To Study The Location, Shape and Morphological Relations of Mandibular foramen and Mandibular lingula in Dry mandibules of South India.

Ms. Amanthi Ganapathi, Dr. M.S. Thenmozhi

Saveetha Dental College and Hospitals, Chennai

*Corresponding Author E-mail: amenthy97@gmail.com

ABSTRACT:

Aim and objective: To measure the location, shape AND morphological relations with mandibular foramen and dry mandibules of south India

Background: The mandibles or jaw bone in the human is largest, strongest and lowest bone in the face .It forms the lower jaw and holds the lower teeth in place. The mandibular foramen is an opening on the internal surface of the Ramus(posterior and perpendicular oriented part of the mandible).The margin of the mandibular foramen is irregular.Lingula is a tongue-like flap of bone that overlaps the mandibular foramen anteriormedially.It is surmounted by a sharp spine, the lingula of the mandible when gives attachment to the spenomandibular ligament ;at its lower and back part is a notch from which gives mylohyoid groove runs obliquely downward and forward, and loges the mylohyoid vessles and nerve.

Reason: The purpose of this study was to obtain morphological parameter of the mandibular foramen and the mandibular lingula.This study is conducted to measure the morphological relations in dry mandibules of south Indian for the knowledge of its surgical application.

KEYWORDS: Mandibular foramen, Morphological location, Inferior alveolar nerve, local anesthesia, Mandibular lingula. .

INTRODUCTION:

The mandible is the largest, strongest bone in the skull; the skull incorporate mandible and cranium. Mandible has a curved body which is convex forwards and has a two board rami that ascends, the rami has coronoid and a condylar processes. The mandibular foramen is an opening in the internal surface of the ramus of the mandible for the mandibular vessels and nerve to pass through it. The mandibular canal starts at the manibular foramen and descends obliquely forward in the ramus, and later in the body of mandible accommodates the inferior alveolar neurovascular bundle. [1]. The inferior alveolar nerve and the vessels enter the mandibular foramen and it makes its extent in the mandibular body and give out fine branches which supplies the mandibular teeth, gums and to the lower lip.

Blockage of the Inferior alveolar nerve under local anesthia is commonly done at the entrance of mandibular foramen during various surgical and dental operations on the mandible and mandibular teeth such as removal of impaction, reductions of fractures and extraction of the teeth. [2] The assessment of the mandibular foramen is of a considerable significance for inferior alveolar nerve ansesthesia, Dento alveolar surgery, planning for endodontic treatments, and lesions diagnosis in that region. Incorrect in the judgmental of its location might be the explanation for an unsuccessful anesthesia of the inferior alveolar nerve [3]. The inferior alveolar vessels and nerves enter through the mandibular foramen, traverse the canal, providing branches to all teeth and supplies and then it creates exit through the mental foramen as mental nerve and vessel [4]. Mandibular foramen has remarkable connection to nerve and vascular structures, the present study on the lingual features provides notable information related to oral and maxillofacial surgical procedures such as the orthognathic surgery, mandibular trauma management, eradication of benign and malignant lesions, preprosthetic surgery and nerve injury during inferior mandibular nerve block [1]. Imperfections in the attainment of the anesthesia of the lower alveolar nerve is generally caused due to the lack of examination of the localization of the mandibular foramen and noticing its variations [3]. The lingula of the mandible is a tongue shaped bone projection which is present on the medial aspect of the ramus, it lies in close relation to the anterior margin of the mandibular foramen. Lingula has been an noted as an important landmark to perform the sagittal spilt ramus osteotomy, the most extensively used surgical technique for proper correctioning of the mandible. On sagittal spilt ramus osteotomy the horizontal cut on the medial aspect of the mandible is done just above to the lingula [5]. According to Nicholson and keros studies analyzed that morphological characteristics of the mandibular foramen and lingula and on which they have arrived a conclusion stating that such structures variability would account for failure to block the inferior alveolar nerve [1]. The past critique revealed the importance of mandibular foramen in the success of Inferior alveolar nerve block. The motivation of the study is to determine the position of the mandibular foramen from various anatomical landmarks and to determine the morphology of mandibular lingula in several dry mandibles of south Indian population and provide valuable information for dental students and dental practitioners

