Jee JH, Ahn HW, Seo KW, Kim SH, Kook YA, Chung KR, Nelson G

En-masse retraction with a preformed nickel-titanium and stainless steel archwire assembly and temporary skeletal anchorage devices without posterior bonding.

- Korean J Orthod 2014;44:236-245

It is always an enjoyable experience to read a well-designed scientific article that has not lost a touch with our daily clinical realities. By leaving posterior dentitions minimally disrupted when they are in good occlusal relationship, one can easily see the merits of the proposed approach. I want to thank the authors for both interesting and practical information which can be readily translated into an orthodontic practice.

Q1. One of the challenges in clinical orthodontics is to maintain congruent arch forms between the upper and the lower throughout the treatment. Given the amount of extraction space to be closed and the design of the preformed C-wires, which include a nickel-titanium (NiTi) wire component, it may be difficult to maintain the coordinated archforms during retraction. What clinical procedures would the authors recommend in order to minimize the amount of deviation of the canines, which may result in positional discrepancies between the second premolars and the canines at the conclusion of space closure?

Q2. Both the Figure 9B and the Table 1 (SN-U1 of about 95° at T1 in both Conventional and Preformed C-wire groups) seem to present a rather under-torqued maxillary incisor position at the end of retraction. Would it be described as the intended results according to the authors' preference? If not, was it recovered during the short period of fixed appliance therapy following the extraction space closure? Besides changing the vectors of retraction force by adjusting the height of the retraction hooks, what do the authors recommend to improve the anterior torque control?

Q3. The authors reported that the total retraction time was reduced by 3.2 months from the conventional to the preformed C-wire group. This fact was later explained that it could be attributed to simultaneous distalization of the maxillary canines along the NiTi archwires in the preformed C-wire group only. However, it was not clear in the article how the retraction period was defined and also whether the reported time difference in space closure was for the maxillary arch only, or for both the maxillary and mandibular arches.Obviously, if it is for the latter, it would make it even more impressive results since there was no reason why one group should do better than the other in the mandibular arch as it was treated with the same biomechanics for the both groups. The authors' comments would be appreciated.

Application of a gable bend adds additional torque control over the maxillary anterior teeth.