EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

this device enhances stability, it is unlikely that every participating specialist was
equally convinced of its efficacy or in what cases it would be most effective.
Additionally, there would seem to be a patient component in the decision: Some
people would be more concerned about preserving their treatment, while others
would be less enthusiastic about dealing with the added efforts to keep the
gingiva healthy around the retaining wire.
Discussion Topics
There are four topics to be addressed here. First, previous research of
similar scope will be acknowledged and discussed in reference to present
findings. Second, possible explanations for the greater stability found in the
present study will be offered. Third, variables that were found to be predictive
of the use of fixed retainers are distinguished. Lastly, the clinical relevancy of the
present study will be reviewed.
Previous Research and Present Findings
Previous long-term retention studies are conflicting. Shah (2003)
reviewed 29 studies dealing with mandibular incisor stability in an effort to
collate current evidence relating to relapse. A wide range was reported between
the various studies regarding postretention periods, sample size, inclusion
criteria, and amount of relapse. Those studies most closely resembling the
present study are reviewed here.
The results of the present study differ from those out of the University of
Washington by Little et al. (1981, 1988). In summary, these two University of
Washington studies showed (a) general relapse of 25% or greater, (b) the success
rate of maintaining satisfactory mandibular incisor alignment (irregularity index
of less than 3.5 mm) over a prolonged period of time was less than 30%, (c) no
significant pretreatment predictors of relapse, (d) relapse is unpredictable, (e)
arch width decreased following retention, and (f) lifetime retention is
recommended as the only practical safeguard. In the present study, the mean
postretention relapse for both retention groups (2.2 mm), as determined by
Little’s irregularity index was less than reported by Little et al. (1981, 1988),
which were 2.9 mm and 3.6 mm, respectively. Overall success of cases in the
present study, as measured by Little’s published acceptable irregularity index of
less than 3.5 mm (Little 1975) was 121/166 or 73%, which contrasts previously
reported acceptable incidences of 30% (Little et al. 1981) and 10% (Little et al.
1988). However, in comparison to the University of Washington studies, we
found that arch width (as measured by intermolar width and intercanine width)
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