After someone made cold light to whiten teeth, the effect was not ideal. Instead of whitening, it turned yellow. It may be drinking drinks such as cola and coffee. The teeth will be stained after the operation. After cold light tooth whitening surgery, doctors will generally tell you not to eat berries or other brightly colored fruits, which will affect the surgical effect. Smoking after cold light whitening surgery will make teeth yellow, because smoke contains tar, which is insoluble in water, so it will accumulate.