## 3 Discussion  
All three cases in this study were in their growth period, and gummy smiles caused by the overreruption of maxillary anterior teeth were observed. There have been various reports on the causes and ways of improving gummy smiles [2; 4; 5; 6; 9; 10]. However, there have been no reports on the spontaneous disappearance of gummy smiles observed during growth. Rather, it has been reported that the amount of exposure of the maxillary anterior teeth does not change during the growth process [19]. We thought, therefore, that it was unlikely that overreruption of the anterior teeth would improve spontaneously during the growth process. In addition, even if orthodontic treatment was started in childhood, it was not desirable to postpone improvement of the gummy smile complaint until the use of multi-bracket appliances. Therefore, in order to improve gummy smiles, we decided to develop a treatment plan that would lead to improvement by means of the application of orthodontic force in the direction of suppressing the eruption of maxillary anterior teeth from the growth stage. The high-pull J-hook headgear is a device that is connected to hooks attached to the anterior teeth of the arch wire of a multi-bracket device, pulling the maxillary anterior teeth  
Figure 16: Panoramic radiograph (**A**) and lateral roentgenographic cephalogram (**B**) of Case 3 at the end of the first stage of treatment. Figure 15: Facial photograph and intra-oral photograph of Case 3 at the end of the first stage of treatment. Facial photograph and enlarged photograph of the mouth at the end of the first stage of treatment (**A**); intra-oral photograph at the end of the first stage of treatment (**B**). upward. By pulling the maxillary anterior teeth upward, the maxillary anterior teeth are pushed down, and the overbite is reduced, thereby facilitating improvement of a deep overbite [20; 21; 22]. Furthermore, since it is often used in combination with a multi-bracket device, there have been no reports of the use of the high-pull J-hook headgear during the growth period. Since the three cases examined here had skeletal maxillary prognathism in the growth period, we decided to improve their skeletal characteristics in the first stage of treatment. In addition, although we considered that pressing down the maxillary anterior teeth using a multi-bracket device after the end of growth would improve the gummy smiles, we thought that the combined use of high-pull J-hook headgear with a removable appliance, would render it possible to actively improve gummy smiles at an early stage by suppressing the eruption of maxillary anterior teeth before the end of the growth period. As patients were in the mixed dentition stage, rather than using the headgear in combination with a multi-bracket device, we devised a plan to attach a loop to a part that is equivalent to the maxillary anterior teeth of a SBJA. This was then used to improve maxillary prognathism, and to use the high-pull J-hook headgear to draw the part corresponding to the maxillary anterior teeth upwards to suppress their eruption and improve the gummy smiles. In general, the effects of BJA include a decrease in the ANB angle due to maxillary growth suppression and mandibular growth promotion, as well as a change in the anteversion of the occlusal plane, clockwise rotation of the mandible, and lingual inclination of the anterior maxillary teeth [23; 24]. The common BJA effect seen in these three cases was the decrease in the ANB angle due to mandibular growth promotion. It has been reported that normally, the SNA angle increases slightly with growth [25]. The general maxillary growth suppression effect of BJA is the reduction in the SNA angle by around 0.5\({}^{\circ}\), but without a significant difference [23; 24]. Here, the SNA angle remained almost unchanged in all three cases. This may be the result of the suppression of the SNA angle, which should increase with normal growth, due to the general effect of BJA, but this is difficult to ascertain.