A study of force application, amount of retarding force, and bracket width in sliding mechanics

Abstract We investigated the relationship of the retraction force to the location of force application, retarding force and bracket width during simulated sliding tooth movement along an arch wire. Point 1 for retraction was located at the center of the bracket, and points 2 and 3 were at 4.0 mm and 6.0 mm from the bracket slot, respectively. Weights of 100 gm, 200 gm, and 400 gm were suspended at 9.0 mm from the bracket slot as the point of simulated center of resistance. Stainless steel standard edgewise wide, medium, and narrow twin brackets were engaged with two elastomeric ligatures on a stainless steel wire (0.016 × 0.016 inch). The bracket was retracted at the rate of 0.1 mm per second for a distance of 2.0 mm. Measurements were repeated six times, and the results were compared with multiple ANOVA tests. For all brackets, with an increase of the retarding weight, the mean retraction force at points 1 and 2 increased but decreased at point 3. The mean retraction force at point 1 for the narrow twin bracket was significantly p p M J O RTHOD D ENTOFAC O RTHOP 1996;109:50-6.)