Adult orthodontic therapy often requires the treatment of cases with scarce cancellous bone and/or roots too close to the cortical plate. In an attempt to recover maxillary and mandibular shape and to improve smile aesthetics, some orthodontic procedures create expansions which place teeth in extreme locations outside the cancellous bone and even in the cortical bone plate. This leads to tooth instability, supporting tissue damage, fenestrations and bone defects. When a diagnosis is achieved using CBCT, it is possible to assess the amount and quality of bone and the location of teeth in the alveolar ridge. Use of aligners permits the movement of individual teeth with minimal reactive movement of the adjacent teeth. With a careful diagnosis and by applying detailed biomechanics, it is possible to place each tooth in a correct and stable location within the alveolar bone.