Pre-prosthetic orthodontics represents a common and useful approach to recreating proper tooth position prior to the rehabilitation phase (implantology and fixed prosthodontics) in adult patients with partial edentulism. Correcting tooth position can not only simplify the restorative procedure, but also result in more precise restoration and, above all, provide more reliable solutions in the long term. The aligner technique makes it possible to create an exact plan of tooth position and movements on a 3D digital setup and to release the forces for the planned movements in a gentler and less biologically invasive way. With proper patient compliance, the aligner orthodontic phase can achieve all the objectives necessary to simplify the following rehabilitating phases such as widening spaces, uprighting molars and intruding overerupted molars in order to recreate ideal conditions for full prosthetic rehabilitation. Particularly when planning molar intrusion with conventional appliances, auxiliary devices such as temporary anchorage devices may be needed to simplify the anchorage. The advantage of using aligners to plan this movement is mainly due to the application of the force that comes from the occlusal surface. This biomechanical approach makes the intrusive force more reliable; the thickness of the aligners will control the reaction force and, as a result, reduce the need for temporary anchorage devices. Keywords: aligner, digital plan, pre-prosthetic orthodontics