Which of the following terms describes the teeth that are used to move an active unit during orthodontic treatment?

The term that accurately describes the teeth used to move an active unit during orthodontic treatment is "anchorage unit." This refers to the teeth or structures that provide resistance against which the active force (generated by appliances) acts. In orthodontics, the active unit typically consists of the teeth that need to be moved, while the anchorage unit consists of teeth or structures that remain stationary, providing the necessary stability for effective tooth movement.

Using the correct terminology is crucial; while the other terms refer to various components of orthodontic mechanics, they do not denote the specific role of anchoring the active unit during treatment. For instance, the passive unit generally refers to teeth that do not move and may not play a direct role in force application. Similarly, a restorative unit is associated with dental repairs and may not have relevance in a purely orthodontic context.