BUJOD 2014-sept-2

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Rai et al

Original Research RADIOGRAPHIC STUDY OF MENTAL FORAMINA Authors: Vaibhav Rai*, MK Sunil**, Raghav Kumar***, Vikash Ranjan****, Ranjana Garg*****, Aarti Trakroo****** ABSTRACT The mental foramen is defined as the entire funnel-like opening in the lateral surface of the mandible at the terminus of the mental canal1. The mental foramen on each side is located on the buccal cortex of the mandibular bone and lies near the apices of the premolars. It has been shown to be located at precisely the same level on most humans (13–15 mm) superior to the inferior border of the mandible. The awareness regarding varied and detailed morphological and morphometric features of mental foramen is of pivotal importance for orthodontists, cosmetic and reconstructive surgeons etc for avoidance of any inadvertent trauma, post surgical neuromuscular complications and morbidity. KEYWORDS : Mental foramen, Mandible, premolars. INTRODUCTION The mental foramen is defined as the entire funnellike opening in the lateral surface of the mandible at the terminus of the mental canal [1]. The mental foramen on each side is located on the buccal cortex of the mandibular bone and lies near the apices of the premolars. It has been shown to be located at precisely the same level on most humans (13–15 mm) superior to the inferior border of the mandible. The opening of the mental foramen is directed outward, upward, and posteriorly, viewed from inside out. The position of mental foramen varies with age, passing from just above the level of the mylohyoid line in the younger age group to a level midway between the upper and the lower border of the bone in adults and in old age the mental foramen opens close to the upper alveolar border. The direction of mental foramen varies with Address For Corresspondence: Dr Vaibhav Rai B-1403, Jaipuria Sunrise Greens Indirapuram Ghaziabad (Uttar Pradesh) Pin Code:201014

age. At birth, mental foramen is directed in a forward direction followed by being directed laterally in early childhood. In adults the foramen has been reported to be in the backward and slightly upward direction. The overall change in direction of mental foramen has been associated with forward growth of the mandible1. The awareness regarding changes in the directionality of mental foramen with age is important as it influences the direction for advancing the needle during the procedure of mental nerve blocking. Morphometry of the mental foramen is substantially helpful in the application of acupressure therapy as well, besides being a useful parameter in craniofacial identification method employed in forensic anthropology and forensic dentistry. It transmits the mental vessels and nerve [2]. The mental nerve is a terminal branch of the inferior alveolar nerve; it supplies sensory innervations to the lower lip, the buccal vestibule, and the gingiva mesial to the first mandibular molar [3]. The mental bundle can be traumatized during surgical procedures, resulting in paresthesia or anaesthesia

*PG Student, *** Professor Dept of Oral Medicine and Maxillofacial Radiology, Dj College Of Dental Sciences and Research, Modinagar, Ghaziabad **Prof and Head, ******PG Student Dept of Oral Medicine And Radiology, Gurunanak Dev Dental College and Research Institute, Patiala, Punjab ****Senior Lecturer Dept of Oral Medicine and Rediology, Darshan Dental College and Hospital, Udaipur *****Associate Professor Dept of Oral Medicine and Radiolgy, Seema Dental College and Hospital, Rishikesh

MAHARAJA KRISHNAKUMARSINHJI BHAVNAGAR UNIVERSITY

Vol. 4 Issue-3 September 2014

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BUJOD in the area innervated by the nerve. Additionally, local anaesthesia of the terminal incisive branches of the inferior alveolar nerve and the mental nerve can be achieved if the mental canal is accurately located and anesthetic solution deposited within it. Thus, accurate information regarding the location and orientation of the mental canal and its foramen [4] can be very important . Eva l u a t i o n o f d e t a i l e d m o r p h o l o g y a n d morphometry of the mental foramen has gained importance in recent times in view of the increasing demand for the replacement of lost teeth by dental implants and the growing awareness regarding maxillofacial uplifts for cosmetic and reconstructional surgeries across all age groups. The awareness regarding varied and detailed morphological and morphometric features of mental foramen is of pivotal importance for orthodontists, cosmetic and reconstructive surgeons etc for avoidance of any inadvertent trauma, post surgical neuromuscular complications and morbidity. MATERIALS & METHODOLOGY The study population comprised of total number 315 subjects comprising of 182 male and 133 female subjects aged between 18yrs to 65yrs, reported to the Department of Oral Medicine and Maxillofacial Radiology, D.J College Of Dental S c i e n c e s A n d Re s e a rc h , M o d i n a ga r. T h e participants were first informed in detail about the study, and a written informed consent was obtained from all the participants. The panoramic radiograph (Primex Company) was taken by Kodak 8000 keeping the standardized angulations and inclinations and with radiation dosage at 80KV & 10mA. The exposure time was 912 seconds.

