Morphology and Variant Anatomy of the Mandibular Canal in a Kenyan Population: A Cone-Beam Computed Tomography Study

Abstract

Study Design

Descriptive cross-sectional study.

Objective

The mandibular canal (MC) exhibits surgically significant anatomical variations in its course and terminal segment among different ethnic groups. The aim of this study was to document a surgically relevant position of the MC, its variants, and related anatomical structures in dentate patients from a select Kenyan population.

Methods

351 hemi mandibular cone-beam computed tomography (CBCT) scans from 202 patients were used to evaluate the MC and mental foramen (MF) for normal morphology, anatomical variations, and their linear relationship to various reference points.

Results

The most frequently encountered course of the MC was the progressive descent type seen in 241 (68.7%) scans. Accessory MC were observed in 15 (4.3%) scans. Accessory MF were observed in 29 (8.3%) scans. The mean diameter of the MC was 3.36 ± .39 mm. The orientation of the MC was more lingual towards the angle of the mandible and more buccal towards the MF. The most frequent position of the main MF in relation to the second premolar was anterior (53.3%). The average distance from the MF to the inferior border of the mandible was 12.17 ± 1.91 mm. The anterior loop of the mental nerve was observed in 18 (5.1%) scans and its mean length was 4.83 ± .89 mm.

Conclusions

Our study revealed significant variations in the position, size, and course of the MC and MF. This knowledge should assist oral surgeons to avoid inadvertent injury to the inferior alveolar neurovascular bundle in the local population.

Keywords

mandibular canal mental foramen cone-beam computed tomography anatomical variation

Introduction

The mandibular canal (MC) is a bilateral bony channel that originates from the mandibular foramen and runs longitudinally towards the mental foramen (MF). It serves as a conduit for the inferior alveolar neurovascular bundle (IANB).¹ In its course, it relates to the roots of the mandibular premolars and molars.

Inadvertent IANB injury has been reported in various fields of dentistry including orthodontics, endodontics, restorative dentistry, and oral and maxillofacial surgery.² An in-depth understanding of the intraosseous course and position of the neurovascular bundle is a prerequisite to performing mandibular surgical procedures. These procedures include but are not limited to dental implant placement, third molar surgery, bilateral sagittal split ramus osteotomy (BSSRO), bone grafting, placement of fracture fixation screws, and mandibular jaw resection.³

Various studies have tried to map out the course of the MC in their populations essentially to form a guide to surgical approaches to the mandible.^4,5 The intraosseous pathway of the MC has been reported as lingual to the roots of the third and second molars, below the roots of the first molar, and buccal to the premolar roots.⁶ Worthington⁷ described 3 configurations of the MC; a straight projection, a progressive curve, and a catenary-like canal. The MF is most commonly found below the second premolar in line with its longitudinal axis and less commonly located between the premolars.⁸ The prevalence of accessory MC has been reported to range from .08% to 43.0%.⁹

The anterior loop of the mental nerve (ALMN) is the anterior and inferior extension beyond the MF of the IAN and its curving back to the MF forming a loop.¹⁰ The identification of this benign anatomical variation is essential for surgical planning, especially for the placement of dental implants in the mental foramen region. This will help to prevent iatrogenic injury to the mental nerve and to ensure effective surgery in this region.¹⁰ The prevalence of ALMN has been reported to range from 0%¹¹ to 88%.¹² A maximum length of 11 mm has been reported.¹²

CBCT scans are accurate three-dimension (3D) imaging modality of dental and maxillofacial structures without magnification or superimposition. The images of maxillofacial structures produced are undistorted and of high resolution. There are many planes for reformatting the images that allow for interactive viewing. Significantly fewer radiation doses are involved in taking CBCT scans, compared to conventional medical-grade computed tomography scans.¹³ These factors make CBCT scans the most appropriate investigative tool for this study.

Materials and Methods

The data used in this descriptive cross-sectional study was obtained from a private imaging facility called Dental and Maxillofacial Imaging Centre (DAMIC) located in Nairobi, Kenya with approval from the Kenyatta National Hospital/University of Nairobi Ethics, Research and Standards committee. Consecutive sampling was used to select a sample of 351 hemi CBCT scans from 202 patients from DAMIC’s electronic database.

