EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
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study occurred during the active phase of treatment, the results suggest that if<br />
relapse does occur, it is most likely to occur soon after treatment and can be<br />
expected to diminish thereafter. Long-term postorthodontic changes were<br />
interpreted as a combination of orthodontic relapse and normal growth and<br />
aging processes.<br />
At the University of Washington, Little, Riedel, and Årtun (1988)<br />
evaluated 31 four-premolar extraction cases from a previous study (Little,<br />
Wallen, and Riedel 1981) at a minimum of 20 years posttreatment. Variables<br />
such as Angle’s classification, patient age at the beginning of treatment, sex,<br />
overbite, overjet, arch width, arch length were analyzed at each examination.<br />
The studies evaluated mandibular anterior alignment. The secondary goal was<br />
to describe treatment and posttreatment changes and search for predictors and<br />
associations of stability. Results indicated that crowding continued to increase<br />
during the 10- to 20-year postretention phase. The authors concluded that,<br />
“Cases responded in a diverse unpredictable manner with no apparent<br />
predictors of future success when considering pretreatment records or the<br />
treated results” (p 423).<br />
Severity of Pretreatment Malocclusion and Posttreatment Stability<br />
Physiologic recovery has been described as, “The type of posttreatment<br />
changes that represent a rebound or reversion toward the original malocclusion”<br />
(Horowitz and Hixon 1969, p 4). Example of changes include: rotations, lower<br />
anterior crowding, collapse following arch expansion, molar relationship<br />
changes, and recurrence of overbite (or open-bite) and overjet. It could be<br />
assumed that cases who demonstrate an increased severity of pretreatment<br />
malocclusion will also exhibit a greater degree of posttreatment relapse.<br />
A recent study at the University of Washington involving 86 patients was<br />
undertaken to identify factors associated with stability (Ormiston et al. 2005).<br />
The sample was divided into 2 groups according to whether their treatment<br />
results were deemed stable or unstable based on the PAR index and irregularity<br />
index. The authors found the initial severity of malocclusion to be negatively<br />
correlated with posttreatment stability. They concluded that patients with more<br />
severe index scores before treatment tended to be less stable.<br />
Incisors that are labially inclined prior to treatment tend to exhibit less<br />
long-term crowding (Sanin and Savara 1973; Gilmore and Little 1984). Class II,<br />
division 1 malocclusions have been reported to exhibit around twice as much<br />
relapse in overbite correction as Class II, division 2 malocclusions according to<br />
Bresonis and Grewe (1974), who analyzed 53 orthodontically treated cases at 5<br />
25