By Ligia Vaida, Simona Cavalu et al.
The efficiency of both types of removable retainers was evaluated according to the following criteria:-Damage of the retainers (fractures—perforated and cracked, loss, unfitting and obvious discolorations) as a result of which the respective retainers could no longer be used, requiring restoration.-Loss of the retainer.-The rate of installation of mild or severe relapse of dento-maxillary anomalies, requiring the use of various therapeutic interventions. Copyright L. Vaida, Simona Cavalu et al.
The study we conducted shows that VFRs are less resistant than HRs, suffering much more fractures compared to HRs (p < 0.001). Mild relapses were reported in both groups without any statistical significance, being more frequently at T1 in both groups—due to inadequate wearing, damage, or loss of retainer. Mild relapses could be remediated by activating the HRs or by manufacturing the VFRs on the setup models. However, severe relapses were significantly more frequent in the HRs group (p < 0.05), especially due to improper wearing. These situations required the resumption of the active orthodontic treatment with a fixed appliance or clear aligners.Most of the patients (8 patients) with severe relapse in our study, belonging to the HRs group, initially showed severe canine abnormalities (accentuated ectopia or impactions), that suggests that HR are associated with a higher risk of relapse in patients who have been orthodontically treated for severe canine malposition. Two of the patients in the VFRs group with severe relapse initially presented canine abnormalities associated with severe dental crowding, while three patients initially presented severe protrusions. However, the thermoplastic retainer has lower resistance in time compared to the Hawley retainer. No differences between groups were found in the rates of loss of the retainers. The risk of severe relapse during the first year of the retention phase is higher when using Hawley retainers. (Copyright L. Vaida, Simona Cavalu et al.).
Full text at https://www.mdpi.com/2227-9067/7/12/295/htm