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.
