A NEW CONCEPT - IMPULSE IN ORTHODONTICS

One of the important uses of extraoral appliances is to counterbalance force systems placed on the reactive, anchor teeth by intraoral appli ances such as space closure springs. Extraoral appliances are often wo rn less than full time, whereas intraoral springs act full time. Anecd otal evidence indicates that sufficient part-time extraoral appliance wear with appropriate force level is sufficient to balance intraoral a ppliance activity while preserving anchorage. A rational explanation i s presented to substantiate this clinical evidence through equating ex traoral impulse (force x time and/or moment x time) to the impulse con veyed to the teeth by intraoral appliance. By adjusting force and/or m oment magnitude in combination with the correct time of application, t he clinician can achieve appropriate energy levels for anchorage in th ree dimensions.