###### Abstract  
A dental implant is currently the most commonly used treatment for patients with lost teeth. There is no biomechanical reference available to study the effect of different occlusion conditions on dental implants with different positions. Therefore, the aim of this study was to conduct a biomechanical analysis of the impact of four common occlusion conditions on the different positions of dental implants using the finite element method. We built a finite element model that included the entire mandible and implanted seven dental implant fixtures. We also applied external force to the position of muscles on the mandible of the superficial masseter, deep masseter, medial pterygoid, anterior temporalis, middle temporalis, and posterior temporalis to simulate the four clenching tasks, namely the incisal clench (INC), intercuspal position (ICP), right unilateral molar clench (RMOL), and right group function (RGF). The main indicators measured in this study were the reaction force on the temporomandibular joint (TMJ) and the fixed top end of the abutment in the dental implant system, and the stress on the mandible and dental implant systems. The results of the study showed that under the occlusion conditions of RMOL, the dental implant system (113.99 MPa) and the entire mandible (46.036 MPa) experienced significantly higher stress, and the reaction force on the fixed-top end of the abutment in the dental implant system (261.09 N) were also stronger. Under the occlusion of ICP, there was a greater reaction force (365.8 N) on the temporomandibular joint. In addition, it was found that the reaction force on the posterior region (26.968 N to 261.09 N) was not necessarily greater than that on the anterior region (28.819 N to 70.431 N). This information can help clinicians and dental implant researchers understand the impact of different chewing forces on the dental implant system at different positions after the implantation. biomechanics; dental implant; finite element analysis; occlusion conditions 1  
[PERSON], Kuo-Chi  
different structures. The most common topic of study is the biomechanical analysis of the length and diameter of the dental implant [4; 5; 6]. From a mechanical point of view, the longer the implant and the larger the diameter, the greater the contact area between the dental implant and the mandible will be, making the implant more resistant to mechanical load. However, sometimes due to the structural limitations of the patient's mandible, it is not possible to use long, thick dental implants. Moreover, some researches have also conducted a biomechanical analysis with regard to the geometric design of the flute shape, thread shape, abutment, screw, and crown of the dental implant [7; 8; 9; 10; 11; 12]. In addition, the material of the implant is also a popular research topic [13; 14]. Regarding the bone structure, there are also biomechanical studies on the bone-implant contact interface [15]. Although there are a number of studies on the design of the dental implant systems, due to the complex structure of the mandible, most studies only evaluated a single tooth and did not analyze in detail the influence of the different positions of the implant. Previous literature has pointed out that the posterior teeth bear greater occlusal forces than the anterior teeth [16], and thus the dental implant system in the posterior teeth region is more likely to be damaged [17]. Therefore, when evaluating the biomechanics of the dental implants, the impact of the different implantation positions should also be taken into account. The most common external force received by the dental implant system is the occlusal force generated by chewing. The magnitude of the bite force may be dissimilar due to the different areas of bite [18]. Most biomechanical studies of dental implant systems usually apply only a single vertical, horizontal, or oblique loading to evaluate the effect of the load after the implantation.