MATERIALS AND METHODS:

This study was carried out in Department of Anatomy, Saveetha dental college and Hospitals, Chennai, India. A total of 31 human dry mandibles were examined. The measurements were taken from the superior border of the ramus(mandibular notch) to the midpoint of the mandibular foramen and then from the midpoint of the mandibular foramen to the inferior border of the ramus. Similarly with the help of anatomical landmarks from the posterior border of the ramus of mandible to the midpoint of the mandibular foramen and from the anterior border of the ramus of the mandible to the midpoint of mandibular foramen. All the measurement was performed directly on each hemi-mandible. Measurements were recorded to the nearest millimeter.

RESULTS:

The results are shown in table 1-6. The table 1-5 gives the average distances to the mandibular foramen from various anatomical borders of the either sides of the mandible and table 6 alone gives the shape of the mandibular lingula. It was found in the study that the mean distance to the mandibular foramen from the anterior border is 1.73, the mean distance from the posterior border was marked to be 1.94, the mean distance from the superior border is 2.67 and the mean distance from the inferior border is 3.0. All the above mentioned values is for the right side of mandible. To the left side of the mandible from the anterior border the average distance will be 1.6, form the posterior border the average distance will be 1.9, from the superior border the distance will be 2.4, and from the inferior border the distance will be 3. It has been clear that there is no much difference between the position of mandibular foramen. Taking into mind about the different shapes of the lingula on either sides of the mandible. The triangular shaped lingula showed more incidences. After that truncated was most common. Nodular and assimilated showed similar in number.

Figure: 1 Distance from anterior border to midpoint of mandibular foramen

Table:-1 Distance from anterior border to midpoint of mandibular foramen

FROM ANTERIOR BORDER	MAX	MIN	AVERAGE
SIDE
RIGHT	2.1	1.3	1.732
LEFT	2.2	1.4	1.687

Figure: 2 Distance from posterior border to the midpoint of mandibular foramen

Table:-2 Distance from posterior border to the midpoint of mandibular foramen

FROM POSTERIOR BORDER	MAX	MIN	AVERAGE
SIDE
RIGHT	2.6	1.4	1.945
LEFT	2.9	1.2	1.91

Figure: 3 From the superior border to the midpoint of mandibular foramen

Table:-3 Distance from superior border to the midpoint of mandibular foramen

FROM SUPERIOR BORDER	MAX	MIN	AVERAGE
SIDE
RIGHT	3.3	2.1	2.671
LEFT	3.3	2	2.44

Figure: 4 from the inferior border to the midpoint of mandibular foramen

Table:-4 Distance from inferior border to the midpoint of mandibular foramen

FROM INFERIOR BORDER	MAX	MIN	AVERAGE
SIDE
RIGHT	4.1	1.9	3.032
LEFT	2.9	2.3	3

DISCUSSION:

