[Problems and risks in the movement of the mandibular anterior teeth]

The key role of the lower anterior incisors as well as the complicated anatomical relationship of this area play a significant part in orthodontic treatment planning. Three fundamental points of view are selected here for discussion: 1. the variability and clinical relevance of the initial periodontal findings, 2. the importance of the symphysis to sagittal and vertical tooth movement, and, 3. the specific problem associated with periodontal bone loss. The few clinical and experimental studies found in the literature indicate that every anterior tooth movement has to be oriented according to the structure and facio-lingual width of the alveolar bone and that movement should progress in a controlled fashion. Rapid tipping tooth movements are to be avoided so as to minimize the risk of bone dehiscences and root resorption. Orthodontic tooth movement should be avoided when the initial findings show a narrow symphysis or questionable labiolingual bone coverage. Pre-orthodontic thin gingiva and alveolar mucosa can be an indication for a mucosal graft aimed at preventing subsequent bone and gingival dehiscences. In the future, systematic 3-D CT analysis of pre-orthodontic and post-orthodontic findings will contribute to a better estimation of the case specific potential of compensatory bone apposition.