Treatment outcome in angle class II, division 1 patients in pre-puberty and puberty after jumping-the-bite appliance

The aim of this study was to investigate whether, and if so, to what extent, skeletal and dento-alveolar developments of the stomatognathic system take a different course due to influence of Tränkmann's jumping-the-bite appliance (JTB) in pre-pubertal and pubertal patients in comparison to untreated control groups presenting the same conditions at baseline. We aim to discover whether the results are better when the device is used on prepubertal children, or those in puberty.

Two lateral cephalograms were scanned in treated children presenting Angle Class II, Division 1 malocclusion; they were scanned in untreated children with the same distoclusion at intervals between at least 11 months and at most 25 months. The same procedure was taken in children in pre-puberty (female, min. = 8.6 yrs, max. = 11 yrs; male, min. = 9 yrs, max. = 12.6 yrs) and in puberty (female, min. = 11 yrs, max. = 14 yrs; male, min. = 12.6 yrs, max. = 15 yrs). The cephalometric analysis was made with the orthodontics-PC-program Onyx Ceph (Image Instruments, Chemnitz, Germany) using a modified Bergen/Hasund analysis [7, 8].

The Angle Class II, Division 1 malocclusion of all treated patients evolved into an Angle Class I occlusion via Tränkmann's JTB design. The location of this transformation was mainly dento-alveolar in both pre-puberty and puberty. The differences between the control and JTB groups concerning the development of cephalometric values in pre-pubertal age were unremarkable if one considers the range of reading error. The exception to this was with angleUP1-NA, which increased more in the control group than in the treated group. angleSNB, arB (mm), angleANB and angleML-NSL showed greater change in the targeted direction in the control group than in the JTB group in pubertal patients. The increase in the arA length (mm) was clearly, but not statistically significantly, inhibited by the JTB in puberty. Comparing both treated groups, one can conclude that cephalometric values developed more favorably in the pre-pubertal than in the pubertal patients, with the exception of angleSNA.