cuspid buttons and place brackets on the cuspids and bicuspids, band the second molars, and proceed to a full straight wire appliance (all teeth are bracketed and banded). Off-Center Bend The tip-back bend (off-center bend) in the vertical plane used to intrude incisors and extrude molars will be discussed in detail in the article concerning Key Three in Class II Correc-tion: Proper Overbite and Overjet. Another use of the off-center bend in the vertical plane is in retraction mechanics. This is demonstrated in Figure 20. In this example an off-center bend is placed mesial to the second bicuspid bracket with the bend pointed occlusally. When a power chain is placed from the second bicuspid to the cuspid, the cuspid retracts and the second bicuspid does not protract. The off-center bend places a large clockwise moment on the second bicuspid. When the power chain is placed, the protracting force it places on the second bicuspid is cancelled out by the clockwise moment tendency rotating the tooth crown to the distal. In the horizontal plane Dr. Mulligan describes four off-center bend configurations to affect maxillary first molar movement: in-bend (placed distal to the cuspid bracket) (Fig. 21), out-bend (placed distal to the cuspid bracket) (Fig. 22), toe-in bend (placed mesial to the molar bracket) (Fig 23), and the toe-out bend (placed mesial to the molar bracket) (Fig. 24). Fig. 24 Fig. 26 Fig. 27 In-Bend Figure 25 shows a clinical case I treated demonstrating the use of in-bends to lingualize the mandibular first molars that presented in buccal crossbite at the beginning of treatment. The mandibular first molars were both in buccal version at the start of treatment. The incisors and cuspids were bracketed and the molars were banded and an .020 SS archwire was placed. In-bends were placed distal to the cuspid brackets. The resultant lingual force on the mandibular first molars moved them back into the arch and out of buccal crossbite. A full appliance was then placed. Out-Bend Figures 26-28 shows a clinical case I treated demon-strating the use of out-bends to buccalize the maxillary first molars. The patient presented with a bilateral Class I molar relationship. The maxillary and mandibular arches were narrow and the dentition was crowded. The patient has an anterior open bite due to a tongue thrust (Fig. 26). Out-bends were placed distal to the maxillary lateral incisor brackets (Fig. 27). The maxillary first molars expanded to the buccal and the arch form was much improved. The anterior open bite was corrected due to the elimination of the tongue thrust (Figs. 27 and 28). Sponta-neous eruption of the un-bracketed maxillary and Fig. 25 28 Winter 2015 JAOS
Journal of the American Orthodontic Society Winter 2015: Page 28
