Not need costly whitening treatments any more, New Crest 3D White Whitestrips Professional Effects is formulated with the same enamel-safe ingredient dentists use, and gives you professional results and whitening that lasts right at home. Please read instructions carefully before using. Slight discomfort is common but in most cases it won't harm your teeth and gum. You can pause for 2~3 days before second use. If your teeth or gum are still in aches and pains, please stop using it.