## 4 Discussion  
This study compares the biomechanical behavior of stimulated mandibular advancement models. The two-osteotomy technique was applied in the FE models which were assigned as transverse isotopic models for constructed teeth, cortical bone, and cancellous bone separately. The material properties in each component of the model were different. These conditions were different from previous FE studies on mandibular advancement [9; 23; 25; 32]. This study's outcomes were measured after applying the physiological loads of masticatory muscle and bite force. Data was collected at five stages of the postoperative healing period. The minimum number of elements that provided accurate results were obtained by the convergence test. Convergence testing is essential for ensuring the accuracy and reliability of finite element simulations. It helps to verify that the numerical solution adequately represents the behavior of the system under study and provides confidence in the validity of the results obtained through FEA [33; 34]. Most of the models in FEA research must past the convergence test so the data from the analysis can be deemed reliable. The NM-Low Z model showed a lower maximum EQV on the fixation system in the second-to-eight-week post-operative stage, although this was higher than the HE model in the first week. This can be explained by the fact that the inferior support of the NM-Low Z model helps to support the mandibular segment when the distal segment is moved forward, as shown in Figure 7. Even though the highest maximum EVQ stress in both models exceeded the yield point of the titanium material, it was the point load at which it could not create the fracture in the fixation system. The clinical implications of failure of the fixation system can be shown as malocclusion occurring after surgery [35]. Both the NM-Low Z and HE models had the same stress distribution patterns, with high stress concentrating on the miniplate attached over the fracture site close to the proximal segment. This was corroborated by [PERSON] et al. [22], who discovered that the maximum stress accumulated at the miniplate's center, close to the fracture location. Also, [PERSON] et al. [23], found the maximum stress field to be located on the region of rigid fixation for Puricelli osteotomy and the Obwegeser-Dal Pont technique. Moreover, [PERSON] et al. [9], found the greatest concentration of mechanical stress to be on the areas of the screw site and upper border of the miniplate closest to the fracture site. Higher-magnitude muscular loading was delivered to the proximal segment based on the position of the anterior temporalis, medial pterygoid, and superficial masseter muscles, causing a shift in the pattern of stress distribution during the healing phase. Two weeks following surgery, a point load of stress was observed on the bicortical screw; thereafter, additional areas of stress were exhibited. Bone stress indicated the risk of a secondary fracture in the mandible. Bone stress over the yield point can lead to bone resorption and the loosening of screws [36]. Thus, the clinical outcome after surgery will show a high relapse rate and the displacements of screws in a radiograph [37]. Both models exhibited bone stress that did not exceed the yield point, yet the NM-Low Z model presented a lower maximum bone stress than the HE  
Figure 7: The inferior support of NM-Low Z model (red arrows). model. It can be mentioned that this osteotomy technique has a lower risk of secondary bone fracture. Evaluation of fracture site stability can be indicated by the equivalent elastic strain. Appropriate micro strains have advantages for the bone-healing process [38]. The range of 200-2000 micro strains may contain the naturally permitted initial requirements of bone healing according to [PERSON]'s law. A favorable strain environment supports osteogenic activity and good bone modeling.