Here’s a cheat sheet for a whiter smile. Before you use whitening products, have your teeth cleaned by your dental hygienist. Clean teeth whiten better than dirty ones because the bleach can more easily penetrate the enamel since it won’t have to work it’s way through a layer of tarter buildup. If you’ve bleached before and you feel some sensitivity, you should use a fluoride treatment before whitening to reduce sensitivity. The chemical reaction of bleaching can open up the microscopic pores of your teeth creating sensitivity in some people. Try Sensodyne ProNamel for 7 days before bleaching, or a prescription fluoride gel from your dentist for faster results. Also steer clear of acidic foods while bleaching – grapefruit, lemons, other citrus fruits and tomatoes can increase sensitivity while using bleach products.