Comparative analysis of mandibular anatomical variations between panoramic radiography and cone beam computed tomography

Bifurcation of the mandibular canal according to sex, age, and facial skeletal pattern: a morphological and morphometric study of cone beam computed tomography

PURPOSE

To assess the presence of mandibular canal bifurcation (BMC) and classify these variations by correlating findings with sex, age and facial skeletal pattern, measurements were made, including height, width, and distance from bifurcation to anatomical cortical bones.

METHODS

BMC was identified in cone beam CT exams of 301 patients and classified according to its origin, location, direction, configuration and ending. The height and width of the MC before and after the bifurcation; height and width of the BMC; and distance from BMC to alveolar (C1), buccal (C2), lingual (C3) and basal (C4) bone cortices were measured. All data were correlated with sex, age, and facial skeletal pattern (class I, II, III). The significance level was 5%.

RESULTS

67 BMC (22.26%) were identified in 55 patients (18.28%). Bifurcations were more prevalent in females (p = 0.57), aged 18-39 years (p = 0.40), class I (p = 0.77). Single bifurcations, located in the posterior region of the mandible, originating in the MC, with a superior direction and ending in the retromolar foramen were more prevalent (p > 0.05). Mean cortical measurements were higher in male individuals, with significant differences only at C1 (p = 0.03). The mean height and width of BMC were 2.24 (± 0.62) and 1.75 (± 0.45) mm. There was no association between BMC classification and the variables studied (p > 0.05).

CONCLUSION

Approximately 1/5 of the population studied had BMC. There were no associations of BMC presence or characteristics with sex, age, and facial skeletal pattern. The distance from bifurcation to alveolar (superior) cortical bone is greater in male individuals.

Radiographic Recognition of Mental Nerve for Secured Dental Implant Placement by Cone-Beam Computed Tomography in Mosul City Population

The study aims to estimate precisely the different levels of mental loop and foramina in the Mosul population of Nineveh governorate in Iraq. It is a cross-sectional study of a previously saved database in the cone-beam computed tomography device. The study sample was 357 patients selected randomly from the database of patients at the Oral Radiology Unit at the Maxillofacial Department in Al-Salam Teaching Hospital. The study variables are mental foramen (MF) position, shape, radiograph appearance, and mental loop presence and direction. The results show that the age group from 19 to 30 years shows the highest percentage (40.1%). Females show more than half of the cases (59.7%). The MF position's highest percentage is shown in 2 areas with the slight differences. These are the long axis of first premolar and the area between first premolar and second premolar (42.6%, 40.9). According to shape variation round shapes are the uppermost percent (53.8%). More than 60% of cases (66.1%) show continuity with the inferior alveolar canal and 50% show no loop presence, and the mental nerve leaves the foramen in a perpendicular direction. In conclusion localization of the MF, nerve, and its loop precisely in both horizontal and vertical directions, both hard and soft tissues in a continuous view. Before arranging any surgical procedure, anatomic markers are crucial. To reduce the danger of harm to the foramen region, the authors thus advised cone-beam computed tomography before scheduling implant surgery, particularly in the mental region of the jaw.

Retrospective evaluation of the morphometric properties of intact maxillary sinus using cone-beam computed tomography for sex estimation in an Indian population

Background

Sex estimation is crucial to forensic examinations. In order to estimate sex, intact bones are used if the majority of bones are severely deformed and recovered in fragments. This study aims to analyze sexual dimorphism in intact maxillary sinuses using CBCT scanning to evaluate morphometric properties for sex identification.

Methods

A total of 318 subjects, consisting of 159 males and 159 females, aged between 20 and 60 years without sinus pathology were included in this diagnostic, retrospective cross-sectional study. Bilateral measurements of the volume, height, width, and length of the maxillary sinuses were obtained and compared to evaluate the differences between sexes. Subsequently, a descriptive analysis using mean and standard deviation was performed, followed by a comparison between sexes with a p-value being less than 0.05 and Student's t-test. Finally, a discriminant analysis was performed separately for the right and left maxillary sinuses.

