In front of the maxillary lateral incisor agenesis (MLIA), the therapeutic options are multiple. Opening or closure of the space, extraction of the sometimes peg-shaped contra-lateral incisor, removable temporary prosthesis, Maryland bridge, bonded cantilever bridge, conventional bridge, implant. MLIA diagnosis is made early by radiographic examination and, from the beginning of the orthodontic phase, it is important to know if the implant solution can be performed. The implant feasibility must meet certain conditions concerning: the bone corridor: height and thickness of the bone, the width of the mesiodistal space and parallelism of the roots of the two adjacent teeth. However, in 60 to 85% of cases, it is necessary to reconstruct the bone and/or gingival structures beforehand. A lingual treatment of a bilateral MLIA illustrates this thinking. The cost/benefit/ safety ratio, but also the age at which the orthodontic treatment is performed, can help to choose the most suitable and most durable solution. Several studies, carried out on the maxillary anterior area, specify what can be the evolution of an implant, 15 to 20 years after its installation, and the results are quite disappointing.