For effective movement in orthodontic treatment, the anchorage unit should be:

In orthodontics, the concept of anchorage is crucial for the effective movement of teeth. The anchorage unit serves as a stable foundation against which movement occurs. When considering the dynamics of tooth movement, a larger anchorage unit is beneficial because it can resist the forces applied to the active unit (the teeth that are being moved).

Having a larger anchorage unit provides greater resistance to unwanted movements and allows for more controlled and precise movements of the teeth being treated. This stability is essential because, during the application of forces, the active unit tends to move in response to these forces. If the anchorage unit is larger, it can absorb and counteract some of this movement, ensuring that the desired outcomes of the orthodontic treatment can be achieved effectively.

In contrast, if the anchorage unit were smaller or equal in size to the active unit, it would be less effective in maintaining the necessary stability during treatment, potentially leading to undesirable movements or complications. Additionally, while patient comfort is important, it is secondary to the principles of biomechanics that govern tooth movement. Thus, the emphasis on the size of the anchorage unit relative to the active unit underscores the foundational mechanics of effective orthodontic treatment.