[About retention].

The aim of temporary retention is not to eliminate every causes of relapse and to ensure the stability of treatment, but to eliminate one cause of relapse: the periodontal reactions consecutive to the orthodontic displacement of teeth. The other causes of relapse must be eliminated by the treatment itself, and not by retention. To be effective the retention must be immediate, complete and prolonged. The most used temporary retainers are: the Hawley retainer, the vacuum-retainers and the bonded retainers. None of which is perfect. Only the permanent retention can ensure the stability whatever the cause of relapse. The risks of permanent retainers are not yet well known.