Unlike treatment with conventional labial brackets, lingual orthodontics relies on constriction mechanics, since the brackets are placed behind the center of resistance of the teeth. This makes space opening for the alignment of blocked-out anterior teeth one of the major challenges of lingual treatment. Insertion and compression of an opencoil spring are difficult and technique-sensitive due to the narrow interbracket distances, even if a labially blocked-out tooth is not tied in to the archwire. A compressed archwire can produce unwanted side effects and will also have to bypass the blocked-out tooth, thereby increasing treatment time.
An alternative to these methods, the bi-helix opening spring, is an inexpensive, custom-made auxiliary that is easily “clipped” into place after bonding and engagement of the blocked-out tooth, without removal of the archwire. Because alignment and space opening are performed simultaneously, treatment time is reduced. The spring can be attached to single or multiple teeth in either
arch, and it has shown virtually no side effects….
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