Results

Males and females showed statistically significant variations in the length, width, and volume of the maxillary sinuses. Specifically, on the right side, males had longer maxillary sinuses than females (t = 5.6203, p < 0.0001). Meanwhile, on the left side, females had wider maxillary sinuses than males (t = 8.621, plt0.0001). In addition, males had greater volumes of maxillary sinuses on the right (t = 6.373, p < 0.0001) and left (t = 3.091, p < 0.0001) sides than females. The results of the discriminant analysis showed that the left width parameter had the highest accuracy of sex estimation (74.21%), followed by the Right Length (70.07%) and left volume (66.66%) parameters. The left height parameter had the lowest accuracy of sex estimation (49.37%).

Conclusion

In forensic odontology, the volume of maxillary sinus can serve as a valid radiographic indicator of sex estimation.

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.

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

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

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

Introduction

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

Materials and Methods

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

Results

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

Conclusion

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

Mental Nerve Anterior Loop Detection in Panoramic and Cone Beam Computed Tomography Radiograph for Safe Dental Implant Placement

Background and aim Different imaging modalities have been used as preoperative assessment tools since the emergence of dental implants. This study aimed to compare the detection and presence of mental nerve anterior loop in cone beam computed tomography (CBCT) radiograph and panoramic radiograph. Material and methods A descriptive, retrospective study was done. The optimal sample size was calculated using Epi Info software. According to the study population (795), the sample size was 259 cases which gave 95% power of the study. A previously taken CBCT and digital panoramic radiographs from the database of Taibah University Dental School and Hospital were observed by two trained and calibrated examiners to determine the presence of a mental nerve anterior loop and compare the two modalities. The mean length of the mental nerve anterior loop was also assessed.  Results Mental nerve anterior loops were detected bilaterally in 57.1% and 17.4% using CBCT and panoramic radiographs, respectively. In CBCT, the right side (20.8%) had a higher prevalence of mental nerve anterior loop than the left side (12%). The mental nerve anterior loop was not visible in 49.4% of the cases using a panoramic radiograph, while CBCT gave 10% of cases as not visible. The mental nerve anterior loop average length was 1.8 ± 0.35 mm and the width was 1.7 ± 0.28 mm. The average distance from the mental foramen to the inferior border of the mandible was 12.1 ± 0.87 mm and the average distance from the mental frogmen to the mandibular midline was 25.1 ± 0.68 mm. Conclusion As differences between CBCT and panoramic radiographs were statistically significant, CBCT is more accurate and reliable. CBCT is recommended to be used as a preoperative assessment tool to minimize nerve injury-related surgical complications during implant placement at the mandibular premolar area.

Assessment of lower third molar space: A comparative radiographic study

Objective:

The aim of this study was to assess lower third molar space using four different radiographic reconstructed Cone Beam Computed Tomography (CBCT) images: orthopantomogram, lateral cephalogram, multiplanar CBCT and a newly introduced three-dimensional (3D) simulation technique.

Methods:

The CBCT scans of 32 individuals (20.97 ± 2.152 years) with a total of 50 lower third molars were collected and analyzed. The ratio between the necessary space and available space for lower third molars was calculated on each radiographic reconstructed image. Repeated-measure analysis of variance followed by multiple comparison tests were used.

Results:

The mean ratio was significantly smaller with cephalograms (0.611 ± 0.263), followed respectively by orthopantomograms (0.756 ± 0.221), multiplanar CBCT (0.789 ± 0.191) and 3D simulation technique (0.807 ± 0.193) (p < 0.001). The lowest mean difference was recorded between multiplanar CBCT and 3D simulation technique (0.017). Intra class correlation coefficient was strong (>0.90) for all techniques except cephalograms.

Conclusions:

The assessment of the lower third molar space differs according to the adopted imaging technique. 3D simulation technique is a useful novel technology that allows an exploration of the crown in many different dimensions and orientations, giving more predictable results than the conventional methods.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Do anatomical variations of the mandibular canal pose an increased risk of inferior alveolar nerve injury after third molar removal?

OBJECTIVES

The present study aimed to assess whether anatomical variations of the mandibular canal are associated with neurosensory disturbances of the inferior alveolar nerve (IAN) following mandibular third molar removal.

