[Retention and relapse. Review of the literature].

The retention after orthodontic intervention is just as important part of the therapy as the activ treatment. It is difficult to find statistical data about the frequency and the average degree of the relapse, but some restitution in lower denture is observable in the 70-90% of the cases, in the postretention period. The upper jaw is also frequently touched, but the prevalence and the rate is milder. The authors of this article tried to collect all the factors which are responsible for the orthodontic relapse and to determine the rules should be kept by the planning and the management of the therapy. The age and the maturity of the patients, the result of the orthodontic intervention, the origin and the character of the anomaly, the type of the retainer, the compliance of the patients; all can influence the chance of the relapse. There are some anomalies which more frequently relapse, contrarily some orthodontic irregularities have quite good long-term prognosis. In the first 6 month after the orthodontic treatment any kind of retainer has to be worn nearly 24 hours/day, later 12-14 hours daily wear seems to be satisfactory. The retention period should be twice longer than the activ orthodontic treatment, posteriorly the appliance can be left gradually. Certainly the length of the retention depends on compliance of the patients. Among the retention appliances the fixed retainers are suggested in the lower front area, because the lower incisors are most frequently relapsed.