[The functional treatment of deep bite--the results of a long-term study].

The amount of overbite reduction and the stability of the results three to 14.5 years post-retention were analysed in a follow-up study of 60 patients who had been treated with functional appliances. To establish therapeutic and posttherapeutic changes in dento-facial relationships, plaster casts and lateral cephalograms were evaluated at the beginning, at the end of treatment and at the follow-up examination. Posttherapeutic deepening of the overbite (> 0.8 mm) was found in 54.2% of the cases, while overbite reduction remained stable in 39%. A number of skeletal and dental factors were found to be involved in overbite reduction and posttreatment deepening. In this connection, changes in the ML-NSL angle, the ML-NL angle and the gonion angle were found to be just as important as the therapeutic and posttherapeutic changes in anterior and posterior facial height and changes in the skeletal pattern. It is emphasized that strict application of retention is of the greatest importance to minimize vertical relapse.