METHODS

Two observers compared the detection of third molar root-nerve relations and bifurcations of the mandibular canal on panoramic radiographs and CBCT images of 201 patients undergoing removal of 357 mandibular third molars. Potential neurosensory disturbances of the IAN were surveyed ten days after surgery. Fisher's Exact was performed to correlate presence of canal variations to postoperative neurosensory disturbances. Positive and negative predictive values (PPV, NPV) and likelihood ratios (LR + , LR-) were calculated.

RESULTS

Thirteen patients reported postoperative altered sensation of the lower lip, with 2 of them having mandibular canal bifurcations on the ipsilateral side of the injury. Fisher's Exact showed that the studied mandibular canal variations were not related to postoperative neurosensory disturbances. CBCT was superior in visualization of anatomical variations of the mandibular canal. Prevalence of bifurcations was 14% on CBCT and 7% on panoramic radiographs. In both imaging modalities and for all parameters, PPVs were low (0.04 - 0.06) and NPVs were high (0.92 - 0.98), with LR ranging around 1.

CONCLUSION

In the present study, the assessed mandibular canal variations had limited predictive value for IAN neurosensory disturbances following third molar removal.

CLINICAL RELEVANCE

While a close relation between the third molar and the mandibular canal remains a high risk factor, mandibular canal variations did not pose an increased risk of postoperative IAN injury after third molar removal.

Automatic Detection of Mandibular Fractures in Panoramic Radiographs Using Deep Learning

Mandibular fracture is one of the most frequent injuries in oral and maxillo-facial surgery. Radiologists diagnose mandibular fractures using panoramic radiography and cone-beam computed tomography (CBCT). Panoramic radiography is a conventional imaging modality, which is less complicated than CBCT. This paper proposes the diagnosis method of mandibular fractures in a panoramic radiograph based on a deep learning system without the intervention of radiologists. The deep learning system used has a one-stage detection called you only look once (YOLO). To improve detection accuracy, panoramic radiographs as input images are augmented using gamma modulation, multi-bounding boxes, single-scale luminance adaptation transform, and multi-scale luminance adaptation transform methods. Our results showed better detection performance than the conventional method using YOLO-based deep learning. Hence, it will be helpful for radiologists to double-check the diagnosis of mandibular fractures.

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.

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

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

Assessing the Prevalence and Morphological Characteristics of Bifid Mandibular Canal Using Cone-Beam Computed Tomography - A Retrospective Cross-Sectional Study

Objectives:

To evaluate the prevalence, location and configuration of bifid mandibular canals so as to avoid injury to the nerve and inadequate anesthesia during surgical procedures.

Materials and Methods:

CBCT scan of 203 patients (125 males and 78 females) was evaluated for the presence and the type of the bifid mandibular canal. They were classified according to Nortje et al. The prevalence rates were determined according to gender, location, and type of bifid mandibular canal. Statistical analysis was performed using IBM SPSS software version 24.

Results:

The prevalence rate of bifid mandibular canals was found to be 10.3% with 12.8% in males and 6.4% in females. The Chi-square test reveals there is a statistically significant difference between the different locations of bifid mandibular canals and most of the canals were present on the right side. The most frequent type of bifid mandibular canal observed was type II dental canal (38.1%), followed by type III forward canal (28.6%), type I retromolar canal (14.3%), and type IV buccolingual canal (14.3%).

Conclusion:

CBCT is suggested for a detailed evaluation and identification of bifid mandibular canals before any surgical procedures to avoid post-operative complications.

2D vs. 3D Radiological Methods for Dental Age Determination around 18 Years: A Systematic Review

The age of a living human being can be determined by applying a number of different methods; the most diffused are skeletal and dental methods, both principally based on X-rays examinations. This systematic review assesses the current evidence regarding the accuracy and reliability of Cone Beam Computed Tomography (CBCT) vs. Orthopantomography (OPG) in age determination. A computerized systematic literature search of studies published up to January 2020 was conducted without language restrictions in order to identify articles comparing CBCT vs. OPG in dental anatomy evaluation, articles evaluating the accuracy of dental methods for age estimation, both with CT and OPG exams, and articles comparing CBCT vs. OPG in terms of radiation dose. CBCT was found to be more accurate compared to OPG in dental anatomy evaluation. When analyzing young adults, an estimation error of two years is considered forensically acceptable. The radiation dose of a CBCT exam is higher compared to an OPG exam. However, the difference is not as marked with small Fields Of View (FOV) and low-resolution protocols. Final conclusion was that a small FOV CBCT centered on the mandibular angle of a young patient is an accurate and safe method for dental age estimation around the age of 18.