location of the mental foramen on each side was recorded in the form. The location of the mental foramen was reported on the basis of gender and symmetry or asymmetry. Readings were obtained from both left and right sides of the mandible. As the position of the foramen was highly dependent on the presence of teeth, cases with missing multiple posterior teeth or considerable drifting of teeth were excluded. The radiographic appearance of mental foramina can be classified into four types by Yosue & Brooks [6] (1989) A continuous type : which shows continuity with the mandibular canal through the mental canal. A separated type: in which the foramen is distinctly separated from the mandibular canal. A diffuse type: in which the foramen has an indistinct border. Unidentified type: in which the mental foramen cannot be identified on the panoramic radiographs under ordinary exposure and viewing conditions. According to Jasser NM and Nwoku AL in 1998 the position of the image of the mental foramen was recorded as follows: Position 1: Situated anterior to the first premolar Position 2: In line with the first premolar Position 3: Between the first and second premolar. Position 4: In line with second premolar Position 5: Between second premolar and first molar. Position 6: In line with first molar

We used the edge of a ruler to identify the longitudinal axis of the nearest tooth and the position of the mental foramen was recorded in relation to this. If the mental foramen was too large or was situated between two teeth, the position of the foramen was established after drawing an imaginary line parallel to the long axis of the teeth. After evaluation of each panoramic radiograph, the


Method to Locate Mental Foramen


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Rai et al

Appearance of mental foramen; A = Continuous; B = Separated; C = Diffuse; D = Unidentified type

RESULTS & DISCUSSION Of the 315 subjects participating in the study, fifteen subjects showed unidentified type (Type IV) of mental foramen and were only considered while recording the appearance of the mental foramen and not during identification of location of mental foramen.



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Pie 1: Frequency of location of mental foramina

Pie 2: Frequency of type of mental foramina on Right and Left sides

Graph 1: Frequency of appearance of symmetrical mental foramina in both genders



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Gender wise distribution of symmetrical mental foramina (n= 207) Graph 1

positioned anywhere between the first and second premolar to in line with first molar.

Determination of frequency in position of symmetrical mental foramen based on gender revealed higher frequency of Position 3(78.9 %) in males as compared to females (73%), whereas the frequency of Position 4 (17.6%) was slightly higher than males (15%)

Position of mental foramen (mental foramen)

Determination of frequency in position of asymmetrical mental foramen based on gender revealed higher frequency of Position 4(58.1%) in males as compared to females (46%) 10

This was in agreement to Fabian et al. (2007) who concluded that the most common position of mental foramen in the dry mandibles of adult black male Tanzanians was mostly below the apices of the second premolar or more posteriorly (80%) ( Position 4). Appearance of Mental Foramen: pie diagram 2 In the present study appearance of the mental foramen (n=315), Separated type is most common followed by Diffused and Continuous. On right side of the mandible Separated Type (n=166; 52.7%) > Diffused Type (n=74; 23.5%) > continuous Type (n=65; 20.6%) > Unidentified Type (n=10; 3.2 %). On the left side of the Separated Type (n=204; 64.8 %) > Diffused Type (n=53; 16.8%) > continuous Type (n=53; 16.8%) > Unidentified Type (n=5; 1.6 %). DISCUSSION The present study provides new data on the position of the mental foramen in the Modinagar population. Although on most standardized panoramic radiographs, the radiographic landmarks of the mental foramen can be seen, the appearance of these landmarks varies without any change of radiographic quality. In the analysis of 300 panoramic radiographs in this study, it was found that the mental foramen was

In the present study, analysis of panoramic radiographs was carried out and the most common position of the mental foramen was Position 3 (between the first and second premolar) (n=180; 60% on right side & n=206; 68.7% on the left side).The next common position was of mental foramen was Position 4 (in line with second premolar) (n=81; 27% on right side & n=61; 20.3% on the left side). None of the panoramic radiographs of patients showed the presence of Position 1& 2 Position 3> Position 4> Position 5> Position 6 Position 3 (Pie 1)has been described as the most common position of mental foramen followed by Position 4 as the second most common position of mental foramen in various studies carried in different populations. (Turkish, Nigerian, Iranian and Asian Indians) [7]

This was in agreement to, Olasoji et al. (2004) who concluded that the most common location of MF was noted in the inter-dental space between the first and second mandibular premolars (Position 3) with an incidence of 34% in radiographs and 32.8% in dry mandibles. This was closely followed by the position that is lying apical to the second premolar (Position 4) with an incidence of 25.5 % and 35.9 % in radiographs and dry mandibles respectively. Gungor et al (2006) [16] observed the most common position of the mental foramen to be between the first premolar and the second premolar (Position 3) in this population. Further supporting our results were the observation made by Haghanifar and Rokouei 11 (2009) who observed that the most common location of MF in Iranian population was between the premolars (Position 3) followed by the position of MF in line with 2nd premolar (Position 4). Rupesh et al., (2011) [13] also justified are results with their observations that the most common position for the mental foramen was Position 3 (46%), followed by Position 4 (32%)



