Fig. 1

Schematic diagram of the sliding and loop mechanics. Schematic diagram of the loop and sliding mechanics. A the anterior teeth were retracted with a closing loop bent between the lateral and canine on a 0.019 × 0.025-in stainless steel arch wire with excessive Spee curve only for the maxillary arch. B sliding mechanics, the anterior teeth were retracted with a power chain from a hook fixed between the lateral and canine on a 0.018 × 0.025-in stainless steel arch wire with excessive Spee curve only for the maxillary arch