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Introduction: Due to the search for more aesthetic and comfortable alternatives to perform orthodontic treatments and to the great technological development, orthodontic aligners have assumed great importance. More and more complex treatments have been carried out with these appliances without, however, having all aspects involved in their use being studied in depth. Its biomechanical planning requires different approaches than those used in fixed orthodontics, as the force systems involved in movements, responses and side effects are distinct, and the professional must be prepared when opting for the technique. Objective: The objective of this article is to perform an evaluation of the force systems created on the space closure with aligners, its characteristics, and problems, as well as make some suggestions to overcome the difficulties inherent to its use. Conclusion: Space closure with aligners is possible, but depends on the correct selection of the patient, in addition to requiring the proper planning of the applied forces. The use of auxiliary resources and overcorrections to address the deficiencies of the aligner systems should always be considered. Digital planning should be used as a map of the force systems that will be applied, and not just as a marketing tool, keeping in mind that determining the objectives and the way to achieve them is the responsibility of the orthodontist, and that treatment plans must be individualized for each situation, following appropriate biomechanical precepts.

Introduction: Iatrogenic root perforations occur in approximately 2% to 12% of cases involving inaccurate root canal access, attempt to locate canal orifices, instrumentation or reinstrumentation and bypassing or removal of fractured instruments. When these perforations are performed in the apical thirds, they may even lead to tooth loss due to the greater complexity of treatment. Objective: The aim of this paper was to report the occurrence of an iatrogenic apical root perforation during retreatment of a mandibular central incisor. Methods: Based on clinical and radiographic examinations, a mandibular right central incisor was diagnosed with pulp necrosis and asymptomatic apical periodontitis. Nonsurgical endodontic therapy was recommended. The final radiographic examination revealed poor endodontic treatment; for this reason, nonsurgical reintervention was the therapy of choice. The final radiograph showed apical perforation due to deviation near the apical limit. It was therefore decided that the case should be merely monitored. Results: Clinical and radiographic followups after 5 years showed the successful outcome of this decision. Conclusion: In clinical situations similar to what is shown in this case report, making the correct clinical decision, considering the characteristics of each case, is more important to long-term success than effective action.

Incisal embrasures play an important role in smile esthetics and influence the attractiveness perception. In general, the semi-rounded embrasure form is the most preferred. Different groups' perceptions on tooth morphology reinforce the importance of patient participation in treatment planning. (J Esthet Restor Dent 29:68-78, 2017).