For this problem, first of all, we need to recognize what the yellow stains on teeth are, in order to take the appropriate approach, as follows: First, if the yellow stains on teeth refer to soft tartar, plaque, calculus, etc., you need to remove the plaque, calculus, food debris and other local stimuli through the method of full mouth cleaning, ultrasonic cleaning, the yellow stains on teeth can be removed, and teeth can restore their original color. Second, if the yellow color on the teeth is due to some yellowing of the teeth themselves, or yellowing of the teeth caused by diseases such as fluorosis and tetracycline teeth, the yellow stains on the teeth need to be removed by methods such as teeth whitening or veneer restoration, in order to make the color of the teeth whiter.