Mandible Is an intersting bone since it depicts morphological changes in relation to age1. Morphological changes like alteration in shape of certain bony process of mandible like lingula [1]. And these variations form interesting mode of of investigation from clinical point of view. The shape of lingula has been described in great detail, and is known from a wide range of literature [2]. Triangular shaped lingula has been described in greater percentage of mandibles by many leading authors. Other than the triangular form, which is truncated, nodular, assimilated forms are represented in Text book illustrations [3,4]. The mandible is the largest and strongest bone of the facial skeleton that is essential for mastication, speech, facial contour and support of the lower dentition. It exhibits marked morphologic variability based on age, sex, population and functional requirements [5]. The important structures of the mandible are the mandibular lingula, a small tongue-shaped bony prominence at the medial surface of the mandible, just anterior to the mandibular foramen. Lingula is small but very significant from an anatomical, clinical and surgical standpoint [6]. The lingula is the site of attachment of the sphenomandibular ligament, and is also a helpful landmark for locating the mandibular foramen, the entrance to the mandibular canal by the inferior alveolar neurovascular bundle [7]. It is especially critical to accurately identify this region when performing an inferior alveolar nerve block, sagittal split ramus osteotomy, fixation of mandibular fractures, orthognathic surgery, and nerve excision or decompression of the inferior alveolar nerve [8]. The lack of understanding of different shapes and positions of the lingula can also be responsible for inadequate local anaesthetic, nerve damage, excessive bleeding or other operative problems [9,10]. Lingula is used to identify the site of injection of local anesthetic or for excision of nerve for facial neuralgia. In the present study, therefore, an attempt has been made to give more information regarding the morphology of lingula.

The present study was descriptive cross sectional study, it was conducted on 200 dry mandibles of humans which were available in the museum of department of anatomy, Shimoga Institute of medicine sciences, shivamogra. In total, 180 mandibles were found of adults and 20 were found of elderly individuals. Of the adult mandibles 135 were identified as male and 45 as female, while of the elderly mandibles 16 were identified as male and four as female. So the last sample consisted of 151 mandibles from males and 49 mandibles from females. In this work, only mandibles with well-preserved mandibular rami and lingulae on both sides were used. Fractured, malformed, pathological and demographically incomplete mandibles were excluded. Both sides of the lingula of each mandible were studied on the medial surface of the mandibular ramus. There were thus 400 lingulae that were evaluated. On the basis of their morphological characteristics, the lingulae were divided into four types: triangular, nodular, assimilated and shortened. The triangular type was identified as a lingula having a wide base and a narrow, rounded or pointed point. The nodular type had the small rounded projection with the majority of the lingula fused to the mandibular ramus with the exception of its apex. The assimilated type was one in which there was complete assimilation on the medial surface of the ramus, by means of a lingula. The broken type had the shape of about a quadrangle, the superior, inferior and posterior margins of which were distinguishable. The right and left sides of the lingula were recorded separately and its distribution was compared by sex and age group. The observations were made by direct visual examination under good illumination. Data collection was undertaken in a structured data collection sheet, relevant findings were added to the sheet. Statistical Analysis Data were entered and analysed using appropriate statistical software. Categorical variables were presented as frequencies and percentages. The chi-square test was used to assess the association between lingular shape and sex or age group. Fisher’s exact test was applied when the expected frequency in any cell was less than five. A p-value of less than 0.05 was considered statistically significant.

The triangular shape was the most frequently observed type of mandibular lingula, accounting for 59.25% of observations in males and 20.25% in females. The assimilated type was found in 8.25% of male mandibles but was not observed in females. The truncated type was identified in 6.00% of males and 3.50% of females, while the nodular type was the least common, occurring in 4.50% of males and 1.00% of females. Overall, all lingular shapes were more frequently observed in male mandibles, with the greatest difference seen for the triangular type. Table 1. Distribution of Mandibular Lingula Shapes According to Sex Shape of lingula Male (%) Female (%) Triangular 59.25 20.25 Truncated 6.00 3.50 Nodular 4.50 1.00 Assimilated 8.25 0.00

The present study compared the differences among the 200 dry human mandibles from the South Indian population in the shape of the mandibular lingula. Four morphological types were recognized: triangular, nodular, assimilated and truncated. The mandibles of both sexes were mostly of the triangular type, the nodular and assimilated types being comparatively rare. These results reaffirm the significant morphological variation of the mandibular lingula and the distribution of its shapes can vary based on sex. The most common type was triangular with 59.25% in males and 20.25% in females. This is similar to previous anatomical studies which identified the triangular shape as the most common anatomical pattern. In a previous exam of 165 adult human mandibles, triangular lingulae were also found at a high prevalence among males. This predominance may be due to developmental characteristics of the mandibular ramus and area around the mandibular foramen related to population [11]. The truncated type was found among 6.0% of the males and 3.5% of the females. Occurrence is not as common as the triangular form, but it did occur about twice as often in males. One of the least common morphological variants, the nodular was observed in 4.5% of males and 1.0% of females. Assimilated: 8.25% of males were observed, but no females were observed. The differences indicate possible sexual differences in lingular morphology but shape of the lingula should not be used alone for sex determination [12]. It might be better used as a supportive feature in conjunction with other well recognized mandibular features. Population-level variation in the morphology of the language could be affected by genetic, developmental, environmental, and functional factors [13]. Differences in size and shape may be due to variations in the masticatory forces, craniofacial growth and development of the mandible. Thus, Anatomical studies of the population can be useful for any dental surgeon, oral and maxillofacial surgeon, anaesthetist, anatomist and forensic specialist who would need information regarding the anatomy of the area for a specific clinical scenario [14-15]. The results of this study can also be of forensic significance. Higher incidence of triangular and assimilated lingulae in male mandibles and the absence of the assimilated shape in female mandibles may explain that they could provide additional information for sex estimation [16]. However, there is an observed overlap in the patterns of the two sexes which makes the use of lingular morphology as an independent method unreliable. More examinations of known age and known sex skeletal remains are needed to make certain forensic statements. Although the study has its limitations. Only mandibles which were dry were used and the results might not reflect the general population of South India. It is possible that the comparison between sexes was also influenced by the difference in frequency of males and females. Furthermore, assessment was largely visual classification that could be influenced by observer differences. Larger and more balanced samples, assessment of interobserver reliability, and radiological and/or three-dimensional morphometric evaluation of the differences between the right and left sides should be further studied.

A considerable variation has been found with the mandibular lingula, which has been triangular, truncated, nodular and assimilated in the mandibles studied from all parts of South India. The triangular type was the most common in both sexes, the nodular and assimilated being less common. There is some degree of sexual variability in the distribution of lingular shapes (between male and female mandibles), but the lingular morphology should not be relied upon as a sexing tool, only as a supplementary. Clinically, knowledge of these anatomical variations is important for the proper localization of the inferior alveolar nerve block, orthognathic surgery, management of mandibular fractures, etc. In the present study certain differences could be observed in the morphology of the mandible. Female mandible was in contrast to male mandible in which mandibles had tribal lingula and triangular lingula respectively. The above findings have great forensic value and can help distinguish mandibles of the sexes as well as serve as a good land mark for clinicians..

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