Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 44

When a force is acting on a single‐point contact on the ectopic tooth, i.e. there is no wire that is fully engaged into a bracket slot, such systems are defined as statically determinate [2]. The biomechanical systems that are statically determinate are simple and efficient because the forces and moments to be applied are easy to calculate, using simple measurements of appliance forces and distances [2].

In statically indeterminate systems the wire is engaged in the brackets of all teeth, including both the active and the reactive (anchor) units of the system. The extent of the forces and the moments developed in relation to the brackets are determined by the wire deflection. When the wire is inserted into two bracket slots, the force systems that are developed in the two units interact and consequently cannot be measured directly. A continuous arch can be considered as a long series of statically indeterminate systems [2].