A Finite Element Modeling and Simulation of Human Temporomandibular Joint with and Without TM Disorders: An Indian Experience Mehak Sharma * , Manoj Soni Department of Mechanical and Automation Engineering, Indira Gandhi Delhi Technical University for Women, New Delhi 110006, India Corresponding Author Email: er.mehaksharma@gmail.com https://doi.org/10.18280/mmep.080303 ABSTRACT Received: 16 January 2020 Accepted: 5 December 2020 Temporomandibular joint (TMJ) is anatomically the most intricate joint which connects the lower jaw to the upper jaw and regulates jaw movements. It significantly deals with mastication and speech. It is hence imperative to study the mechanics and functioning of the jaw joint to devise alternative solutions for its replacement whenever required. Further, human skulls are anthropologically categorized into three types – African, Asian and European. Out of these, the Indian skull is also a bit different than its Asian counterparts because of its osteology and skeletal biology. Hence, a comprehensive biomechanical and computational study is essential to provide customized solutions. For the present study, four different loading conditions are selected to perform finite element analysis on the human skull, Anonymized and unidentifiable CT scan data sets from open-source web platforms are converted to STL and then 3D models using 3D slicer. Finite element analysis of jaw joint is carried out. Results based on Von Mises stress studies show significant behavioral differences under varying load conditions. Hence, it is crucial to identify solutions for TMJ disorders of the Indian population. Keywords: finite element analysis, TMJ, jaw joint, biomechanics, stress distribution, bruxism, clenching 1. INTRODUCTION The temporomandibular joint is both ginglymus (hinging joint) and arthrodial (sliding joint), which is why it is often labeled as ginglymoarthrodial joint as shown in Figure 1. It is an extensively used joint in the human skull and body. TMJ opens and closes numerous times daily and is vital for speech, snoring, mastication, deglutition, yawning and the involuntary alliance of articular pairs [1]. Since a multitude of Indian population is suffering from TMJ disorders, therefore it is critical to address TMJ issues taking all considerable frames of reference. There is paucity in understanding connections among muscle behavior, jaw motions, craniofacial morphology and all the forces acting on TMJ. Extensive research and awareness are needed to understand the etiology of temporomandibular joint disorders found in Indian patients. New inventions and methods should be adopted and followed to analyze, avert, and alleviate these disorders. The analysis of mandibular biomechanics helps us understand the mechanism, activity and pattern of temporomandibular disorders can be presumed by analyzing the TMJ biomechanics. This will aid in up-gradation in the design and performance of prosthetic devices, thereby enhancing the serviceable life of these devices. TMJ prosthetic replacement is an extensive surgery and it is only advisable as last resort. Testings and experiments on TMJs of actual human beings are also avoided because administering experimental devices inside the TMJ can cause severe harm to its tissue. Therefore researchers, surgeons, diagnosticians and scientists use in-vitro techniques such as CT scanning, laser 3D scanning, finite element analysis (FEA) and other analytical technologies for extensive research in TMJ biomechanics. Spencer and Demes discussed in a classic study of basic joint mechanics to assess the differences in size and shapes of jaw mandible and it is also [2] useful in understanding the bite forces for different generations and races. Chen and Xu discussed and constituted a 2-D FE model of human TMJ which deduced the distribution of stresses [3] between condylar, temporal surfaces and articular disk. Finite element analysis has been in use for the study of the biomechanics of joint since the 70s, Richmond et al. successfully incorporated the morphology and biomechanical [4-9] properties of bone, muscles and tissues in constructing and improving FEA models that can calculate the stresses and strains. On the other hand, Kober et al., Strait et al., Ren et al., and Milne et al. [10- 13] demonstrated various errors arising in substantially depicting the anatomy, internal structure, mechanisms, muscle forces, loads and spatial constraints using FEA technique. Richmond et al. successfully incorporated the morphology and biomechanical [14] properties of bone, muscles and tissues in constructing and improving FEA models that can calculate the stresses and strains. There is a relative certainty that FEA is a vital tool for studying the biomechanics of TMJ, keeping the evidence of errors alongside [15-20]. Aoun et al., presented a hypothesis (also used in the current study) to elaborate the functioning of TMJ in three static [17] mandible positions by clenching using FEA models and thus the behavior of natural TMJ has been characterized using computational analysis. Dimitroulis, an Australian medical pioneer in the field of study of Temporomandibular joint has narrowly discussed the vitality of extensive studies to understand TMJ, its functioning, mechanisms, disorders, diseases, solutions, replacements, surgical needs and the whole rationale in the Indian context. Mathematical Modelling of Engineering Problems Vol. 8, No. 3, June, 2021, pp. 347-355 Journal homepage: http://iieta.org/journals/mmep 347