Inclusion Criteria

1. Age >20 years old.

2. Full mandibular arch CBCT scan.

3. Presence of at least 2 of the following 3 teeth: second premolar, first molar, and second molar.

Exclusion Criteria

1. Presence of supernumerary teeth, bone pathology, impacted teeth, or fractures obscuring visualization in the region of interest or changing the position of the MC or MF.

All images had been acquired using a CS 9300^® CBCT unit (Carestream Dental, Carestream Health Inc 150 Verona St Rochester NY 14608, USA) with a thin film transistor sensor and charge-coupled device detector technology. The jaw program pane selected was single jaw full acquisition (10 × 5 cm) for lower jaw exam and voxel size of 180 μm. The set tube current and voltage were 4 milliamperes (mA) and 85 or 90 kilovoltage (kV) respectively. The CBCT unit height had been adjusted and a chin guide utilized while scanning to ensure that the occlusal plane was horizontal. The detector completed a full scan of the patient’s head in an average of 8.01 seconds. CS Imaging software (Carestream Dental, Carestream Health Inc 150 Verona St Rochester NY 14608, USA) was used to capture, process, and store the original two-dimension (2D) projection views and the reconstructed 3D data.

This data was retrieved from DAMIC’s electronic database and used to reconstruct and analyze each jaw in the orthogonal plane using a computer CS 3D visualization and measurement software. The variables of the study were assessed, and attention given to the selected reference points for purposes of standardization. Both sides of the mandible were studied independently. Patient contact and consent were not required for this study. The parameters assessed included:

1. The topographical course of the mandibular canal according to the Worthington classification

2. The diameter of the MC

3. The distance between the MC and the buccal cortical plate (BCP), lingual cortical plate (LCP), inferior border of the mandible (IBM), second premolar root apex, first molar distal root apex, and second molar distal root apex

4. The presence of accessory mandibular canals and accessory mental foramina

5. The position of the main mental foramen in relation to the second premolar

6. The presence and length of the anterior loop of the mental nerve

Data Analysis

Categorical variables were summarized using percentages and frequencies while continuous variables were summarized using the mean and standard deviation. Independent samples t test and chi-square test were used to analyze the distance between the MC and the BCP, LCP, IBM, root apex of the second premolar, distal root apex of the molar and distal root apex of the second molar to determine whether there was a statistically significant difference between males and females. A P-value <.05 was considered statistically significant.

Minimizing Errors and Biases

All measurements on the sampled CBCT images were carried out in the orthogonal plane by the principal investigator after training, familiarization, and calibration in manipulating the software and taking morphometric measurements by an oral and maxillofacial radiologist. To assess inter-observer variability, every 35^th CBCT image had repeat morphometric measurements done by the radiologist. An overall intraclass correlation coefficient (ICC) of .989 (P < .001) demonstrated excellent agreement of the measurements for inter-observer variability.

Results

A total of 351 hemi mandibular CBCT scans from 202 patients were retrieved and included in this study. 142 scans were from 81 (40.1%) male and 209 scans were from 121 (59.9%) female patients giving a male to female ratio was .7:1. The mean age was 40.4 ± 14.2 years with an age range from 20 to74 years. The median age was 39 years (IQR 28.0 – 50.0). There were 180 (51.3%) right side and 171 (48.7%) left side scans.

In assessing the course of the MC, the progressive descent type was seen in 241 (68.7%) scans, the catenary-like type in 77 (21.9%) scans, and the straight projection type in 33 (9.4%) scans (Figure 1).

Figure 1.

Sample images from the study showing CBCT reconstructions of the mandible with nerve tracings showing variations in the course of MC observed: A – Progressive descent, B – Catenary-like, C – Straight projection.

Chi-square analysis showed no statistically significant difference in the occurrence of the 3 courses of the MC between the genders (catenary-like P = .176, progressive descent P = .906, straight projection P = .083).

Accessory MC were observed in 15 (4.3%) CBCT scans (Figure 2). Of these 5 (33.3%) were males and 10 (66.7%) were females. The probability of this observation was not statistically significant (χ², df, P = .330, 1, .566).

Figure 2.

Sample images from the study showing CBCT reconstructions of A – Right mandible and B – Left mandible demonstrating accessory MCs observed.

Accessory MF were observed in 29 (8.3%) scans (Figure 3). Of these, 11 (37.9%) were males and 18 (62.1%) were females. The probability of this observation was assessed using chi-square test and no statistically significant difference was found (χ², df, P = .084, 1, .772).

