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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 7  |  Issue : 2  |  Page : 45-48

Location of mental foramen in a group of Libyan patients: An orthopantomographic study


1 Department of Periodontology, University of Benghazi, Benghazi, Libya
2 Department of Pediatric Dentistry, Faculty of Dentistry, University of Benghazi, Benghazi, Libya
3 Al Noor Dental Clinic, Tripoli, Libya
4 AFH, Jizan, KSA

Date of Submission11-Sep-2019
Date of Decision25-Sep-2019
Date of Acceptance01-Jan-2000
Date of Web Publication22-Oct-2019

Correspondence Address:
Ahmed Ali Musrati
Department of Pediatric Dentistry, Faculty of Dentistry, University of Benghazi, Benghazi
Libya
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/dmr.dmr_21_19

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  Abstract 


Background and Objective: The mental foramen (MF) is a crucial landmark because the mental nerves and vessels exit through it. Therefore, marking its location is important when performing surgeries, placement of dental implants, or administering anesthesia and hence avoiding nerve damage. As the exact location and shape of the MF is not similar in different population groups, this study was the first one conducted to determine MF shape and position in a group of Libyan patients. Aim: The aim of this study was to determine the vertical and horizontal positions of the MF, in addition to its size and shape as seen in orthopantomogram (OPG) radiograph of Libyan patients. Age and gender differences in relation to the position and shape of MF were also evaluated. Materials and Methods: Out of 200 digital OPGs studied by two examiners, 123 fulfilled the inclusion criteria. Scanora Lite software (Palodex, Tuusula, Finland) program was used to measure the size of the MF as well as to determine its vertical and horizontal positions. The shape of the foramen was determined visually using the magnification tool of the software. Chi-square and t-test were applied. Results: The most common position of the MF was between first and second premolar, being closer to the second premolar for females and under the second premolar for males. The vertical location of the MF varied drastically with no statistical significant difference in both sides or between males and females. The difference in dimensions on the left and right sides was not statistically significant. The most common shape of MF was of the continuous type, and the tests showed significant difference with age and gender. Conclusion: The position and shape of MF is a crucial landmark for consideration of mental nerves and vessels when performing surgeries or administering anesthesia. The location of the MF on OPGs of Libyan patients regardless of gender is commonly below and between the mandibular premolar teeth closer to the second premolar, and the most common shape is a continuous type.

Keywords: Libya, MENA, mental foramen, Tripoli


How to cite this article:
Elhassan AT, Musrati AA, Ehtiwash NM, Peeran SW, Alzahrani FM. Location of mental foramen in a group of Libyan patients: An orthopantomographic study. Dent Med Res 2019;7:45-8

How to cite this URL:
Elhassan AT, Musrati AA, Ehtiwash NM, Peeran SW, Alzahrani FM. Location of mental foramen in a group of Libyan patients: An orthopantomographic study. Dent Med Res [serial online] 2019 [cited 2019 Nov 12];7:45-8. Available from: http://www.dmrjournal.org/text.asp?2019/7/2/45/269669




  Introduction Top


The mental foramen (MF) is the oblique anatomical opening in the body of the mandible close to the premolar area. The mental nerve and vessels exit it to supply sensory sensation and nutrition to the labial gingiva and alveolar mucosa from premolar area to the midline. They also supply the ipsilateral part of the chin and lip.[1] Any iatrogenic accident during surgical intervention close to the foramen could lead to different types of nerve injuries. When permanent injury is encountered, the patient would feel paresthesia or experience anesthesia on the affected side for the rest of his/her life and the surgeon might face medicolegal consequences. Therefore, the correct determination of its position is of fundamental value for both surgeons and patients.

As the position of the foramen is impossible to determine by clinical examination, radiography is mandatory for its localization. The foramen must be carefully evaluated in the radiograph when performing different kinds of surgeries, especially orthognathic surgery, fixation of mandibular fracture, soft-tissue graft, or implant placement.

