In just 1 hour once a month, Crest 3D White Monthly Whitening Boost Whitestrips will keep your smile brilliantly white. These strips provide the boost you need to keep your smile white all year long. www.crest.com. For a monthly boost to your white smile and touch-ups between teeth whitening treatments. Use once a month for 1 hour. Uses the same enamel-safe teeth whitening ingredients dentists use.; A comfortable at home teeth whitening experience. Advanced Seal Technology’s no slip grip stays put so you can talk and drink water while whitening teeth.; 12 teeth whitening strip treatments, each with 1 upper and 1 lower strip.