The present study is conducted on the mandibles of the population of south India .the findings of this study may be utilized by the dental surgeons in assessing the position of the mandibular foramen in the local population while using the inferior alveolar nerve block for local anesthesia. In the study ,it was found that the mandibular foramen was situated at a average distance of 1.72 mm (right) and 1.68mm (left) from the anterior border to the midpoint of the mandibular foramen, the average distance of 1.9 mm (right) and 1.9mm (left) from the posterior border to the midpoint of the mandibular foramen, the average distance of 2.6mm (right) and2.4mm (left) from the superior border to the midpoint of the mandibular foramen, the average distance of 3.03mm (right) and 3mm (left) from the inferior border to the midpoint of the mandibular foramen. The mandibular foramen was situated immediately that posterior to the center of the ramus. Whereas it was stated that the mandibular foramen was located in the third quadrant anterioposteriorly, the mean distance of mandibular foramen from the anterior border of ramus was 16mm on the right side and 16.27mm on the left side and that from the posterior border was found to be 10.21 mm and 10.28 mm on the right and left side respectively. It also stated that the mean size of the anterior dimension was greater than that of the mean size of the posterior dimension of the ramus of the mandible at all the instances, the mandibular foramen was found to be located in the third quadrant anterioposteriorly,there was no right and left side dominance in the ramus size and with the position of the mandibular foramen [3]. lavanya et al. found that the average distance if mandibular from the mandibular notch was found to be around 20-25mm in both dentulous and edentulous mandibles. The same was found to be around 16mm from anterior border of the ramus and around 13mm from the posterior border of the ramus on both groups of mandibles. In dentulous mandibles,the average distance from the third molar tooth was found to be around 15-17mm [6]. The knowledge of mandibular foramen location will be helpful for the new innovations about oral inferior alveolar nerve block technique and fir study of dental X-rays [3]. Nicholson’s study stated that the average distance of mandibular foramen could be the reason behind the occasional failure for inferior alveolar nerve block. This study concluded that the variability was not significant enough for an anesthesia failure. [7]. In the year 2011 Ashkenazi et al. studied the effect of age on the anteroposterior position of the mandibular foramen and on the size of the gonial angle, it was found that the anterior movement of mandibular foramen decreased size if gonial angle occurred due to age changes and dentition which was related to growth process. So, But our study data could not identify this [8]. In the present study triangular shape lingula were showing more incidence than other type. After triangular shape lingula nodular shape lingula was more common type Z, nodular and assimilated were present equal in number. In shape of coronoid process triangular are more common after that hook shaped lingula was found next and then rounded shaped are present. The study reported made out of 157 dry mandibles incidence of hook shaped was about 27.4%, triangular 49% and rounded type 23.6%, it was also found that the incidence of rounded type almost equal to male, triangular slightly more in females, while hook type more in male mandibles [9]. In a study conducted by Tanveer et al. reported that triangular process more commonly present in males than females. And rounded was more prevalent in females [10]. From our study the position of mandibular foramen seems to be determined by the distance from the anatomical landmarks to the mandibular foramen. Most of the study has taken mandibular notch as one of their main reference point to locate the position of mandibular foramen at the center of the ramus.Since mandibular notch cannot be felt externally it was not the only factor to influence the position of mandibular foramen but, also measuring from the anterior, posterior border of the ramus and in vertical plane superior and inferior.

CONCLUSION:

This study shows the location of the mandibular foramen which will help dental practitioners and dental surgeons for the proper identification of mandibular foramen for giving inferior alveolar nerve block for dental procedures.

REFERENCE:

1 Vikas. C. Desai, Desai SD, Hussain Saheb Shaik et al. Morphological study of Mandible. Journal of Pharmaceutical Sciences and Research.Vol.6 (4), 2014,175-177

2 Afadhali. D. Russa, Flora M. Fabian. Position of the Mandibular foramen in adult male Tanzania Mandibles. Italian Journal of Anatomy and Embryology.Vol.1198, n.3: 163-168, 2014

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7 Nicholson ML. A study of the position of mandibular foramen in adult human mandible. Anat Rec.1985;212:110-2.

8 Ashkenazi M, Taubman L, Gavish A. Age-associated changes of the mandibular foramen position in anteroposterior dimension and of the mandibular angles in dry human mandibles. Anat Rec.2011; 294:1319-25.

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Received on 07.05.2016 Modified on 25.05.2016

Research J. Pharm. and Tech. 2016; 9(7):893-897.

DOI: 10.5958/0974-360X.2016.00170.0

TRIANGULAR			TRUNCATED			NODULAR			ASSIMILATED
RIGHT	LEFT	TOTAL	RIGHT	LEFT	TOTAL	RIGHT	LEFT	TOTAL	RIGHT	LEFT	TOTAL
16	14	30	6	8	14	6	3	9	3	6	9