The best radiographs that can show MF are orthopantomogram (OPG), cone-beam computed tomography (CT), and CT scan. Despite being more accurate than OPG, the periapical radiograph is less useful in viewing the MF because of the limited size of the film or the shallow floor of the mouth that prevent proper alignment of the film and hence prevent complete visualizing of the foramen.[2],[3],[4],[5]

In this study, digital OPG was used to evaluate the MF as it shows the vertical and horizontal positions of the MF. Furthermore, the appearance of the foramen and continuity with the mandibular canal could be studied. One drawback of the OPG is the 20%–25% magnification that it produces from the actual size.[6],[7] This was overcome by the Scanoralite program, which processes the image and provides the real dimensions.

As the MF has been reported to differ in shape, size, and position in different population,[8],[9],[10],[11],[12],[13] this study was aimed to evaluate these variables among Libyan patients.


  Materials and Methods Top


The examiners choose good-quality digital radiograph of patients who attended a private polyclinic in Tripoli, Libya, between December 2014 and January 2017 and who required OPG as part of their dental treatment. Only high-quality digital OPGs that show clearly the MF and allow easy measurement were included. The patients signed consent forms before conducting this study.

The age of the patients ranged from 21 to 63 years. They were divided into two age groups: Group A (21–40 years) and Group B (41–63 years).

The OPGs were taken using digital radiograph by experienced staff under standard exposure settings (kV ??10 mA; 11.0 s).

The inclusion criteria were as follows:

  1. Clearly visible MF
  2. Presence of mandibular teeth at least to the first molars
  3. Teeth have fully erupted with an absence of major crowding.


The exclusion criteria were as follows:

  1. The age of the patient is below 18 years
  2. Over eruption, crowding, or spacing between teeth
  3. Presence of a fracture or a lesion that prevent identification of the MF
  4. Presence of bone loss around teeth
  5. Orthodontic patients
  6. Absence (or extraction) of mandibular premolars.


One investigator was responsible for the selection of the OPGs according to the inclusion and exclusion criteria. The radiographs were viewed digitally on a computer using Scanora Lite software (Palodex, Tuusula, Finland). A measurement tool of the software allowed recording the vertical and horizontal positions of the foramen and also measuring the size of the foramen Gupta et al.[2] classified the appearance of the foramen as follows:

  1. Continuous: Foramen which is continuous with the mandibular canal
  2. Separated: Clear bordered foramen which is separated from mandibular canal
  3. Diffuse type: Foramen which has an indistinct border
  4. Unidentified type: The foramen that could not be identified on the panoramic radiographic.


The horizontal location in relation to the apices of the teeth was determined and categorized[13],[14] as follows:

  1. Anterior to the first premolar
  2. In line with the long axis of the first premolar
  3. Between first and second premolars
  4. In line with the long axis of the second premolar
  5. Between the second premolar and first molar
  6. In line with the long axis of the first molar.


The horizontal location was determined and categorized as above by digitally drawing a vertical line that extends from alveolar bone to lower border of the mandible passing through long axis of the MF; then, we visually determine the location as above categories (a-f) [Figure 1]. For the vertical position, three vertical measurements were taken:
Figure 1: Horizontal relation: A vertical line is drawn along the long axis of the second premolar and the horizontal relation of the mental foramen is determined either:(a) Anterior to the first premolar, (b) In line with the long axis of the first premolar,(c) Between the first and second premolars,(d) In line with the long axis of the second premolar, (e) Between the second premolar and first molar,(f) In line with the long axis of the first molar

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  1. From the alveolar border to the upper border of the foramen (X)
  2. From the upper border to the lower border of the foramen (Y)
  3. From the lower border of the foramen to the inferior border of the mandible (Z) [Figure 2].
Figure 2: Vertical position of the mental foramen (X, Y, Z) relations: upper arrow is X (distance from alveolar bone to mental foramen), lower arrow is Z (distance from the mental foramen to the lower border of the mandible), and Y is the vertical diameter of the mental foramen