Figure 3.

Sample images from the study showing CBCT reconstructions of the mandible demonstrating the main MF and accessory MF observed.

Only 1 CBCT scan showed both accessory MC and accessory MF in the same patient. This finding was not statistically significant (χ², df, P = .053, 1, 1.000).

The diameter of the MC was 3.38 ± .39 mm at the root apex of the second premolar, 3.33 ± .37 mm at the distal root apex of the first molar, and 3.37 ± .39 mm at the distal root apex of the second molar (Figure 4). The overall mean diameter was 3.36 ± .39 mm. It was greater in males at all the reference points, a finding that was statistically significant at all 3 points (Table 1).

Figure 4.

Sample images from the study showing the diameter of the MC as measured at A – second premolar root apex, B – first molar distal root apex, and C – second molar distal root apex.

Table 1.

Comparison of the Diameter of the Mandibular Canal Between Males and Females.

Diameter (mm) of MC at	Mean ± SD	Male ± SD	n	Female ± SD	n	T, df, p
Root apex of 2^nd premolar	3.38 ± .39	3.47 ± .43	115	3.32 ± .36	170	3.25, 283, .002
Distal root apex of 1^st molar	3.33 ± .37	3.42 ± .37	125	3.26 ± .35	178	3.86, 301, <.001
Distal root apex of 2^nd molar	3.37 ± .39	3.48 ± .41	136	3.29 ± .37	195	4.32, 329, <.001

The mean distance between the MC and the root apices of reference teeth was 4.05 ± 2.10 mm at the root apex of the second premolar, 6.00 ± 2.73 mm at the distal root apex of the first molar and 3.20 ± 2.25 mm at the distal root apex of the second molar (Figure 5). This distance was longer in males at all reference points, a finding that was statistically significant at the root apex of the second premolar and the distal root apex of the second molar (Table 2)

Figure 5.

Sample images from the study showing the distance as measured from the MC to A – second premolar root apex, B – first molar distal root apex, and C – second molar distal root apex.

Table 2.

Comparison of the Distance from the Mandibular Canal to the Root Apices of Reference Teeth Between Males and Females.

Distance (mm) from MC to	Mean ± SD	Male ± SD	n	Female ± SD	n	T, df, p
Root apex of 2^nd premolar	4.05 ± 2.10	4.44 ± 2.41	115	3.79 ± 1.81	170	2.61, 283, .014
Distal root apex of 1^st molar	6.00 ± 2.73	6.19 ± 3.00	125	5.86 ± 2.51	178	1.02, 301, .325
Distal root apex of 2^nd molar	3.20 ± 2.25	3.56 ± 2.42	136	2.95 ± 2.10	195	2.46, 329, .014

The mean distance between the MC and BCP was 4.24 ± 1.51 mm at the root apex of the second premolar, 6.36 ± 1.75 mm at the distal root apex of the first molar, and 5.94 ± 1.84 mm at the distal root apex of the second molar (Figure 6). This distance was longer in males at all reference points, a finding that was statistically significant at all points (Table 3).

Figure 6.

Sample images from the study showing the distance as measured from the MC to BCP at A – second premolar root apex, B – first molar distal root apex, and C – second molar distal root apex.

Table 3.

Comparison of the Distance from the Mandibular Canal to the Buccal Cortical Plate Between the Genders.

Distance (mm) from MC to BCP at	Mean ± SD	Male ± SD	n	Female ± SD	n	T, df, p
Root apex of 2^nd premolar	4.24 ± 1.51	4.78 ± 1.56	115	3.88 ± 1.37	170	5.14, 283, <.001
Distal root apex of 1^st molar	6.36 ± 1.75	6.75 ± 1.83	125	6.09 ± 1.64	178	3.31, 301, .001
Distal root apex of 2^nd molar	5.94 ± 1.84	6.20 ± 1.82	136	5.75 ± 1.84	195	2.20, 329, .028

The mean distance between the MC and LCP was 6.44 ± 2.24 mm at the root apex of the second premolar, 3.34 ± 1.63 mm at the distal root apex of the first molar, and 3.23 ± 1.46 mm at the distal root apex of the second molar (Figure 7). This distance was shorter in males than females except at the distal root apex of the first molar. The difference between the genders was statistically significant only at the distal root apex of the second molar (Table 4).

