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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 1  |  Page : 16-19

Position and symmetry of mental foramen: A radiographic study in bareilly population


1 Department of Oral Medicine and Radiology, Sarjug Dental College and Hospital, Darbhanga, India
2 Department of Psychiatry, Sri Krishna Medical College and Hospital, Muzaffarpur, Bihar, India
3 Department of Oral Medicine and Radiology, Institute of Dental Sciences, Bareilly, India
4 Department of Public Health Dentistry, Institute of Dental Sciences, Bareilly, India
5 Department of Oral Medicine and Radiology, Yashodha Superspeciality Hospital, Ghaziabad, Uttar Pradesh, India
6 Department of Oral Pathology and Microbiology, Sarjug Dental College and Hospital, Darbhanga, India

Date of Submission26-Jun-2016
Date of Acceptance21-Jun-2017
Date of Web Publication04-Aug-2017

Correspondence Address:
Abhijeet Alok
Department of Oral Medicine and Radiology, Sarjug Dental College and Hospital, Hospital Road, Laheriasarai, Darbhanga- 846 003, Bihar
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.JIAOMR_69_16

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   Abstract 

Introduction: The mental foramen is located in the apical region of the mandibular premolars. Variations in its position can be a cause of complications during local anesthesia or surgical procedures as well as in the diagnosis of lesions periapically. Aims and Objectives: The aim of this study was to determine the position and symmetry of mental foramen on a digital orthopantomogram (OPG), and the objective was to determine the frequency of location of mental foramen in relation to apices of teeth and interdental spaces on the panoramic radiographs. Materials and Methods: The study was done in the Department of Oral Medicine and Radiology, and 750 participants were selected in this study whose radiographic evaluation of mental foramen was done using OPG. The position of the image of the mental foramen was recorded according to criteria given by Wei Cheong Ngeow and Yusof Yuzawati. Statistical Analysis: The collected data were subsequently processed and analyzed using SPSS statistical package version 17. Results: We found that mental foramen is located below the second premolar in 74.4% of the patients followed by between two premolars in 19.3% of the population. In both males and females, most common position was in line with the second premolar followed by between two premolars. The mental foramen was symmetrical in 613 patients (81.7%) and asymmetrical in 137 patients (18.3%). Conclusion: In the present study, it was found that the most common position of the mental foramen was below second premolar followed by between two premolars. It was symmetrical in 81.7% of the population. In males and females, the most common position was below second premolar followed by between two premolars.

Keywords: Diagnosis, mandible, mental foramen, orthopantomogram, premolar


How to cite this article:
Alok A, Singh ID, Panat SR, Singh S, Kishore M, Jha A. Position and symmetry of mental foramen: A radiographic study in bareilly population. J Indian Acad Oral Med Radiol 2017;29:16-9

How to cite this URL:
Alok A, Singh ID, Panat SR, Singh S, Kishore M, Jha A. Position and symmetry of mental foramen: A radiographic study in bareilly population. J Indian Acad Oral Med Radiol [serial online] 2017 [cited 2019 Dec 8];29:16-9. Available from: http://www.jiaomr.in/text.asp?2017/29/1/16/212091


   Introduction Top


The accurate identification of the mental foramen is important for both diagnostic and clinical procedures. Lack of knowledge regarding the correct position of mental foramen leads to repeated failure during injections and operative procedures.[1] The radiographic appearance of the mental foramen may result in the misdiagnosis of a radiolucent lesion in the apical area of the mandibular premolar teeth. As such, various events affecting these teeth, such as odontogenic infection and orthodontic, endodontic, periodontal, or surgical misadventure, may result in neurosensory disturbance of the mental nerves.[2] In an orthopantomogram (OPG), entire body of the mandible can be viewed, which allows a more accurate location of the mental foramen in both the horizontal and vertical dimensions. There are no absolute anatomical landmarks for reference and the foramen cannot be clinically visualized or palpated. Therefore, the reported anatomical position of the mental foramen has been variable, with the most common location being below the apex of the second premolar or between the apices of first and second premolars. The position of the mental foramen varies among races and genders. There have been variations in the mental foramen ranging from difference in the shape and position to presence of accessory foramen or even complete absence in some cases.[3]


   Materials and Methods Top


The present study was conducted in the Department of Oral Medicine and Radiology, where 750 patients of both genders aged between 18–65 years were included. An informed consent was taken from all the patients. The study was approved by the ethical committee of the institute. This study was conducted over a period of 3 years including patients aged 18–65 years as the inclusion criteria. This was not a retrospective study. Exclusion criteria included:

  1. Nonvisualization of the mental foramen bilaterally on OPG
  2. Presence of periodontal lesions
  3. Patients with previous orthodontic treatment
  4. Presence of a radiolucent lesion in the lower jaw anywhere in the area of the mental foramen.


