## 3 Results
### Overall Displacements  
The CONVENTIONAL RPD model revealed significant displacement in the sagittal plane, particularly noticed on the bottom of the acrylic where the highest absolute values were identified. All displacement occurred in the posterior-anterior direction (towards the natural teeth) and showed the least value in the occlusal surfaces of the acrylic teeth and on the occlusal rests that seat on the premolars Figure 3, with a mean value of \(-190\pm 36\)\(\mu\)m. The same pattern was identified in the IARPD PM model. Nevertheless, comparison of the values registered for the two homologous bands reveals that the displacements in the IARPD PM occur at a scale of hundred times smaller. The mean displacement in the sagittal plane for the IARPD PM model was \(-6.30\pm 2.33\)\(\mu\)m.  
In the IARPD MO model, displacements were registered from posterior to anterior with approximation to the remaining teeth (negative values), but also from anterior to posterior, however, most elements showed no displacement (as represented in light green). The highest movement of approximation to the remaining teeth was observed in the clasps and occlusal rests whereas the opposite movement was detected in the portion of the lower border of the acrylic between the abutmen  
Figure 2: Loading conditions applied to all three models as a uniform pressure equivalent to a 240 N force along the Z direction (purely vertical), applied to a 78.5 mm\({}^{2}\) circle in the geometric center of the loading plate, designed by CAD for perfect fitting to the occlusal surfaces of the acrylic teeth. Displacement in the Z direction was mainly responsible for the displacement magnitude of the RPDs, accompanying the direction of the applied force, i.e., downwards, in the direction of the underlying soft tissues. For CONVENTIONAL and IARPD PM models there was a noticeable trend of sinking of the acrylic portion of the RPD with displacements increasing with the increase of the distance to the supports (teeth or implant). Despite the similar pattern of vertical displacement of these two models, the tissue ward movement was higher in the CONVENTIONAL RPD model and the difference between models reduced from being 250 times higher in the most anterior portion of the framework and acrylic to 40 times in the distal extreme of the two prostheses. In the IARPD MO model, on the contrary, the least vertical displacement was registered in the region of the implants and the largest displacements in the apical direction were associated with the anterior region, where the framework contacts the abutment teeth. Mean values for the three models were, respectively, \(-\)710 \(\pm\) 84 \(\upmu\)m, \(-\)14 \(\pm\) 6.4 \(\upmu\)m and \(-\)4 \(\pm\) 0.81 \(\upmu\)m. The corresponding maximum values were \(-\)900, \(-\)28.4 and \(-\)5.5 \(\upmu\)m.  
The magnitude of displacements is plotted in Figure 4. In conformity with the reported magnitudes for the horizontal and vertical displacements, the CONVENTIONAL and IARPD PM models presented similar distributions. Overall, these distributions were symmetrical and f the highest displacement taking place in the acrylic portions, increasing from mesial to the distal free end of the acrylic flange. Though also symmetrical, the IARPD MO model revealed the highest displacements in the most proximal portion of the acrylic and in the clasp assembly and indirect retainer. The lowest displacements were found in the vicinity of the implant attachment. Figure 4: Distribution of the global displacements of the elements in each of the three models: CONVENTIONAL RPD (**left**), IARPD PREMOLARS (**center**), IARPD MOLARS (**right**). Non-matching colour scales. Homologous bands of the CONVENTIONAL RPD and IARPD PM models have 100 times discrepancy in values. Figure 3: Band plot of the displacement in the Y direction for the three models analysed: CONVENTIONAL Removable partial denture (RPD) (**left**), implant-assisted removable partial denture) IARPD PM (**center**), IARPD MO (**right**). Non-matching colour scales.