Figure 7.

Sample images from the study showing the distance as measured from the MC to LCP at A – second premolar root apex, B – first molar distal root apex, and C – second molar distal root apex.

Table 4.

Comparison of the Distance from the Mandibular Canal to the Lingual Cortical Plate Between the Genders.

Distance (mm) from MC to LCP at	Mean ± SD	Male ± SD	n	Female ± SD	n	T, df, p
Root apex of 2^nd premolar	6.44 ± 2.24	6.36 ± 2.39	115	6.49 ± 2.13	170	−.457, 283, .648
Distal root apex of 1^st molar	3.34 ± 1.63	3.35 ± 1.80	125	3.33 ± 1.50	178	.090, 301, .928
Distal root apex of 2^nd molar	3.23 ± 1.46	3.04 ± 1.50	136	3.36 ± 1.41	195	−1.99, 329, .048

The mean distance between the MC and IBM was 8.31 ± 1.90 mm at the root apex of the second premolar, 6.78 ± 1.92 mm at the distal root apex of the first molar, and 6.88 ± 2.19 mm at the distal root apex of the second molar (Figure 8). This distance was longer in males than females, a finding that was statistically significant only at the root apex of the second premolar (Table 5).

Figure 8.

Sample images from the study showing the distance as measured from the MC to IBM at A – second premolar root apex. B – first molar distal root apex and C – second molar distal root apex.

Table 5.

Comparison of the Distance from the Mandibular Canal to the Inferior Border of Mandible Between Males and Females.

Distance (mm) from MC to IBM at	Mean ± SD	Male ± SD	n	Female ± SD	n	T, df, p
Root apex of 2^nd premolar	8.31 ± 1.90	8.79 ± 2.00	115	7.98 ± 1.75	170	3.62, 283, <.001
Distal root apex of 1^st molar	6.78 ± 1.92	6.99 ± 2.12	125	6.64 ± 1.76	178	1.57, 301, .119
Distal root apex of 2^nd molar	6.88 ± 2.19	6.97 ± 2.25	136	6.81 ± 2.14	195	.63, 329, .528

The most frequent position of the main MF in relation to the second premolar was anterior (187, 53.3%), followed by below (121, 34.5%) and the least frequent position was posterior (43, 12.3%) (Figure 9). Chi-square analysis showed no statistically significant difference in the position of the MF in relation to the second premolar between the genders (Anterior P = .166, Below P = .112, Posterior P = .841)

Figure 9.

Sample images from the study showing the different positions of the main MF in relation to the second premolar observed: A – Anterior, B – Below, C – Posterior.

The mean distance between the MF and IBM was 12.17 ± 1.91 mm (Figure 10). This distance was found to be found to be longer in males than females, a finding that was statistically significant (t, df, P = 9.85, 349, <.001).

Figure 10.

Sample images from the study showing the distance as measured from the MF to the IBM A – Right side, B – Left side.

The ALMN was observed in 18 (5.1%) CBCT scans studied (Figure 11). Of these, 6 (33.3%) were male patients and 12 (66.7%) were female patients. The probability of this observation was assessed using chi-square test and no statistically significant difference was found (χ², df, P = .40, 1, .527). The mean length of the ALMN was measured and found to be 4.83 ± .89 mm. There was no statistically significant difference in the length of the ALMN between the genders.

Figure 11.

Sample images from the study showing CBCT reconstructions of the mandible demonstrating the anterior loop of the mental nerve (ALMN) A – voxel size 180 μm, B – voxel size 7.7 mm.

Discussion

Significant anatomical variations of the course of the MC and the terminal segment of the IANB have been reported to various extents among different ethnic groups and populations. In the past, studies on the MC and its variants were limited to cadaver, dry skull and 2D imaging studies. The limitations of these techniques are well documented. CBCT studies of the MC represent a relatively new area of research, and most studies have been conducted in the last few years. Increased interest in this subject has been driven by greater frequency of placement of endosseous dental implants, advanced orthognathic surgery procedures, and the need to avoid morbidity associated with IANB injury during surgical procedures

The most frequently observed course of the MC was the progressive descent type, a finding similar to that from a Nepalese study of 150 CBCT scans.¹⁴ The progressive descent type is not favorable for placement of implants in the second M region as the MC is closest to the root apices and at risk of inadvertent encroachment. The catenary-like type provides the most amount of space for implant placement especially in the first molar region while the straight projection type is the least favorable for placement of implants posterior to the MF. Similar to this study, Mirbeigi⁶ found no relationship between gender and the pattern of the MC course.