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BUJOD In contrary to our study Ngeow and Yuzawati [5] (2003) reported that the most common position for the mental foramen was in line with the longitudinal axis of the second premolar (Position 4) with an incidence of 69.24 % on both sides. According to this study, the second most common location of MF in Malay subjects was position 3 with an incidence of 19.6 % (MF lying in between first and second premolar). [8]

Igbigbi and Lebona (2005) concluded that the most common position for the mental foramen was (Position 4), followed by position 3 (MF lying in between first and second premolar). Kim et al., (2006) [9] observed that the mental foramina were present below the second premolar (Position-4) with an incidence of 64.3% (Clinical observations), followed by the positioning of MF between Island 2nd premolar in 26.8% cases (Position 3). The incidence of Position 4 was as high as 62.5% (Radiographic observations). Agarwal and Gupta (2011) [12] observed that the most common position of MF was in line with the longitudinal axis of the 2nd premolar tooth (position 4)

which is the study is carried out are equally important factors which could influence the status of variability. CONCLUSION The most common locations of the mental foramen are between the two premolars and in line with the second premolar (below and/or mesial to the second premolar). The mental foramina are usually symmetrically located on both sides. These results were in accordance to Yosue & Brooks (1989) 6 who concluded that most frequent appearance of mental foramen was separated type. REFERENCES 1.

Phillips JL, Weller RN, Kulild JC (1992) The mental foramen: 2. Radiographic position in relation to the mandibular second premolar. J Endod 18, 271-274.

2.

Woelfel JB, Scheid RC. Structures that form the foundation for tooth function. Dental Anatomy: Its relevance to dentistry. 6th ed. Newyork: Lippincott, Williams and Wilkins: 2002.

3.

Moiseiwtsch 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.

4.

Phillips JL,Weller RN, Kulild JC. The mental foramen: Part1. Size, orientation and positional relationship to the mandibular second premolar. J Endod 1990; 16:221-3

5.

Ngeow WC, Yuzawati Y. The location of the mental foramen in a selected Malay population. J Oral Sci 2003; 45:171-5.

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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.

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Olasoji HO, Tahir A, Ekanem AU, Abubakar AA. Radiographic and anatomic locations of mental foramen in northern Nigerian adults.Niger Postgard Med J 2004; 11:230-3

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Igbigbi PS, Lebona S. The Position and

Sankar et al (2011) [14] concluded that frequency of MF lying below the second premolar tooth (position 4) was found to be highest (73.2%). [15]

Osunwoke et al (2012) observed the most common position of mental foramen in this population to be in line with the long axis of second premolar , (position 4) with an incidence of 54.24 st %, followed by the position between the 1 and 2nd premolars (position 3) with an incidence of (25.42%). Variations in the positioning of mental foramen in different population have been discussed in the literature and a number of factors have been suggested. Among the various underlying factors the position of mental foramen, varied because of dietary and chewing habits , gender differences, geographical factors, varied ethnic and racial factors. However it could be presumed that the methodology used as well as the type of material on



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BUJOD dimensions of the mental foramen in adult M a l a w i a n m a n d i b l e s . We s t A f r J Med.2005;24(3): 184-9

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Indian population on digital panoramic radiographs. J. Med. Sci. 2011;2:90-95. 14.

S a n k a r D K , B h a n u S P, S u s a n P J . Morphometrical and morphological study of mental foramen in dry dentulous mandibles of South Andhra population of India. Indian J Dent Res. Jul-Aug 2011; 22(4):542-6.

9.

Kim IS, Kim SG, Kim YK, Kim JD. Position of the mental foramen in a Korean population: a clinical and radiographic study. Implant Dent. 2006 Dec; 15(4):404-11.

10.

Fabian FM. Position, shape and direction of opening of the mental foramen in dry mandibles of Tanzanian adult black males. Ital J Anat Embryol. 2007 Jul-Sep; 112 (3):169-77.

15.

Osunwoke E, Amah-Tariah F, Sapira M. Position ,Direction and size of the Mental Foramina of the Mandibles of Adult Male South Nigereians. The Internet Journal of Biological Anthtroplogy 2012; 5(1):1-4.

11.

Haghanifar S, Rokouei M. Radiographic evaluation of the mental foramen in a selected Iranian population. Indian J Dent Res. 2009 Apr-Jun; 20(2):150-2.

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12.

Agarwal R, Gupta S. Morphometric Analysis of Mental Foramen in Human Mandibles of South Gujarat. People's Journal of Scientific Research. Jan 2011; 4 (1):15-18.

Gungor K, Ozturk M, Semiz M, Brooks SL. A radiographic study of location of mental foramen in a selected Turkish population on panoramic radiograph Coll Antropol. Dec 2006;30(4):801-5.

13.

Rupesh S, Winnier JJ, John SA, Joy T, Roa AP et al. Radiographic Study of the location of mental foramen in a randomly selected Asian

Source of Support :

NIL

Conflict of Interest :

NOT DECLARED

Date of Submission :

26-02-2014

Review Completed :

14-08-2014



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