In the mid 1970s, Schudy and Schudy developed and described an edgewise bimetric system in which there were brackets with 0.016-inch slots on the incisors and canines and brackets with 0.022-inch slots on the premolars and molars. Modeling after Schudy and Schudy, Gianelly devised a similar, preadjusted system called the bidimensional system, in which the incisor brackets have 0.018-inch slots while the remaining teeth have brackets with 0.022-inch slots. We have further modified the bidimensional system and developed a dual-slot system. Hence, this article compares the bidimensional and dual-slot systems and provides justification for both. The main concerns regarding the bidimensional and dual-slot systems are posterior “play” and lack of three-dimensional control. We rationalize both as well as the self-ligating hybrid and dual-slot system. Orthodontics 2011;12:10–21.

Key words: bidimensional, bimetric, self-ligating, dual slot