Abstract
Abstract Objectives: To compare the effectiveness of Hawley and vacuum-formed retainer (VFR) usage protocols on post-treatment stability. Methods: The inclusion criteria included patients who initially presented with mild or moderate pretreatment crowding and a Class I or Class II malocclusion. The retention protocols were defined as Group 1: Hawley retainers, 12 months full-time wear; Group 2: Hawley retainers, six months full-time, six months night-only wear; Group 3: VFR, 12 months full-time wear; Group 4: VFR, six months full-time, six months night-only wear. Study models were taken prior to treatment (T0), after debonding (T1), six months after debonding (T2), and 12 months after debonding (T3). Little’s irregularity index, intercanine and intermolar widths, arch length, overjet and overbite were measured. Repeated measure ANOVA with one-fixed factor, one-way ANOVA, Kruskal Wallis or Welch’s heteroscedastic F-test, were applied. Results: Fifty-eight patients were analysed at T2, and 52 patients at T3. There was no significant difference between the effectiveness of a Hawley appliance or VFRs on arch stability after six months. The intercanine width changes from the sixth to 12th month of retention showed a significant difference (p = 0.016) between Group 2 (-0.38 ± 0.58 mm) and Group 3 (0.39 ± 0.94 mm). Conclusions: Different wearing regimens of a Hawley appliance or VFR retainers did not reveal any difference determined by Little’s irregularity index. Full-time usage of VFRs provided better intercanine width retention than night-only Hawley retainer wear in the maxillary arch.
Highlights
IntroductionBeyond establishing an ideal occlusion and aesthetics through treatment, is the maintenance of achieved corrections
An orthodontic challenge, beyond establishing an ideal occlusion and aesthetics through treatment, is the maintenance of achieved corrections
The inclusion criteria for the subjects were: (1) mild or moderate initial crowding, (2) a Class I or Class II malocclusion according to the ANB angle and molar relationship, (3) treated only with fixed appliances, (4) non-extraction treatment, (5) no missing teeth, (6) no syndromes, (7) older than 14 years of age, (8) compliance with the retention protocol prescribed by the orthodontist
Summary
Beyond establishing an ideal occlusion and aesthetics through treatment, is the maintenance of achieved corrections. A broad range of different protocols has been recommended for retention and, in a recent systematic review,[1] it was concluded that there is not enough high-quality evidence to recommend a single specific retention approach. Either fixed or removable appliances are possible alternatives during the post-treatment retention phase. The advantages of removable retainers can be listed as the easier maintenance of oral hygiene by removing the appliance during tooth cleaning,. Joondeph et al.[11] described retention as a 12-month healing phase, in which the newly completed tooth movements are stabilised. The usage protocol of retention appliances during this ‘healing period’ is a matter for debate.
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