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  Results Top


Out of the 200 panoramic digital radiographs which were evaluated, 123 radiographs fulfilled the inclusion criteria. They were 76 radiographs for females and 47 for males. The age of the patients ranged from 21 to 63 years. The shape of the MF was “continuous” for 55% of females and 53% of males, followed by “separated” (24% females and 10% males), then “diffuse” (9% females and 9% males) and finally “undefined” (9% females and 4% males). Regarding the age groups (A: 21–40 years and B: above 40 years) both have the continuous shape as the most common [Table 1].
Table 1: The shape of mental foramen on panoramic radiograph

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The most common horizontal position of the MF was between the first and the second premolars, being closer to the second premolar for females 56% and under the second premolar in males 61% [Table 2].
Table 2: The horizontal location of mental foramen (in relation to the apices of the teeth on the panoramic radiograph)

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The average position of the MF relative to the apex of second premolar was found to be 52% on the mesial side, 3% on the distal side and 47.5% intersecting with the apex of respective second premolar [Table 3].
Table 3: Average position of the mental foramen relative to the apex of the second premolar

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The average vertical dimension of the MF was 3.3 mm for males and 2.7 mm for females, and the average vertical distance from the foramen to the alveolar bone level was 21 mm for males and 17 mm for females. Finally, the average distance from the foramen to the inferior border of the mandible was 12 mm for males and 10 mm for females [Table 4].
Table 4: Vertical location of the mental foramen (mm)

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  Discussion Top


Since there is a need to study the disparity that occurs in the position of the MF in the Libyan population.[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18],[19],[20] To the best of our knowledge, this study is the first to consider the MF position in Libya. All factors that could affect the results such as alveolar bone loss around teeth, fractures, lesions in the area, crowding, and spacing or absence of teeth were excluded.

Many previous studies have used conventional OPGs (using hard films),[1] or periapical radiographs.[16] Conventional OPGs could have a magnification error of up to 20%–25%,[9],[10],[11] and periapical radiographs cannot show the continuity with the mandibular canal. Therefore, we used digital radiographs to overcome both of these problems and for easier recording and saving of the measurements.

Different studies showed different results regarding the position of the foramen; for instance, Gupta et al. and Al-Khateeb et al.[2],[12] showed that location C (between the first and second premolars) was the most common location without gender differences, whereas the present study showed the same position C when both genders are combined. However, gender difference exists placing males in location D (in line with the second premolar) and females in location C.

Same as the shape of the foramen, studies do differ; for example, Yosue and Brooks[13],[14] evaluated 297 patients and reported that the most frequent shape was separated (43%), followed by diffuse (24%), continuous (21%), and unidentified (12%), whereas in the present study, it was “continuous” (54.5%), followed by “separated” (22.8%), “diffuse” (14.6%), and finally “undefined” (8%).

In the present study, the average position of MF relative to the apex of the second premolar was found to be 52% on the mesial side, which is analogous to the findings by Gupta et al.[2] and Phillips et al.[1],[4] However, in contrast to the study by Gupta et al., the present study showed that the second most horizontal position was under the second premolar (47.5%) and then distal to second premolar (3%).

For the vertical location of the foramen, it did not vary drastically between males and females x/z (1.75 and 1.70, respectively).

The results from our study showed that the size of the MF is greater in males than females (3.3 mm and 2.7 mm, respectively).


