A study on improving tongue functions of open-bite children at the mixed dentition period--modifications of a removable habit-breaker appliance and their sonographic analysis

Abstract

In open-bite cases at developing dental stages, oral morphologies have been thought to have a close relationship to tongue movement. The aim of this study was to design a new type of removable habit-breaker, and to examine its effects on tongue movement compared with the conventional habit-breaker. The examinees in the mixed dentition period, who had anterior open bite with tongue thrust, consisted of two groups: 10 children who had been treated with conventional habit-breakers with tongue cribs (the upper group), and 10 children treated with the modified habit-breakers (the lower group). And 10 children with normal occlusion of the same age were added, as a control group. The tongue movements during swallowing, with and without the appliances, were analyzed twice: at the start of, and 6 months after, application of the appliances, by sonography. The results were as follows. 1. The design of a habit-breaker was decided according to the results of a preliminary experiment. The appliance had not only a resin-fence but also a tongue-lifting guide. 2. The upper group showed significant changes in the movement only at the lateral margin of the tongue after 6 months, with and without the appliance. 3. The lower group, however, showed significant changes in the movement at the wider area of the tongue, including the central groove formation, just after applying the appliance, and after 6 months, with and without the appliance. 4. The present results indicated that the modified appliance was more effective in improving tongue function than the conventional habit-breaker.