# Experimental & FEM Analysis of Orthodontic Mini-Inplant Design on Primary Stability
## 3 Results  
The pull-out simulation is performed by applying concentrated force with 5 N increments. The maximum pull-out forces that could be applied on the implant-bone system, along with the maximum Von Mises stresses and displacements, for both implant types are shown in Table 3.  
Based on data from Table 3, it can be established that the Tomas(r)-pin can manage a greater pull-out force. Although Perfect Anchor manages lower pull-out forces on the contact zone between the implant and cortical bone, greater stresses are developed. This phenomenon is attributed to the impact of mini-implant geometry, and it can be explained by the fact that Tomas(r)-pin has greater thread core diameters and conicity regarding the Perfect Anchor. Each force increment gives information about the pull-out force-displacement ratio for certain load conditions. This way, pull-out test diagram is created, by which experimental results are verified. As in the case of experimental pull-out test diagram, linearity between the force increment and displacement level of mini-implant is noticed. Figure 7a shows Von Mises stresses generated on the cortical bone for the system with Tomas(r)-pin. The maximum stress on the cortical bone amounts to 495.719 MPa. Additionally, the uniform distribution of greater stresses is noticed around the mini-implant insertion zone. Figure 7b shows Von Mises stresses generated on the cortical bone for the system with Perfect Anchor. The maximum stress on the cortical bone amounts to 585.625 MPa. Unlike the system with Tomas(r)-pin, there is no uniform stress distribution. In addition, this system generates bigger stress, and it only occurs in a specific zone, while the rest of mini-implant insertion zone is less loaded than in the previous case. \begin{table}
\begin{tabular}{c c c} \hline
**Implant Type** & **Tomas®-pin** & **Perfect Anchor** \\ \hline Maximum concentrated force [N] & 216.9 & 163.1 \\ \hline Maximum Von Mises stress [MPa] & 495.719 & 585.625 \\ \hline Maximum displacement [mm] & 1.806 & 1.540 \\ \hline \end{tabular}
\end{table} 
Table 3: Analysis Results. Figure 8a shows Von Mises stresses generated on the Tomas(r)-pin mini-implant. The maximum stress occurs on implant tread coil and amounts to 998.556 MPa, which exceeds the yield strength of 880 MPa for Ti6 Al4V material. The high-stress value on the thread coil is developed due to the high-stress concentration caused by the tiny and sharp thread coil. Figure 8 (top-right) shows a cross-section of the most stressed implant zone with the effects on the surrounding cortical bone. The nearby cortical bone cross-section has a maximum stress of 452.945 MPa, which means that the maximum cortical bone stress does not occur in the same location as the highest stress on mini-implant thread coil. Figure 8c shows Von Mises stresses generated on the Perfect Anchor mini-implant. The maximum stress occurs on the implant tread coil and amounts to 1129.84 MPa, which exceeds the yield strength of 880 MPa for Ti6 Al4V material. Same as in previous case, this is caused due to the high-stress concentration. Figure 8a,b shows a cross-section of the most stressed implant zone with the effects on the surrounding cortical bone. The nearby cortical bone cross-section has a maximum stress of 417.862 MPa, which means that the maximum cortical bone stress does not occur in the same location as the highest stress on the mini-implant thread coil. Figure 7: Von Mises stress generated on the cortical bone (**a**): Thomas®-pin and (**b**): Perfect Anchor. Figure 9 shows the maximum displacements for the implant-bone system with finite elements meshes for Tomas(r)-pin (Figure 9a) and Perfect Anchor (Figure 9b). Figure 10 shows a comparative pull-out diagram of Tomas(r)-pin and Perfect Anchor mini-implants along with the values obtained with FEM analysis.