Which one of the following actions is usually achieved with the use of a fixed orthodontic appliance rather than a removable orthodontic appliance?

The use of fixed orthodontic appliances is particularly effective for actions like derotation of teeth because they provide continuous, controlled forces that can effectively alter the positions and alignments of the teeth over a prolonged period. Fixed appliances are bonded to the teeth and remain in place until the orthodontic treatment is complete, allowing for precise adjustments and effective torque control. This means that the orthodontist can specifically target the rotational movement of teeth, which is crucial for correcting rotations that can arise from misalignment.

While removable orthodontic appliances can address various orthodontic issues, they are often less precise and less effective for intricate adjustments like derotation. Removable appliances require patient compliance to wear them the recommended number of hours per day, and they may not apply the same level of consistent force as fixed appliances, making them less suitable for certain complex movements.

In contrast, while some of the other options like correction of crossbite, reduction of overbite, and reduction of overjet can be managed by both fixed and removable appliances, fixed appliances typically offer more effectiveness and reliability for derotation, particularly when multiple teeth need to be adjusted simultaneously. Thus, fixed appliances become the preferred choice in such scenarios, ensuring thorough and reliable alignment corrections.