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.

Observation of double mandibular canals and types of bifid canals in dry skulls

Background/Aim: The aim of the present study was to assess prevalence and morphologic mandibular canal variations in dry skulls. Material and Methods: Panoramic radiographs were obtained of 57 skulls among the academic collection at the University of Pittsburgh. Orthodontic wire was inserted through the mandibular canal as a reference point at panoramic images for localization of the course of the mandibular canal. Results: Double mandibular canals were present in 2 out of 57 skulls (3,5%); one of them was unilateral the other one was bilateral. Additionally, bifurcation of the mandibular canal and different types of configurations were assessed. In five of the specimens (8,8%) bifid canals were identified. Among them, one case (1,7%) was identified as a forward type. In one case additional canal (1,7%), was detected in the retromolar region, which joined the main canal. Three of the specimens (5,3%) showed accessory canal types. These were the canals that detached from the main canal and proceeded towards the molar teeth roots (dental type). All of these bifid canal types were unilateral. Conclusions: Our results depicted the anatomical variations of the mandibular canal. Dental practitioners should be aware of this underestimated but not a rare occurrence of mandibular canal variations in order to avoid complication during surgical procedures.

Osteoporosis and Jaw Abnormalities in Panoramic Radiography of Chronic Liver Failure Patients

INTRODUCTION

Patients with chronic liver failure (CLF) are faced with many complications, because this organ is involved in various metabolic activities. Hepatic osteodystrophy is one of the major health issues encountered by this group of patients. The current study evaluated osteoporosis and bone changes in oral panoramic radiographies of cirrhotic patients.

MATERIALS AND METHODS

In this study, 138 panoramic views of CLF patients, candidates for liver transplant (65 females, 73 males, aged 19-68 years) referred to Shiraz University Dental Clinic (Shiraz, Iran) for pretransplant oral examination, were evaluated. Also 138 healthy individuals (69 females, 69 males, aged 18-70 years) referred to the same clinic were examined. Abnormalities such as osteoporosis, pathologic radiolucencies, pathologic calcifications, tonsilloliths, condylar degeneration, and other findings in the alveolar bones were recorded.

RESULTS

Osteoporosis was a common finding in CLF patients (p<0.001), and the probability of detecting low bone density in the panoramic view was 20.37 times higher among patients than healthy subjects. The probability of detecting pathologic jaw radiolucencies was 8.92 times higher in the case group than in the controls (p<0.001). Other bone abnormalities such as condylar degeneration and idiopathic osteosclerosis were also more prevalent in CLF patients compared to healthy subjects (p<0.001).

CONCLUSION

Cirrhotic patients are prone to osteoporosis of the alveolar bones. Also, pathologic jaw radiolucencies as a result of oral infections are more prevalent in this group of patients. Routine oral panoramic views are acceptable and cost-effective radiographies for use in detecting such abnormalities in the alveolar bones as well as overall dental health. These findings also support the importance of dental health examinations prior to liver transplantation to reduce the risk of organ rejection.

Undetected Small Accessory Mental Foramina Using Cone-Beam Computed Tomography

INTRODUCTION

The accessory foramina could not be identified on some imaging modalities such as surface-rendered images. The purpose of this study was to investigate the ability of surface-rendered images in detecting these foramina.

MATERIALS AND METHODS

We analyzed 20 accessory mental foramina (AMF) in nine mandibles removed from cadavers with cone-beam computed tomography (CBCT) and assessed in surface-rendered images. All AMF were divided into three groups depending on their visibility.

RESULTS

Group 1 included AMF that were clearly visible as foramina, Group 2 were not clearly visible but could be recognized with concave parts, and Group 3 were not visible and the smooth surface of the bone was observed. Group 1 ranged from 1.3 to 5.1 mm², Group 2 from 0.3 to 3.8 mm², and Group 3 from 0.2 to 1.1 mm². A statistically significant difference in the mean size between Groups 1 and 3 was observed. Even if the AMF are smaller (e.g., 1 mm in diameter), they should still be avoided to prevent injury.