Studies have shown the prevalence of accessory MC to range from .80% to 43%.⁹ Table 6 compares findings on the prevalence of accessory canals in other populations to the select Kenyan population in this study. The presence of accessory MC is potentially a cause of inadequate anesthesia following administration of an inferior alveolar nerve block. Third molar disimpaction, BSSRO, and bone harvesting in the ramus are procedures that carry an inherent risk of causing damage to an accessory MC that ends in a retromolar foramen. Iatrogenic injury will often lead to bleeding, paresthesia, or neuroma formation. Knowledge of the prevalence of accessory MC in the local population and their identification using correct imaging modalities is an important component of safe surgical practice.

Table 6.

The Prevalence of Bifid and Trifid Mandibular Canals in Literature.

Researcher	Study Type	Radiography	BMC	TMC
Gakonyo¹⁵	Cross-sectional (800 scans)	CBCT	26 cases (3.25%)	0
Auluck¹⁶	Case report	OPG	5 cases	1 case
Naitoh⁹	Cross-sectional (244 scans)	CBCT	105 cases (43%)	0
Kaufman¹⁷	Case report	CT	1 case	0
Dario¹⁸	Case report	OPG	1 case	0
Sanchis¹⁹	Cross-sectional (2012 patients)	OPG	7 cases (.35%)	0
Claeys²⁰	Case report	CT	1 case	0
Bogdán²¹	Cadaveric study (46 mandibles)	—	8 cases (17.4%)	1 case (2.2%)
Bogdán²¹	Cross-sectional (1000 patients)	OPG	2 cases (.2%)
Miloglu²²	Case report	CT	1 case	0
Karamifar²³	Case report	OPG	1 case	1 case
Current study	Cross-sectional (351 scans)	CBCT	15 cases (4.3%)	0

BMC – Bifid mandibular canal, TMC – Trifid mandibular canal, CT – Computed tomography scan, OPG – Orthopantomogram, CBCT – Cone-beam computed tomography scan.

This study considered all foramina occurring around the main MF to be accessory MF and the prevalence rates contrasted to findings from other studies in Table 7. When accessory MF are present, the neurovascular structures that pass through the MF will ramify and follow the alternative courses present. Knowledge of the presence of accessory MF is important when carrying out peripheral neurectomy for neuropathic pain syndromes. Failure to identify and include accessory mental nerves during this procedure is a common cause of persistent pain post-operatively in the area of distribution of the mental nerve. From the findings of this study, it is clear that there are variations in the prevalence of accessory MF in different populations.

Table 7.

Prevalence of Accessory MF in Literature.

Researcher (Ethnic Group)	Prevalence of accessory MF (%)
Sawyer (Russians)²⁴	1.5
Sawyer (Hungarians)²⁴	3.0
Sawyer (French)²⁴	2.6
Sawyer (black Americans)²⁴	5.7
Sawyer (white Americans)²⁴	1.4
Sawyer (Greeks)²⁴	3.3
Sawyer (Egyptians)²⁴	3.6
Gakonyo¹⁵ (Kenyans)	2.5
Sharma²⁵ (indians)	6.46
Japanese studies²⁶	6.7 to 12.5
Current study	8.3

MF – Mental Foramen.

Ikeda²⁷ reported the average diameter of the MC to be 3.4 mm, findings in line with this study at 3.36 mm. In contrast, Hamid²⁸ reported smaller mean diameters of 2.7 mm on CT scan measurement and 2.9 mm on electronic digital calipers measurement of sections of 5 adult Sudanese cadaveric mandibles. The variance from the current study could be attributed to the cadaver mandibles undergoing some degree of shrinkage resulting in the smaller values. Differences in body sizes between the populations considered may also be a contributing factor. Several diseases of the bone can affect the MC diameter by increasing or decreasing its size as seen in osteolytic malignant diseases and lesions exhibiting perineural spread.²⁹ Any changes in the diameter of the MC in a cancer patient should be considered when planning resection margins. Knowledge of the average diameter of the normal MC will help in detecting any abnormal changes in its size, further underscoring the importance of this study.

