with three on the right and two on the left side. No significant sex preference was discovered. This is the largest study ever to be conducted to evaluate the prevalence of AMF. With nearly one in 15 individuals found to have AMF, clinicians must be acutely aware of this anatomical variation and treatment plan for each case accordingly. Clin. Anat. 32:1048-1052, 2019. © 2019 Wiley Periodicals, Inc.

Review of Risk Assessment of Major Anatomical Variations in Clinical Dentistry: Accessory Foramina of the Mandible.

Most of the studies of the mandible's anatomical variations have presented the authors' speculations, and only a limited number has provided evidence that demonstrated the actual complications injury to the variant structures caused. To our knowledge, no study has evaluated the risks associated with these variant anatomical structures' injury. We reviewed articles that described clinical cases of the injury to, and anatomical studies of, three anatomical variants of the mandible-the accessory mental, lingual, and retromolar foramina-with which dentists are relatively familiar and that are mentioned often in the context of implant and third molar surgeries, to describe risk assessment methods with which to evaluate potential complications preoperatively. Only a limited number of the clinical reports of injury to the mandible's accessory foramina were available. The potential severe complication of injury of the accessory mental foramen (AMF) is sensory disturbance of the lower lip. Risk of neurosensory disturbance of lower lip can be assessed by AMF/MF ratio and positional relations to the MF. Potential severe complication of injury of the lingual foramen is bleeding and hemorrhage in the oral cavity's floor. Risk of bleeding can be assessed by diameter and positional relation between the mental spine/mylohyoid line. A risk assessment of the retromolar foramen could not be made because of inadequate data. We hope the risk assessments suggested will encourage dentists to predict intraoperative/postoperative complications caused by damaging the mandible's accessory foramina. Clin. Anat. 32:672-677, 2019. © 2019 Wiley Periodicals, Inc.

Double mandibular canal and triple mental foramina: detection of multiple anatomical variations in a single patient.

Having complete information about a patient's mandibular canal and mental foramen is fundamental to performing safer procedures and avoiding intraoperative and postoperative complications. Cone beam computed tomography (CBCT) produces accurate images for the analysis of maxillomandibular bone structures and is widely used in dentistry. The aim of this study is to report a case of mandibular bifid canal associated with triple mental foramina that was revealed with CBCT images. A 45-year-old woman was referred for a CBCT scan of remaining bone quantity to assist in preoperative implant planning. The patient had reported problems related to anesthesia during extraction of the mandibular right second and third molars. Examination showed bilateral bifurcation of the mandibular canal, from the mandibular foramen to the gonial angle. In addition, exteriorization of the mandibular canal was noticed in 3 regions; that is, there were 3 distinct mental foramina. Clinicians must be aware of these anatomical variations in the mandibular region during dental procedures to avoid complications such as difficulty in obtaining anesthesia or postoperative sensory dysfunction.