## 2 Materials and Methods
According to these sources, pathological bruxism forces of up to 800 N may occur at the level of the premolar. This value was considered the pathological upper limit in the present study. An important aspect of research in this field is the evaluation of the effects of these forces not only on the dental crown but also along the entire axis of the tooth, including the supporting structures. Figure 4: Application of forces and constraints. Red arrows represent the resultant masticatory force vector inclined at 15\({}^{\circ}\) to the long axis of the tooth. Green arrows indicate boundary conditions mimicking the periodontal ligament–bone interface. Additionally, it is important to note that the upper limit of axial force that the periodonium can withstand without causing irreversible changes is approximately 200 N. Exceeding this threshold may lead to periodontal damage [25]. Among the occlusal parameters involved in the dynamics of bruxism, the contact angle plays a significant role, influencing both the distribution of masticatory forces and the degree of dental wear. This angle reflects the geometry of the guidance provided by occlusal morphology during mandibular movements such as lateral excursions, protrusion, and retrusion. In the context of bruxism, the contact angle becomes particularly relevant, as the abnormal and repetitive trajectory of the mandible leads to pathological contact between opposing surfaces. Therefore, the contact angle indicates the direction and intensity of the parafunctional forces exerted on the teeth and periodontium. In the case of premolars, the contact angle plays a crucial role in determining the directions and magnitudes of the parafunctional forces generated during bruxism. Even a minor change in this angle can lead to a significant redistribution of force vectors, increasing tangential components and favoring the emergence of shear stress. These stresses, when applied repeatedly and in unfavorable directions, can exceed the resistance capacity of dento-periodontal tissues and restorative materials, increasing the risk of microcracks, material debonding, and structural failure. Particularly, when forces are directed obliquely to the tooth axis, they may be amplified by the specific geometry of the cusps, leading to localized stress concentrations with disproportionate impacts on the root and ligament attachment areas. Therefore, the magnitudes of parafunctional forces should not be evaluated in isolation but rather in correlation with occlusal morphology and the direction of force application in order to fully understand the biomechanical risks associated with bruxism [26]. In this study, the application of forces of 400 N, 600 N, and 800 N--values exceeding the maximum physiological threshold of 200 N--revealed the occurrence of cracks within restored dental structures, particularly in the context of minor variations in the contact angle obtained through modeling (Table 2). These observations are especially relevant in cases of eccentric bruxism, characterized by lateral mandibular movements (grinding), where the effects of the applied forces become disproportionate. In such scenarios, the cusps of opposing teeth tend to \"slide\" over each other at biomechanically unfavorable angles, generating horizontal components of force that are transmitted to the dental roots and periodontal ligaments [27]. These horizontal forces may exceed the physiological adaptive capacity of the tooth's supporting apparatus, which, over time, can lead to the development of extensive occlusal wear surfaces and dentin exposure accompanied by dentin hypersensitivity, as well as chronic periodontal inflammation due to the constant transmission of para-axial forces to the alveolar bone [28]. The highest stress levels have been observed in patients with bruxism, where occlusal stress can reach values of up to 1000 N. Due to the dynamic, unpredictable, and variable nature of mastication, accurately assessing actual stress levels remains a major challenge in biomechanical analysis.