CONCLUSIONS

The clinician should be aware that smaller foramina might not be detected on these images.

[Cone beam computed tomography evaluation of bifid mandibular canals in the adult population in Sichuan Province]

OBJECTIVE

To investigate the incidence of bifid mandibular canals (BMC), and analyze the types, courses, and anatomic features of the variant canals in the adult population in Sichuan Province.

METHODS

Five hundred patients (1 000 hemimandibles) underwent cone beam computed tomography (CBCT) were included in this study. The incidence, bifurcate types and courses of the BMC were evaluated.

RESULTS

The incidence of BMC was 13.8% (69/500) in the study, 9.2% in terms of total hemimandibles. The most frequently type was retromolar canals, followed by the dental and buccolingual type, meanwhile the lowest was the forward type. The mean diameter of the accessory canals was 0.90 mm and the mean length was 9.39 mm.

CONCLUSIONS

CBCT used in this study has shown that the incidence of BMC assessed by CBCT was significantly higher than panoramic radiography. Furthermore, CBCT can depict the position, course, size and the branches of the mandibular canals.
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Investigation of an optimized scanning protocol for the dentomaxillofacial region using 320-slice multidetector computed tomography

OBJECTIVES

To propose an imaging protocol that provides satisfactory image quality for oral examination while minimizing radiation dosage using 320-slice multidetector CT (MDCT).

METHODS

An anthropomorphic head phantom was scanned using 320 MDCT with protocols combining different scanning modes: volume scanning (whole or local) vs helical scanning (80- or 64-slice detectors); tube voltage settings (80 kVp, 120 kVp and 135 kVp); and tube current settings (60 mA, 80 mA, 100 mA and 120 mA). A total of six anatomical bone structures and three anatomical soft-tissue structures were assessed using quantitative and qualitative analysis in the three orthographic planes (axial, sagittal and coronal). A figure of merit (FOM) was used to determine the optimal imaging protocol in terms of tube voltage, tube current and scanning mode.

RESULTS

The 80-kVp setting had the worst quantitative and qualitative results (both p < 0.001) compared with the 135-kVp and 120-kVp settings, especially for soft-tissue structures. A significant difference was noted for the scores obtained using a tube current between 120 mA and 60 mA by quantitative analysis, but not by qualitative analysis. Volume scans using either whole or local modes had a significantly higher FOM than helical scanning of 80 or 64 slices.

CONCLUSIONS

In 320 MDCT, a protocol using 135 kVp, 80 mA and the volume-scanning mode (whole or local) offers adequate visualization of both soft-tissue and bone structures while keeping the radiation dose as low as possible. This may therefore be considered a first choice among a wide selection of scanning protocols for dentomaxillofacial CT.

Prevalence of bifid mandibular canals by cone beam computed tomography

PURPOSE

The aim of this study was to evaluate the prevalence of bifid mandibular canals (BMC) by cone beam computed tomography (CBCT).

MATERIALS AND METHODS

We examined CT scans from 300 patients both male and female, aged 25 to 87 years. The subjects were divided into groups according to gender, male group (MG) and female group (FG) as well as subgroups according to the side, right (R) and left (L). Tomographic acquisitions were performed on the device I-Cat ® Classic. Image analysis was performed on the XoranCat ® software of the equipment itself, aided by image filters associated with transverse, oblique, and panoramic reconstruction cuts for analysis of the BMC. The results were displayed as descriptive analysis of the values and comparisons between factors were performed using ANOVA at a significance level of 95 %.

RESULTS

BMC was observed in 80 cases (26.67 %), of which, 39 (48.75 %) were in males and 41 (51.25 %) in females; no difference was seen between genders, neither by affected side, although the right side was more frequently affected (66.67 %) when both genders were combined.

CONCLUSION

The prevalence of BMC is significant and should not be overlooked.

