[Changes in clinical crown length during multiband treatment].

The clinical crown lengths of the incisors and first molars of 50 adolescents were measured on dental casts prior to and five to seven months following end of treatment and the differences were recorded. The patients were treated with fixed appliances for an average of 23 months. In addition, initial crown lengths were compared to those of ten children who were four years younger on average. Treatment time and objectives were recorded. Statistically significant differences were determined by means of the t-test. In order to test for correlations between treatment objectives, duration of treatment and change in clinical crown length, correlation analysis was used. The results were: clinical crown length increases physiologically from ten to 14 years of age by about 0.175 mm per year. During fixed appliance therapy in adolescents, the clinical crown length increases. This is accelerated when employing extrusive mechanics, whereas intrusive mechanics reduce this tendency. There is no evidence to suggest that the process is accelerated by the type of appliance.