Forces In Orthodontics

A force is defined as a push or pull exerted on an object that tends to alter its state of rest or motion. In orthodontics this force is transmitted through the bracket-archwire system to the tooth which then transmits it to the PDL and alveolar bone. The PDL acts as a viscoelastic medium that cushions and distributes the applied stress initiating a cascade of cellular reactions leading to bone remodeling.Forces are characterized by magnitude direction point of application and line of action. The magnitude determines how much stress is applied to the tooth; the direction determines the type of movement; the point of application is usually at the bracket; and the line of action defines the moment created about the center of resistance of the tooth. When the line of action passes through the center of resistance a bodily or translatory movement occurs. If it passes away from it a rotational movement occurs due to the creation of a moment.Forces in orthodontics form the foundation of controlled tooth movement. A deep understanding of biomechanics ensures efficient treatment minimal tissue damage and stable results.