The findings from this study on the distance of the MC from the root apices of the reference teeth suggest a catenary-like course of the MC. This may imply that morphometric assessment of the course of the MC is more objective than the observational assessment that was done. Further inference from this finding is that longer endosseous implants can be placed in the body of the mandible region compared to the mental and angle of mandible areas. Sharma²⁵ reported the MC being closest to the roots of the second molar but noted the distance between the MC and periapex of mandibular teeth increased gradually anteriorly with the longest distance being from the periapex of the second premolar. This is consistent with a progressive descent course and may suggest that the difference from the current study constitutes ethnic differences in anatomical structures between the study populations.

The findings from this study are in keeping with other studies in the assertion that the MC orientation is more lingual towards the angle of the mandible and more buccal towards the MF.^8,30 The buccolingual orientation of the MC is an important parameter that requires in-depth analysis before BSSRO and monocortical plating. Similarly, the decision to orient an endosseous implant either buccally or lingually to avoid encroachment into the canal is largely dependent on knowledge of the buccolingual thickness of the mandible and the position of the MC.

In this study, the distance between the MC and the IBM progressively increased from posterior to anterior. This finding was consistent between the genders and similar to findings by Shrestha¹⁴ and Nemati.³¹ Surgeons must possess a good understanding of the position of the MC relative to the IBM as, during mandibular plating procedures, inappropriate positioning of the plate could lead to encroachment into the MC and neurovascular damage.

The tooth position of the MF provides a quick landmark to the surgeon or anesthetist in identifying the mental nerve and administering a mental nerve block. However, aberrant tooth positions do exist and can lead to failed anesthesia when tooth position is used as the only guide in administering a mental block. Moiseiwitsch³² in a North American Caucasian population and Mbajiorgu³³ in a black Zimbabwean population concluded that the MF was commonly located anterior to the second premolar, findings in agreement with the current study. On the other hand, Shankland³⁴ in an Asian Indian population and Oguz³⁵ in a Turkish population reported that the MF was located most of the time directly below the second premolar. These results indicate ethnic and racial differences in the position of the MF. Surgeons would do well to have epidemiological knowledge of the position of the MF in their local populations. Nonetheless, a radiographic guide remains an important tool in localizing the MF.

The mean distance from the MF to the IBM in this study showed minimal variance from studies by Loyal³⁶ in a Kenyan cadaveric study, Sheikhi³⁷ in a CBCT study on an Iranian population, and Neiva¹² in a Caucasian American dry skull study. Further to this, the distance was longer in males than in females, a statistically significant finding. This finding of gender dimorphism in the distance between the MF and IBM agrees with findings from several other studies.^37,38 Knowledge of the morphometric relationship of the MF to surrounding landmarks is important in implant surgery especially when the reference teeth or radiographic images are not available.

The prevalence of the ALMN has been reported to range from 0%¹¹ to 88%.¹² A maximum length of 11 mm¹² has been reported. These findings demonstrate considerable variance from those of the current study. Iatrogenic damage to the ALMN can lead to discomfort of unspecified duration in the lower labial gingiva and lip. Damage rates to the ALMN have been reported in the range of 17 – 38% during genioplasty³⁹ and 8.5 – 24% when placing implants.⁴⁰ Observing a fixed distance anterior to the MF is not safe, and the ALMN length should be determined for each individual to avoid injury to the mental nerve. CBCT scans allow for assessment of the mandible with precision and reliability in determining the presence and length of the ALMN.⁴¹

Limitations

The study was carried out in 1 private CBCT imaging facility thus limiting the ability to use the results to make inferences in the general population. Systemic medical conditions afflicting the patients that could have affected the bone quality and quantity were also not known. Further, the observational nature of the study could not allow for an objective assessment of age changes in the mandibular canal. Lastly, standardization could not be done to the extent of the same radiographer having taken all the CBCT scans rather to all scans having being taken on the same CBCT machine.

Conclusions

Anatomic variations of the MC and related surrounding structures can greatly influence surgical treatment modalities in the mandible. This study will be helpful to surgeons in avoiding inadvertent encroachment in to the MC and injury of the IANB during mandibular surgeries. Considering the limitations of the study, further multicentric CBCT studies should be designed and carried out in the general population to refine these results.

