Commentary

One of the most disappointing aspects of carrying out, or undergoing orthodontic treatment is that the result achieved at the end of active treatment may be unstable. The tendency for teeth to return towards their pre-treatment position following orthodontic treatment is well documented.1,2 However, in some individuals, increasing malalignment of the incisor teeth continues over a period of years and decades. The cause of this is not well understood but may result from further growth, changes in the occlusion and altered pressure from the lips, cheeks and tongue.3,4 As a result, most orthodontists now recommend long-term retention. The main choice facing the clinician at the end of active treatment is whether to use a fixed retainer bonded to the lingual surfaces of the anterior teeth, or removable retainers which are under the control of the patient.

Ultimately, if the patient fails to wear the removable retainers or the fixed retainers break, or are removed, irregularity of the incisors may ensue. The patient may decide to accept the position and the possibility of further worsening malalignment, to retain the teeth in their current position or to seek re-treatment. This Cochrane review aims to investigate any evidence comparing different forms of active retreatment using a variety of appliances, and also no active treatment. Although relapse can affect both the upper and lower incisors, this review investigates interventions in the lower arch only. A conventional on-line search strategy was employed as well as a hand search of the four major orthodontic journals. Interestingly, the authors also handsearched four different Chinese journals but did not include any Scandinavian or Australian publications, for example. This may reflect the fact that the review emanated from authors who are predominantly Chinese.

Since this review seeks to compare interventions for managing relapse, it is to all intents and purposes comparing the efficacy and efficiency of different types of orthodontic tooth alignment, albeit for re-treatment. It therefore ends up essentially looking at studies which compare alignment of teeth using conventional fixed appliances (either labial or lingual) or removable appliances (either a series of active aligners or removable appliances constructed from acrylic and wire). The electronic search (following removal of duplicate publications) revealed 527 publications meeting the search criteria. However, none was found to focus on interventions to correct relapse or indeed compared interventions. No randomised clinical trials meeting the inclusion criteria were found.

The authors conclude that the experience of the orthodontist will ultimately prove to be the deciding factor in selecting the best suitable form of intervention to treat relapse.

Practice points

  • Any patient undergoing orthodontic treatment should be prepared to wear retainers long term

  • Although this study shows that there is inadequate information relating to the efficacy of different forms of therapy for retreatment, most orthodontists would prefer to use fixed appliances for significant tooth movements and may use aligners for minor re-treatments