If the upper teeth are too short to show the upper teeth when you smile, you can have your front teeth straightened by elongating them, or if it is a severe deep overjet, you need to open the bite. 1. Short upper teeth: the upper teeth are too short, resulting in the inability to reveal the upper teeth when smiling. An orthodontic appliance can be worn to elongate the front teeth by depressing the back teeth and improve the curvature of the front teeth by aligning the teeth through orthodontics, so as to improve the situation of not revealing the upper teeth when smiling. 2. Severe deep overjet: orthodontic appliances are needed to improve the situation of not showing upper teeth when smiling by elevating the back teeth to depress the front teeth and adjusting the lip inclination of the front teeth, improving the positional relationship of the front teeth, and adjusting the curvature of the fitting curve through orthodontics. The correction of not showing upper teeth when smiling should seek medical treatment in time, and the doctor will know the line to conduct detailed measurements and examination, and develop a comprehensive orthodontic program to avoid delaying the condition.