Temporomandibular disorders (TMD) encompass clinically analogous conditions characterized by pain and functional impairments of the masticatory system, temporomandibular joints (TMJs), and associated structures. Prevalent TMD symptoms include pain in the hard and soft tissues associated with TMJ and the masticatory muscles, restricted jaw mobility, and TMJ clicking (Ingawale and Goswami, 2009). The prevalence of TMD is high (more than 30 %) globally (Alrizqi and Aleissa, 2023, Bertoli et al., 2018, Qvintus et al., 2020, Talaat et al., 2018, Valesan et al., 2021). In one statistic for a specific population sample, over 70 % of people showed at least one symptom of TMD (Lung et al., 2018). The pathogenesis of TMD exhibits complexity and involves a multifactorial etiology. Parafunctional habits, such as bruxism and prolonged clenching, along with trauma to the TMJ or masticatory muscles, were frequently reported as causative factors (Gauer and Semidey, 2015, Ingawale and Goswami, 2009). Additionally, malocclusion and psychological factors (such as mental stress and anxiety) were also considered possible contributors to the development of TMD (Gauer and Semidey, 2015, Ingawale and Goswami, 2009). The majority of the etiologies primarily implicate the alterations in the biomechanical environment within TMJs (Abe et al., 2013, Commisso et al., 2014, Gholampour et al., 2019, Huang et al., 2002, Jiao et al., 2010, Ramirez-Yanez et al., 2004). Consequently, it becomes vital to assess the TMJ biomechanics to discern the underlying causes of TMD and formulate diagnostic and therapeutic protocols for such disorders.

In dental biomechanics, especially concerning the TMJ, finite element modeling (FEM) has become an invaluable instrument for exploring the intricate internal mechanical environment of the TMJ. The challenges of directly measuring the mechanical environment within the human TMJ are substantial. Consequently, FEM has been widely embraced for its effectiveness and accuracy in simulating mechanical responses in intricate systems. Several studies have employed FEM to analyze the TMJ loads and condylar movements during orofacial activities (Laird et al., 2020, Shu et al., 2020a, Vatu et al., 2018). Moreover, FEM is also valuable for assessing the biomechanical effects of surgical interventions for jaw deformities (Liu et al., 2018, Shu et al., 2018, Ueki et al., 2010) and for simulating surgical procedures in virtual surgeries for improved preoperative planning (Shu et al., 2020b, Shu et al., 2019). The application of FEM has significantly advanced our understanding of TMJ biomechanics. Moving forward, as the TMJ field delves into more challenging research, the continued reliance on FEM is anticipated for comprehensive insights.

Previous research has examined the relationship between TMJ diseases and underlying mechanistic factors. Certain investigations ascribed degenerative changes (usually known as osteoarthritis) to the dysfunction in the remodeling process (Arnett et al., 1996a, Arnett et al., 1996b), which can arise when excessive or sustained mechanical stresses surpass the normal adaptive capacity. Furthermore, excessive or unbalanced loads experienced by TMJ can contribute to internal derangement (disc displacement) (Tanaka et al., 2008a, Tanaka and Koolstra, 2008). An investigation explored the direct correlation between mechanical parameters and TMD symptoms, revealing that abnormal stress distributions within the disc lead to articular clicking, and asymmetrical stress distributions within the articular fossa suggest deviations in mouth opening (Shao et al., 2022). Nevertheless, existing research on the association between TMD and mechanical parameters remains insufficient and incomplete, and no strong link has been established. This study aimed to evaluate the magnitude and distribution of stresses within TMJ under incisal clenching in individuals diagnosed with TMD while concurrently providing insights into the biomechanical underpinnings of TMD pathogenesis.