Supplemental Material

Supplemental Material - Morphology and Variant Anatomy of the Mandibular Canal in a Kenyan Population: A Cone-Beam Computed Tomography Study

Supplemental Material for Morphology and Variant Anatomy of the Mandibular Canal in a Kenyan Population: A Cone-Beam Computed Tomography Study by Andrew Okiriamu, Fawzia Butt, Florence Opondo, and Fredrick Onyango in Craniomaxillofacial Research & Innovation

Supplemental Material

Supplemental Material - Morphology and Variant Anatomy of the Mandibular Canal in a Kenyan Population: A Cone-Beam Computed Tomography Study

Footnotes

Acknowledgments

We wish to express our gratitude to Mr Wycliffe Ayieko of the University of Nairobi, Public Health department, for carrying out all the statistical analysis in this research. We would also like to thank the management at Dental and Maxillofacial Imaging Centre (DAMIC) Nairobi for allowing us to use data from their electronic database in this research.

Declaration of conflicting interests

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Andrew Okiriamu

Supplemental Material

Supplemental material for this article is available online.

References

de Oliveira-Santos

Souza

PHC

de Azambuja Berti-Couto

, et al. Assessment of variations of the mandibular canal through cone beam computed tomography. Clin Oral Invest. 2012;16(2):387-393.

Levine

Goddard

Dodson

. Inferior alveolar nerve canal position: A clinical and radiographic study. J Oral Maxillofac Surg. 2007;65(3):470-474.

Ngeow

. Is there a “safety zone” in the mandibular premolar region where damage to the mental nerve can be avoided if periapical extrusion occurs? J Can Dent Assoc. 2010;76:a61.

Mirbeigi

Kazemipoor

Khojastepour

. Evaluation of the course of the inferior Alveolar Canal: The first CBCT study in an iranian population. Pol J Radiol. 2016;81:338-341.

Laçin

Aytuğar

Veli

. Cone-beam computed tomography evaluation of bifid mandibular canal in a Turkish population. Int Dent Res. 2018;8:78-83.

Olivier

. The inferior dental canal and its nerve in the adult. Br Dent J. 1928;49:356-358.

Worthington

. Injury to the inferior alveolar nerve during implant placement: A formula for protection of the patient and clinician. Int J Oral Maxillofac Implants. 2004;19(5):731-734.

Smajilagić

Dilberović

. Clinical and anatomy study of the human mental foramen. Bosn J Basic Med Sci. 2004;4(3):15-23.

Naitoh

Hiraiwa

Aimiya

Ariji

. Observation of bifid mandibular canal using cone-beam computerized tomography. Int J Oral Maxillofac Implants. 2009;24(1):155-159.

10.

Apostolakis

Brown

. The anterior loop of the inferior alveolar nerve: Prevalence, measurement of its length and a recommendation for interforaminal implant installation based on cone beam CT imaging. Clin Oral Implants Res. 2012;23(9):1022-1030.

11.

Kim

Kang

, et al. Morphological assessment of the anterior loop of the mandibular canal in Koreans. Anat Cell Biol. 2015;48(1):75-80.

12.

Neiva

Gapski

Wang

. Morphometric analysis of implant-related anatomy in Caucasian skulls. J Periodontol. 2004;75(8):1061-1067.

13.

Patel

Dawood

Ford

Whaites

. The potential applications of cone beam computed tomography in the management of endodontic problems. Int Endod J. 2007;40(10):818-830.

14.

Shrestha

Mansur

Humagain

Koju

Maskey

Radiographic assessment of mandibular canal in Nepalese population: a study based on cone beam computed tomography images. Journal of Chitwan Medical College, 2019;9(4), 52-56.

15.

Gakonyo

. Double Inferior Alveolar Nerve Canals and Mental Foramina in the Mandible : A Computed Tomography Study at a Private Dental Clinic in Kenya [Dissertation]. University of Pretoria; 2017. https://repository.up.ac.za/handle/2263/65870

16.

Auluck

Pai

Mupparapu

. Multiple mandibular nerve canals: Radiographic observations and clinical relevance. Report of 6 cases. Quintessence Int. 2007;38(9):781-787.

17.

Kaufman

Serman

Wang

. Bilateral mandibular accessory foramina and canals: A case report and review of the literature. Dentomaxillofacial Radiol. 2000;29(3):170-175.

18.

Dario

. Implant placement above a bifurcated mandibular canal: A case report. Implant Dent. 2002;11(3):258-261.

19.

