Computer analyses of two active plate modifications

The aim of this study was to determine tooth movements in the upper dental arch using a simulated original model during the time of activation of two active plates modifications, symmetrically and asymmetrically cut plates. The changes of the dental arch dimensions and precise evaluation of the distribution of the forces produced by appliance were analysed by recording tooth movements. In order to register tooth movements more precisely two referral points were notched on each tooth thus creating 38 variables which defined weight and lengths of the dental arch. The symmetrically cut active plates used to obtain transversal expansion affect equally both sides and cause symmetrical movements of premolars, less of molars and canines, whereas they have no effect on incisors. The asymmetrically cut active plates used to obtain transversal expansion affect more the side of smaller active part of the plate. Movements are larger at the premolars than at molars and canines, and minimal at incisors. The results of this study confirm the data from the literature and a logical interdependence of the force and movements thus emphasising the importance of anchorage in orthodontic therapy.