Radiological evaluation of the patient was done using OPG model Orthoralix DDE (GENDEX, USA) digital panoramic system (Tube Potential: 60–90 kv, Tube Current: 2–15 mA, Total Filtration: >2.5 mm, time: 13.9 s). The magnification factor for the region from the posterior border of ramus to canine, as reported by the manufacturer, is 1.25. Other parameters which were followed are: (1) The Frankfort horizontal plane was parallel to the floor, (2) the medial sagittal plane bisected the face into two equal halves, (3) the canine plane passed through the long axis of the canine. All images were taken by same radiologist following a standardized protocol for patient positioning and exposure parameter settings. All radiographs were analyzed by the same radiologist. No intraobserver variability was assessed. Assessment of radiographs was made digitally. No alteration of image was done digitally to facilitate better visibility. All those radiographs were excluded where mental foramen was not visible clearly. The position of the image of the mental foramen was recorded according to criteria given by Wei Cheong Ngeow and Yusof Yuzawati. They were:

  1. Position 1: Situated anterior to the first premolar
  2. Position 2: In line with the first premolar
  3. Position 3: Between the first and second premolars
  4. Position 4: In line with the second premolar
  5. Position 5: Between the second premolar and first molar
  6. Position 6: In line with the first molar.


The radiographs were chosen according to the following criteria:

  1. High quality with respect to angulations and contrast
  2. All mandibular teeth from the right first molar to the left first molar were present
  3. Radiographs in which the lower teeth (between 36 and 46) were missing, had deep caries, root canal treatment, or various restorations were eliminated because of possible associated periapical radiolucency
  4. Radiographs not having any radiolucent or radiopaque lesion in the lower arch and showing no radiographic exposure or processing artefacts
  5. Radiographs that showed the lower canine was missing were excluded because of the possibility of mesial premolar drift.


The positions of the mental foramen were recorded in line with the longitudinal axis of a tooth using software tool. If the mental foramen was too large or was between two teeth, the position of the foramen was indicated by drawing a line parallel to the long axis of the teeth using digital software. In addition, the side that showed more radiolucency was designated the side of the mental foramen analysis.


   Results Top


The present study was undertaken for radiographic determination of the position and symmetry of mental foramen. A total of 750 patient’s OPGs were evaluated in this study. Of the 750 patient’s OPGs, 480 were males (64%) and 270 were females (36%). The most common (modal) position in the present study was in line with second premolar (position 4) for right side (n = 555, 74%) and on the left side (n = 561, 74.8%) followed by position 3, i.e., between first and second premolar on the right side (n = 143, 19.1%). On the left side, the second most common position was between the first and second premolar on the left side (position 3) (n = 146, 19.5%). No cases were reported in position 1 [Table 1]. In males, the most common position of mental foramen was position 4 (n = 719, 74.9%) followed by position 3 and position 5, 2, and 6. In females, the most common position noticed was position 4 (n = 397, 73.5%) followed by position 3, i.e., in between first and second premolar (n = 105, 19.4%) [Graph 1]. A total of 1116 out of 1500 mental foramen were found to be in position 4 in line with second premolar (n = 1116, 74.4%). A total of 289 (19.3%) were found to be in position 3. Ninety-two (6.1%) were found in position 5. Two (0.1%) were found in position 2. One mental foramen (0.1%) was found in position 6 [Table 2].

Table 1: Sex-wise distribution of mental foramen


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Table 2: Frequency of mental foramen


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The mental foramen was symmetrical in 613 patients (81.7%) and asymmetrical in 137 patients (18.3%). For the symmetrically placed mental foramen, the most common position was position 4 (n = 501, 81.7%). No case with symmetrical mental foramen was noted in positions 1, 2, and 6 [Table 3] and [Graph 2]. Among asymmetrical mental foramen, the most common position was position 4, followed by positions 3, 5, 2, and 6. No case with asymmetrical foramen was noted in position 1 [Table 4]. The results of the present study showed that the most common position for the mental foramen was in line with the second premolar in the given population.

