Torque and vertical control of maxillary incisors for an esthetic smile using TSADs implanted in various areas: Biomechanical considerations

Abstract

Esthetic smiles are an increasingly important focus of orthodontic treatment. Factors related to maxillary incisors, such as smile arc, maxillary gingival exposure, and maxillary crown torque, are related to esthetic smiles. It is very important to consider these factors during orthodontic treatment. However, with conventional orthodontic treatment using traditional anchorage, torque and vertical control of maxillary incisors, which are closely related to esthetic smile, were significant challenges, but with the introduction of temporary skeletal anchorage devices (TSADs), control of maxillary incisors has become easier to accomplish along with premolar extractions. Importantly, the various clinical applications and biomechanics of TSADs must be understood because of the variety of sites where the TSADs can be implanted. In general, the torque and vertical position of the maxillary incisors can be controlled by adjusting the line of action of force by changing the length of the lever arm and the vertical position of the TSADs. In this article, we classify TSADs for esthetic control of the maxillary incisors into anterior labial TSADs, posterior buccal TSADs, and palatal TSADs according to the implant sites, presenting various cases and discussing the biomechanics associated with them. Esthetic smiles are an increasingly important focus of orthodontic treatment. Factors related to maxillary incisors, such as smile arc, maxillary gingival exposure, and maxillary crown torque, are related to esthetic smiles. It is very important to consider these factors during orthodontic treatment. However, with conventional orthodontic treatment using traditional anchorage, torque and vertical control of maxillary incisors, which are closely related to esthetic smile, were significant challenges, but with the introduction of temporary skeletal anchorage devices (TSADs), control of maxillary incisors has become easier to accomplish along with premolar extractions. Importantly, the various clinical applications and biomechanics of TSADs must be understood because of the variety of sites where the TSADs can be implanted. In general, the torque and vertical position of the maxillary incisors can be controlled by adjusting the line of action of force by changing the length of the lever arm and the vertical position of the TSADs. In this article, we classify TSADs for esthetic control of the maxillary incisors into anterior labial TSADs, posterior buccal TSADs, and palatal TSADs according to the implant sites, presenting various cases and discussing the biomechanics associated with them.