Abstract: Objective: To observe the clinical effect of TOMY self-ligation appliance technique in the treatment of anterior crossbite and moderate crowding, and to explore its clinical application. Methods: A patient, manifested as anterior crossbite and moderate dentition crowing, diagnosed as Angle class Ⅲ subclass malocclusion, MaoⅡ1+Ⅰ1 malocclusion, high angle,and facial asymmetry, was selected. This patient was treated with TOMY self-ligation appliance technique without tooth extraction. The length and width of the dental arch, the width of the alveolar bone and the width of the basal arch were measured before and after treatment; the lateral radiographs of the patient were taken too. Results: After treatment,the upper and lower dentition arranged in neat rows, reached a neutral occlusal relationship;SNA, SNB and ANB had no obvious changes; the lip inclination of anterior teeth was increased by 10 degrees, and reached the normal value;the upper and lower dental arch width, alveolar bone width, basal bone arch width and dental arch length were lower than before treatment. Conclusion: For the patient with anterior crossbite and moderate dental crowding treated with non-extraction, the TOMY self-ligation technique can be considered to use, by increasing the arch width and length to improve the anterior crossbite and moderate crowding, in order to achieve the effective treatment.

Key words: TOMY self-ligation appliance technique, moderate dentition crowing, non-extraction treatment, anterior crossbite