Osteometric Measures of Mandible on Its Various Aspects in South Indian Dry Skull

Introduction: Mandible is the single bone articulated with cranium forming a temporomandibular joint and it contributes to the lower jaw containing teeth. The mandible is composed of the body and the ramus. Aim: Aim of this study is to find the distance between each parameter in different mandibles. Materials and Methods: The present study has utilized 30 south indian dry skulls from the Anatomy Department of Anatomy, Saveetha Dental college. The following parameters are taken to measure by using vernier calipers. They are the maximum distance between the mandibular incisors, mandibular inter canine, mandibular 1st premolar, mandibular molar, mandibular coronoid process, mandibular condylar process, mandibular notch on either side. The results were analysed statistically by using t-test calculator in Graph pad. Results: From the study it was observed that the mean distance between the mandibular incisors is 15.658 ± 1.642416 , mandibular inter canine 29.0025 ± 9.04636, mandibular 1st premolar 40.746 ± 2.543341, mandibular molar 62.076 ± 3.4988, mandibular coronoid process 85.8735 ± 5.10615, mandibular condylar process 103.013 ± 3.794, mandibular notch on either side 88.368 ± 3.5832 (Table 1 & Figs. 1-6). Conclusion: The present study thus concluded that the morphometric analysis of the mandible is of utmost importance in determining the gender, anatomical studies, clinical and anthropometric studies. Original Research Article Ranjeet and Premavathy; JPRI, 33(64B): 161-167, 2021; Article no.JPRI.79196 162


INTRODUCTION
Mandible is the strongest and largest bone of the face which forms the lower jaw. It is the only bone articulated with cranium forming the temporomandibular joint [1][2][3]. The lower jaw contains teeth which include incisors, canines, premolars and molars [4]. The mandible is the bone that develops from the first pharyngeal arch, the Meckel's cartilage is primordia for the developing mandible [5,6]. The mandible consists of body, ramus, notch, and coronoid and condylar process, alveolar sockets with teeth. Further it possesses mandibular foramen which transmits inferior alveolar nerves and vessels, mylohyoid groove in the inner surface of the mandible transmits mylohyoid nerves and vessels [7,8]. The lines, ridges and rough areas of the mandible give attachment to muscles and ligaments [9,10]. The sphenomandibular ligaments, stylomandibular ligaments and pterygomandibular raphe are attached to the mandible [11,12]. The muscles of mastication such as masseter, temporalis, medial and lateral pterygoid are attached and suprahyoid groups of muscles such as mylohyoid, geniohyoid are attached to the mandible [13].
The horizontally curved portion of the mandible creates a lower jawline and rami is situated vertically with respect to the body, whereas the coronoid process give attachment to the the temporalis muscle as mentioned above and condylar process or head of the mandible articulates with mandibular fossa [14,11,[15][16][17]. Thus the joint permits greater mobility for the process of mastication and speaking [18]. The individual tooth present in the mandibular sockets has its own functions. They are incisors cutting the food, cut and tear by the canine, and it acts as a guide post to the rest of the teeth [19,20]. Mandibular 1st premolar is the tooth located laterally from both the mandibular canines of the mouth but mesial form both mandibular second premolar its functions is similar to that of canines in regard to tearing being the principal action during mastication, commonly known as chewing [21,22]. Mandibular molar is the tooth located distally from both the mandibular second premolar of the mouth but mesial form both mandibular second molars [23]. The coronoid process of the mandible is thin, triangular, sharp projection, flattened from side to side and gives attachment to the tendon of the temporalis muscle [11,15,16]. The shape of the coronoid process may vary [23,24]. The condylar process is rounded elevation of the mandible called head, compressed anteroposteriorly and elongated from side to side [25]. Anteriorly it possesses a small depression called pterygoid fovea that provides insertion to the lateral pterygoid, main depressor of the temporomandibular joint [26,27]. The coronoid and condylar processes are outpouching of the ramus of the mandible. The ramus is flattened from side to side having borders and a surface provides attachments to muscles and ligaments, the superior border of the ramus forms the mandibular notch [28]. From this the present study aimed to analyses the mandible from its various aspects by morphometrically [29].