  Conclusion Top


Determining the exact anatomical location and shape of the MF is of fundamental clinical application. According to literature, the shape and location can vary between societies. Our study in a group of Libyan patients reported similar results to some previous studies. It showed the continuous shape as the most common. Regarding the horizontal position, the most common position was between the first and the second premolars. The vertical position varies, but generally, it was under the apices of the mandibular premolars.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Phillips JL, Weller RN, Kulild JC. The mental foramen: 1. Size, orientation, and positional relationship to the mandibular second premolar. J Endod 1990;16:221-3.  Back to cited text no. 1
    
2.
Gupta V, Pitti P, Sholapurkar A. Panoramic radiographic study of mental foramen in selected Dravidians of South Indian population: A hospital based study. J Clin Exp Dent 2015;7:e451-6.  Back to cited text no. 2
    
3.
Moiseiwitsch JR. Position of the mental foramen in a North American, white population. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:457-60.  Back to cited text no. 3
    
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Phillips JL, Weller RN, Kulild JC. The mental foramen: 2. Radiographic position in relation to the mandibular second premolar. J Endod 1992;18:271-4.  Back to cited text no. 4
    
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Phillips JL, Weller RN, Kulild JC. The mental foramen: 3. Size and position on panoramic radiographs. J Endod 1992;18:383-6.  Back to cited text no. 5
    
6.
Shankland WE 2nd. The position of the mental foramen in Asian Indians. J Oral Implantol 1994;20:118-23.  Back to cited text no. 6
    
7.
Afkhami F, Haraji A, Boostani HR. Radiographic localization of the mental foramen and mandibular canal. J Dent (Tehran) 2013;10:436-42.  Back to cited text no. 7
    
8.
Chkoura A, El Wady W. Position of the mental foramen in a Moroccan population: A radiographic study. Imaging Sci Dent 2013;43:71-5.  Back to cited text no. 8
    
9.
Sanderink GC, Visser WN, Kramers EW. The origin of a case of severe image distortion in rotational panoramic radiography. Dentomaxillofac Radiol 1991;20:169-71.  Back to cited text no. 9
    
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Choi YG, Kim YK, Eckert SE, Shim CH. Cross-sectional study of the factors that influence radiographic magnification of implant diameter and length. Int J Oral Maxillofac Implants 2004;19:594-6.  Back to cited text no. 10
    
11.
Samawi SS, Burke PH. Angular distortion in the orthopantomogram. Br J Orthod 1984;11:100-7.  Back to cited text no. 11
    
12.
Al-Khateeb T, Al-Hadi Hamasha A, Ababneh KT. Position of the mental foramen in a northern regional Jordanian population. Surg Radiol Anat 2007;29:231-7.  Back to cited text no. 12
    
13.
Yosue T, Brooks SL. The appearance of mental foramina on panoramic radiographs. I. Evaluation of patients. Oral Surg Oral Med Oral Pathol 1989;68:360-4.  Back to cited text no. 13
    
14.
Yosue T, Brooks SL. The appearance of mental foramina on panoramic and periapical radiographs. II. Experimental evaluation. Oral Surg Oral Med Oral Pathol 1989;68:488-92.  Back to cited text no. 14
    
15.
Kqiku L, Weiglein A, Kamberi B, Hoxha V, Meqa K, Städtler P, et al. Position of the mental foramen in kosovarian population. Coll Antropol 2013;37:545-9.  Back to cited text no. 15
    
16.
Haghanifar S, Rokouei M. Radiographic evaluation of the mental foramen in a selected Iranian population. Indian J Dent Res 2009;20:150-2.  Back to cited text no. 16
[PUBMED]  [Full text]  
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Ngeow WC, Yuzawati Y. The location of the mental foramen in a selected Malay population. J Oral Sci 2003;45:171-5.  Back to cited text no. 17
    
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Gada SK, Nagda SJ. Assessment of position and bilateral symmetry of occurrence of mental foramen in dentate Asian population. J Clin Diagn Res 2014;8:203-5.  Back to cited text no. 18
    
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Al Jasser NM, Nwoku AL. Radiographic study of the mental foramen in a selected Saudi population. Dentomaxillofac Radiol 1998;27:341-3.  Back to cited text no. 19
    
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Fishel D, Buchner A, Hershkowith A, Kaffe I. Roentgenologic study of the mental foramen. Oral Surg Oral Med Oral Pathol 1976;41:682-6.  Back to cited text no. 20
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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