Orthodontics in Adults: Complex Movements, Pre-Prosthetic Preparation and Multidisciplinary Coordination

Orthodontic treatment in adults has grown exponentially over the last twenty years, driven by the spread of clear aligners lowering the aesthetic barrier to access, increased life expectancy resulting in a longer prosthetic maintenance phase, and growing awareness that many complex prosthetic problems can be solved more predictably and biologically correctly through orthodontic preparation. Unlike treatment in growing patients — where the main goal is correcting malocclusion within remaining growth — orthodontic treatment in adults is frequently partial, aimed at creating optimal conditions for prosthetic or implant restorations, following a "backward planning" logic starting from the desired prosthetic outcome toward the necessary orthodontic movement.

Uprighting tilted molars — straightening a molar that has tilted mesially after loss of the adjacent premolar or second premolar — is one of the most common movements in pre-implant orthodontics. The tilted molar reduces the mesial interradicular space available for implant placement and shows coronal tipping that compromises occlusion and load distribution. Uprighting can be performed with a partial fixed appliance (a second or third molar as distal anchorage, a beta-titanium uprighting spring or an activated rectangular-section wire), with clear aligners (effective for tilts <20° with adequate staging), or with a TAD mesial to the molar allowing uprighting force without depending on dental anchorage. Uprighting of 2-4 mm typically creates the additional interradicular space needed for safe implant placement and improves bone contour for pre-implant regeneration.

Intruding extruded teeth — typically the tooth opposing a missing element that has migrated vertically due to lack of occlusal contact — is another common indication in pre-prosthetic adult orthodontics. The extruded tooth reduces the vertical space available for the opposing implant restoration, and reducing it is necessary before or alongside implant treatment to allow correct implant placement at the edentulous site. Intrusion in adult teeth — without the pediatric patient's bone growth vitality — is biologically slower and less predictable than in children, with intrusion rates of 0.5-0.8 mm/month using forces of 15-25 gf. The risk of root resorption is greater in intrusion than in other movements (especially with blunt or short roots), requiring periapical radiographic monitoring every 3 months. After reaching the desired position, stabilization with a fixed retainer is mandatory to prevent the tooth re-erupting under lower occlusal load.

Orthodontic closure of edentulous spaces — an alternative to implantology for spaces of 7-9 mm in a single arch — is an underused option in adults, mainly considered in younger patients (<30 years) where bone and periodontal tissue respond favorably to closure and adjacent teeth are free of restorations. The biological rationale for space closure relies on mesializing the second molar toward the extracted first molar's site: the second molar in the first molar's position restores occlusal support without a foreign body, with long-term stability results comparable to implantology at >10 year follow-up. The main limitations of space closure in adults are: the difficulty of bodily mesial movement of the second molar in D2 bone (requiring high forces, long times, risk of anterior anchorage loss), possible vertical alveolar bone loss at the closure site, and the need to re-prepare the second molar prosthetically to adapt it to the first molar's anatomy (a different emergence profile).

Multidisciplinary coordination in complex adult orthodontics — with a prosthodontist, periodontist, implant specialist, and sometimes an orthognathic surgeon — requires structured communication going beyond simple "consultation". The ideal multidisciplinary treatment plan is developed in a team meeting before starting any treatment, defining: the final prosthetic goal (position, shape and size of the definitive restorations), the orthodontic movements needed to achieve it (space required, implant parallelism, intrusion), the timing of each phase (pre-implant orthodontics → implant surgery → healing → orthodontic finishing → definitive prosthesis), and the criteria for assessing each phase's completion before proceeding to the next. Communicating this integrated plan to the patient — with realistic timelines, aggregate costs, and each professional's responsibility — is the basis for genuine informed consent and expectation management.

Clear aligners in pre-prosthetic adult orthodontics have shown documented effectiveness for uprighting tilted molars <20°, intruding extruded teeth <3 mm, and creating implant space <2 mm per side. Their limitations in this specific context — less root torque control for molars, lower effectiveness in bodily movement, absolute dependence on compliance — must be weighed case by case against the advantages of invisibility and comfort that increase adult patient willingness to undergo treatment. The digital aligner planning workflow — with the ability to visualize the movement plan in 3D, discuss it with the patient, and modify it before production — is particularly useful in this context for multidisciplinary communication and for documenting the rationale behind the planned movements.