MATERIALS AND METHODS
The present study has utilized 30 south Indian dry skulls adopted from the Department of anatomy from Saveetha Dental College and Hospitals. All the linear distances were measured by using a digital vernier caliper. The following parameters are studied on the mandible of south Indian dry skull. They are maximum distance between the mandibular incisors, maximum distance between the mandibular inter canine, maximum distance between the mandibular 1 st premolar, maximum distance between the mandibular molar, maximum distance between the mandibular coronoid process, maximum distance between the mandibular condylar process maximum distance between the mandibular notch. The obtained results were analysed and represented in graphs. The present study was approved by Institutional Review Board, Saveetha Dental College and Hospitals, Saveetha Institute of Technical Medical Sciences.

Statistical Analysis
The present study utilized a t-test calculator in Graph pad with 95% significance for statistical analysis. The measurements done by using following parameters such as maximum distance of mandibular incisors and canine, mandibular 1st premolar and molar, mandibular coronoid processes and condylar processes.

RESULTS
The present study was observed that the mean with standard deviation distance between the mandibular incisors is 15.658 ± 1.642416 , mandibular inter canine 29.0025 ± 9.04636 , mandibular 1st premolar 40.746 ± 2.543341, mandibular molar 62.076 ± 3.4988, mandibular coronoid process 85.8735 ± 5.10615, mandibular condylar process 103.013 ± 3.794, mandibular notch on either side 88.368 ± 3.5832 (Table 1 & Figs. 1-6). But for statistical analysis, the study chose the following parameters. They are the difference observed between maximum incisors and canines, p value is < 0.0001, difference observed between maximum distance of mandibular 1st premolar distance and molar. The p value is 0.0001 and the maximum distance between right and left condylar and coronoid processes. The p value is 0.0001.

Fig. 1. Bar graph depicts maximum mandibular incisors distance and maximum mandibular inter canine distance. X -axis represents maximum mandibular incisors distance and maximum mandibular inter canine distance. Y -axis represents measurements in mm .
There was a significant difference observed between maximum incisors and canines, p value is < 0.0001 Fig. 2. Bar graph depicts maximum mandibular 1st premolar distance and maximum mandibular molar distance. X -axis represents maximum mandibular 1st premolar distance and maximum mandibular molar distance. Y -axis represents measurements in mm. It shows that maximum mandibular molar distance is greater than maximum mandibular 1st premolar.
There was a significant difference observed between maximum distance of mandibular 1st premolar distance and molar. The p value is < 0.0001

Fig. 3. Bar graph depicts maximum inter coronoid distance and maximum inter notch distance and maximum condylar distance. X -axis represents maximum inter coronoid distance, maximum inter notch distance and maximum condylar distance. Y -axis represents measurements in mm.
There was a significant difference observed between maximum distance between right and left condylar and coronoid processes. The p value is < 0.0001 Similar to the present other study also analyzed the mandible but there is no significant difference observed between right and left side of the mandible [30]. But in the present study significant differences were observed between maximum incisors and canines (p value is < 0.0001), distance of mandibular 1st premolar distance and molar (p value is < 0.0001) and maximum distance of right and left condylar and coronoid processes (p value is < 0.0001).
The studies showing that this morphometric study is used for to predict sex accurately [31]. The mandibular measurements are not only helpful in anatomical studies, anthropometric, determining sex, etc. but also helpful in assessing facial index. In fact, the mandible also contributes a major part i.e lower jaw. Similarly study was conducted to determine the facial height inclusive of mandible [32], mandibular measurements may be helpful in determining the sex [33]. The limitations of the present study are small size and the study is further continued with larger sample size and interpreted with new findings.

CONCLUSION
The mandible is the important skull bone and only movable bone, contributing for the lower facial skeleton. There are so many morphometric studies conducted with condyles, ramus, coronoid process, etc. Similarly the present study also conducted above mentioned parameters. These measurements are of utmost importance in anatomical, anthropometric and various clinical studies as well.

CONSENT
It is not applicable.

ETHICAL APPROVAL
The present study was approved by Institutional Review Board, Saveetha Dental College and Hospitals, Saveetha Institute of Technical Medical Sciences.