Multiple accessory foramina of the mandibular ramus: risk factor for oral surgery

A 27-year-old female was referred to our hospital with a chief complaint of removal of an impacted right mandibular third molar. Panoramic radiography showed two small circular radiolucencies on the right mandibular ramus. Computed tomography revealed that one of the radiolucencies was an accessory foramen located lateral to the mandibular ramus, and the other radiolucency was an accessory foramen located medial to the ramus; it was also connected to the mylohyoid groove. Continuity with the mandibular canal was confirmed for both accessory foramina. After explaining the risks of extraction, the patient decided against surgery and the impacted tooth was left in situ. Most patients have at least one or more accessory foramina in the mandible; however, accessory foramina of the lateral aspect of the mandibular ramus have not been reported. The high resolution of cone-beam computed tomography and three-dimensional reconstructed images enable improved detection of accessory foramina. Therefore, additional accessory foramina that are similar to those found in the present case could be found in the future using such imaging modalities.

Anatomical variations of mandibular canal detected by panoramic radiography and CT: a systematic review and meta-analysis

OBJECTIVES

To investigate the anatomical variations of the mandibular canal through assessment in situ, panoramic radiography, CT or CBCT and assess their frequency.

METHODS

Articles were selected from databases (Cochrane Library, LILACS, ProQuest, PubMed, Scopus, Web of Science and Google Scholar), articles without limitations of language, in which the main objective was to evaluate the frequency of bifurcation of the mandibular canal through assessment in situ, panoramic radiography, CT or CBCT were selected. A meta-analysis of prevalence using random effects was performed.

RESULTS

Using a selection process in two phases, 15 articles were identified, and a meta-analysis was conducted. The results from these meta-analyses showed that the overall prevalence of anatomical variations for in situ studies was 6.46%, and through assessment of panoramic radiography and CT or CBCT the overall prevalence shown was 4.20% and 16.25%, respectively.

CONCLUSIONS

There are two types of variations of the mandibular canal: the retromolar canal and bifid mandibular canal. The frequency variations through assessing in situ, panoramic radiography and CT or CBCT were 6.46%, 4.20% and 16.25%, respectively.

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.

Descriptive study of the bifid mandibular canals and retromolar foramina: cone beam CT vs panoramic radiography

OBJECTIVES

To examine the presence and morphologic characteristics of bifid mandibular canals (BMCs) and retromolar foramens (RFs) using cone beam CT (CBCT) and to determine their visualization on panoramic radiographs (PANs).

METHODS

A sample of 225 CBCT examinations was analysed for the presence of BMCs, as well as length, height, diameter and angle. The diameter of the RF was also determined. Subsequently, corresponding PANs were analysed to determine whether the BMCs and RFs were visible or not.

RESULTS

The BMCs were observed on CBCT in 83 out of the 225 patients (36.8%). With respect to gender, statistically significant differences were found in the number of BMCs. There were also significant differences in anatomical characteristics of the types of BMCs. Only 37.8% of the BMCs and 32.5% of the RFs identified on CBCT were also visible on PANs. The diameter had a significant effect on the capability of PANs to visualize BMCs and RFs (B = 0.791, p = 0.035; B = 1.900, p = 0.017, respectively).

CONCLUSIONS

PANs are unable to sufficiently identify BMCs and RFs. The diameter of these anatomical landmarks represents a relevant factor for visualization on PANs. Pre-operative images using only PANs may lead to underestimation of the presence of BMCs and to surgical complications and anaesthetic failures, which could have been avoided. For true determination of BMCs, a CBCT device should be considered better than a PAN.

Determination of the location of the mental foramen: a critical review

INTRODUCTION

The mental foramen (MF) is an important landmark to consider during surgical endodontic procedures. The purpose of this review article was to discuss the variety of techniques that have been developed to determine the location of the MF, to make recommendations for the current best technique available, and to discuss upcoming technologies.

METHODS

Articles that have addressed the location of the MF were evaluated for information pertinent to include in this review.

RESULTS

Different technologies have been used to help operators determine the clinical location of the MF. Most of the techniques have shortcomings such as magnification, radiation, and cost. Cone-beam computed tomographic imaging is the best current available imaging technology to determine the accurate location of the MF, but it has shortcomings such as radiation, cost, and not being real time, which means the data must be interpreted at a later time than when the information was computed.

CONCLUSIONS

In the future, magnetic resonance imaging and ultrasound technologies seem to provide promising noninvasive imaging techniques.