Sanchis

Peñarrocha

Soler

. Bifid mandibular canal. J Oral Maxillofac Surg. 2003;61(4):422-424.

20.

Claeys

Wackens

. Bifid mandibular canal: Literature review and case report. Dentomaxillofacial Radiol. 2005;34(1):55-58.

21.

Bogdán

Pataky

Barabás

Németh

Huszár

Szabó

. Atypical courses of the mandibular canal: Comparative examination of dry mandibles and x-rays. J Craniofac Surg. 2006;17(3):487-491.

22.

Miloglu

Yilmaz

Caglayan

. Bilateral bifid mandibular canal: A case report. Med Oral Patol Oral Cir Bucal. 2009;14(5):E244-E246.

23.

Karamifar

Shahidi

Tondari

. Bilateral bifid mandibular canal: Report of two cases. Indian J Dent Res. 2009;20(2):235-237.

24.

Sawyer

Kiely

Pyle

. The frequency of accessory mental foramina in four ethnic groups. Arch Oral Biol. 1998;43(5):417-420.

25.

Sharma

Yadav

Dubey

Thakur

Hafiz

Paul

. Evaluation of inferior alveolar canal and its variations using Cone-beam CT-scan. J Adv Med Dent Sci Res. 2019;7(9):153-160.

26.

Toh

Kodama

Yanagisako

Ohmori

. Anatomical study of the accessory mental foramen and the distribution of its nerve. Okajimas Folia Anat Jpn. 1992;69(2–3):85-88.

27.

Ikeda

Nowicki

Haughton

. Multiplanar MR and anatomic study of the mandibular canal. AJNR Am J Neuroradiol. 1996;17(3):579-584.

28.

Hamid

Suliman

. Diameter of the inferior alveolar canal - a comparative CT and macroscopic study of sudanese cadaveric mandibles. J Evol Med Dent Sci. 2021;10:342-346.

29.

Mojaver

Sahebjamie

Tirgary

Eslami

Rezvani

. Enlargement of mandibular canal with tongue paresthesia caused by extranodal B-cell Lymphoma: A case report. Oral Oncol Extra. 2005;41(41):97-99.

30.

Komal

Bedi

Wadhwani

Aurora

Chauhan

. Study of normal anatomy of mandibular canal and its variations in indian population using CBCT. J Maxillofac Oral Surg. 2020;19(1):98-105.

31.

Nemati

Ashouri Moghadam

Dalili Kajan

Mohtavipour

Amouzad

. An analysis of visibility and anatomic variations of mandibular canal in digital panoramic radiographs of dentulous and edentulous patients in Northern Iran populations. J Dent. 2016;17(2):112-120.

32.

Moiseiwitsch

. Position of the mental foramen in a North American, white population. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1998;85(4):457-460.

33.

Mbajiorgu

Mawera

Asala

Zivanovic

. Position of the mental foramen in adult black Zimbabwean mandibles: A clinical anatomical study. Cent Afr J Med. 1998;44(2):24-30.

34.

Shankland

. The position of the mental foramen in Asian Indians. J Oral Implantol. 1994;20(2):118-123.

35.

Oguz

Bozkir

. Evaluation of location of mandibular and mental foramina in dry, young, adult human male, dentulous mandibles. W Indian Med J. 2002;51(1):14-16.

36.

Loyal

Butt

Ogeng’o

. The surgical relevance of the anatomic position of the extraosseous mental nerve in a Kenyan population. Pan Afr Med J. 2014;18:51.

37.

Sheikhi

Kheir

. CBCT Assessment of mental foramen position relative to anatomical landmarks. Int J Dent. 2016;2016:5821048.

38.

Thakur

Reddy

KVK

Sivaranjani

Khaja

. Gender determination by mental foramen and height of the body of the mandible in dentulous patients a radiographic study. J Indian Acad Forensic Med. 2014;36(1):13-18.

39.

Hoenig

. Sliding osteotomy genioplasty for facial aesthetic balance: 10 years of experience. Aesthetic Plast Surg. 2007;31(4):384-391.

40.

Walton

. Altered sensation associated with implants in the anterior mandible: A prospective study. J Prosthet Dent. 2000;83(4):443-449.

41.

Filo

Schneider

Locher

Kruse

Lübbers

. The inferior alveolar nerve’s loop at the mental foramen and its implications for surgery. J Am Dent Assoc. 2014;145(3):260-269.

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