What is the difference between active and passive forces in orthodontic systems?

Active forces in orthodontic systems are those that exert a direct influence to move teeth into desired positions. These forces are generated by the application of orthodontic appliances such as braces, springs, or elastics that push or pull against the teeth, prompting movement. For example, when an active force is applied to a bracket connected to a wire, it helps initiate the movement of the tooth along the archwire towards a more favorable position.

Passive forces, on the other hand, do not initiate movement; instead, they may be involved in stabilizing teeth or providing support to the active elements of the orthodontic system. These forces can result from components that resist various types of movements, such as friction between the wire and brackets or the natural tension of ligatures, without actually causing the teeth to move.

Understanding the distinction between active and passive forces is crucial for orthodontic treatment planning, as it underlies how and why certain movements occur. Active forces are essential for achieving tooth movement, while passive forces play a supportive role in maintaining stability and control during the treatment process.