Table 3: Symmetrical mental foramen


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Table 4: Asymmetrical mental foramen


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   Discussion Top


There is considerable debate regarding the normal position of mental foramen in different populations.[4] It was found that according to most authors the mental foramen is usually located between the lower premolars.[5],[6] However, there are some studies that reported that mental foramen most commonly lies near the apex of the second premolar.[7]

The result of the present study showed that the most common position of mental foramen is in line with second premolar (position 4) for the right side (n = 555, 74%) and left side (n = 561, 74.8%) followed by between first and second premolar on the right side (n = 143, 19.1%). On the left side, the second most common position was between the first and second premolar in the left side (position 3) (n = 146, 19.5%) followed by position 5 (n = 41, 5.5%). No cases were reported in position 1 and 6. This result coincides with observations made by Ngeow et al.,[1] Sankar et al.,[7] Ukoha et al.,[8] and Gangotri et al.[9] Studies done in other ethnic and racial groups like Chinese, Asian, Indian, and Nigerians showed the location of the mental foramen most commonly along the longitudinal axis of the second premolar tooth.[2],[10],[11]

Knowing the site of the mental foramen allows for accurate delivery of local anesthesia for dental procedures and the avoidance of damage to the nerve in surgical procedures such as periapical surgery, cyst enucleation, periodontal surgery such as flap operation, and mandibular bony osteotomy. It also aids in interpreting anatomical landmarks in oral pathology and forensics. Radiography is the only available noninvasive method for diagnosis and treatment planning of major surgical procedures of the mandible. Panoramic radiographs are commonly used for screening, diagnosis, and selecting the best possible surgical approach. The location of the mental foramen could change during the development of the jaws; therefore, panoramic radiographs taken from patients who had completed their development were evaluated in this study. In addition, patients having missing teeth were excluded from the study because the evaluation was made according to the present canines, premolars, and molars. We utilized panoramic radiographs because they have certain advantages over intraoral radiography. It includes a greater area of hard and soft tissues and also the visualized area in continuity, thus, allowing a more accurate location of the mental foramen in both horizontal and vertical dimensions. On the other hand, periapical radiographs may not show several positions of the mental foramen if it is below the edge of the film. Hence correct identification of mental foramen is must before any surgery or any implant surgery or before any prosthesis. Therefore, this study was done for identification of mental foramen radiographically. This is the only study that was done on such a large patient size of 750, however, further studies are recommended with larger sample size, so that radiographic determination of position and symmetry of mental foramen can be evaluated.


   Conclusion Top


The mental foramen is an important anatomical landmark in the orofacial region. The position of the mental foramen varies between ethnic groups. In the present study, it was found that the most common position of mental foramen in the given population was below the second premolar followed by between two premolars. It was symmetrical in 81.7%. In males and females, the most common position was below the second premolar followed by between two premolars. It is very important to know the exact position of mental foramen for clinical as well as diagnostic purposes. Hence, this study was conducted for determining the position of the mental foramen radiographically.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
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. 1
    
2.
Shankland WE. The position of mental foramen in Asian Indians. J Oral Implantol 1994;68:118-23.  Back to cited text no. 2
    
3.
Hasan T, Fauzi M, Hasan D. Bilateral absence of mental foramen – A rare variation. Int J Anat Variations 2010;3:167-9.  Back to cited text no. 3
    
4.
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. 4
[PUBMED]  [Full text]  
5.
Seema S, Bhavana D, Kamlesh T. Morphometric analysis of mental foramen in human mandibles of Gujarat region. Int J Sci Res 2014;1:36-7.  Back to cited text no. 5
    
6.
Kquiku L, Weiglein A, Kamberi B, Hoxha V, Meqa K, Stadtler P. Position of the mental foramen in Kosovarian population. Coll Antropol 2013;37:545-9.  Back to cited text no. 6
    
7.
Sankar DK, Bhanu SP, Susan PJ. Morphometric and morphological study of mental foramen in dry dentulous mandibles of South Andhra population of India. Indian J Dent Res 2011;22:542-6.  Back to cited text no. 7
[PUBMED]  [Full text]  
8.
Ukoha UU, Umeasalugo KE, Ofoego UC, Ejimofor OC, Nzeako HC, Edokwe CG. Position, shape and direction of the mental foramen in mandibles in South-Eastern Nigeria. Int J Biomed Res 2013;4:499-503.  Back to cited text no. 8
    
9.
Gangotri S, Patni VM, Sathwane RS. Radiographic determination of position and symmetry of mental foramen in Central Indian population. J Indian Acad Oral Med Radiol 2011;23:101-3.  Back to cited text no. 9
  [Full text]  
10.
Green RM. The position of the mental foramen: A comparison between the southern (Hong Kong) Chinese and other ethnic and racial groups. Oral Surg Oral Med Oral Pathol 1987;63:287-90.  Back to cited text no. 10
    
11.
Phillips JL, Weller RN, Kulild JC. The mental foramen: Radiographic position in relation to the mandibular second premolar. J Endod 1992;18:271-4.  Back to cited text no. 11
    



 
 
    Tables

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



 

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