The retention phase after placement of fixed appliances can last from 6 months to a year. In this study, 2 distinct types of retainers were evaluated for their effectiveness based on tooth rotation, overjet, overbite, and intercanine and intermolar width. The study involved 196 patients who wore a Hawley device and 201 patients who wore vacuum-formed retainers (VFR) based on standardized designs. The VFR were worn 24 hours a day during week one, removed only for eating and for brushing, then worn for 12 hours daily. The Hawley retainers were worn 24 hours a day for 3 months, and removed only for toothbrushing. After the initial 3 months, they were worn for 12 hours a day. Casts of the maxilla and mandible were evaluated at debonding and after 6 months of retention.
Differences due to retainer type were significant for those patients wearing VFR appliances, more so for the mandible than the maxilla. The changes in irregularity for the Hawley group during the 6-month period were double those for the VFR group. While the retainers were worn according to typical regimens, VFR patients showed better mandibular incisor alignment maintenance than those wearing Hawley retainers. In one study, no advantage was shown over VFR retention. VFR are easier to fabricate than Hawley appliances and may be more cost effective when considering the number of appliances per patient that are lost.
(Source: Dental Abstracts, Volume 53, Issue 5, 2008)
