EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

ABSTRACT
Instability of the occlusion is a common problem following orthodontic
treatment. The purpose of the present research was to evaluate posttreatment
relapse at long-term recall (> 10 years) in cases (A) treated with temporary fixed
mandibular retention plus Hawley retainers compared to (B) a similar group
retained with just removable retention (standard Hawley type retainers alone).
Fixed retainers were removed after having been in place for about 2.5 years.
Following this period, use of removable retention was left up to the discretion of
the patient in both groups. Data consisted of orthodontic records of 166
American whites, all of whom had received comprehensive orthodontic
treatment, collected from multiple private practice orthodontists using
conventional Edgewise mechanics. Records were analyzed at pretreatment, end
of treatment, and at long-term posttreatment recall examination (mean = 16 years
after treatment). The mandibular Incisor Irregularity index at recall averaged 1.9
mm in the fixed group and 2.5 mm in the Hawley-only group. This ½-mm
difference is marginally significant statistically (P = 0.03), but seems trivially
small clinically. A 1.0 mm change in Incisor Irregularity during treatment was
shown to be associated with 0.13 mm of relapse long term. Mandibular
intercanine width increased (mean = 1.2 mm) during treatment, but decreased by
almost the same amount by the recall examination. Maxillary and mandibular
arch widths became slightly narrower after treatment. Overbite and overjet both
increased after treatment. Results of the present study seem more stable than
those reported in most long-term studies; however, there is little clinical support
for a fixed-retention phase given the modest (½-mm) difference in Incisor
Irregularity.
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