The effects of third-order torque and self - Saint Louis University

ecently such brackets have had limited sales. The design
of orthodontic products specifically aimed at minimizing
friction has resulted in the reintroduction of self-
ligating bracket systems to mainstream orthodontics. Since
the introduction of the Damon 2 (Ormco Corporation,
Glendora, CA) and the In-Ovation (GAC International,
Bohemia, NY) brackets in 2000, the use of self-ligating
systems in orthodontic practices has become more common. 63
Most major orthodontic vendors now offer a self-ligating
system in addition to traditional, open-slot, bracket
designs. These newer brackets are claimed to reduce
friction, contribute to improved hygiene, lessen anchorage
loss, and shorten chair- as well as treatment-time. 55,63-66
Several studies have reported that self-ligating brackets
contribute to lessened sliding-friction potential compared
to that from traditionally tied brackets. 9,48,55,57,67-70
Since the recent gain in popularity of self-ligation,
several new designs have become commercially available to
the orthodontist. In general, these brackets fall into one
of two categories based on the design of the slot-closure
(Table 2-1). An “active” clip is a resilient spring-clip
that snaps closed and reduces the depth of the slot to
approximately 0.018 inches. Because this clip can store
energy when it is activated by a lingual malalignment, a
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