This provides not only the perfect bonding contact, but also enforces the proper positioning of the power-arm on the specific spot, due to the unique complementarity between tooth and power-arm surface. This is how the individual base of the 3D printed power-arm guides itself to proper positioning, as planned in the virtual setup. The purpose of this work was also to inspire that such AM workflow is available for the designing or redesigning of any customized intraoral biomedical appliance. Moreover,  
Figure 1: Example of common prefabricated metallic power-arms with a surface for attachment to a tooth. that process can be completed upon the combination of technical and clinical research, as evidenced in Scheme 1. The power-arm is not an essential feature of every orthodontic treatment. However, in difficult tooth movements, it is a crucial tool. Especially in biomechanics, where forces must be applied close to the tooth's center of resistance to avoid tooth tipping. The power-arm-enabled biomechanical approach offers a critical instrument for treatment efficiency. Figure 2 explains the importance of controlled force application in regard to the center of tooth resistance, which can result in significantly different clinical outcomes. The center of tooth resistance (Cr), also called the center of tooth rotation, is a virtual point around which the tooth rotates when force is applied to its crown. This point is not approachable directly, as it is usually located in two-thirds of the length of the root. Its location always differs, as it strongly depends on the level of surrounding bone, as well as the root length and shape. When force is applied to a tooth crown (above the Cr), the tooth movement is described as tipping, which is frequently undesirable. When force is applied at the level of Cr, the resulting tooth movement is described as bodily movement. This is the orthodontically preferred movement. This type of tooth movement is crucial to treatment predictability and efficiency. Our aim with this research was also to inspire new ideas for manufacturing individualized devices not just for orthodontic tooth movement. The use of mathematical modeling and simulations of material stress upon load is a useful step to improving the intraoral resiliency of any 3D printed intraoral appliance. Our clinical observation of the resiliency of AM appliances provides further information about the material's long-term behavior in hostile environments, such as in oral cavities [9]. The correction of malocclusion is performed by moving the teeth to ideal positions and inclinations. One of the main problems associated with moving teeth is that the roots  
Figure 2: Clinical difference in tooth movement after application of the same force in regard to the center of tooth rotation (Cr), resulting in tipping or bodily movement. of the teeth need to be moved together with the tooth crown. The roots are deep in the alveolar bone and are inaccessible to common orthodontic biomechanics. For this reason, it is necessary to apply gentle and continuous forces of orthodontic leverage to the roots, and these can be applied only on visible and accessible parts of the tooth--the tooth crown. To be effective in orthodontic treatment, we need effective biomechanics. To achieve effective biomechanics, we need to translate the biomechanical vector of the force as close to the center of resistance of the tooth as possible. This center of resistance of the tooth is located approximately in two thirds of the length of the root. To have this leverage, we use the so-called power-arms. These arms have a body which includes a connecting surface for connection to the surface of the tooth crown, which we call the base. The arm is blade-shaped and is also provided with a plurality of recesses in the medial or distal edges of the arm, which serve to connect the traction device--the elastics. Power-arms are not new to orthodontics [8]. The possibility to create them with AM is exciting, and the opportunity to have them fully individualized is inspiring.